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De-la-Cruz IM, Oyama K, Núñez-Farfán J. The chromosome-scale genome and the genetic resistance machinery against insect herbivores of the Mexican toloache, Datura stramonium. G3 (BETHESDA, MD.) 2024; 14:jkad288. [PMID: 38113048 PMCID: PMC10849327 DOI: 10.1093/g3journal/jkad288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 09/21/2023] [Accepted: 12/11/2023] [Indexed: 12/21/2023]
Abstract
Plant resistance refers to the heritable ability of plants to reduce damage caused by natural enemies, such as herbivores and pathogens, either through constitutive or induced traits like chemical compounds or trichomes. However, the genetic architecture-the number and genome location of genes that affect plant defense and the magnitude of their effects-of plant resistance to arthropod herbivores in natural populations remains poorly understood. In this study, we aimed to unveil the genetic architecture of plant resistance to insect herbivores in the annual herb Datura stramonium (Solanaceae) through quantitative trait loci mapping. We achieved this by assembling the species' genome and constructing a linkage map using an F2 progeny transplanted into natural habitats. Furthermore, we conducted differential gene expression analysis between undamaged and damaged plants caused by the primary folivore, Lema daturaphila larvae. Our genome assembly resulted in 6,109 scaffolds distributed across 12 haploid chromosomes. A single quantitative trait loci region on chromosome 3 was associated with plant resistance, spanning 0 to 5.17 cM. The explained variance by the quantitative trait loci was 8.44%. Our findings imply that the resistance mechanisms of D. stramonium are shaped by the complex interplay of multiple genes with minor effects. Protein-protein interaction networks involving genes within the quantitative trait loci region and overexpressed genes uncovered the key role of receptor-like cytoplasmic kinases in signaling and regulating tropane alkaloids and terpenoids, which serve as powerful chemical defenses against D. stramonium herbivores. The data generated in our study constitute important resources for delving into the evolution and ecology of secondary compounds mediating plant-insect interactions.
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Affiliation(s)
- Ivan M De-la-Cruz
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
- Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Lomma, Alnarp 230 53, Sweden
| | - Ken Oyama
- Escuela Nacional de Estudios Superiores (ENES), Universidad Nacional Autónoma de México (UNAM), Campus Morelia, Morelia, Michoacán 8701, Mexico
| | - Juan Núñez-Farfán
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
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2
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Assessing Phenotypic Variability in Some Eastern European Insular Populations of the Climatic Relict Ilex aquifolium L. PLANTS 2022; 11:plants11152022. [PMID: 35956499 PMCID: PMC9370372 DOI: 10.3390/plants11152022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/21/2022] [Accepted: 07/29/2022] [Indexed: 11/17/2022]
Abstract
Through its natural or cultivated insular population distribution, Ilex aquifolium L. is a paramount species which is exceptionally suitable for studying phenotypic variability and plasticity through the assessment of morphological, physiological, biochemical and genomic features with respect to acclimation and/or adaptation efficiency. The current study is focused on four insular populations of Ilex aquifolium from Eastern Europe (i.e., in Romania, Hungary, Serbia and Bulgaria), and presents an initial evaluation of phenotypic variability in order to conclude our research on phylogenetic relationships and phytochemical profiles, including several descriptive and quantitative morphological traits. Taken together, the data from different methods in this paper indicate that the Bulgarian and Romanian populations can be distinguished from each other and from Serbian and Hungarian populations, while the latter show a higher level of resemblance with regards to their quantitative morphological traits. It is likely that these morphological traits are determined through some quantitative trait loci implicated in stress responses generated by light, temperature, soil water, soil fertility and salinity conditions that will need to be analysed in terms of their physiological, genomic and metabolomics traits in future studies.
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3
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Coughlan JM, Brown MW, Willis JH. The genetic architecture and evolution of life-history divergence among perennials in the Mimulus guttatus species complex. Proc Biol Sci 2021; 288:20210077. [PMID: 33823671 PMCID: PMC8059554 DOI: 10.1098/rspb.2021.0077] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 03/12/2021] [Indexed: 02/06/2023] Open
Abstract
Ecological divergence is a fundamental source of phenotypic diversity between closely related species, yet the genetic architecture of most ecologically relevant traits is poorly understood. Differences in elevation can impose substantial divergent selection on both complex, correlated suites of traits (such as life-history), as well as novel adaptations. We use the Mimulus guttatus species complex to assess if the divergence in elevation is accompanied by trait divergence in a group of closely related perennials and determine the genetic architecture of this divergence. We find that divergence in elevation is associated with differences in life-history, as well as a unique trait, the production of rhizomes. The divergence between two perennials is largely explained by few mid-to-large effect quantitative trait loci (QTLs). However, the presence of QTLs with correlated, but opposing effects on multiple traits leads to some hybrids with transgressive trait combinations. Lastly, we find that the genetic architecture of the ability to produce rhizomes changes through development, wherein most hybrids produce rhizomes, but only later in development. Our results suggest that elevational differences may shape life-history divergence between perennials, but aspects of the genetic architecture of divergence may have implications for hybrid fitness in nature.
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Affiliation(s)
- Jenn M. Coughlan
- Biology Department, Duke University, 125 Science Dr., Durham, NC 27708, USA
- Biology Department, University of North Carolina, 250 Bell Tower Dr., Chapel Hill, NC 27599, USA
| | - Maya Wilson Brown
- Biology Department, Duke University, 125 Science Dr., Durham, NC 27708, USA
- Department of Plant Biology, Michigan State University, 612 Wilson Rd, East Lansing, MI 48824, USA
| | - John H. Willis
- Biology Department, Duke University, 125 Science Dr., Durham, NC 27708, USA
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Chen Z, Zheng Z, Luo W, Zhou H, Ying Z, Liu C. Detection of a major QTL conditioning trichome length and density on chromosome arm 4BL and development of near isogenic lines targeting this locus in bread wheat. MOLECULAR BREEDING : NEW STRATEGIES IN PLANT IMPROVEMENT 2021; 41:10. [PMID: 37309472 PMCID: PMC10236078 DOI: 10.1007/s11032-021-01201-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 01/04/2021] [Indexed: 06/14/2023]
Abstract
Trichomes are differentiated epidermal cells and can be found on above ground organs of nearly all land plants. Results from previous studies show that trichomes play important roles against a wide range of both biotic and abiotic stresses. By examining differences between parental genotypes of available populations, we identified a population of recombinant inbred lines showing clear segregation for trichome density and length. Assessing the F8 lines of the population growing in the field detected a major locus on chromosome arm 4BL. This locus was detected based the assessments of either fully expanded third leaves or flag leaves after anthesis. Based on the position of the QTL, an SSR marker was used to identify heterozygous plants at this locus from F5 lines derived from the same cross for the F8 population. Three pairs of near isogenic lines targeting this locus were obtained from these heterozygous plants. Difference in trichome length between the two lines with opposite alleles for each of these NIL pairs were similar to that between the two parental genotypes for the mapping populations, confirming that this single locus is mainly responsible for the trichome characteristics measured in this study. The allele with long and dense trichome is dominant as this characteristic was shown by the heterozygous individuals at this marker locus. Apart from the targeted locus, NIL pairs have highly homogeneous genetic backgrounds. Thus, the NILs could be invaluable in understanding the relationship between trichome density and resistance or tolerance to various biotic and abiotic stresses. Supplementary Information The online version contains supplementary material available at 10.1007/s11032-021-01201-8.
