不同价态无机砷胁迫下水稻秧苗的营养生理与分子响应

为揭示水稻秧苗响应砷胁迫的营养生理机制,以"汕优63"为受体材料,采用水培方法研究了水稻秧苗在不同价态无机砷胁迫下其形态学指标(根长、株高和干重)及植株中N、P、K含量等生理响应,并采用实时荧光定量PCR (FQ-PCR)分析了不同价态无机砷胁迫下水稻秧苗根和叶中与N、P、K吸收相关的4个关键酶基因的表达差异.结果表明,砷胁迫可显著降低水稻的根长、株高、干重,As(Ⅲ)的抑制作用大于As(Ⅴ);As(Ⅲ)主要抑制水稻秧苗对磷、钾的积累,而As(Ⅴ)主要抑制氮的积累;不同价态无机砷胁迫下,水稻秧苗根部,叶部与N、P、K吸收相关的基因表达均下调,且As(Ⅲ)主要影响磷酸根离子转运蛋白和钾离子转运蛋白的表达,而As(Ⅴ)则主要影响硝酸根离子转运蛋白和氨离子转运蛋白的表达.可见,不同价态无机砷胁迫对水稻营养生理机制的影响存在差异.

Nutrition physiological and molecular response of rice seedling to varying inorganic arsenic stress

To explore nutrition physiologcial mechanism in rice seedlings under arsenic stress, a hydroponics experiment was conducted on nutrition physiological and molecular response of "Shanyou63" rice seedlings under stress of different forms of inorganic arsenic. Morphological indexes of root length, shoot height and dry weight, and NPK content in plants were analyzed after As(III) and As( V) treatments. More importantly, four rice genes correlating with key enzymes regulating NPK absorption were determinted by Real-time Fluorescent Quantitative PCR to evaluate expression changes under stress of different forms of inorganic arsenic. The results show that root length, plant height, and dry weight of rice seedlings significantly drop after treatment of arsenic. As(III) is more toxic than As( V). While phosphorus and potassium accumulation is suppressed mainly by As(III), nitrogen on the other hand is suppressed mainly by As( V). A less regulated gene expression in relation to nitrogen, phosphorus and potassium absorption is observed after arsenic treatment. As(III) has a greater suppression on phosphate and potassium transporter protein expression than As( V). As( V) on the other hand has a greater suppression on nitrate and ammonium transporter protein expression than As(III). This implies that As(III) and As( V) differently influence nutrition physiological mechanism of rice seedlings.