Silicon (Si) has beneficial function in enhancing plant resistance to biotic and abiotic stresses. Rice is a typical Si-accumulating plant. In this research, UV-B tolerant rice accession Lemont, UV-B sensitivity rice Dular and their low silicon rice gene 1 (Lsi1) transgenic lines were used to explore the relationships between silicon and rice UV-B tolerance. It was found that rice cultured in Si-deficiency solution had lower gene transcript levels of phenylalanine ammonia lyase (PAL), photolyase (PL), and lower contents of total phenolics and flavonoids in leaves than that in Si-containing solution. The same tendency was found in the case when the rice accessions were supplementarily exposed to UV-B radiation, although both gene expression level and antioxidants concentrations were increased. Further, Lsi1-suppressed or overexpressed transgenic rice lines of Lemont, and Lsi1-overexpressed transgenic rice line of Dular were also detected in the same treatments. The results showed that gene transcript level of PAL and PL was increased in Lsi1-overexpressed transgenic line, but down-regulated in Lsi1-RNAi line of Lemont as compared with their wild types (WT) under normal light condition. The expression level of the two genes in all entries was enhanced after UV-B radiation treatment, and it was the highest in Lsi1-overexpressed line of Lemont, followed by their WT, and lowest in Lsi1-RNAi line. The same tendency was also found in the content of total phenolics and flavonoids. The similar results were further confirmed in the overexpression of Lsi1 in Dular. The findings suggested that rice UV-B tolerance could be effectively mediated by enhancing/inhibiting expression of Lsi1.%硅能提高植物对生物和非生物胁迫的抗性,水稻是吸收硅较多的作物之一.本研究以UV-B耐性水稻Lemont和UV-B敏感水稻Dular及其转硅吸收基因(Lsi1)的水稻为材料,研究硅与水稻耐UV-B辐射的关系.结果发现,自然光照条件下,缺硅培养的UV-B耐性水稻Lemont和UV-B敏感水稻Dular叶片的苯丙氨酸解氨酶(phenylalanine ammonia lyase,PAl)和光裂解酶(photolyase,PL)基因的表达以及总酚、类黄酮的含量都分别低于加硅的处理；UV-B辐射后,上述指标在不同硅处理的两水稻中都增加和增强,但缺硅培养的水稻仍显著低于加硅培养的水稻.进一步分别以Lsi1被抑制、增强的两种转基因Lemont水稻,以及Lsi1增强的转基因Dular水稻为材料,采用加硅培养的方式对转基因水稻的上述指标进行研究,结果也发现,抑制水稻Lsi1基因表达,其叶片PAL、PL基因表达也下调,总酚、类黄酮含量降低,此结果与缺硅培养下的野生型植株相似；增强表达Lsi1基因则结果相反.UV-B辐射后,上述指标也增强和增加,但在相同的水稻品种中仍表现为Lsi1被抑制的植株最低,Lsi1增强的植株最高.研究结果表明,通过调节水稻Lsi1能够改变水稻耐UV-B辐射的能力.
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