Attenuated accumulation of jasmonates modifies stomatal responses to water deficit

To determine whether drought-induced root jasmonate [jasmonic acid (JA) and jasmonic acid-isoleucine (JA-Ile)] accumulation affected shoot responses to drying soil, near-isogenic wild-type (WT) tomato (Solanum lycopersicum cv. Castlemart) and the def-1 mutant (which fails to accumulate jasmonates during water deficit) were self- and reciprocally grafted. Rootstock hydraulic conductance was entirely rootstock dependent and significantly lower in def-1, yet def-1 scions maintained a higher leaf water potential as the soil dried due to their lower stomatal conductance (gs). Stomatal sensitivity to drying soil (the slope of gsversus soil water content) was low in def-1 self-grafts but was normalized by grafting onto WT rootstocks. Although soil drying increased 12-oxo-phytodienoic acid (OPDA; a JA precursor and putative antitranspirant) concentrations in def-1 scions, foliar JA accumulation was negligible and foliar ABA accumulation reduced compared with WT scions. A WT rootstock increased ...为探究干旱诱导的根系茉莉酸类[茉莉酸（jasmonic acid, JA）与茉莉酸-异亮氨酸（JA-Ile）]积累是否会影响植株地上部对干旱土壤的响应，本研究以近等基因野生型（WT）番茄（Solanum lycopersicum cv. 卡斯马马特）以及在水分亏缺条件下无法积累茉莉酸类物质的def-1突变体为材料，开展了自体嫁接与相互嫁接实验。砧木导水率完全由砧木基因型决定，且def-1砧木的导水率显著低于野生型；但随着土壤逐渐干旱，def-1接穗的叶片水势得以维持在更高水平，这得益于其更低的气孔导度（gs）。def-1自体嫁接植株对土壤干旱的气孔敏感性（气孔导度与土壤含水量的变化斜率）较低，而将def-1接穗嫁接至WT砧木后，该敏感性可恢复至正常水平。尽管土壤干旱会提升def-1接穗中12-氧-植物二烯酸（12-oxo-phytodienoic acid, OPDA，一种JA前体且被认为是潜在抗蒸腾剂）的浓度，但与WT接穗相比，def-1接穗的叶片JA积累量可忽略不计，且叶片脱落酸（ABA）积累量有所降低。野生型砧木可促进……