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Affiliation(s)
- Zhitong Chen
- Agricultural Ecology Institute, Fujian Academy of Agricultural Sciences, Fuzhou, 350013 China
- CSIRO Agriculture & Food, 306 Carmody Road, St Lucia, QLD 4067 Australia
| | - Zhi Zheng
- CSIRO Agriculture & Food, 306 Carmody Road, St Lucia, QLD 4067 Australia
| | - Wei Luo
- CSIRO Agriculture & Food, 306 Carmody Road, St Lucia, QLD 4067 Australia
- Triticeae Research Institute, Sichuan Agricultural University, Wenjiang, Chengdu, 611130 Sichuan China
| | - Hong Zhou
- CSIRO Agriculture & Food, 306 Carmody Road, St Lucia, QLD 4067 Australia
- Triticeae Research Institute, Sichuan Agricultural University, Wenjiang, Chengdu, 611130 Sichuan China
| | - Zhaoyang Ying
- Agricultural Ecology Institute, Fujian Academy of Agricultural Sciences, Fuzhou, 350013 China
| | - Chunji Liu
- CSIRO Agriculture & Food, 306 Carmody Road, St Lucia, QLD 4067 Australia
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Wei Z, Cheng Y, Zhou C, Li D, Gao X, Zhang S, Chen M. Genome-Wide Identification of Direct Targets of the TTG1-bHLH-MYB Complex in Regulating Trichome Formation and Flavonoid Accumulation in Arabidopsis Thaliana. Int J Mol Sci 2019; 20:ijms20205014. [PMID: 31658678 PMCID: PMC6829465 DOI: 10.3390/ijms20205014] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 09/27/2019] [Accepted: 10/08/2019] [Indexed: 12/17/2022] Open
Abstract
Extensive studies have shown that the MBW complex consisting of three kinds of regulatory proteins, MYB and basic helix–loop–helix (bHLH) transcription factors and a WD40 repeat protein, TRANSPARENT TESTA GLABRA1 (TTG1), acts in concert to promote trichome formation and flavonoid accumulation in Arabidopsis thaliana. TTG1 functions as an essential activator in these two biological processes. However, direct downstream targets of the TTG1-dependent MBW complex have not yet been obtained in the two biological processes at the genome-wide level in A. thaliana. In the present study, we found, through RNA sequencing and quantitative real-time PCR analysis, that a great number of regulatory and structural genes involved in both trichome formation and flavonoid accumulation are significantly downregulated in the young shoots and expanding true leaves of ttg1-13 plants. Post-translational activation of a TTG1-glucocorticoid receptor fusion protein and chromatin immunoprecipitation assays demonstrated that these downregulated genes are directly or indirectly targeted by the TTG1-dependent MBW complex in vivo during trichome formation and flavonoid accumulation. These findings further extend our understanding of the role of TTG1-dependent MBW complex in the regulation of trichome formation and flavonoid accumulation in A. thaliana.
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Affiliation(s)
- Zelou Wei
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Yalong Cheng
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China.
- Qinling National Forest Ecosystem Research Station, Huoditang, Ningshan 711600, Shaanxi, China.
| | - Chenchen Zhou
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Dong Li
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Xin Gao
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Shuoxin Zhang
- College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China.
- Qinling National Forest Ecosystem Research Station, Huoditang, Ningshan 711600, Shaanxi, China.
| | - Mingxun Chen
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Agronomy, Northwest A&F University, Yangling 712100, Shaanxi, China.
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6
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Huang Y, Wu Q, Wang S, Shi J, Dong Q, Yao P, Shi G, Xu S, Deng R, Li C, Chen H, Zhao H. FtMYB8 from Tartary buckwheat inhibits both anthocyanin/Proanthocyanidin accumulation and marginal Trichome initiation. BMC PLANT BIOLOGY 2019; 19:263. [PMID: 31215400 PMCID: PMC6582506 DOI: 10.1186/s12870-019-1876-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 06/06/2019] [Indexed: 05/13/2023]
Abstract
BACKGROUND Because flavonoids and trichomes play crucial roles in plant defence, their formation requires fine transcriptional control by multiple transcription factor families. However, little is known regarding the mechanism of the R2R3-MYB transcription factors that regulate both flavonoid metabolism and trichome development. RESULTS Here, we identified a unique SG4-like-MYB TF from Tartary buckwheat, FtMYB8, which harbours the C2 repression motif and an additional TLLLFR repression motif. The expression profiles of FtMYB8 combined with the transcriptional activity of PFtMYB8 promoter showed that FtMYB8 mRNA mainly accumulated in roots during the true leaf stage and flowering stage and in bud trichomes and flowers, and the expression of this gene was markedly induced by MeJA, ABA and UV-B treatments but repressed by dark treatment. Overexpression of FtMYB8 in Arabidopsis reduces the accumulation of anthocyanin/proanthocyanidin by specifically inhibiting TT12 expression, which may depend on the interaction between FtMYB8 and TT8. Interestingly, this interaction may also negatively regulate the marginal trichome initiation in Arabidopsis leaves. CONCLUSIONS Taken together, our results suggest that FtMYB8 may fine-tune the accumulation of anthocyanin/proanthocyanidin in the roots and flowers of Tartary buckwheat by balancing the inductive effects of transcriptional activators, and probably regulate trichome distribution in the buds of Tartary buckwheat.
