Table_1_Genome-Wide Associations of Chlorophyll Fluorescence OJIP Transient Parameters Connected With Soil Drought Response in Barley.doc

One hundred and nine accessions of spring barley seedlings were phenotyped under soil drought conditions. Chlorophyll fluorescence induction (OJIP) parameters, leaf water content, relative turgidity, net assimilation rate (PN), and water use efficiency (WUE) of plants were measured. All the tested lines were genotyped by means of DArT sequencing (DArTseq) technology. For association mapping a 11,780 polymorphic DArTseq and 4,725 DArTseq SNP markers were used. Our results revealed dissimilar patterns of the relationships between OJIP-parameters under control and drought conditions. A high level of correlation between parameters characterizing Photosystem's II (PSII) energy trapping efficiency (Fv/Fm) and photochemical events downstream of PSII reaction center (e.g., Performance Index—PICSo) was observed only in the case of drought-treated plants. Generally, OJIP parameters were correlated with leaf water content (less in control). This correlation was weaker with WUE, and absent with PN. Under drought stress, 6,252 genotype × phenotype associations, which passed false discovery rate (FDR) verification, were found between all the studied phenotypic characteristics (23, including 19 OJIP parameters) and 2,721 markers. On the other hand, only 282 associations passed FDR test in the control. They comprised 22 phenotypic parameters and 205 markers. Probing for gene annotations of sequences was performed for markers associated with Fv/Fm for both drought and control, markers were associated with studied traits in both control and drought, as well as for markers associated with both OJIP and other physiological parameters in drought. Our work allowed us to conclude that drought treatment differentiates the studied lines through the revealing of relationships between water content and the damages to PSII reaction centers or different components of PSII energy transfer chain. Moreover, the former was not connected with net photosynthesis rate.

本研究以109份春大麦幼苗为供试材料，在土壤干旱条件下开展表型鉴定。测定了植株的叶绿素荧光诱导动力学（OJIP）参数、叶片含水量、相对膨压、净同化速率（PN）以及水分利用效率（WUE）。采用DArT测序（DArTseq）技术对所有供试材料进行基因型分型。关联定位分析共使用了11780个多态性DArTseq标记与4725个DArTseq单核苷酸多态性（SNP）标记。研究结果显示，对照组与干旱组的OJIP参数间关联模式存在显著差异。仅在干旱处理植株中，光系统II（PSII）能量捕获效率（Fv/Fm）相关参数与PSII反应中心下游光化学事件（如性能指数PICSo）之间呈现高度相关性。总体而言，OJIP参数与叶片含水量存在相关性（对照组中相关性更弱）；该相关性与WUE的关联程度较弱，与PN则无显著关联。在干旱胁迫下，本研究共检测到6252个通过错误发现率（FDR）验证的基因型-表型关联，涉及全部23项表型性状（含19项OJIP参数）与2721个分子标记。反观对照组，仅282个关联通过FDR检验，涉及22项表型参数与205个分子标记。针对干旱组与对照组中与Fv/Fm相关的分子标记、两组中与目标性状相关的标记，以及干旱组中同时与OJIP参数及其他生理性状相关的标记，本研究均开展了序列基因注释查询。本研究结论表明，干旱处理通过揭示叶片含水量与PSII反应中心损伤或PSII能量传递链各组分受损之间的关联，实现了对供试材料的区分。此外，该关联与净光合速率并无关联。