Utilizing MIKC-type MADS-box protein SOC1 for yield potential enhancement in maize

Cloning and functional analysis of ZmMADS42 gene in maize

Maize (Zea mays L.) is the most important cereal crop in the world. Flowering period and photoperiod play important roles in the reproductive development of maize. This study, investigated ZmMADS42, a gene that is highly expressed in the shoot apical meristem. Agrobacterium infection was used to successfully obtain overexpressed ZmMADS42 plants. Fluorescence quantitative PCR revealed that the expression of the ZmMADS42 gene in the shoot apical meristem of transgenic plants was 2.8 times higher than that of the wild-type(WT). In addition, the expression of the ZmMADS42 gene in the endosperm was 2.4 times higher than that in the wild-type. The seed width of the T2 generation increased by 5.35%, whereas the seed length decreased by 7.78% compared with that of the wild-type. Dissection of the shoot tips of transgenic and wild-type plants from the 7-leaf stage to the 9-leaf stage revealed that the transgenic plants entered the differentiation stage earlier and exhibited more tassel meristems during their vegetative growth period. The mature transgenic plants were approximately 20 cm shorter in height and had a lower panicle position than the wild-type plants. Comparing the flowering period, the tasseling, powdering, and silking stages of the transgenic plants occurred 10 days earlier than those of the wild-type plants. The results showed that the ZmMADS42 gene played a significant role in regulating the flowering period and plant height of maize.

Regulatory frameworks involved in the floral induction, formation and developmental programming of woody horticultural plants: a case study on blueberries

Flowering represents a crucial stage in the life cycles of plants. Ensuring strong and consistent flowering is vital for maintaining crop production amidst the challenges presented by climate change. In this review, we summarized key recent efforts aimed at unraveling the complexities of plant flowering through genetic, genomic, physiological, and biochemical studies in woody species, with a special focus on the genetic control of floral initiation and activation in woody horticultural species. Key topics covered in the review include major flowering pathway genes in deciduous woody plants, regulation of the phase transition from juvenile to adult stage, the roles of CONSTANS (CO) and CO-like gene and FLOWERING LOCUS T genes in flower induction, the floral regulatory role of GA-DELLA pathway, and the multifunctional roles of MADS-box genes in flowering and dormancy release triggered by chilling. Based on our own research work in blueberries, we highlighted the central roles played by two key flowering pathway genes, FLOWERING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1, which regulate floral initiation and activation (dormancy release), respectively. Collectively, our survey shows both the conserved and diverse aspects of the flowering pathway in annual and woody plants, providing insights into the potential molecular mechanisms governing woody plants. This paves the way for enhancing the resilience and productivity of fruit-bearing crops in the face of changing climatic conditions, all through the perspective of genetic interventions.

Dynamic transcriptome landscape of developing maize ear

Seed number and harvesting ability in maize (Zea mays L.) are primarily determined by the architecture of female inflorescence, namely the ear. Therefore, ear morphogenesis contributes to grain yield and as such is one of the key target traits during maize breeding. However, the molecular networks of this highly dynamic and complex grain-bearing inflorescence remain largely unclear. As a first step toward characterizing these networks, we performed a high-spatio-temporal-resolution investigation of transcriptomes using 130 ear samples collected from developing ears with length from 0.1 mm to 19.0 cm. Comparisons of these mRNA populations indicated that these spatio-temporal transcriptomes were clearly separated into four distinct stages stages I, II, III, and IV. A total of 23 793 genes including 1513 transcription factors (TFs) were identified in the investigated developing ears. During the stage I of ear morphogenesis, 425 genes were predicted to be involved in a co-expression network established by eight hub TFs. Moreover, 9714 ear-specific genes were identified in the seven kinds of meristems. Additionally, 527 genes including 59 TFs were identified as especially expressed in ear and displayed high temporal specificity. These results provide a high-resolution atlas of gene activity during ear development and help to unravel the regulatory modules associated with the differentiation of the ear in maize.