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Affiliation(s)
- Yunji Huang
- College of Life Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya’an, 625014 Sichuan Province China
| | - Qi Wu
- College of Life Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya’an, 625014 Sichuan Province China
| | - Shuang Wang
- College of Life Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya’an, 625014 Sichuan Province China
| | - Jiaqi Shi
- College of Life Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya’an, 625014 Sichuan Province China
| | - Qixin Dong
- College of Life Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya’an, 625014 Sichuan Province China
| | - Panfeng Yao
- College of Life Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya’an, 625014 Sichuan Province China
| | - Guannan Shi
- College of Life Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya’an, 625014 Sichuan Province China
| | - Shuangxiu Xu
- College of Life Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya’an, 625014 Sichuan Province China
| | - Renyu Deng
- College of Life Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya’an, 625014 Sichuan Province China
| | - Chenglei Li
- College of Life Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya’an, 625014 Sichuan Province China
| | - Hui Chen
- College of Life Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya’an, 625014 Sichuan Province China
| | - Haixia Zhao
- College of Life Science, Sichuan Agricultural University, No. 46, Xinkang Road, Ya’an, 625014 Sichuan Province China
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7
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Wang L, Zhou CM, Mai YX, Li LZ, Gao J, Shang GD, Lian H, Han L, Zhang TQ, Tang HB, Ren H, Wang FX, Wu LY, Liu XL, Wang CS, Chen EW, Zhang XN, Liu C, Wang JW. A spatiotemporally regulated transcriptional complex underlies heteroblastic development of leaf hairs in Arabidopsis thaliana. EMBO J 2019; 38:embj.2018100063. [PMID: 30842098 DOI: 10.15252/embj.2018100063] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 02/08/2019] [Accepted: 02/15/2019] [Indexed: 11/09/2022] Open
Abstract
Heteroblasty refers to a phenomenon that a plant produces morphologically or functionally different lateral organs in an age-dependent manner. In the model plant Arabidopsis thaliana, the production of trichomes (epidermal leaf hairs) on the abaxial (lower) side of leaves is a heteroblastic mark for the juvenile-to-adult transition. Here, we show that the heteroblastic development of abaxial trichomes is regulated by a spatiotemporally regulated complex comprising the leaf abaxial fate determinant (KAN1) and the developmental timer (miR172-targeted AP2-like proteins). We provide evidence that a short-distance chromatin loop brings the downstream enhancer element into close association with the promoter elements of GL1, which encodes a MYB transcription factor essential for trichome initiation. During juvenile phase, the KAN1-AP2 repressive complex binds to the downstream sequence of GL1 and represses its expression through chromatin looping. As plants age, the gradual reduction in AP2-like protein levels leads to decreased amount of the KAN1-AP2 complex, thereby licensing GL1 expression and the abaxial trichome initiation. Our results thus reveal a novel molecular mechanism by which a heteroblastic trait is governed by integrating age and leaf polarity cue in plants.
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Affiliation(s)
- Long Wang
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China
| | - Chuan-Miao Zhou
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China
| | - Yan-Xia Mai
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China
| | - Ling-Zi Li
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Jian Gao
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Guang-Dong Shang
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Heng Lian
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China
| | - Lin Han
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Tian-Qi Zhang
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China
| | - Hong-Bo Tang
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Hang Ren
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Fu-Xiang Wang
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Lian-Yu Wu
- ShanghaiTech University, Shanghai, China
| | | | - Chang-Sheng Wang
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Er-Wang Chen
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Xue-Ning Zhang
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China.,University of Chinese Academy of Sciences, Shanghai, China
| | - Chang Liu
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
| | - Jia-Wei Wang
- National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences (CAS), Shanghai, China .,ShanghaiTech University, Shanghai, China
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8
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Ochoa-López S, Rebollo R, Barton KE, Fornoni J, Boege K. Risk of herbivore attack and heritability of ontogenetic trajectories in plant defense. Oecologia 2018; 187:413-426. [PMID: 29392442 DOI: 10.1007/s00442-018-4077-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 01/16/2018] [Indexed: 11/30/2022]
Abstract
Ontogeny has been identified as a main source of variation in the expression of plant phenotypes. However, there is limited information on the mechanisms behind the evolution of ontogenetic trajectories in plant defense. We explored if risk of attack, herbivore damage, heritability, and phenotypic plasticity can promote or constrain the evolutionary potential of ontogenetic trajectories in three defensive traits. We exposed 20 genotypes of Turnera velutina to contrasting environments (shadehouse and field plots), and measured the cyanogenic potential, trichome density, and sugar content in extrafloral nectar in seedlings, juveniles and reproductive plants. We also assessed risk of attack through oviposition preferences, and quantified herbivore damage in the field. We estimated genetic variance, broad sense heritability, and evolvability of the defensive traits at each ontogenetic stage, and of the ontogenetic trajectories themselves. For plants growing in the shadehouse, we found genetic variation and broad sense heritability for cyanogenic potential in seedlings, and for trichome density at all ontogenetic stages. Genetic variation and heritability of ontogenetic trajectories was detected for trichome density only. These genetic pre-requisites for evolution, however, were not detected in the field, suggesting that environmental variation and phenotypic plastic responses mask any heritable variation. Finally, ontogenetic trajectories were found to be plastic, differing between shadehouse and field conditions for the same genetic families. Overall, we provide support for the idea that changes in herbivore pressure can be a mechanism behind the evolution of ontogenetic trajectories. This evolutionary potential, however, can be constrained by phenotypic plasticity expressed in heterogeneous environments.
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Affiliation(s)
- Sofía Ochoa-López
- Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, Ciudad Universitaria, CP. 04510, Mexico City, Mexico
| | - Roberto Rebollo
- Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, Ciudad Universitaria, CP. 04510, Mexico City, Mexico
| | - Kasey E Barton
- Department of Botany, University of Hawai'i at Mānoa, 3190 Maile Way, Room 101, Honolulu, HI, 96822, USA
| | - Juan Fornoni
- Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, Ciudad Universitaria, CP. 04510, Mexico City, Mexico
| | - Karina Boege
- Instituto de Ecología, Universidad Nacional Autónoma de México, Apartado Postal 70-275, Ciudad Universitaria, CP. 04510, Mexico City, Mexico.
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9
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Busta L, Hegebarth D, Kroc E, Jetter R. Changes in cuticular wax coverage and composition on developing Arabidopsis leaves are influenced by wax biosynthesis gene expression levels and trichome density. PLANTA 2017; 245:297-311. [PMID: 27730411 DOI: 10.1007/s00425-016-2603-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 09/29/2016] [Indexed: 05/20/2023]
Abstract
Wax coverage on developing Arabidopsis leaf epidermis cells is constant and thus synchronized with cell expansion. Wax composition shifts from fatty acid to alkane dominance, mediated by CER6 expression. Epidermal cells bear a wax-sealed cuticle to hinder transpirational water loss. The amount and composition of the cuticular wax mixture may change as organs develop, to optimize the cuticle for specific functions during growth. Here, morphometrics, wax chemical profiling, and gene expression measurements were integrated to study developing Arabidopsis thaliana leaves and, thus, further our understanding of cuticular wax ontogeny. Before 5 days of age, cells at the leaf tip ceased dividing and began to expand, while cells at the leaf base switched from cycling to expansion at day 13, generating a cell age gradient along the leaf. We used this spatial age distribution together with leaves of different ages to determine that, as leaves developed, their wax compositions shifted from C24/C26 to C30/C32 and from fatty acid to alkane constituents. These compositional changes paralleled an increase in the expression of the elongase enzyme CER6 but not of alkane pathway enzymes, suggesting that CER6 transcriptional regulation is responsible for both chemical shifts. Leaves bore constant numbers of trichomes between 5 and 21 days of age and, thus, trichome density was higher on young leaves. During this time span, leaves of the trichome-less gl1 mutant had constant wax coverage, while wild-type leaf coverage was initially high and then decreased, suggesting that high trichome density leads to greater apparent coverage on young leaves. Conversely, wax coverage on pavement cells remained constant over time, indicating that wax accumulation is synchronized with cell expansion throughout leaf development.
