The Role of Brassica Rapa FLC Genes In Flowering Time.

The goal of the current project was to find out what genes were responsible for the evolutionary change in flowering time.  My first question was: Is there allelic variation in the genes, and if so are alleles correlated with flowering time? I hypothesized that there would be allelic variation correlated with flowering time.  I also hypothesized that gene expression would first increase and then decrease.  We examined the relationship between flowering time and genetic variation in B. rapa Flowering Locus C (FLC) genes which suppress flowering.  I looked at the 1^st intron, because it is responsible for gene expression. A total of 30 samples, 15 from the 1997 Backbay (BB) population and 15 from the 2004 (BB) population were used for amplification of the 1^st intron using PCR and sent off for sequencing to look for allelic variation in three of the FLC genes.  Sequence data of the 1^st intron revealed no allelic variation, which did not support my hypothesis. In addition, for future experiments there is a need to have an established method for studying gene expression through the course of development within an individual. No one has looked at variation within a single individual or natural population. My second question was: how does expression change over the course of development of an individual?  I hypothesized that gene expression would start off high and then decrease over time. One FLC gene was used to view gene expression using Quantitative real-time PCR (qRT PCR) to determine how gene expression changes over the course of development within a single individual. qRT-PCR showed an increase in expression from the first to the second sampling time point, followed by a decrease. The initial increase did not occur in all of the samples, so more analyses will have to be done.  There was little to no allelic variation shown with my sequence data, which resulted in my hypothesis not being supported. This could be because random samples were used with little difference in flowering time. I hypothesized that gene expression would first increase and then decrease, but my results showed and initial decrease then increase. Based on these results, there is a need to be more tests and analyses in the future.  [This research was supported, in part, by a grant from NSF HBCU-UP (#HRD-0625289) awarded to Dr. Sarwan Dhir* Ph.D., Director for the Center for Biotechnology, Fort Valley State University, Fort Valley, GA 31030].