拟南芥SPL1基因参与调节低磷条件下的根际酸化反应

SPL1 is Involved in the Regulation of Rhizosphere Acidification Reaction Under Low Phosphate Condition in Arabidopsis

根际酸化是植物适应低磷胁迫的重要策略,但植物是如何感知和转导低磷信号,进而促进根际酸化的分子机制至今还不十分清楚。利用p H指示剂(溴甲酚紫)显色法从拟南芥(Arabidopsis thaliana)T-DNA插入突变体库中分离得到了1株低磷诱导根际酸化缺失突变体spl1。在含溴甲酚紫的低磷培养基上培养8小时,野生型拟南芥根际培养基的颜色变为黄色,而突变体spl1根际培养基的颜色没有明显变化,表明spl1的低磷根际酸化反应能力降低。当低磷胁迫处理延长20天,spl1叶片的花青素积累明显高于野生型。同时也出现,即使在磷营养正常条件下,spl1突变体也表现出根毛数量与长度增加的特征。进一步的研究表明,在低磷条件下,spl1突变体根部的磷含量略高于野生型,与磷转运相关基因的表达量明显高于野生型。分子遗传学分析结果表明,SPL1基因受低磷胁迫诱导,主要在拟南芥的叶片和花等组织中表达,其编码的蛋白广泛分布在细胞的各个部位。以上结果表明,SPL1参与介导低磷诱导的拟南芥根际酸化反应,调节多种低磷胁迫反应及低磷条件下磷饥饿诱导基因的表达。

Under low phosphate（Pi）, the rhizosphere acidification of plants is a vital strategy to cope with low Pi stress. However, how plants perceive and transduce the low Pi signal and acidify the rhizosphere is not clear. A mutant, spl1, with decreased rhizosphere acidification induced by low Pi, was isolated from a T-DNA library by using the p H indicator（bromocresol purple）. After 8 h incubation in low Pi medium containing bromocresol purple, the color of the rhizosphere of wild-type（WT） seedlings on the low Pi medium turned yellow, whereas that of the rhizosphere of spl1 seedlings did not change, which suggested decreased rhizosphere acidification capacity of spl1. The anthocyanin content was higher for spl1 than the WT with 20 days of low Pi treatment. The number and the length of root hairs of spl1 increased under normal conditions. Further research suggested that the Pi content of the spl1 mutant was slightly decreased in shoot but increased in root under Pi deficiency. Moreover, the expression of Pi transport-related genes in the spl1 mutant increased under Pi deficiency. Molecular genetics analysis revealed that the expression of SPL1 was induced by low Pi stress. SPL1 was mainly expressed in Arabidopsis leaves and flower tissues and the SPL1 protein was widely distributed in each part of the cell. These results indicate that SPL1 is involved in low Pi-induced rhizosphere acidification, regulation of multiple low Pi responses and Pi starvation-induced gene expression.