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Affiliation(s)
- Lucas Busta
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada
| | - Daniela Hegebarth
- Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada
| | - Edward Kroc
- Department of Statistics, University of British Columbia, 3182 Earth Sciences Building, 2207 Main Mall, Vancouver, BC, V6T 1Z4, Canada
- Department of Educational and Counselling Psychology, and Special Education, University of British Columbia, 2125 Main Mall, Vancouver, BC, V6T 1Z4, Canada
| | - Reinhard Jetter
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.
- Department of Botany, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada.
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10
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Matías-Hernández L, Aguilar-Jaramillo AE, Cigliano RA, Sanseverino W, Pelaz S. Flowering and trichome development share hormonal and transcription factor regulation. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:1209-19. [PMID: 26685187 DOI: 10.1093/jxb/erv534] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Gibberellins (GAs) and cytokinins (CKs) are plant hormones that act either synergistically or antagonistically during the regulation of different developmental processes. In Arabidopsis thaliana, GAs and CKs overlap in the positive regulation of processes such as the transition from the vegetative to the reproductive phase and the development of epidermal adaxial trichomes. Despite the fact that both developmental processes originate in the rosette leaves, they occur separately in time and space. Here we review how, as genetic and molecular mechanisms are being unraveled, both processes might be closely related. Additionally, this shared genetic network is not only dependent on GA and CK hormone signaling but is also strictly controlled by specific clades of transcription factor families. Some key flowering genes also control other rosette leaf developmental processes such as adaxial trichome formation. Conversely, most of the trichome activator genes, which belong to the MYB, bHLH and C2H2 families, were found to positively control the floral transition. Furthermore, three MADS floral organ identity genes, which are able to convert leaves into floral structures, are also able to induce trichome proliferation in the flower. These data lead us to propose that the spatio-temporal regulation and integration of diverse signals control different developmental processes, such as floral induction and trichome formation, which are intimately connected through similar genetic pathways.
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Affiliation(s)
- Luis Matías-Hernández
- Centre for Research in Agricultural Genomics, CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra (Cerdanyola del Vallès) 08193 Barcelona, Spain Sequentia Biotech, Parc Científic de Barcelona (PCB), 08028 Barcelona, Spain
| | - Andrea E Aguilar-Jaramillo
- Centre for Research in Agricultural Genomics, CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra (Cerdanyola del Vallès) 08193 Barcelona, Spain
| | | | - Walter Sanseverino
- Sequentia Biotech, Parc Científic de Barcelona (PCB), 08028 Barcelona, Spain
| | - Soraya Pelaz
- Centre for Research in Agricultural Genomics, CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra (Cerdanyola del Vallès) 08193 Barcelona, Spain ICREA (Institució Catalana de Recerca i EstudisAvançats), Barcelona, Spain
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11
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Whitney KD, Broman KW, Kane NC, Hovick SM, Randell RA, Rieseberg LH. Quantitative trait locus mapping identifies candidate alleles involved in adaptive introgression and range expansion in a wild sunflower. Mol Ecol 2015; 24:2194-211. [PMID: 25522096 DOI: 10.1111/mec.13044] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 12/05/2014] [Accepted: 12/12/2014] [Indexed: 01/14/2023]
Abstract
The wild North American sunflowers Helianthus annuus and H. debilis are participants in one of the earliest identified examples of adaptive trait introgression, and the exchange is hypothesized to have triggered a range expansion in H. annuus. However, the genetic basis of the adaptive exchange has not been examined. Here, we combine quantitative trait locus (QTL) mapping with field measurements of fitness to identify candidate H. debilis QTL alleles likely to have introgressed into H. annuus to form the natural hybrid lineage H. a. texanus. Two 500-individual BC1 mapping populations were grown in central Texas, genotyped for 384 single nucleotide polymorphism (SNP) markers and then phenotyped in the field for two fitness and 22 herbivore resistance, ecophysiological, phenological and architectural traits. We identified a total of 110 QTL, including at least one QTL for 22 of the 24 traits. Over 75% of traits exhibited at least one H. debilis QTL allele that would shift the trait in the direction of the wild hybrid H. a. texanus. We identified three chromosomal regions where H. debilis alleles increased both female and male components of fitness; these regions are expected to be strongly favoured in the wild. QTL for a number of other ecophysiological, phenological and architectural traits colocalized with these three regions and are candidates for the actual traits driving adaptive shifts. G × E interactions played a modest role, with 17% of the QTL showing potentially divergent phenotypic effects between the two field sites. The candidate adaptive chromosomal regions identified here serve as explicit hypotheses for how the genetic architecture of the hybrid lineage came into existence.
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Affiliation(s)
- Kenneth D Whitney
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131-0001, USA
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12
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Hauser MT. Molecular basis of natural variation and environmental control of trichome patterning. FRONTIERS IN PLANT SCIENCE 2014; 5:320. [PMID: 25071803 PMCID: PMC4080826 DOI: 10.3389/fpls.2014.00320] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Accepted: 06/17/2014] [Indexed: 05/17/2023]
Abstract
Trichomes are differentiated epidermal cells on above ground organs of nearly all land plants. They play important protective roles as structural defenses upon biotic attacks such as herbivory, oviposition and fungal infections, and against abiotic stressors such as drought, heat, freezing, excess of light, and UV radiation. The pattern and density of trichomes is highly variable within natural population suggesting tradeoffs between traits positively affecting fitness such as resistance and the costs of trichome production. The spatial distribution of trichomes is regulated through a combination of endogenous developmental programs and external signals. This review summarizes the current understanding on the molecular basis of the natural variation and the role of phytohormones and environmental stimuli on trichome patterning.
