Dataset Information

Candidate regulators of Early Leaf Development in Maize Perturb Hormone Signalling and Secondary Cell Wall Formation When Constitutively Expressed in Rice.

ABSTRACT: All grass leaves are strap-shaped with a series of parallel veins running from base to tip, but the distance between each pair of veins, and the cell-types that develop between them, differs depending on whether the plant performs C3 or C4 photosynthesis. As part of a multinational effort to introduce C4 traits into rice to boost crop yield, candidate regulators of C4 leaf anatomy were previously identified through an analysis of maize leaf transcriptomes. Here we tested the potential of 60 of those candidate genes to alter leaf anatomy in rice. In each case, transgenic rice lines were generated in which the maize gene was constitutively expressed. Lines grouped into three phenotypic classes: (1) indistinguishable from wild-type; (2) aberrant shoot and/or root growth indicating possible perturbations to hormone homeostasis; and (3) altered secondary cell wall formation. One of the genes in class 3 defines a novel monocot-specific family. None of the genes were individually sufficient to induce C4-like vein patterning or cell-type differentiation in rice. A better understanding of gene function in C4 plants is now needed to inform more sophisticated engineering attempts to alter leaf anatomy in C3 plants.

SUBMITTER: Wang P

PROVIDER: S-EPMC5495811 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature

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Candidate regulators of Early Leaf Development in Maize Perturb Hormone Signalling and Secondary Cell Wall Formation When Constitutively Expressed in Rice.

Wang Peng P Karki Shanta S Biswal Akshaya K AK Lin Hsiang-Chun HC Dionora Mary Jacqueline MJ Rizal Govinda G Yin Xiaojia X Schuler Mara L ML Hughes Tom T Fouracre Jim P JP Jamous Basel Abu BA Sedelnikova Olga O Lo Shuen-Fang SF Bandyopadhyay Anindya A Yu Su-May SM Kelly Steven S Quick W Paul WP Langdale Jane A JA

Scientific reports 20170703 1

All grass leaves are strap-shaped with a series of parallel veins running from base to tip, but the distance between each pair of veins, and the cell-types that develop between them, differs depending on whether the plant performs C3 or C4 photosynthesis. As part of a multinational effort to introduce C4 traits into rice to boost crop yield, candidate regulators of C4 leaf anatomy were previously identified through an analysis of maize leaf transcripto ...[more]

PMID: 28674432

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Project description:BackgroundLeaf angle is a key trait for maize plant architecture that plays a significant role in its morphological development, and ultimately impacting maize grain yield. Although many studies have been conducted on the association and localization of genes regulating leaf angle in maize, most of the candidate genes identified are associated with the regulation of ligule-ear development and phytohormone pathways, and only a few candidate genes have been reported to enhance the mechanical strength of leaf midrib and vascular tissues.ResultsTo address this gap, we conducted a genome-wide association study (GWAS) using the leaf angle phenotype and genotyping-by-sequencing data generated from three recombinant inbred line (RIL) populations of maize. Through GWAS analysis, we identified 156 SNPs significantly associated with the leaf angle trait and detected a total of 68 candidate genes located within 10 kb upstream and downstream of these individual SNPs. Among these candidate genes, Zm00001d045408, located on chromosome 9 emerged as a key gene controlling the angles of both the ear leaf and the second leaf above the ear leaf. Notably, this new gene's homolog in Arabidopsis promotes cell division and vascular tissue development. Further analysis revealed that a SNP transversion (G/T) at 7.536 kb downstream of the candidate gene Zm00001d045408 may have caused a reduction in leaf angles of the ear and the second leaf above the ear leaf. Our analysis of the 10 kb region downstream of this candidate gene revealed a 4.337 kb solo long-terminal reverse transcription transposon (solo LTR), located 3.112 kb downstream of Zm00001d045408, with the SNP located 87 bp upstream of the solo LTR.ConclusionsIn summary, we have identified a novel candidate gene, Zm00001d045408 and a solo LTR that are associated with the angles of both the ear leaf and the second leaf above the ear leaf. The future research holds great potential in exploring the precise role of newly identified candidate gene in leaf angle regulation. Functional characterization of this gene can help in gaining deeper insights into the complex genetic pathways underlying maize plant architecture.

