Marino Rosanna, Ponnaiah Maharajah, Krajewski Pawel, Frova Carla, Gianfranceschi Luca, Pè M Enrico, Sari-Gorla Mirella
Department of Biomolecular Sciences and Biotechnology, University of Milano, Via Celoria 26, 20133, Milan, Italy.
Mol Genet Genomics. 2009 Feb;281(2):163-79. doi: 10.1007/s00438-008-0401-y. Epub 2008 Nov 19.
In order to unravel the genetic architecture underlying plant response to drought, we adopted an integrated approach, combining transcript profiling and quantitative trait loci (QTL) mapping. In fact, improving plant tolerance to water stress is an important, but, at the same time, a difficult task, since plant tolerance is the result of many complex mechanisms acting at different levels of plant organization, and its genetic basis is largely unknown. The phenotypic data, concerning yield components and flowering 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 significant QTLs distributed on nine chromosomes were identified. 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 field conditions. Two hundred and fifty-two genes were significantly affected 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 differentially 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 differentially expressed genes mapped in the same chromosomal segments harbouring QTLs for tolerance, thus representing candidate genes for further functional studies.
为了揭示植物对干旱响应的遗传结构，我们采用了一种综合方法，将转录谱分析和数量性状基因座（QTL）定位相结合。事实上，提高植物对水分胁迫的耐受性是一项重要但同时也很困难的任务，因为植物的耐受性是许多在植物组织不同水平起作用的复杂机制的结果，其遗传基础在很大程度上尚不清楚。对142个玉米重组自交系（RIL）群体在充分浇水条件或水分胁迫下生长的产量构成因素和开花时间的表型数据进行连锁分析，以检测耐旱QTL。共鉴定出30个基因组区域，其中包含分布在9条染色体上的50个显著QTL。同时，使用定制的靶向寡核苷酸芯片监测代表未成熟玉米籽粒转录组的1000个基因的表达水平。利用该DNA芯片，我们比较了在对照和水分胁迫田间条件下生长的两种敏感基因型和两种耐旱基因型（从我们的RIL中提取）授粉后10天籽粒的转录本。至少在一种基因型中，有252个基因受到胁迫的显著影响。从其中一组基因中开发了49个新的分子标记。通过对其中大多数标记进行定位以及对其他调控序列进行电子定位，88个差异表达基因被定位到我们的连锁图谱上，加上现有的186个标记，图谱上标记的总数达到274个。88个差异表达基因中有22个定位在含有耐受性QTL的相同染色体区段，因此代表了进一步功能研究的候选基因。
