水稻SUMO化E3连接酶SIZ1调控缺磷条件下根的发育和根构型形成

植物应对磷胁迫的方法之一是改变根系的构型。以水稻SUMO化E3连接酶SIZ1突变体ossiz1为供试材料,研究了OsSIZ1在水稻根发育中的作用以及其与磷胁迫、生长素之间的关系。与野生型相比,OsSIZ1抑制ossiz1种子根和不定根的伸长,促进侧根密度的增加和根毛的增多。缺磷时,突变体ossiz1的反应更强烈,即不定根伸长、侧根密度增大和根毛增多的趋势更加明显。说明OsSIZ1参与调控水稻根构型的改变,低磷时效果更明显。ossiz1地上部和地下部的总磷浓度显著高于野生型,说明OsSIZ1在水稻中负调控磷素的吸收利用。定量RT-PCR结果显示,ossiz1中OsYUCCA1和OsPIN1a/1b的相对表达量显著高于野生型,说明OsSIZ1负调控根中生长素的合成与极性运输,并且缺磷时负调控作用减弱。结果表明,SUMO化E3连接酶OsSIZ1调控缺磷条件下根构型的形成,而且这一过程可能是通过调控生长素分布完成的。

OsSIZ1 Regulates the Development and Architecture of the Roots under Phosphate Starvation Conditions in Rice

Plants cope with the low P environment by altering their root architecture. Here, we studied the role of SUMO E3 ligase SIZ1 on the root development and architecture, and the relationship among OsSIZ1, phosphate stress and auxin using ossiz1 mutants. Compared with wild type (WT), the ossiz1 mutation inhibited the elongation of seminal roots and adventitious roots, promoted lateral roots formation and root hair proliferation. However, the response of the ossiz1 mutation was stronger than WT under Pi deficiency, namely, the trend of root elongation and the increase of the lateral root density and the root hair number of ossiz1 were more obvious relative to WT seedlings. This suggests that OsSIZ1 regulates the root architecture, and the effect is more obvious under Pi deficiency. The total P concentration of shoots and roots in ossiz1 is higher than WT, this suggests that OsSIZ1 negatively regulates phosphorus acquisition and use. And relative expression of OsYUCCA1 and OsPIN1a/1b in ossiz1 roots is markedly up regulated compared with WT. This suggests that OsSIZ1 negatively regulates the auxin biosynthesis and polar auxin transport, which is weakened under Pi deficient conditions. Together, these results suggest that OsSIZ1 regulates Pi starvation induced root architecture remodeling possibly through the control of auxin patterning.