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Affiliation(s)
- Marie-Theres Hauser
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life SciencesVienna, Austria
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13
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Bloomer RH, Lloyd AM, Symonds VV. The genetic architecture of constitutive and induced trichome density in two new recombinant inbred line populations of Arabidopsis thaliana: phenotypic plasticity, epistasis, and bidirectional leaf damage response. BMC PLANT BIOLOGY 2014; 14:119. [PMID: 24885520 PMCID: PMC4108038 DOI: 10.1186/1471-2229-14-119] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 04/25/2014] [Indexed: 05/23/2023]
Abstract
BACKGROUND Herbivory imposes an important selective pressure on plants. In Arabidopsis thaliana leaf trichomes provide a key defense against insect herbivory; however, trichome production incurs a fitness cost in the absence of herbivory. Previous work on A. thaliana has shown an increase in trichome density in response to leaf damage, suggesting a mechanism by which the cost associated with constitutively high trichome density might be mitigated; however, the genetic basis of trichome density induction has not been studied. RESULTS Here, we describe the mapping of quantitative trait loci (QTL) for constitutive and damage induced trichome density in two new recombinant inbred line populations of A. thaliana; mapping for constitutive and induced trichome density also allowed for the investigation of damage response (plasticity) QTL. Both novel and previously identified QTL for constitutive trichome density and the first QTL for induced trichome density and response are identified. Interestingly, two of the four parental accessions and multiple RILs in each population exhibited lower trichome density following leaf damage, a response not previously described in A. thaliana. Importantly, a single QTL was mapped for the response phenotype and allelic variation at this locus appears to determine response trajectory in RILs. The data also show that epistatic interactions are a significant component of the genetic architecture of trichome density. CONCLUSIONS Together, our results provide further insights into the genetic architecture of constitutive trichome density and new insights into induced trichome density in A. thaliana specifically and to our understanding of the genetic underpinnings of natural variation generally.
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Affiliation(s)
- Rebecca H Bloomer
- Institute of Fundamental Sciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
| | - Alan M Lloyd
- Institute for Cellular and Molecular Biology, University of Texas, Austin, TX, USA
| | - V Vaughan Symonds
- Institute of Fundamental Sciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
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14
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Nogueira A, El Ottra JHL, Guimarães E, Machado SR, Lohmann LG. Trichome structure and evolution in Neotropical lianas. ANNALS OF BOTANY 2013; 112:1331-50. [PMID: 24081281 PMCID: PMC3806532 DOI: 10.1093/aob/mct201] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2012] [Accepted: 07/19/2013] [Indexed: 05/11/2023]
Abstract
BACKGROUND AND AIMS Trichomes are epidermal outgrowths generally associated with protection against herbivores and/or desiccation that are widely distributed from ferns to angiosperms. Patterns of topological variation and morphological evolution of trichomes are still scarce in the literature, preventing valid comparisons across taxa. This study integrates detailed morphoanatomical data and the evolutionary history of the tribe Bignonieae (Bignoniaceae) in order to gain a better understanding of current diversity and evolution of trichome types. METHODS Two sampling schemes were used to characterize trichome types: (1) macromorphological characterization of all 105 species currently included in Bignonieae; and (2) micromorphological characterization of 16 selected species. Individual trichome morphotypes were coded as binary in each vegetative plant part, and trichome density and size were coded as multistate. Ancestral character state reconstructions were conducted using maximum likelihood (ML) assumptions. KEY RESULTS Two main functional trichome categories were found: non-glandular and glandular. In glandular trichomes, three morphotypes were recognized: peltate (Pg), stipitate (Sg) and patelliform/cupular (P/Cg) trichomes. Non-glandular trichomes were uniseriate, uni- or multicellular and simple or branched. Pg and P/Cg trichomes were multicellular and non-vascularized with three clearly distinct cell layers. Sg trichomes were multicellular, uniseriate and long-stalked. ML ancestral character state reconstructions suggested that the most recent common ancestor (MRCA) of Bignonieae probably had non-glandular, Pg and P/Cg trichomes, with each trichome type presenting alternative histories of appearance on the different plant parts. For example, the MRCA of Bignonieae probably had non-glandular trichomes on the stems, prophylls, petiole, petiolule and leaflet veins while P/Cg trichomes were restricted to leaflet blades. Sg trichomes were not present in the MRCA of Bignonieae independently of the position of these trichomes. These trichomes had at least eight independent origins in tribe. CONCLUSIONS The patterns of trichome evolution indicate that most morphotypes are probably homologous in Bignonieae and could be treated under the same name based on its morphological similarity and common evolutionary history, in spite of the plethora of names that have been previously designated in the literature. The trichome descriptions presented here will facilitate comparisons across taxa, allowing inferences on the relationsthips between trichome variants and future studies about their functional properties.
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Affiliation(s)
- Anselmo Nogueira
- Universidade de São Paulo, Instituto de Biociências, Departamento de Botânica, Rua do Matão, 277, São Paulo, SP, 05508-090, Brazil
| | - Juliana Hanna Leite El Ottra
- Universidade de São Paulo, Instituto de Biociências, Departamento de Botânica, Rua do Matão, 277, São Paulo, SP, 05508-090, Brazil
| | - Elza Guimarães
- UNESP-Universidade Estadual Paulista, Instituto de Biociências de Botucatu, Departamento de Botânica, Caixa Postal 510, Botucatu, SP, 18618-000, Brazil
| | - Silvia Rodrigues Machado
- UNESP-Universidade Estadual Paulista, Instituto de Biociências de Botucatu, Departamento de Botânica, Caixa Postal 510, Botucatu, SP, 18618-000, Brazil
| | - Lúcia G. Lohmann
- Universidade de São Paulo, Instituto de Biociências, Departamento de Botânica, Rua do Matão, 277, São Paulo, SP, 05508-090, Brazil
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15
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Bloomer RH, Juenger TE, Symonds VV. Natural variation in GL1 and its effects on trichome density in Arabidopsis thaliana. Mol Ecol 2012; 21:3501-15. [PMID: 22625421 DOI: 10.1111/j.1365-294x.2012.05630.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The ultimate understanding of how biological diversity arises, is maintained, and lost depends on identifying the genes responsible. Although a good deal has been discovered about gene function over the past few decades, far less is understood about gene effects, that is, how natural variation in a gene contributes to natural variation in phenotypes. Trichome density in Arabidopsis thaliana is an ideal trait for studies of natural molecular and phenotypic variation, as trichome initiation is genetically well-characterized and trichome density is highly variable in and among natural populations. Here, we show that variation at GLABRA1 (GL1), an R2R3 MYB transcription factor gene, which has a role in trichome initiation, has qualitative and likely quantitative effects on trichome density in natural accessions of A. thaliana. Specifically, we characterize four independent loss-of-function alleles for GL1, each of which yields a glabrous phenotype. Further, we find that a pattern of common polymorphisms confined to the GL1 locus is associated with quantitative variation for trichome density. While mutations resulting in a glabrous phenotype are primarily coding changes, the pattern resulting in quantitative variation spans both coding and regulatory regions. These data show that GL1 is an important source of trichome density variation within A. thaliana and, along with recent reports, suggest that the TTG1 epidermal cell fate pathway generally may be the key molecular genetic source of natural trichome density variation and an important model for the study of molecular evolution.