Molecular evolution, diversification, and expression assessment of MADS gene family in Setaria italica, Setaria viridis, and Panicum virgatum

KEY MESSAGE

This paper sheds light on the evolution and expression patterns of MADS genes in Setaria and Panicum virgatum. SiMADS51 and SiMADS64 maybe involved in the ABA-dependent pathway of drought response. The MADS gene family is a key regulatory factor family that controls growth, reproduction, and response to abiotic stress in plants. However, the molecular evolution of this family is rarely reported. Here, a total of 265 MADS genes were identified in Setaria italica (foxtail millet), Setaria viridis (green millet), and Panicum virgatum (switchgrass) and analyzed by bioinformatics, including physicochemical characteristics, subcellular localization, chromosomal position and duplicate, motif distribution, genetic structure, genetic evolvement, and expression patterns. Phylogenetic analysis was used to categorize these genes into M and MIKC types. The distribution of motifs and gene structure were similar for the corresponding types. According to a collinearity study, the MADS genes have been mostly conserved during evolution. The principal cause of their expansion is segmental duplication. However, the MADS gene family tends to shrink in foxtail millet, green millet, and switchgrass. The MADS genes were subjected to purifying selection, but several positive selection sites were also identified in three species. And most of the promoters of MADS genes contain cis-elements related to stress and hormonal response. RNA-seq and quantitative Real-time PCR (qRT-PCR) analysis also were examined. SiMADS genes expression levels are considerably changed in reaction to various treatments, following qRT-PCR analysis. This sheds fresh light on the evolution and expansion of the MADS family in foxtail millet, green millet, and switchgrass, and lays the foundation for further research on their functions.

Multiple transcriptome comparisons reveal the essential roles of FLOWERING LOCUS T in floral initiation and SOC1 and SVP in floral activation in blueberry

The flowering mechanisms, especially chilling requirement-regulated flowering, in deciduous woody crops remain to be elucidated. Flower buds of northern highbush blueberry cultivar Aurora require approximately 1,000 chilling hours to bloom. Overexpression of a blueberry FLOWERING LOCUS T (VcFT) enabled precocious flowering of transgenic “Aurora” mainly in non-terminated apical buds during flower bud formation, meanwhile, most of the mature flower buds could not break until they received enough chilling hours. In this study, we highlighted two groups of differentially expressed genes (DEGs) in flower buds caused by VcFT overexpression (VcFT-OX) and full chilling. We compared the two groups of DEGs with a focus on flowering pathway genes. We found: 1) In non-chilled flower buds, VcFT-OX drove a high VcFT expression and repressed expression of a major MADS-box gene, blueberry SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (VcSOC1) resulting an increased VcFT/VcSOC1 expression ratio; 2) In fully chilled flower buds that are ready to break, the chilling upregulated VcSOC1 expression in non-transgenic “Aurora” and repressed VcFT expression in VcFT-OX “Aurora”, and each resulted in a decreased ratio of VcFT to VcSOC1; additionally, expression of a blueberry SHORT VEGETATIVE PHASE (VcSVP) was upregulated in chilled flower buds of both transgenic and non-transgenic’ “Aurora”. Together with additional analysis of VcFT and VcSOC1 in the transcriptome data of other genotypes and tissues, we provide evidence to support that VcFT expression plays a significant role in promoting floral initiation and that VcSOC1 expression is a key floral activator. We thus propose a new hypothesis on blueberry flowering mechanism, of which the ratios of VcFT-to-VcSOC1 at transcript levels in the flowering pathways determine flower bud formation and bud breaking. Generally, an increased VcFT/VcSOC1 ratio or increased VcSOC1 in leaf promotes precocious flowering and flower bud formation, and a decreased VcFT/VcSOC1 ratio with increased VcSOC1 in fully chilled flower buds contributes to flower bud breaking.

Genome-Wide Identification of the MADS-Box Gene Family during Male and Female Flower Development in Chayote (Sechium edule)

