1
|
Mahapatra K, Roy S. SOG1 transcription factor promotes the onset of endoreduplication under salinity stress in Arabidopsis. Sci Rep 2021; 11:11659. [PMID: 34079040 PMCID: PMC8172935 DOI: 10.1038/s41598-021-91293-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 05/20/2021] [Indexed: 01/24/2023] Open
Abstract
As like in mammalian system, the DNA damage responsive cell cycle checkpoint functions play crucial role for maintenance of genome stability in plants through repairing of damages in DNA and induction of programmed cell death or endoreduplication by extensive regulation of progression of cell cycle. ATM and ATR (ATAXIA-TELANGIECTASIA-MUTATED and -RAD3-RELATED) function as sensor kinases and play key role in the transmission of DNA damage signals to the downstream components of cell cycle regulatory network. The plant-specific NAC domain family transcription factor SOG1 (SUPPRESSOR OF GAMMA RESPONSE 1) plays crucial role in transducing signals from both ATM and ATR in presence of double strand breaks (DSBs) in the genome and found to play crucial role in the regulation of key genes involved in cell cycle progression, DNA damage repair, endoreduplication and programmed cell death. Here we report that Arabidopsis exposed to high salinity shows generation of oxidative stress induced DSBs along with the concomitant induction of endoreduplication, displaying increased cell size and DNA ploidy level without any change in chromosome number. These responses were significantly prominent in SOG1 overexpression line than wild-type Arabidopsis, while sog1 mutant lines showed much compromised induction of endoreduplication under salinity stress. We have found that both ATM-SOG1 and ATR-SOG1 pathways are involved in the salinity mediated induction of endoreduplication. SOG1was found to promote G2-M phase arrest in Arabidopsis under salinity stress by downregulating the expression of the key cell cycle regulators, including CDKB1;1, CDKB2;1, and CYCB1;1, while upregulating the expression of WEE1 kinase, CCS52A and E2Fa, which act as important regulators for induction of endoreduplication. Our results suggest that Arabidopsis undergoes endoreduplicative cycle in response to salinity induced DSBs, showcasing an adaptive response in plants under salinity stress.
Collapse
Affiliation(s)
- Kalyan Mahapatra
- Department of Botany, UGC Center for Advanced Studies, The University of Burdwan, Golapbag Campus, Burdwan, West Bengal, 713 104, India
| | - Sujit Roy
- Department of Botany, UGC Center for Advanced Studies, The University of Burdwan, Golapbag Campus, Burdwan, West Bengal, 713 104, India.
| |
Collapse
|
2
|
Kinetics of DNA Repair in Vicia faba Meristem Regeneration Following Replication Stress. Cells 2021; 10:cells10010088. [PMID: 33430297 PMCID: PMC7825715 DOI: 10.3390/cells10010088] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/29/2020] [Accepted: 01/04/2021] [Indexed: 12/14/2022] Open
Abstract
The astonishing survival abilities of Vicia faba, one the earliest domesticated plants, are associated, among other things, to the highly effective replication stress response system which ensures smooth cell division and proper preservation of genomic information. The most crucial pathway here seems to be the ataxia telangiectasia-mutated kinase (ATM)/ataxia telangiectasia and Rad3-related kinase (ATR)-dependent replication stress response mechanism, also present in humans. In this article, we attempted to take an in-depth look at the dynamics of regeneration from the effects of replication inhibition and cell cycle checkpoint overriding causing premature chromosome condensation (PCC) in terms of DNA damage repair and changes in replication dynamics. We were able to distinguish a unique behavior of replication factors at the very start of the regeneration process in the PCC-induced cells. We extended the experiment and decided to profile the changes in replication on the level of a single replication cluster of heterochromatin (both alone and with regard to its position in the nucleus), including the mathematical profiling of the size, activity and shape. The results obtained during these experiments led us to the conclusion that even “chaotic” events are dealt with in a proper degree of order.
