S01 - Session O8 - Functional analysis of soybean microRNAs on flowering time regulation

Authors: Prem Bhalla *, Sangil Lee, Mohan Singh

Floral transition in plants underpins crop yield. Understanding the control of floral transition is critical to ensuring future food security for the growing population. However, the molecular mechanisms on phase changes of crop plants is less well studied than in model plants such as Arabidopsis and rice, primarily due to the complexity of the genome as the crop of agricultural significance usually has a polyploid genome where genes are present in multiple copies. MicroRNAs (miRNAs) are small non-coding RNAs consisting of 20 to 24 nucleotides (nt) that play central regulatory roles in gene expression. miRNAs, such as miR156 and miR172, have been shown to play significant roles in various pathways that regulate the onset of flowering by acting in either negative or positive ways to initiate the reproductive phase. miR156, one of the highly conserved plant miRNAs, plays master regulator roles in vegetative development and the extension of the juvenile stage of plant development. On the other hand, the expression of miR172 has been correlated with the reproductive stage. Soybean is a major crop due to its unique trait of nitrogen symbiosis fixation, as well as its seeds containing 40% protein and 20% oil. Soybean is used for human and animal feed as it provides an affordable protein source. Soybean has a palaeo-polyploid genome with nearly 75% of its genes present in multiple copies. We investigated the functions of soybean microRNAs, gma-miR156a and gma-miR172a on the vegetative and reproductive growth of transgenic plants. Our results showed that ectopic expression of the microRNAs in transgenic tobacco plants affected the regulation of flowering time.