Effect of partial rootzone drying on the concentration of zeatin-type cytokinins in tomato (Solanum lycopersicum L.) xylem sap and leaves
Effect of partial rootzone drying on the concentration of zeatin-type cytokinins in tomato (Solanum lycopersicum L.) xylem sap and leaves
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DOI：
10.1093/jxb/erl116
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发表时间：
2007-01-01
影响因子：
6.9
通讯作者：
Dodd, Ian C.
中科院分区：
文献类型：
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作者：
Kudoyarova, Guzel R.;Vysotskaya, Lidia B.;Dodd, Ian C.
干旱土壤中根中细胞分裂素(CK)的输出减少可能是影响地上部生理的根-冠信号。虽然一些研究表明，土壤干燥降低了从根部采集的木质部汁液的CK浓度，但尚不清楚这是否会改变叶片中的木质部CK浓度([CKxyl])和散叶CK浓度。番茄(Solanum Lycopsicum L.)种植植物时，根部在两个土柱之间分开。在实验期间，将水加到两个柱(充分浇水；WW)或一个柱(部分根区干燥；PRD)。灌溉WW植物的目的是弥补每天的蒸腾损失，而PRD植物获得的蒸腾损失是这个数字的一半。用Scholander压力室加压收集木质部汁液，用薄层层析法分离不同形态的玉米素核苷后，用针对玉米素核苷的特异性抗体对玉米素型CKs进行免疫测定。PRD使全株蒸腾速率降低22%，叶水势降低0.08 Mpa，木质部脱落酸(ABA)浓度增加2.5倍。虽然PRD没有引起[CKxyl]的明显变化，但它使充分展开的叶片的CK浓度降低了46%。[CKxyl]保持而不是增加，而蒸腾作用下降，这表明CK进入木质部的负荷也随着土壤干燥而减少。叶片CK浓度不随CK施用量成比例下降，表明CK代谢等其他机制对PRD植株叶片CK状况有影响。讨论了地上部CK状态下降的原因和后果。
Decreased cytokinin (CK) export from roots in drying soil might provide a root-to-shoot signal impacting on shoot physiology. Although several studies show that soil drying decreases the CK concentration of xylem sap collected from the roots, it is not known whether this alters xylem CK concentration ([CKxyl]) in the leaves and bulk leaf CK concentration. Tomato (Solanum lycopersicum L.) plants were grown with roots split between two soil columns. During experiments, water was applied to both columns (well-watered; WW) or one (partial rootzone drying; PRD) column. Irrigation of WW plants aimed to replace transpirational losses every day, while PRD plants received half this amount. Xylem sap was collected by pressurizing detached leaves using a Scholander pressure chamber, and zeatin-type CKs were immunoassayed using specific antibodies raised against zeatin riboside after separating their different forms (free zeatin, its riboside, and nucleotide) by thin-layer chromatography. PRD decreased the whole plant transpiration rate by 22% and leaf water potential by 0.08 MPa, and increased xylem abscisic acid (ABA) concentration 2.5-fold. Although PRD caused no detectable change in [CKxyl], it decreased the CK concentration of fully expanded leaves by 46%. That [CKxyl] was maintained and not increased while transpiration decreased suggests that loading of CK into the xylem was also decreased as the soil dried. That leaf CK concentration did not decline proportionally with CK delivery suggests that other mechanisms such as CK metabolism influence leaf CK status of PRD plants. The causes and consequences of decreased shoot CK status are discussed.