Collapse
|
3
|
Borges F, Donoghue MTA, LeBlanc C, Wear EE, Tanurdžić M, Berube B, Brooks A, Thompson WF, Hanley-Bowdoin L, Martienssen RA. Loss of Small-RNA-Directed DNA Methylation in the Plant Cell Cycle Promotes Germline Reprogramming and Somaclonal Variation. Curr Biol 2020; 31:591-600.e4. [PMID: 33275892 DOI: 10.1016/j.cub.2020.10.098] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/24/2020] [Accepted: 10/30/2020] [Indexed: 02/07/2023]
Abstract
5-methyl cytosine is widespread in plant genomes in both CG and non-CG contexts. During replication, hemi-methylation on parental DNA strands guides symmetric CG methylation on nascent strands, but non-CG methylation requires modified histones and small RNA guides. Here, we used immortalized Arabidopsis cell suspensions to sort replicating nuclei and determine genome-wide cytosine methylation dynamics during the plant cell cycle. We find that symmetric mCG and mCHG are selectively retained in actively dividing cells in culture, whereas mCHH is depleted. mCG becomes transiently asymmetric during S phase but is rapidly restored in G2, whereas mCHG remains asymmetric throughout the cell cycle. Hundreds of loci gain ectopic CHG methylation, as well as 24-nt small interfering RNAs (siRNAs) and histone H3 lysine dimethylation (H3K9me2), without gaining CHH methylation. This suggests that spontaneous epialleles that arise in plant cell cultures are stably maintained by siRNA and H3K9me2 independent of the canonical RNA-directed DNA methylation (RdDM) pathway. In contrast, loci that fail to produce siRNA may be targeted for demethylation when the cell cycle arrests. Comparative analysis with methylomes of various tissues and cell types suggests that loss of small-RNA-directed non-CG methylation during DNA replication promotes germline reprogramming and epigenetic variation in plants propagated as clones.
Collapse
Affiliation(s)
- Filipe Borges
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA; Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, 78000 Versailles, France
| | - Mark T A Donoghue
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Chantal LeBlanc
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Emily E Wear
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Milos Tanurdžić
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Benjamin Berube
- Cold Spring Harbor Laboratory School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Ashley Brooks
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - William F Thompson
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Linda Hanley-Bowdoin
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Robert A Martienssen
- Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA.
| |
Collapse
|
4
|
Wear EE, Song J, Zynda GJ, Mickelson-Young L, LeBlanc C, Lee TJ, Deppong DO, Allen GC, Martienssen RA, Vaughn MW, Hanley-Bowdoin L, Thompson WF. Comparing DNA replication programs reveals large timing shifts at centromeres of endocycling cells in maize roots. PLoS Genet 2020; 16:e1008623. [PMID: 33052904 PMCID: PMC7588055 DOI: 10.1371/journal.pgen.1008623] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 10/26/2020] [Accepted: 08/28/2020] [Indexed: 12/20/2022] Open
Abstract
Plant cells undergo two types of cell cycles–the mitotic cycle in which DNA replication is coupled to mitosis, and the endocycle in which DNA replication occurs in the absence of cell division. To investigate DNA replication programs in these two types of cell cycles, we pulse labeled intact root tips of maize (Zea mays) with 5-ethynyl-2’-deoxyuridine (EdU) and used flow sorting of nuclei to examine DNA replication timing (RT) during the transition from a mitotic cycle to an endocycle. Comparison of the sequence-based RT profiles showed that most regions of the maize genome replicate at the same time during S phase in mitotic and endocycling cells, despite the need to replicate twice as much DNA in the endocycle and the fact that endocycling is typically associated with cell differentiation. However, regions collectively corresponding to 2% of the genome displayed significant changes in timing between the two types of cell cycles. The majority of these regions are small with a median size of 135 kb, shift to a later RT in the endocycle, and are enriched for genes expressed in the root tip. We found larger regions that shifted RT in centromeres of seven of the ten maize chromosomes. These regions covered the majority of the previously defined functional centromere, which ranged between 1 and 2 Mb in size in the reference genome. They replicate mainly during mid S phase in mitotic cells but primarily in late S phase of the endocycle. In contrast, the immediately adjacent pericentromere sequences are primarily late replicating in both cell cycles. Analysis of CENH3 enrichment levels in 8C vs 2C nuclei suggested that there is only a partial replacement of CENH3 nucleosomes after endocycle replication is complete. The shift to later replication of centromeres and possible reduction in CENH3 enrichment after endocycle replication is consistent with a hypothesis that centromeres are inactivated when their function is no longer needed. In traditional cell division, or mitosis, a cell’s genetic material is duplicated and then split between two daughter cells. In contrast, in some specialized cell types, the DNA is duplicated a second time without an intervening division step, resulting in cells that carry twice as much DNA. This phenomenon, which is called the endocycle, is common during plant development. At each step, DNA replication follows an ordered program in which highly compacted DNA is unraveled and replicated in sections at different times during the synthesis (S) phase. In plants, it is unclear whether traditional and endocycle programs are the same, especially since endocycling cells are typically in the process of differentiation. Using root tips of maize, we found that in comparison to replication in the mitotic cell cycle, there is a small portion of the genome whose replication in the endocycle is shifted in time, usually to later in S phase. Some of these regions are scattered around the genome and mostly coincide with active genes. However, the most prominent shifts occur in centromeres. The shift to later replication in centromeres is noteworthy because they orchestrate the process of separating duplicated chromosomes into daughter cells, a function that is not needed in the endocycle.
