Jasmonates (JAs) are a class of important phytohormones that control multiple physiological aspects of plant development, growth, and defense. It remains unclear whether JA-activated transcription factors MYC2, MYC3, and MYC4 (MYC2/3/4), which are the most extensively studied components in the JA signaling pathway, play a regulatory role floral transition. 

Prof. YU Diqiu and his team of Xishuangbanna Tropical Botancial Garden (XTBG) of the Chinese Academy of Sciences conducted a study to examine the role of MYC2/3/4 in floral transition.  

The researchers firstly analyzed the flowering phenotypes of myc2 mutants, myc2/3, myc2/4, and myc3/4 double mutants, and a myc2/3/4 triple mutant. Under long day (LD) or short day (SD) conditions, myc2/3 and myc2/4 double mutants exhibited earlier-flowering phenotypes compared with the wildtype, indicating that MYC2 plays a more important role than MYC3/4 in regulating floral transition 

In contrast, the flowering times of the myc2, myc3, myc4 single mutant and myc3/4 double mutant were comparable with that of wild-type plants. 

Moreover, the myc2/3/4 triple mutant exhibited an earlier-flowering phenotype compared with myc2/3 and myc2/4 double mutants under both LD and SD conditions. 

Their study provides compelling evidence showing that MYC2/ 3/4 redundantly modulate flowering under both LD and SD conditions. 

The study showed that the myc2/3 and myc2/4 double mutants as well as the myc2/3/4 triple mutant all consistently exhibited early flowering phenotype under both LD and SD, indicating thatMYC2/3/4 are required for JA-mediated inhibition of flowering at least in growth conditions. 

The study entitled “The bHLH Transcription Factors MYC2, MYC3, and MYC4 Are Required for Jasmonate-Mediated Inhibition of Flowering in Arabidopsis” has been published in Molecular Plant.