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Affiliation(s)
- R H Bloomer
- Institute of Molecular BioSciences, Massey University, Private Bag 11222, Palmerston North, New Zealand
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16
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Symonds VV, Hatlestad G, Lloyd AM. Natural allelic variation defines a role for ATMYC1: trichome cell fate determination. PLoS Genet 2011; 7:e1002069. [PMID: 21695236 PMCID: PMC3111535 DOI: 10.1371/journal.pgen.1002069] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 03/24/2011] [Indexed: 11/19/2022] Open
Abstract
The molecular nature of biological variation is not well understood. Indeed, many questions persist regarding the types of molecular changes and the classes of genes that underlie morphological variation within and among species. Here we have taken a candidate gene approach based on previous mapping results to identify the gene and ultimately a polymorphism that underlies a trichome density QTL in Arabidopsis thaliana. Our results show that natural allelic variation in the transcription factor ATMYC1 alters trichome density in A. thaliana; this is the first reported function for ATMYC1. Using site-directed mutagenesis and yeast two-hybrid experiments, we demonstrate that a single amino acid replacement in ATMYC1, discovered in four ecotypes, eliminates known protein–protein interactions in the trichome initiation pathway. Additionally, in a broad screen for molecular variation at ATMYC1, including 72 A. thaliana ecotypes, a high-frequency block of variation was detected that results in >10% amino acid replacement within one of the eight exons of the gene. This sequence variation harbors a strong signal of divergent selection but has no measurable effect on trichome density. Homologs of ATMYC1 are pleiotropic, however, so this block of variation may be the result of natural selection having acted on another trait, while maintaining the trichome density role of the gene. These results show that ATMYC1 is an important source of variation for epidermal traits in A. thaliana and indicate that the transcription factors that make up the TTG1 genetic pathway generally may be important sources of epidermal variation in plants. Among the goals of modern evolutionary biology is to identify the molecular genetic sources of natural variation. Although genetic mapping has led to an increased understanding of the genetic architecture of natural variation, there are surprisingly few cases where the molecular source of the variation has been identified. Here, we utilize previous mapping results to identify the gene and ultimately a polymorphism that underlies natural variation for a dynamic trait in Arabidopsis thaliana: trichome density. We show that plants carrying a knock-out of the bHLH transcription factor ATMYC1 have a reduced trichome density phenotype; this is the first reported function for ATMYC1. Using traditional and molecular genetic approaches, we identify a single base change in natural alleles of ATMYC1, which leads to an amino acid replacement that qualitatively alters protein–protein interactions with known partners, presumably altering the trichome cell fate pathway. In a broad screen for molecular variation in ATMYC1, we identify a dense block of amino acid replacements that differentiates two high-frequency allele types. Although this block of variation does not appear to affect trichome density, based on paralogs of ATMYC1, we propose that this variation has arisen due to directional selection on another epidermal trait.
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Affiliation(s)
- V Vaughan Symonds
- Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America.
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17
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Anderson JT, Mitchell-Olds T. Ecological genetics and genomics of plant defenses: Evidence and approaches. Funct Ecol 2010; 25:312-324. [PMID: 21532968 DOI: 10.1111/j.1365-2435.2010.01785.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Herbivores exert significant selection on plants, and plants have evolved a variety of constitutive and inducible defenses to resist and tolerate herbivory. Assessing the genetic mechanisms that influence defenses against herbivores will deepen our understanding of the evolution of essential phenotypic traits.Ecogenomics is a powerful interdisciplinary approach that can address fundamental questions about the ecology and evolutionary biology of species, such as: which evolutionary forces maintain variation within a population? and What is the genetic architecture of adaptation? This field seeks to identify gene regions that influence ecologically-important traits, assess the fitness consequences under natural conditions of alleles at key quantitative trait loci (QTLs), and test how the abiotic and biotic environment affects gene expression.Here, we review ecogenomics techniques and emphasize how this framework can address long-standing and emerging questions relating to anti-herbivore defenses in plants. For example, ecogenomics tools can be used to investigate: inducible vs. constitutive defenses; tradeoffs between resistance and tolerance; adaptation to the local herbivore community; selection on alleles that confer resistance and tolerance in natural populations; and whether different genes are activated in response to specialist vs. generalist herbivores and to different types of damage.Ecogenomic studies can be conducted with model species, such as Arabidopsis, or their relatives, in which case myriad molecular tools are already available. Burgeoning sequence data will also facilitate ecogenomic studies of non-model species. Throughout this paper, we highlight approaches that are particularly suitable for ecological studies of non-model organisms, discuss the benefits and disadvantages of specific techniques, and review bioinformatic tools for analyzing data.We focus on established and promising techniques, such as QTL mapping with pedigreed populations, genome wide association studies, transcription profiling strategies, population genomics, and transgenic methodologies. Many of these techniques are complementary and can be used jointly to investigate the genetic architecture of defense traits and selection on alleles in nature.
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Affiliation(s)
- Jill T Anderson
- Institute for Genome Sciences and Policy, Department of Biology, Duke University, P.O. Box 90338, Durham, North Carolina 27708, USA
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18
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Holeski LM, Chase-Alone R, Kelly JK. The genetics of phenotypic plasticity in plant defense: trichome production in Mimulus guttatus. Am Nat 2010; 175:391-400. [PMID: 20180699 DOI: 10.1086/651300] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Insect herbivory is a major driving force of plant evolution. Phenotypic plasticity and developmental variation provide a means for plants to cope with variable herbivory. We characterized the genetics of developmental variation and phenotypic plasticity in trichome density, a putative defensive trait of Mimulus guttatus (yellow monkeyflower). Our results are evaluated in relation to the optimal defense theory, which provides testable predictions for plastic and developmental patterns in defense traits. We found that both developmental stage and simulated insect damage affected trichome production, but in different ways. Plants were more likely to produce at least some trichomes on later leaves than on earlier leaves, regardless of damage. Damage did not affect the average probability of producing trichomes, but it did increase the density of hairs on trichome-positive plants. We mapped trichome quantitative trait loci (QTL) by selectively genotyping a large panel of recombinant inbred lines derived from two highly divergent populations. Several highly pleiotropic QTL influenced multiple aspects of the trichome phenotype (constitutive, developmental, and/or plastic responses). Only one of the QTL influenced trichome induction following damage. In a result that is consistent with a central prediction of optimal defense theory, the high allele at this location was from the ancestral population with low constitutive trichome production.
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Affiliation(s)
- Liza M Holeski
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA.