Collapse
Affiliation(s)
- Emily E. Wear
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
- * E-mail:
| | - Jawon Song
- Texas Advanced Computing Center, University of Texas, Austin, Texas, United States of America
| | - Gregory J. Zynda
- Texas Advanced Computing Center, University of Texas, Austin, Texas, United States of America
| | - Leigh Mickelson-Young
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Chantal LeBlanc
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Tae-Jin Lee
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - David O. Deppong
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - George C. Allen
- Department of Horticultural Science, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Robert A. Martienssen
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Matthew W. Vaughn
- Texas Advanced Computing Center, University of Texas, Austin, Texas, United States of America
| | - Linda Hanley-Bowdoin
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - William F. Thompson
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| |
Collapse
|
5
|
Dvořáčková M, Raposo B, Matula P, Fuchs J, Schubert V, Peška V, Desvoyes B, Gutierrez C, Fajkus J. Replication of ribosomal DNA in Arabidopsis occurs both inside and outside the nucleolus during S phase progression. J Cell Sci 2018; 131:jcs.202416. [PMID: 28483825 DOI: 10.1242/jcs.202416] [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: 02/10/2017] [Accepted: 04/06/2017] [Indexed: 12/14/2022] Open
Abstract
Ribosomal RNA genes (rDNA) have been used as valuable experimental systems in numerous studies. Here, we focus on elucidating the spatiotemporal organisation of rDNA replication in Arabidopsis thaliana To determine the subnuclear distribution of rDNA and the progression of its replication during the S phase, we apply 5-ethynyl-2'-deoxyuridine (EdU) labelling, fluorescence-activated cell sorting, fluorescence in situ hybridization and structured illumination microscopy. We show that rDNA is replicated inside and outside the nucleolus, where active transcription occurs at the same time. Nascent rDNA shows a maximum of nucleolar associations during early S phase. In addition to EdU patterns typical for early or late S phase, we describe two intermediate EdU profiles characteristic for mid S phase. Moreover, the use of lines containing mutations in the chromatin assembly factor-1 gene fas1 and wild-type progeny of fas1xfas2 crosses depleted of inactive copies allows for selective observation of the replication pattern of active rDNA. High-resolution data are presented, revealing the culmination of replication in the mid S phase in the nucleolus and its vicinity. Taken together, our results provide a detailed snapshot of replication of active and inactive rDNA during S phase progression.
Collapse
Affiliation(s)
- Martina Dvořáčková
- Laboratory of Molecular Complexes of Chromatin, Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Kamenice 5, Brno 62500, Czech Republic
| | - Berta Raposo
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, Madrid 28049, Spain
| | - Petr Matula
- Department of Computer Graphics and Design, Faculty of Informatics, Masaryk University, Botanická 554/68a, Brno 60200, Czech Republic
| | - Joerg Fuchs
- Breeding Research Department, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstrasse 3, Stadt Seeland D-06466, Germany
| | - Veit Schubert
- Breeding Research Department, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Corrensstrasse 3, Stadt Seeland D-06466, Germany
| | - Vratislav Peška
- Laboratory of Molecular Complexes of Chromatin, Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Kamenice 5, Brno 62500, Czech Republic.,Department of Cell Biology and Radiology, Institute of Biophysics ASCR, v.v.i., Královopolská 135, Brno 61265, Czech Republic
| | - Bénédicte Desvoyes
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, Madrid 28049, Spain
| | - Crisanto Gutierrez
- Department of Genome Dynamics and Function, Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, Madrid 28049, Spain
| | - Jiří Fajkus
- Laboratory of Molecular Complexes of Chromatin, Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Kamenice 5, Brno 62500, Czech Republic .,Department of Cell Biology and Radiology, Institute of Biophysics ASCR, v.v.i., Královopolská 135, Brno 61265, Czech Republic.,Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, Brno 61137, Czech Republic
| |
Collapse
|
6
|
Zynda GJ, Song J, Concia L, Wear EE, Hanley-Bowdoin L, Thompson WF, Vaughn MW. Repliscan: a tool for classifying replication timing regions. BMC Bioinformatics 2017; 18:362. [PMID: 28784090 PMCID: PMC5547489 DOI: 10.1186/s12859-017-1774-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 07/30/2017] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Replication timing experiments that use label incorporation and high throughput sequencing produce peaked data similar to ChIP-Seq experiments. However, the differences in experimental design, coverage density, and possible results make traditional ChIP-Seq analysis methods inappropriate for use with replication timing. RESULTS To accurately detect and classify regions of replication across the genome, we present Repliscan. Repliscan robustly normalizes, automatically removes outlying and uninformative data points, and classifies Repli-seq signals into discrete combinations of replication signatures. The quality control steps and self-fitting methods make Repliscan generally applicable and more robust than previous methods that classify regions based on thresholds. CONCLUSIONS Repliscan is simple and effective to use on organisms with different genome sizes. Even with analysis window sizes as small as 1 kilobase, reliable profiles can be generated with as little as 2.4x coverage.
