Xiangqiang Zhan Bangshing Wang Hongjiang Li Renyi Liu Rajwant K. Kalia Jian-Kang Zhu and Viswanathan Chinnusamy. Arabidopsis proline-rich protein important for development and abiotic stress tolerance is involved in microRNA biogenesis. PNAS 2012
MicroRNAs (miRNAs) are important for plant development and stress responses. However factors regulating miRNA metabolism are not completely understood. SICKLE (SIC) a proline-rich protein critical for development and abiotic stress tolerance of Arabidopsis was identified in this study. Loss-of-function sic-1 mutant plants exhibited a serrated sickle-like leaf margin reduced height delayed flowering and abnormal inflorescence phyllotaxy which are common characteristics of mutants involved in miRNA biogenesis. The sic-1 mutant plants accumulated lower levels of a subset of miRNAs and transacting siRNAs but higher levels of corresponding primary miRNAs than the WT. The SIC protein colocalizes with the miRNA biogenesis component HYL1 in distinct subnuclear bodies. sic-1 mutant plants also accumulated higher levels of introns from hundreds of loci. In addition sic-1 mutant plants are hypersensitive to chilling and salt stresses. These results suggest that SIC is a unique factor required for the biogenesis of some miRNAs and degradation of some spliced introns and important for plant development and abiotic stress responses.
