Addressing drought tolerance in maize by transcriptional profiling and mapping

Abstract

In order to unravel the genetic architecture underlying plant response to drought, we adopted an integrated approach, combining transcript proWling and quantitative trait loci (QTL) mapping. In fact, improving plant tolerance to water stress is an important, but, at the same time, a diYcult task, since plant tolerance is the result of many complex mechanisms acting at diVerent levels of plant organization, and its genetic basis is largely unknown. The phenotypic data, concerning yield components and Xowering time, of a population of 142 maize Recombinant Inbred Lines (RILs), grown under well watered conditions or under water stress, were submitted to linkage analysis to detect drought-tolerance QTLs. Thirty genomic regions containing 50 signiWcant QTLs distributed on nine chromosomes were identiWed. At the same time, a customized targeted oligoarray was used to monitor the expression levels of 1,000 genes, representative of the immature maize kernel transcriptome. Using this DNA array we compared transcripts from 10 days after pollination kernels of two susceptible and two drought tolerant genotypes (extracted from our RILs) grown under control and water stress Weld conditions. Two hundred and Wfty-two genes were signiWcantly aVected by stress in at least one genotype. From a set of these, 49 new molecular markers were developed. By mapping most of them and by in silico mapping other regulated sequences, 88 diVerentially expressed genes were localized onto our linkage map, which, added to the existing 186 markers, brought their total number on the map to 274. Twenty-two of the 88 diVerentially expressed genes mapped in the same chromosomal segments harbouring QTLs for tolerance, thus representing candidate genes for further functional studies.

The ZmASR1 Protein Influences Branched-Chain Amino Acid Biosynthesis and Maintains Kernel Yield in Maize under Water-Limited Conditions

“…These results were unexpected based on our previous PQL study, which did not reveal any QTL for maize yield and its component in the vicinity of the ZmASR1 chromosomal region (de Vienne et al, 1999;Jeanneau et al, 2002). Nevertheless, it may be pointed out that recently identified QTLs for ear length under waterstressed conditions (Lu et al, 2006) and female flowering time (Marino et al, 2009) are centered on the ZmASR1 locus. The finding that ZmASR1-OE plants demonstrated significant improvements in ear leaf area and shoot biomass yield, as well as increases in leaf dry weight and total chlorophyll content, implies that these improvements in vegetative productivity translated into improvements in reproductive performance and kernel yield.…”

Combined Large-Scale Phenotyping and Transcriptomics in Maize Reveals a Robust Growth Regulatory Network

“…Previously, in-depth phenotyping of 103 lines of a biparental RIL population derived from the inbred parents B73 and H99 (Marino et al, 2009) was combined with transcriptome profiling to dissect leaf size, growth, and shoot-related traits into phenotypic and molecular components . Here, a similar analysis was conducted on the recently established multiparent MAGIC population , and results of both analyses were integrated.…”

“…A subset of 103 lines of a biparental RIL population derived from a cross between parental lines B73 and H99 (Marino et al, 2009) and a subset of 94 lines of a MAGIC maize population (Dell'Acqua et al, 2015) was phenotyped and sampled for RNA sequencing. The subset of 94 lines was chosen randomly from the set of 529 lines that was genotyped and phenotyped in the field (Dell' Acqua et al, 2015).…”

The relationship of proline content and metabolism on the productivity of maize plants

“…However there was also a higher total protein content found in leaf samples taken in 2009 (data not shown). It can be assumed that drought stimulated protein synthesis in the leaves, such as heat shock proteins, molecular chaperones, antioxidative enzymes or protein factors that might be involved in the regulation of signal transduction and expression of genes related to stress response, as reported by Marino et al 29 There was a large influence of both the locality in which they were grown and genotype on leaf, silk and pollen proline levels in the plants analysed. Plants grown at Porec had higher proline content in all tissues which were examined and both P5CS and PDH activities were lower in comparison with plants grown at Bicko Selo ( Table 2).…”