The MADS-box gene plays an important role in plant growth and development. As an important vegetable of Cucurbitaceae, chayote has great edible and medicinal value. So far, there is little molecular research on chayote, and there are no reports on the MADS-box transcription factor of chayote. In this study, the MADS-box gene family of chayote was analyzed for the first time, and a total of 70 MADS-box genes were identified, including 14 type I and 56 type II MICK MADS genes. They were randomly distributed on 13 chromosomes except for chromosome 11. The light response element, hormone response element and abiotic stress response element were found in the promoter region of 70 MADS genes, indicating that the MADS gene can regulate the growth and development of chayote, resist abiotic stress, and participate in hormone response; GO and KEGG enrichment analysis also found that SeMADS genes were mainly enriched in biological regulation and signal regulation, which further proved the important role of MADS-box gene in plant growth and development. The results of collinearity showed that segmental duplication was the main driving force of MADS gene expansion in chayote. RNA-seq showed that the expression levels of SeMADS06, SeMADS13, SeMADS26, SeMADS28, SeMADS36 and SeMADS37 gradually increased with the growth of chayote, indicating that these genes may be related to the development of root tubers of 'Tuershao'. The gene expression patterns showed that 12 SeMADS genes were specifically expressed in the male flower in 'Tuershao' and chayote. In addition, SeMADS03 and SeMADS52 may be involved in regulating the maturation of male flowers of 'Tuershao' and chayote. SeMADS21 may be the crucial gene in the development stage of the female flower of 'Tuershao'. This study laid a theoretical foundation for the further study of the function of the MADS gene in chayote in the future.

Genome wide association analysis for yield related traits in maize

BACKGROUND

Understanding the genetic basis of yield related traits contributes to the improvement of grain yield in maize.

RESULTS

Using 291 excellent maize inbred lines as materials, six yield related traits of maize, including grain yield per plant (GYP), grain length (GL), grain width (GW), kernel number per row (KNR), 100 kernel weight (HKW) and tassel branch number (TBN) were investigated in Jinan, in 2017, 2018 and 2019. The average values of three environments were taken as the phenotypic data of yield related traits, and they were statistically analyzed. Based on 38,683 high-quality SNP markers in the whole genome of the association panel, the MLM with PCA model was used for genome-wide association analysis (GWAS) to obtain 59 significantly associated SNP sites. Moreover, 59 significantly associated SNPs (P < 0.0001) referring to GYP, GL, GW, KNR, HKW and TBN, of which 14 SNPs located in yield related QTLs/QTNs previously reported. A total of 66 candidate genes were identified based on the 59 significantly associated SNPs, of which 58 had functional annotation.

CONCLUSIONS

Using genome-wide association analysis strategy to identify genetic loci related to maize yield, a total of 59 significantly associated SNP were detected. Those results aid in our understanding of the genetic architecture of maize yield and provide useful SNPs for genetic improvement of maize.

Height to first pod: A review of genetic and breeding approaches to improve combine harvesting in legume crops

Height from soil at the base of plant to the first pod (HFP) is an important trait for mechanical harvesting of legume crops. To minimise the loss of pods, the HFP must be higher than that of the blades of most combine harvesters. Here, we review the genetic control, morphology, and variability of HFP in legumes and attempt to unravel the diverse terminology for this trait in the literature. HFP is directly related to node number and internode length but through different mechanisms. The phenotypic diversity and heritability of HFP and their correlations with plant height are very high among studied legumes. Only a few publications describe a QTL analysis where candidate genes for HFP with confirmed gene expression have been mapped. They include major QTLs with eight candidate genes for HFP, which are involved in auxin transport and signal transduction in soybean [Glycine max (L.) Merr.] as well as MADS box gene SOC1 in Medicago trancatula, and BEBT or WD40 genes located nearby in the mapped QTL in common bean (Phaseolus vulgaris L.). There is no information available about simple and efficient markers associated with HFP, which can be used for marker-assisted selection for this trait in practical breeding, which is still required in the nearest future. To our best knowledge, this is the first review to focus on this significant challenge in legume-based cropping systems.

Identification and expression analysis of the MADS-box genes of Kentucky bluegrass during inflorescence development

