Characterization of Photoperiod Response Genes in Chickpea

In climates that experience short growing seasons due to drought, heat or end-of-season frost, early flowering time is a highly desirable trait for chickpeas.  In this study, we have mapped, sequenced and characterized what is likely to be Efl-1, an ortholog of the Arabidopsis gene ELF3 that confers early flowering and photoperiod insensitivity.   In a RIL population derived from a cross between CDC Frontier and ICCV 96029, this gene was mapped to the site of a QTL on Ca5 that explained approximately 60% of flowering time variation under SD.  Sequencing in ICCV 96029 revealed an 11-bp deletion in the first exon that was predicted to result in a premature stop codon.  The effect of this mutation was tested by transgenic complementation in the Arabidopsis elf3-1 mutant, with the Frontier form of ELF3 complementing elf3-1, while the 96029 form had relatively little effect on flowering time.  Analysis of circadian clock function failed to show any clear loss of rhythm in the expression of clock genes in ICCV 96029 grown under continuous light, possibly suggesting an alternative mode of action for this gene in chickpea.  This polymorphism does not appear to be widely-distributed within global chickpea germplasm, indicating that this mutation arose relatively recently.  The implications of our findings for the development of early flowering chickpeas will be discussed.