Abstract
UVB radiation causes cyclobutane pyrimidine dimers (CPDs) to form on the DNA of living organisms. This study found that overexpression of the silicon absorbance gene Lsi1 reduced the accumulation of CPDs in rice, which profited from the reactivation by photolyase. The transcript abundance of deoxyribodipyrimidine photolyase (Os10g0167600) was generally correlated with the silicon content of the rice, and the up-regulation of Os10g0167600 was found to be highest in the UVB-treated Lsi1-overexpressed (Lsi1-OX) rice. A trans-acting factor, methyl-CpG binding domain protein (OsMeCP), was found to interact with the cis-element of Os10g0167600. The nucleic location of OsMeCP effectively enabled the transcriptional regulation. Compared with the WT, the level of OsMeCP was lower in the Lsi1-OX rice but higher in the Lsi1-RNAi line. Rice cultured in a high silicate-concentration solution also exhibited less OsMeCP abundance. Overexpression of OsMeCP led to lower Os10g0167600 transcript levels and a higher CPD content than in the WT, but the reverse was true in the OsMeCP-RNAi line. These findings indicate that OsMeCP acts as a negative regulator of silicon, and can mediate the repression of the transcription from Os10g0167600, which inhibits the photoreactivation of the photolyase involved in the repair of CPDs.
Highlights
cyclobutane pyrimidine dimers (CPDs) photolyase activity, which increases the plants’ resistance to growth damage from ultraviolet B (UVB) compared with wild-type (WT) plants[13]
Exposing the rice to UVB radiation led to increased CPD and 6-4 PP contents in the leaf DNA
The CPD content was significantly lower in the leaves of the Lsi1-OX line than in the WT after exposure to UVB radiation
Summary
CPD photolyase activity, which increases the plants’ resistance to growth damage from UVB compared with wild-type (WT) plants[13]. The activity of CPD photolyase in rice can be regarded as a symbolic factor for evaluating the sensitivity of rice to UVB radiation[13,14]. Beneficial elements such as silicon have been reported to contribute to the enhancement of UVB resistance in rice[15,16]. Fang et al inhibited and overexpressed Lsi[1] on rice to generate two types of rice with different silicon contents, and compared their gene expression profiles after exposure to UVB. We conducted a comparative study of the expression of photolyase encoded genes to select the responsible gene in types of rice with different silicon contents.
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