MADS-box genes play vital roles in multiple biological processes of plants growth and development, especially inflorescence development. In the present study, a comprehensive investigation into the identification and classification of MADS-box genes in Kentucky bluegrass (Poa pratensis) has not been reported. Here, based on the transcriptome of inflorescence, we identified 44 PpMADS-box genes, and gave an overview of the physicochemical properties, phylogeny, protein structures, and potential functions of the proteins encoded by these genes through various bioinformatics software for the first time. Analysis of physicochemical properties revealed that most PpMADS-box were alkaline proteins and possessed similar conserved motifs. Additionally, it was demonstrated that 33 PpMADS-box proteins without signal peptide, leading peptide, transmembrane structure and located in the nucleus were not transported or secreted, so directly played transcriptional regulatory roles in the nucleus. Then, peptide sequences BLAST search and analysis of phylogenetic relationships with MADS-box proteins of P. pratensis, Arabidopsis thaliana, and Oryza sativa were performed. It was found that 44 PpMADS-box proteins were separated into 33 MIKC-type (3 BS, 1 AGL17, 8 AP3/P2, 3 AP1, 5 SEP, 6 SOC and 7 AG genes, respectvely) and 11 type I-type, which include 7 Mγ and 4 Mα. Furthermore, the relative expression levels of the selected 12 genes (MADS3, 15, 16, 17, 18, 20, 24, 27, 30, 36, 38 and 40) at the booting stage, pre-anthesis, anthesis, post-anthesis, and seed filling stage of inflorescences, as well as leaves and roots of the corresponding stages of inflorescences were analyzed, showing that most PpMADS-box genes were highly expressed mainly in young leaves and later inflorescences, and had complex patters in roots. Morever, except for PpMADS30 being highly expressed in the leaves, others were significantly highly expressed in inflorescence and/ or roots, demonstrating PpMADS-box genes also regulate leaves and roots development in plant. This study provides valuable insights into the MADS-box family genes in Kentucky bluegrass and its potential functional characteristics, expression pattern, and evolution in floral organogenesis and even reproduction development. @media print { .ms-editor-squiggler { display:none !important; } } .ms-editor-squiggler { all: initial; display: block !important; height: 0px !important; width: 0px !important; }.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-022-01216-1.

zmm28 transgenic maize increases both N uptake- and N utilization-efficiencies

Biotechnology has emerged as a valuable tool in the development of maize (Zea mays L.) hybrids with enhanced nitrogen (N) use efficiency. Recent work has described the positive effects of an increased and extended expression of the zmm28 transcription factor (Event DP202216) on maize yield productivity. In this study, we expand on the previous findings studying maize N uptake and utilization in DP202216 transgenic hybrids compared to wild-type (WT) controls. Isotope ¹⁵N labeling demonstrates that DP202216 hybrids have an improved N uptake during late-vegetative stages (inducing N storage in lower leaves of the canopy) and, thus, N uptake efficiency (N uptake to applied N ratio) relative to WT. Through both greater N harvest index and reproductive N remobilization, transgenic plants were able to achieve better N utilization efficiency (yield to N uptake ratio). Our findings suggest the DP202216 trait could open new avenues for improving N uptake and utilization efficiencies in maize.

Characterization of Phytohormones and Transcriptomic Profiling of the Female and Male Inflorescence Development in Manchurian Walnut (Juglans mandshurica Maxim.)

Flowers are imperative reproductive organs and play a key role in the propagation of offspring, along with the generation of several metabolic products in flowering plants. In Juglans mandshurica, the number and development of flowers directly affect the fruit yield and subsequently its commercial value. However, owing to the lack of genetic information, there are few studies on the reproductive biology of Juglans mandshurica, and the molecular regulatory mechanisms underlying the development of female and male inflorescence remain unclear. In this study, phytohormones and transcriptomic sequencing analyses at the three stages of female and male inflorescence growth were performed to understand the regulatory functions underlying flower development. Gibberellin is the most dominant phytohormone that regulates flower development. In total, 14,579 and 7188 differentially expressed genes were identified after analyzing the development of male and female flowers, respectively, wherein, 3241 were commonly expressed. Enrichment analysis for significantly enriched pathways suggested the roles of MAPK signaling, phytohormone signal transduction, and sugar metabolism. Genes involved in floral organ transition and flowering were obtained and analyzed; these mainly belonged to the M-type MADS-box gene family. Three flowering-related genes (SOC1/AGL20, ANT, and SVP) strongly interacted with transcription factors in the co-expression network. Two key CO genes (CO3 and CO1) were identified in the photoperiod pathway. We also identified two GA20xs genes, one SVP gene, and five AGL genes (AGL8, AGL9, AGL15, AGL19, and AGL42) that contributed to flower development. The findings are expected to provide a genetic basis for the studies on the regulatory networks and reproductive biology in inflorescence development for J. mandshurica.