Collapse
Affiliation(s)
- Gregory J Zynda
- Texas Advanced Computing Center, University of Texas at Austin, 10100 Burnet Road, Austin, 78758-4497, TX, USA
| | - Jawon Song
- Texas Advanced Computing Center, University of Texas at Austin, 10100 Burnet Road, Austin, 78758-4497, TX, USA
| | - Lorenzo Concia
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, 27695-7612, NC, USA
| | - Emily E Wear
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, 27695-7612, NC, USA
| | - Linda Hanley-Bowdoin
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, 27695-7612, NC, USA
| | - William F Thompson
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, 27695-7612, NC, USA
| | - Matthew W Vaughn
- Texas Advanced Computing Center, University of Texas at Austin, 10100 Burnet Road, Austin, 78758-4497, TX, USA.
| |
Collapse
|
7
|
Velázquez-López I, León-Cruz E, Pardo JP, Sosa-Peinado A, González-Andrade M. Development of new hCaM-Alexa Fluor ® biosensors for a wide range of ligands. Anal Biochem 2017; 516:13-22. [PMID: 27744023 DOI: 10.1016/j.ab.2016.10.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 10/05/2016] [Accepted: 10/11/2016] [Indexed: 11/17/2022]
Abstract
Eight new fluorescent biosensors of human calmodulin (hCaM) using Alexa Fluor® 350, 488, 532, and 555 dyes were constructed. These biosensors are thermodynamically stable, functional, and highly sensitive to ligands of the CaM. They resolve the problem of CaM ligands with similar spectroscopic properties to the intrinsic and extrinsic fluorophores of other biosensors previously reported. Additionally, they can be used in studies of protein-protein interaction through Förster resonance energy transfer (FRET). The variation in Tm (range 78.07-81.47 °C; 79.05 to WT) is no larger than two degrees in all cases in regards to CaM WT. The Kds calculated with all biosensors for CPZ and BIMI (a new inhibitor of CaM) are in the range of 0.45-1.86 and 0.69-1.54 μm respectively. All biosensors retain their ability to activate Calcineurin about 70%. Structural models built "in silico" show their possible conformation taking the fluorophores in protein thus we can predict system stability. Finally, these new biosensors represent a biotechnological development applied to an analytical problem, which aims to determine accurately the affinity of inhibitors of CaM without possible interference, to be put forward as possible drugs related to CaM.
Collapse
Affiliation(s)
- I Velázquez-López
- Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, C.P 04510, Mexico
| | - E León-Cruz
- Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, C.P 04510, Mexico
| | - J P Pardo
- Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, C.P 04510, Mexico
| | - A Sosa-Peinado
- Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, C.P 04510, Mexico
| | - M González-Andrade
- Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, C.P 04510, Mexico.
| |
Collapse
|
8
|
Mickelson-Young L, Wear E, Mulvaney P, Lee TJ, Szymanski ES, Allen G, Hanley-Bowdoin L, Thompson W. A flow cytometric method for estimating S-phase duration in plants. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:6077-6087. [PMID: 27697785 PMCID: PMC5100020 DOI: 10.1093/jxb/erw367] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The duration of the DNA synthesis stage (S phase) of the cell cycle is fundamental in our understanding of cell cycle kinetics, cell proliferation, and DNA replication timing programs. Most S-phase duration estimates that exist for plants are based on indirect measurements. We present a method for directly estimating S-phase duration by pulse-labeling root tips or actively dividing suspension cells with the halogenated thymidine analog 5-ethynl-2'-deoxyuridine (EdU) and analyzing the time course of replication with bivariate flow cytometry. The transition between G1 and G2 DNA contents can be followed by measuring the mean DNA content of EdU-labeled S-phase nuclei as a function of time after the labeling pulse. We applied this technique to intact root tips of maize (Zea mays L.), rice (Oryza sativa L.), barley (Hordeum vulgare L.), and wheat (Triticum aestivum L.), and to actively dividing cell cultures of Arabidopsis (Arabidopsis thaliana (L.) Heynh.) and rice. Estimates of S-phase duration in root tips were remarkably consistent, varying only by ~3-fold, although the genome sizes of the species analyzed varied >40-fold.
Collapse
Affiliation(s)
- Leigh Mickelson-Young
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Emily Wear
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Patrick Mulvaney
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - Tae-Jin Lee
- Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695, USA
- Present address: Syngenta Crop Protection, LLC, Research Triangle Park, NC 27709, USA
| | - Eric S Szymanski
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
- Present address: Department of Biochemistry, Duke University, Durham, NC 27710, USA
| | - George Allen
- Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695, USA
| | - Linda Hanley-Bowdoin
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| | - William Thompson
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA
| |
Collapse
|