Max Planck Institute for Plant Breeding Research, Quantitative Crop Genetics, 50829 Cologne, Germany.
BMC Plant Biol. 2013 Dec 13;13:213. doi: 10.1186/1471-2229-13-213.
Improving nutrient homeostasis is a major challenge of a sustainable maize cultivation, and cornerstone to ensure food supply for a growing world population. Although, iron constitutes an important nutrient, iron availability is limited. In this respect, iron deficiency associated chlorosis causes severe yield losses every year. Natural variation of the latter trait has yet not been addressed in maize and was therefore studied in the present analysis.
In this study, we i) report about the contrasting chlorosis phenotypes of the inbreds B73 and Mo17 at 10 and 300 μM iron regime, ii) identified over 400 significantly regulated transcripts (FDR < 0.05) within both inbreds at these growth conditions by deep RNA-Sequencing, iii) linked the gained knowledge with QTL information about iron deficiency related traits within the maize intermated B73 by Mo17 (IBM) population, and iv) highlighted contributing molecular pathways. In this respect, several genes within methionine salvage pathway and phytosiderophore synthesis were found to present constitutively high expression in Mo17, even under sufficient iron supply. Moreover, the same expression pattern could be observed for two putative bHLH transcription factors. In addition, a number of differentially expressed genes showed a co-localisation with QTL confidence intervals for iron deficiency related traits within the IBM population.
Our study highlights differential iron deficiency associated chlorosis between B73 and Mo17 and represents a valuable resource for differentially expressed genes upon iron limitation and chlorosis response. Besides identifying two putative bHLH transcription factors, we propose that methionine salvage pathway and sterol metabolism amongst others; underlie the contrasting iron deficiency related chlorosis phenotype of both inbreds. Altogether, this study emphasizes a contribution of selected genes and pathways on natural trait variation within the IBM population.
提高养分稳态是可持续玉米种植的主要挑战，也是确保不断增长的世界人口粮食供应的基石。尽管铁是一种重要的营养物质，但铁的可用性是有限的。在这方面，与缺铁相关的黄化每年都会导致严重的产量损失。目前还没有在玉米中研究过这种特性的自然变异，因此在本分析中进行了研究。
在这项研究中，我们：i）报告了自交系 B73 和 Mo17 在 10 和 300 μM 铁浓度下的对比黄化表型，ii）通过深度 RNA 测序在这两种自交系中鉴定了 400 多个差异表达的转录本（FDR < 0.05），iii）将所得知识与玉米互交 B73 由 Mo17（IBM）群体中与缺铁相关性状的 QTL 信息联系起来，iv）突出了贡献的分子途径。在这方面，在 Mo17 中，即使在铁供应充足的情况下，几种蛋氨酸回收途径和植物铁载体合成的基因也被发现表达水平较高。此外，两个假定的 bHLH 转录因子也可以观察到相同的表达模式。此外，一些差异表达的基因与 IBM 群体中与缺铁相关性状的 QTL 置信区间有共同定位。
我们的研究强调了 B73 和 Mo17 之间与缺铁相关的黄化差异，并为铁限制和黄化反应时差异表达基因提供了有价值的资源。除了鉴定两个假定的 bHLH 转录因子外，我们还提出蛋氨酸回收途径和固醇代谢等途径；是这两个自交系中与缺铁相关的黄化表型差异的基础。总的来说，这项研究强调了选定基因和途径对 IBM 群体中自然性状变异的贡献。
