Poster Abstract

The inhibition of plant growth is recognized as the primary effect of water deficit. The effort to minimize the impact of drought on growth and consequently yield requires new approaches to bridge the gap between traditional breeding and molecular genetics. Plant adaptation to environmental stresses is dependent upon the activation of cascades of molecular networks, signal transduction pathways, and the expression of stress-related genes and metabolites. The objective of the study is to understand the mechanisms involved in plant growth maintenance during water deficit by comparing gene expression in well-watered plants with those under water stress and to try to associate the differentially expressed genes with genomic regions linked with drought traits. To identify genes associated with growth maintenance under drought, transcriptome analyses of four maize lines from a CIMMYT mapping population (2 drought-tolerant and 2 drought susceptible) were performed in a multiple-organ study (leaf, silk and root) under well-watered and water-deficit conditions (at water potential of -0.5 MPa). The studied lines were chosen for their contrasting responses of leaf elongation rate to soil water potential and were tested in controlled environments (greenhouse and growth chamber experiments for silk and root tissue in France and Switzerland), and in field environments (for leaf and silk tissue in Mexico). EASE pathway assignments tool allows to identify general classes of genes that are over-represented and was used to classify the differentially expressed genes from the microarray expression profiling in functional categories of interest related to growth maintenance. It revealed that 12, 112, 58 and 92 candidate genes are associated with growth functional category and 102, 886, 415 and 848 are associated with diverse metabolic processes, respectively in root and silk tissue from the greenhouse experiments and in leaf and silk tissue from the field experiments. The growth-associated genes include important enzymes such as alpha- and beta-expansins, xyloglucan endo-transglucosylase/hydrolase; and important phytohormones factors such as auxin response factor, brassinosteroid precursor or ethylene response factor. Association studies will be carried out to re-confirm the selected candidate genes using an allele-mining approach. By re-sequencing these genes in genotypes known to have different responses to growth maintenance under drought, we will look for SNPs that are associated with growth maintenance within a diverse panel of maize lines. The expected output will be a drought genetic map for tissue elongation, combining genes expression data, QTLs data, and markers data (SSRs, RFLPs, SNPs).

English

Lucia Segura

CIMMYT Staff Publications Collection