Transcriptome Analyses Show Changes in Gene Expression Triggered by a 31-bp InDel within OsSUT3 5'UTR in Rice Panicle

Pollen development and its fertility are obligatory conditions for the reproductive success of flowing plants. Sucrose transporter 3 (OsSUT3) is known to be preferentially expressed and may play critical role in developing pollen. A 31-bp InDel was identified as a unique variation and was shown to be responsible for the expression of downstream gene in our previous study. In this study, to analyze the changes of gene expression triggered by 31-bp InDel during pollen development, two vectors (p385-In/Del::OsSUT3-GUS) were constructed and then stably introduced into rice. Histochemical and quantitative real-time PCR (qRT-PCR) analysis of transgenic plants showed that 31-bp deletion drastically reduced the expressions of downstream genes, including both OsSUT3 and GUS in rice panicle at booting stage, especially that of OsSUT3. The transcriptome profile of two types of panicles at booting stage revealed a total of 1028 differentially expressed genes (DEGs) between 31-bp In and 31-bp Del transgenic plants. Further analyses showed that 397 of these genes were significantly enriched for the 'metabolic process' and 'binding'. Among them, nineteen genes had a strong relationship with starch and sucrose metabolism and were identified as candidate genes potentially associated with the starch accumulation in rice pollen, which that was also verified via qRT-PCR. In summary, 31-bp InDel plays a crucial role not only in the regulation of downstream genes but in the expression of sucrose-starch metabolizing genes in multiple biological pathways, and provides a different regulation mechanism for sucrose metabolism in pollen.