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19
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Hilscher J, Schlötterer C, Hauser MT. A single amino acid replacement in ETC2 shapes trichome patterning in natural Arabidopsis populations. Curr Biol 2009; 19:1747-51. [PMID: 19818620 DOI: 10.1016/j.cub.2009.08.057] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 08/19/2009] [Accepted: 08/21/2009] [Indexed: 01/26/2023]
Abstract
Our understanding of the evolution of organismal diversity is restricted by the current resolution of the genotype-phenotype map. In particular, the genetic basis of environmentally relevant phenotypic variation among natural populations remains poorly understood. Trichomes are single-cell outgrowths on the surface of plant leaves and other above-ground organs. Consistent with trichomes' suggested function to protect plants from predators and abiotic stressors [1-3], trichome density is strikingly variable among natural populations (e.g., [2, 4]). Despite substantial progress in the genetic dissection of trichome development [5], how trichome number is modulated in natural populations remains enigmatic. Here, we show that the ENHANCER OF TRY AND CPC 2 (ETC2) from the single-repeat R3 MYB family is the major locus determining trichome patterning in natural Arabidopsis populations. Our study identifies a single amino acid substitution in ETC2 (K19E) as the causal quantitative trait nucleotide (QTN). We suggest that this amino acid replacement might affect the stability of the ETC2 repressor, which results in a reduced trichome number. This is consistent with the view that morphology can evolve by coding changes that can subtly modulate protein activity as well as cis-regulatory changes that alter expression patterns.
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Affiliation(s)
- Julia Hilscher
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Vienna, Austria
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20
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Yoshida Y, Sano R, Wada T, Takabayashi J, Okada K. Jasmonic acid control of GLABRA3 links inducible defense and trichome patterning in Arabidopsis. Development 2009; 136:1039-48. [PMID: 19234066 DOI: 10.1242/dev.030585] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Once attacked by herbivores, plants regenerate new leaves with increased trichome density as an inducible defense. Trichomes are specified from neighboring epidermal cells through local cell-cell interactions in the leaf primordia. However, the molecular mechanism of how herbivore-induced damage at older leaves remodels the pattern of trichome fate specification at newly forming leaves is largely unknown. In this study, we show that mutations in either the biosynthetic or signaling pathway of jasmonates (JAs),long-distance wound signals, abolish the wound-induced formation of trichomes. To identify the factors linking JA signaling to trichome fate specification,we isolated a novel class of mutants, unarmed (urm), which lack trichome induction but show otherwise normal responses to JAs. URM9 encodes an Importin β family protein, and URM23 is identical to TRANSPARENT TESTA GLABRA1 (TTG1), the product of which interacts with the bHLH transcription factor GLABRA3 (GL3). Loss of either URM9 or URM23 disrupts the subnuclear localization of GL3, thus implicating GL3 in trichome induction. The expression of GL3 was enhanced by JA treatment prior to trichome initiation. Genetic analysis of multiple trichome mutants shows that GL3, in concert with the R2R3-Myb transcription factor GLABRA1 (GL1), promotes trichome fate in response to JA in a dosage-dependent manner. These results indicate that GL3 is a key transcription factor of wound-induced trichome formation acting downstream of JA signaling in Arabidopsis.
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Affiliation(s)
- Yuki Yoshida
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
- Center for Ecological Research, Kyoto University, Otsu 520-2113, Japan
| | - Ryosuke Sano
- Plant Science Center, RIKEN, Yokohama 230-0045, Japan
| | - Takuji Wada
- Plant Science Center, RIKEN, Yokohama 230-0045, Japan
| | - Junji Takabayashi
- Center for Ecological Research, Kyoto University, Otsu 520-2113, Japan
| | - Kiyotaka Okada
- Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
- National Institute for Basic Biology, Okazaki 444-8585, Japan
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21
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Dilkes BP, Spielman M, Weizbauer R, Watson B, Burkart-Waco D, Scott RJ, Comai L. The maternally expressed WRKY transcription factor TTG2 controls lethality in interploidy crosses of Arabidopsis. PLoS Biol 2008; 6:2707-20. [PMID: 19071961 PMCID: PMC2596861 DOI: 10.1371/journal.pbio.0060308] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Accepted: 10/29/2008] [Indexed: 11/18/2022] Open
Abstract
The molecular mechanisms underlying lethality of F1 hybrids between diverged parents are one target of speciation research. Crosses between diploid and tetraploid individuals of the same genotype can result in F1 lethality, and this dosage-sensitive incompatibility plays a role in polyploid speciation. We have identified variation in F1 lethality in interploidy crosses of Arabidopsis thaliana and determined the genetic architecture of the maternally expressed variation via QTL mapping. A single large-effect QTL, DR. STRANGELOVE 1 (DSL1), was identified as well as two QTL with epistatic relationships to DSL1. DSL1 affects the rate of postzygotic lethality via expression in the maternal sporophyte. Fine mapping placed DSL1 in an interval encoding the maternal effect transcription factor TTG2. Maternal parents carrying loss-of-function mutations in TTG2 suppressed the F1 lethality caused by paternal excess interploidy crosses. The frequency of cellularization in the endosperm was similarly affected by both natural variation and ttg2 loss-of-function mutants. The simple genetic basis of the natural variation and effects of single-gene mutations suggests that F1 lethality in polyploids could evolve rapidly. Furthermore, the role of the sporophytically active TTG2 gene in interploidy crosses indicates that the developmental programming of the mother regulates the viability of interploidy hybrid offspring.
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Affiliation(s)
- Brian P Dilkes
- Section of Plant Biology and Genome Center, University of California Davis, Davis, California, United States of America
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Melissa Spielman
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Renate Weizbauer
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Brian Watson
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Diana Burkart-Waco
- Section of Plant Biology and Genome Center, University of California Davis, Davis, California, United States of America
| | - Rod J Scott
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Luca Comai
- Section of Plant Biology and Genome Center, University of California Davis, Davis, California, United States of America
- Department of Biology, University of Washington, Seattle, Washington, United States of America
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22
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Maes L, Inzé D, Goossens A. Functional specialization of the TRANSPARENT TESTA GLABRA1 network allows differential hormonal control of laminal and marginal trichome initiation in Arabidopsis rosette leaves. PLANT PHYSIOLOGY 2008; 148:1453-64. [PMID: 18784284 PMCID: PMC2577244 DOI: 10.1104/pp.108.125385] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Accepted: 09/07/2008] [Indexed: 05/20/2023]
Abstract
Trichome initiation in Arabidopsis (Arabidopsis thaliana) is controlled by the TRANSPARENT TESTA GLABRA1 (TTG1) network that consists of R2R3- and R1-type MYB-related transcription factors, basic helix-loop-helix (bHLH) proteins, and the WD40 protein TTG1. An experimental method was designed to investigate the molecular mechanisms by which jasmonates, cytokinins, and gibberellins modulate Arabidopsis leaf trichome formation. All three phytohormones provoked a seemingly common effect on cell patterning by promoting trichome initiation but caused strikingly distinct effects on cell and trichome maturation. The phytohormonal control was mediated by transcriptional regulation of the established TTG1 complex and depended on the R2R3-MYB factor GLABRA1. However, unsuspected degrees of functional specialization of the bHLH factors and a resultant differential molecular regulation of trichome initiation on leaf lamina and leaf margins were revealed. Trichome formation on leaf lamina relied entirely on GLABRA3 and ENHANCER OF GLABRA3. Conversely, TRANSPARENT TESTA8 (TT8) was particularly important for marginal trichome development. This hitherto unknown role for TT8 in trichome formation further underscored the functional redundancy between the three TTG1-dependent bHLH proteins.
