Abstract:
Mg-K homeostasis is essential for plant response to abiotic stress, but its regulation remains largely unknown. MsWRKY44 cloned from alfalfa was highly expressed in leaves and petioles. Overexpression of it inhibited alfalfa growth, and promoted leaf senescence and alfalfa sensitivities to acid and Al stresses. The leaf tips, margins and interveins of old leaves occurred yellow spots in MsWRKY44-OE plants under pH4.5 and pH4.5 +Al conditions. Meanwhile, Mg-K homeostasis was substantially changed with reduction of K accumulation and increases of Mg as well as Al accumulation in shoots of MsWRKY44-OE plants. Further, MsWRKY44 was found to directly bind to the promoters of MsMGT7 and MsCIPK23, and positively activated their expression. Transiently overexpressed MsMGT7 and MsCIPK23 in tobacco leaves increased the Mg and Al accumulations but decreased K accumulation. These results revealed a novel regulatory module MsWRKY44-MsMGT7/MsCIPK23, which affects the transport and accumulation of Mg and K in shoots, and promotes alfalfa sensitivities to acid and Al stresses.
摘要:
Mg-K稳态对于植物对非生物胁迫的反应至关重要,但它的规定在很大程度上仍然未知。从苜蓿中克隆的MsWRKY44在叶片和叶柄中高表达。它的过度表达抑制了苜蓿的生长,并促进叶片衰老和苜蓿对酸和铝胁迫的敏感性。叶尖,在pH4.5和pH4.5Al条件下,MsWRKY44-OE植物的边缘和叶间出现黄色斑点。同时,随着MsWRKY44-OE植物枝条中K积累的减少和Mg和Al积累的增加,Mg-K稳态发生了实质性变化。Further,发现MsWRKY44直接结合MsMGT7和MsCIPK23的启动子,并正激活它们的表达。烟草叶片中瞬时过表达的MsMGT7和MsCIPK23增加了Mg和Al的积累,但降低了K的积累。这些结果揭示了一个新的调控模块MsWRKY44-MsMGT7/MsCIPK23,它影响Mg和K在芽中的运输和积累,并促进苜蓿对酸和铝胁迫的敏感性。