超表达miR528增强盐胁迫下水稻幼苗K^(+)稳态

Overexpression of miR528 Enhances K^(+) Homeostasis in Rice Seedling under Salt Stress

为了探究miR528是否参与维持盐胁迫条件下水稻(Oryza sativa)幼苗K;的稳态及其可能的调控机制,以miR528超表达株系miR528-OE1、miR528-OE2和T-DNA插入突变体mir528及其相应的野生型水稻为试验材料,研究盐胁迫条件下miR528的表达模式,分析盐胁迫条件下不同水稻材料的生长情况、地上部和根K;含量、根K;流速及K;通道基因的表达量。结果表明,水稻幼苗miR528受盐胁迫诱导表达。与无盐胁迫处理(对照)相比,miR528-OE1、miR528-OE2地上部和根鲜、干质量受盐胁迫抑制程度低于其野生型水稻中花11(ZH11),而突变体mir528的根鲜、干质量受盐胁迫抑制程度高于其野生型水稻Dongjin(DJ)。盐胁迫条件下,ZH11地上部、根K;含量分别下降至对照的43.41%、23.67%,miR528-OE1、miR528-OE2地上部、根K;含量均极显著或显著高于ZH11,而突变体mir528根K;含量显著低于DJ。瞬时盐胁迫迅速诱导根K;外排,在盐处理后3~4 min出现峰值,miR528-OE根K;外排的峰值明显低于ZH11,而突变体mir528根K;外排的峰值明显高于DJ。在正常条件下,与ZH11相比,miR528-OE1、miR528-OE2幼苗根GORK(Guard cell outward rectifying K;channel)基因表达量显著提高;与DJ相比,突变体mir528幼苗根GORK基因表达量显著降低。在盐胁迫处理1 h时,miR528-OE1、miR528-OE2幼苗根GORK基因表达量分别显著、极显著下降;而与DJ相比,突变体mir528幼苗根GORK基因表达量显著增加。综上,超表达miR528能提高水稻的耐盐性,提高盐胁迫条件下水稻对K;的保留能力,这可能是通过下调GORK基因的表达量来实现的。

In order to investigate whether miR528 is involved in maintaining K+homeostasis in rice seedlings under salt stress and its possible regulatory mechanism,transgenic lines overexpressing miR528(miR528-OE1 and miR528-OE2),T-DNA insertion mutant mir528 and their wild types(Zhonghua 11and Dongjin)were used as experimental materials. The expression pattern of miR528 was explored under salt stress,and the growth,K+content in shoot and root,K^(+)flux in root and the expression levels of K+channel related genes in different rice materials were studied under salt stress. The results indicated that the expression of miR528 in rice seedlings was induced by salt stress. Compared with the control without salt stress,the fresh and dry weights of shoots and roots were less inhibited by salt stress in miR528-OE1 and miR528-OE2 than those in wild type Zhonghua 11,but the fresh and dry weights of roots were more inhibited by salt stress in mir528 than those in Dongjin. Under salt stress,the K+content in shoot and root of Zhonghua 11 decreased to 43. 41% and 23. 67% of the control,respectively;the K^(+)contents in shoot and root of miR528-OE1 and miR528-OE2 were significantly higher than those of Zhonghua 11,while the K+content in root of mir528 was significantly lower than that of Dongjin. Instantaneous addition of salt rapidly induced K^(+)efflux from roots. The peak value appeared at 3—4 min after salt treatment. The peak value of K+efflux from root of miR528-OE was obviously lower than that of Zhonghua 11,while the peak value of K^(+)efflux from root of mir528 was obviously higher that of Dongjin. Under the normal condition,the expression levels of GORK(guard cell outward rectifying K+channel) in roots of miR528-OE1 and miR528-OE2seedlings significantly increased compared with Zhonghua 11,but the expression level of GORK in root of mir528 seedling significantly decreased compared with Dongjin. At 1 h after salt treatment,the expression levels of GORK in roots of miR528-OE1 and miR528-OE2 seedlings significantly decreased,but the expression level of GORK in root of mir528 seedling significantly increased compared with Dongjin. In conclusion,overexpression of miR528 can improve salt tolerance of rice and enhance K+retention ability under salt stress,which may be achieved by down-regulating GORK expression under salt stress.