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Affiliation(s)
- Lies Maes
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Ghent University, 9052 Ghent, Belgium
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23
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Abstract
Mimulus guttatus (yellow monkeyflower) frequently produce glandular trichomes, a trait that may resist herbivory. Constitutive production of trichomes is variable both within and among populations of M. guttatus and most of this variation is genetic. This study demonstrates that damage on early leaves can induce increased trichome production on later leaves, a plastic response that is likely adaptive. Moreover, this study shows that this induction can be maternally transmitted, increasing trichome density in progeny before they experience herbivory. This transgenerational response must involve a yet undescribed epigenetic mechanism. These experiments also show genetic variation among plants in the capacity for both within and between plant generation induction. Despite the clear evolutionary importance of variation in constitutive and induced herbivory-resistance traits, few other studies have noted genetic variation in both within a plant species.
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Affiliation(s)
- L M Holeski
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, USA.
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24
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Pfalz M, Vogel H, Mitchell-Olds T, Kroymann J. Mapping of QTL for resistance against the crucifer specialist herbivore Pieris brassicae in a new Arabidopsis inbred line population, Da(1)-12 x Ei-2. PLoS One 2007; 2:e578. [PMID: 17593977 PMCID: PMC1892800 DOI: 10.1371/journal.pone.0000578] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Accepted: 06/01/2007] [Indexed: 12/28/2022] Open
Abstract
Background In Arabidopsis thaliana and other crucifers, the glucosinolate-myrosinase system contributes to resistance against herbivory by generalist insects. As yet, it is unclear how crucifers defend themselves against crucifer-specialist insect herbivores. Methodology/Principal Findings We analyzed natural variation for resistance against two crucifer specialist lepidopteran herbivores, Pieris brassicae and Plutella xylostella, among Arabidopsis thaliana accessions and in a new Arabidopsis recombinant inbred line (RIL) population generated from the parental accessions Da(1)-12 and Ei-2. This RIL population consists of 201 individual F8 lines genotyped with 84 PCR-based markers. We identified six QTL for resistance against Pieris herbivory, but found only one weak QTL for Plutella resistance. To elucidate potential factors causing these resistance QTL, we investigated leaf hair (trichome) density, glucosinolates and myrosinase activity, traits known to influence herbivory by generalist insects. We identified several previously unknown QTL for these traits, some of which display a complex pattern of epistatic interactions. Conclusions/Significance Although some trichome, glucosinolate or myrosinase QTL co-localize with Pieris QTL, none of these traits explained the resistance QTL convincingly, indicating that resistance against specialist insect herbivores is influenced by other traits than resistance against generalists.
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Affiliation(s)
- Marina Pfalz
- Department of Genetics & Evolution, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Heiko Vogel
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Thomas Mitchell-Olds
- Department of Genetics & Evolution, Max Planck Institute for Chemical Ecology, Jena, Germany
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Juergen Kroymann
- Department of Genetics & Evolution, Max Planck Institute for Chemical Ecology, Jena, Germany
- * To whom correspondence should be addressed. E-mail:
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Perchepied L, Kroj T, Tronchet M, Loudet O, Roby D. Natural variation in partial resistance to Pseudomonas syringae is controlled by two major QTLs in Arabidopsis thaliana. PLoS One 2006; 1:e123. [PMID: 17205127 PMCID: PMC1762404 DOI: 10.1371/journal.pone.0000123] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Accepted: 11/30/2006] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Low-level, partial resistance is pre-eminent in natural populations, however, the mechanisms underlying this form of resistance are still poorly understood. METHODOLOGY/PRINCIPAL FINDINGS In the present study, we used the model pathosystem Pseudomonas syringae pv. tomato DC3000 (Pst) - Arabidopsis thaliana to study the genetic basis of this form of resistance. Phenotypic analysis of a set of Arabidopsis accessions, based on evaluation of in planta pathogen growth revealed extensive quantitative variation for partial resistance to Pst. It allowed choosing a recombinant inbred line (RIL) population derived from a cross between the accessions Bayreuth and Shahdara for quantitative genetic analysis. Experiments performed under two different environmental conditions led to the detection of two major and two minor quantitative trait loci (QTLs) governing partial resistance to Pst and called PRP-Ps1 to PRP-Ps4. The two major QTLs, PRP-Ps1 and PRP-Ps2, were confirmed in near isogenic lines (NILs), following the heterogeneous inbred families (HIFs) strategy. Analysis of marker gene expression using these HIFs indicated a negative correlation between the induced amount of transcripts of SA-dependent genes PR1, ICS and PR5, and the in planta bacterial growth in the HIF segregating at PRP-Ps2 locus, suggesting an implication of PRP-Ps2 in the activation of SA dependent responses. CONCLUSIONS/SIGNIFICANCE These results show that variation in partial resistance to Pst in Arabidopsis is governed by relatively few loci, and the validation of two major loci opens the way for their fine mapping and their cloning, which will improve our understanding of the molecular mechanisms underlying partial resistance.
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Affiliation(s)
- Laure Perchepied
- Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR Centre National de la Recherche Scientifique/National Institute for Agronomical Research 2594, Castanet-Tolosan, France
| | - Thomas Kroj
- Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR Centre National de la Recherche Scientifique/National Institute for Agronomical Research 2594, Castanet-Tolosan, France
| | - Maurice Tronchet
- Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR Centre National de la Recherche Scientifique/National Institute for Agronomical Research 2594, Castanet-Tolosan, France
| | - Olivier Loudet
- National Institute for Agronomical Research (INRA), Versailles, France
| | - Dominique Roby
- Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR Centre National de la Recherche Scientifique/National Institute for Agronomical Research 2594, Castanet-Tolosan, France
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Wu R, Lin M. Functional mapping - how to map and study the genetic architecture of dynamic complex traits. Nat Rev Genet 2006; 7:229-37. [PMID: 16485021 DOI: 10.1038/nrg1804] [Citation(s) in RCA: 220] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The development of any organism is a complex dynamic process that is controlled by a network of genes as well as by environmental factors. Traditional mapping approaches for analysing phenotypic data measured at a single time point are too simple to reveal the genetic control of developmental processes. A general statistical mapping framework, called functional mapping, has been proposed to characterize, in a single step, the quantitative trait loci (QTLs) or nucleotides (QTNs) that underlie a complex dynamic trait. Functional mapping estimates mathematical parameters that describe the developmental mechanisms of trait formation and expression for each QTL or QTN. The approach provides a useful quantitative and testable framework for assessing the interplay between gene actions or interactions and developmental changes.
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Affiliation(s)
- Rongling Wu
- School of Forestry and Biotechnology, Zhejiang Forestry University, Lin'an, Zhejiang 311300, People's Republic of China.
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