Project description:BACKGROUND: R2R3 MYB proteins constitute one of the largest plant transcription factor clades and regulate diverse plant-specific processes. Several R2R3 MYB proteins act as regulators of secondary cell wall (SCW) biosynthesis in Arabidopsis thaliana (At), a dicotyledenous plant. Relatively few studies have examined SCW R2R3 MYB function in grasses, which may have diverged from dicots in terms of SCW regulatory mechanisms, as they have in cell wall composition and patterning. Understanding cell wall regulation is especially important for improving lignocellulosic bioenergy crops, such as switchgrass. RESULTS: Here, we describe the results of applying phylogenic, OrthoMCL, and sequence identity analyses to classify the R2R3 MYB family proteins from the annotated proteomes of Arabidposis, poplar, rice, maize and the initial genome (v0.0) and translated transcriptome of switchgrass (Panicum virgatum). We find that the R2R3 MYB proteins of the five species fall into 48 subgroups, including three dicot-specific, six grass-specific, and two panicoid grass-expanded subgroups. We observe four classes of phylogenetic relationships within the subgroups of known SCW-regulating MYB proteins between Arabidopsis and rice, ranging from likely one-to-one orthology (for AtMYB26, AtMYB103, AtMYB69) to no homologs identifiable (for AtMYB75). Microarray data for putative switchgrass SCW MYBs indicate that many maintain similar expression patterns with the Arabidopsis SCW regulators. However, some of the switchgrass-expanded candidate SCW MYBs exhibit differences in gene expression patterns among paralogs, consistent with subfunctionalization. Furthermore, some switchgrass representatives of grass-expanded clades have gene expression patterns consistent with regulating SCW development. CONCLUSIONS: Our analysis suggests that no single comparative genomics tool is able to provide a complete picture of the R2R3 MYB protein family without leaving ambiguities, and establishing likely false-negative and -positive relationships, but that used together a relatively clear view emerges. Generally, we find that most R2R3 MYBs that regulate SCW in Arabidopsis are likely conserved in the grasses. This comparative analysis of the R2R3 MYB family will facilitate transfer of understanding of regulatory mechanisms among species and enable control of SCW biosynthesis in switchgrass toward improving its biomass quality.

Project description:GBB1, a heterotrimeric G-protein β-subunit gene, was shown to be a key regulator of fumonisin B(1) (FB(1) ) biosynthesis in the maize pathogen Fusarium verticillioides. In this study, we performed functional analyses of genes that encode putative RGS (regulators of G-protein signalling) proteins and PhLPs (phosducin-like proteins) in F. verticillioides. These proteins are known to regulate heterotrimeric G-protein activity by altering the intrinsic guanosine triphosphatase (GTPase) activity, which, in turn, influences the signalling mechanisms that control fungal growth, virulence and secondary metabolism. Our aim was to isolate and characterize gene(s) that are under the transcriptional control of GBB1, and to test the hypothesis that these genes are directly associated with FB(1) regulation and fungal development in F. verticillioides on maize kernels. We first identified eight genes (two PhLPs and six RGSs) in the F. verticillioides genome, and a subsequent transcriptional expression study revealed that three RGS genes were up-regulated in the gbb1 deletion (Δgbb1) mutant and one RGS gene was up-regulated in the wild-type. To characterize their function, we generated knockout mutants using a homologous recombination strategy. When grown on autoclaved nonviable kernels, two mutants (ΔflbA2 and ΔrgsB) produced significantly higher levels of FB(1) compared with the wild-type progenitor, suggesting that the two mutated genes are negative regulators of FB(1) biosynthesis. ΔflbA2 also showed a severe curly conidia germination pattern, which was contradictory to that observed in the Δgbb1 strain. Strikingly, when these mutants were grown on live maize kernels, we observed contrasting FB(1) and conidiation phenotypes in fungal mutants, which strongly suggests that these G-protein regulators have an impact on how F. verticillioides responds to host/environmental factors. Our data also provide evidence that fungal G-protein signalling is important for modulating the ethylene biosynthetic pathway in maize kernels.

Dataset Information

Candidate regulators of Early Leaf Development in Maize Perturb Hormone Signalling and Secondary Cell Wall Formation When Constitutively Expressed in Rice.

Publications

Candidate regulators of Early Leaf Development in Maize Perturb Hormone Signalling and Secondary Cell Wall Formation When Constitutively Expressed in Rice.

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