Identification and Characterization of Genes underlying Natural variation in Flowering Time in Arabidopsis thaliana

It is essential for plants to coincide their flowering with favorable conditions for production of fruits and seeds to enhance their reproductive success. Flowering at the right time requires responding to diverse range of environmental and internal signals and integrating the signals into a single decision: floral transition, the switch from vegetative to reproductive phase. The regulation of flowering time is most extensively studied in the model organism, Arabidopsis thaliana. The identified flowering time genes are integrated into six distinct but interlinked genetic pathways, known as vernalization, autonomous, photoperiod, temperature, age and hormone pathways. In addition, studies have shown links between flowering time and other factors, including sugar metabolism, nutrient availability, drought and herbivore predation. All the genetic pathways form a complex network that enable the plant to monitor its external and internal conditions, and converge the information to regulate floral integrators such as FLOWERING LOCUS T (FT), LEAFY (LFY) and SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1), which promote the decision to floral transition. Arabidopsis distribute across a wide range of latitude and altitude; thus face diverse environmental conditions. The regulation on flowering time reflects adaptation to the populations’ local environment; consequently, diverse natural variations exist in flowering time regulators. Quantitative trait loci (QTL) analysis is a tool frequently used to identify the genetic basis of such variation. In this chapter briefly reviews the current knowledge on the flowering time regulation and the principle of QTL analysis, which is often exploited to study the natural variation in flowering time genes