Figure 9.

Working model explaining how WRKY53 regulates rice CTB stage. In wild-type plants under cold stress, WRKY53 expression is induced, leading to the repression of GA biosynthesis and a decline in GA contents. Lower GA leads to higher SLR1 protein abundance and lower GAMYB transcript levels. SLR1 then interacts with and suppresses TDR/UDT1 transcriptional activity, finally resulting in impaired pollen development and a decreased seed setting rate. In the wrky53 mutant subjected to cold stress, GA biosynthesis is no longer repressed by WRKY53; GA contents do not significantly decline; SLR1-mediated suppression of TDR/UDT1 is alleviated to facilitate normal development of anthers and pollen; and GAMYB transcript levels are not significantly decreased. Therefore, normal seed setting occurs.