Liu Haipei, Able Amanda J, Able Jason A
School of Agriculture, Food and Wine, University of Adelaide, Waite Research Institute, PMB 1, Glen Osmond, SA 5064, Australia.
Funct Plant Biol. 2017 May;44(5):538-551. doi: 10.1071/FP16294.
In Mediterranean environments, water-deficit stress that occurs before anthesis significantly limits durum wheat (Triticum turgidum L. ssp. durum) production. Stress tolerant and stress sensitive durum varieties exhibit genotypic differences in their response to pre-anthesis water-deficit stress as reflected by yield performance, but our knowledge of the mechanisms underlying tolerance is limited. We have previously identified stress responsive durum microRNAs (miRNAs) that could contribute to water-deficit stress tolerance by mediating post-transcriptional silencing of genes that lead to stress adaptation (e.g. miR160 and its targets ARF8 (auxin response factor 8) and ARF18). However, the temporal regulation pattern of miR160-ARFs after induction of pre-anthesis water-deficit stress in sensitive and tolerant varieties remains unknown. Here, the physiological responses of four durum genotypes are described by chlorophyll content, leaf relative water content, and stomatal conductance at seven time-points during water-deficit stress from booting to anthesis. qPCR examination of miR160, ARF8 and ARF18 at these time-points revealed a complex stress responsive regulatory pattern, in the flag leaf and the head, subject to genotype. Harvest components and morphological traits measured at maturity confirmed the stress tolerance level of these four varieties for agronomic performance, and their potential association with the physiological responses. In general, the distinct regulatory pattern of miR160-ARFs among stress tolerant and sensitive durum varieties suggests that miRNA-mediated molecular pathways may contribute to the genotypic differences in the physiological traits, ultimately affecting yield components (e.g. the maintenance of harvest index and grain number).
在地中海环境中，抽穗前发生的缺水胁迫显著限制了硬粒小麦（Triticum turgidum L. ssp. durum）的产量。耐胁迫和胁迫敏感的硬粒小麦品种在对抽穗前缺水胁迫的反应上表现出基因型差异，这一点通过产量表现得以体现，但我们对耐受性潜在机制的了解有限。我们之前已鉴定出对胁迫有反应的硬粒小麦微小RNA（miRNA），它们可能通过介导导致胁迫适应的基因的转录后沉默（例如miR160及其靶标ARF8（生长素反应因子8）和ARF18）来促进对缺水胁迫的耐受性。然而，在敏感和耐受品种中，抽穗前缺水胁迫诱导后miR160 - ARFs的时间调控模式仍不清楚。在此，描述了四种硬粒小麦基因型在从孕穗期到抽穗期的缺水胁迫期间七个时间点的叶绿素含量、叶片相对含水量和气孔导度等生理反应。在这些时间点对miR160、ARF8和ARF18进行qPCR检测，结果显示在旗叶和穗部存在受基因型影响的复杂胁迫反应调控模式。在成熟期测量的收获构成要素和形态性状证实了这四个品种在农艺性能方面的胁迫耐受水平，以及它们与生理反应的潜在关联。总体而言，耐胁迫和敏感硬粒小麦品种之间miR160 - ARFs的不同调控模式表明，miRNA介导的分子途径可能导致生理性状的基因型差异，最终影响产量构成要素（例如收获指数和粒数的维持）。
