Data from: 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 drought-induced ABA and JA accumulation in def-1 scions, but decreased OPDA accumulation. Xylem-borne jasmonates were biologically active, since supplying exogenous JA via the transpiration stream to detached leaves decreased transpiration of WT seedlings but had the opposite effect in def-1. Thus foliar accumulation of both ABA and JA at WT levels is required for both maximum (well-watered) gs and stomatal sensitivity to drying soil.

为探究干旱诱导的根系茉莉酸类物质[茉莉酸（jasmonic acid, JA）与茉莉酸-异亮氨酸缀合物（jasmonic acid-isoleucine, JA-Ile）]积累是否会调控地上部对土壤干旱的响应，本研究以近等基因系野生型（WT）番茄（Solanum lycopersicum cv. Castlemart）以及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，进行了自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接穗的叶片水势维持水平更高，这源于其更低的气孔导度（stomatal conductance, gs）。def-1自嫁接植株对土壤干旱的气孔敏感性（即气孔导度与土壤含水量的变化斜率）较低，而将def-1接穗嫁接到野生型砧木上后，该气孔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前体及潜在抗蒸腾剂）的浓度，但def-1接穗的叶片JA积累量极低，且叶片ABA积累量较野生型接穗显著降低。野生型砧木可提高def-1接穗中干旱诱导的ABA与JA积累量，却会降低OPDA的积累水平。木质部运输的茉莉酸类物质具备生物学活性：通过蒸腾流向离体叶片施加外源JA，可降低野生型幼苗的蒸腾速率，但对def-1突变体幼苗的蒸腾速率则产生相反效应。综上，要实现水分充足条件下的最大气孔导度，以及对土壤干旱的正常气孔敏感性，叶片ABA与JA的积累量均需达到野生型水平。