Fisher Lorraine H C, Han Jiwan, Corke Fiona M K, Akinyemi Aderemi, Didion Thomas, Nielsen Klaus K, Doonan John H, Mur Luis A J, Bosch Maurice
Institute of Biological, Environmental and Rural Sciences, Aberystwyth University Aberystwyth, UK.
The National Plant Phenomics Centre, Institute of Biological, Environmental and Rural Sciences, Aberystwyth University Aberystwyth, UK.
Front Plant Sci. 2016 Nov 29;7:1751. doi: 10.3389/fpls.2016.01751. eCollection 2016.
Drought is an important environmental stress limiting the productivity of major crops worldwide. Understanding drought tolerance and possible mechanisms for improving drought resistance is therefore a prerequisite to develop drought-tolerant crops that produce significant yields with reduced amounts of water. (Brachypodium) is a key model species for cereals, forage grasses, and energy grasses. In this study, initial screening of a Brachypodium germplasm collection consisting of 138 different ecotypes exposed to progressive drought, highlighted the natural variation in morphology, biomass accumulation, and responses to drought stress. A core set of ten ecotypes, classified as being either tolerant, susceptible or intermediate, in response to drought stress, were exposed to mild or severe (respectively, 15 and 0% soil water content) drought stress and phenomic parameters linked to growth and color changes were assessed. When exposed to severe drought stress, phenotypic data and metabolite profiling combined with multivariate analysis revealed a remarkable consistency in separating the selected ecotypes into their different pre-defined drought tolerance groups. Increases in several metabolites, including for the phytohormones jasmonic acid and salicylic acid, and TCA-cycle intermediates, were positively correlated with biomass yield and with reduced yellow pixel counts; suggestive of delayed senescence, both key target traits for crop improvement to drought stress. While metabolite analysis also separated ecotypes into the distinct tolerance groupings after exposure to mild drought stress, similar analysis of the phenotypic data failed to do so, confirming the value of metabolomics to investigate early responses to drought stress. The results highlight the potential of combining the analyses of phenotypic and metabolic responses to identify key mechanisms and markers associated with drought tolerance in both the Brachypodium model plant as well as agronomically important crops.
干旱是一种重要的环境胁迫因素，限制了全球主要农作物的产量。因此，了解耐旱性以及提高抗旱性的可能机制，是培育耐旱作物的先决条件，这类作物能够在减少用水量的情况下实现高产。短柄草是谷类作物、饲草和能源草的关键模式物种。在本研究中，对138种不同生态型的短柄草种质资源进行渐进干旱处理的初步筛选，突出了形态、生物量积累以及对干旱胁迫反应方面的自然变异。一组核心的十种生态型，根据对干旱胁迫的反应分为耐旱型、敏感型或中间型，分别接受轻度或重度（土壤含水量分别为15%和0%）干旱胁迫，并评估与生长和颜色变化相关的表型参数。当受到重度干旱胁迫时，表型数据、代谢物谱分析与多变量分析相结合，结果显示在将所选生态型分为不同的预定义耐旱组方面具有显著的一致性。几种代谢物的增加，包括植物激素茉莉酸和水杨酸以及三羧酸循环中间产物，与生物量产量呈正相关，并且黄色像素计数减少；这表明衰老延迟，这两个都是作物改良以应对干旱胁迫的关键目标性状。虽然代谢物分析在轻度干旱胁迫后也将生态型分为不同的耐受组，但对表型数据的类似分析却未能做到这一点，这证实了代谢组学在研究对干旱胁迫早期反应方面的价值。研究结果突出了结合表型和代谢反应分析的潜力，以识别与短柄草模式植物以及具有重要农艺价值作物的耐旱性相关的关键机制和标记。
