Identification of bulbing related genes in short day, non vernalization requiring onion

Expression analysis and association of bulbing to FLOWERING LOCUS T (FT) gene in short day onion (Allium cepa L.)

“…In long day variety (Brown Spanish) the expression of AcFT4 was very low as compared to short day onion indicating that this gene may not be involved in bulbing initiation in LD onion. Expression of AcFT5 was high in prebulbing stage and increased in expression at bulb initiation stage (stage 2) in short day and then decreased rapidly and these results are in conformity with the results of Dalvi et al (2016) who also reported that AcFT5 expression pattern was high in the pre bulbing stage up to 60 days and then decreased thereafter. In case of the expression of AcFT6, it was observed that the expression increased rapidly till 60 DAT in short day (SD) onion and then decreased rapidly in 75 days after transplanting.…”

“…These results are contrary to our studies where expression of AcFT1 increased upto stage 2 (60 DAT) but decreased at 75 DAT in short day variety. Dalvi et al (2016) also observed strong expression of AcFT2 and AcFT3 in late bulbing stage and concluded that these genes might be responsible for maintaining vegetative growth instead of bulbing. In comparison to their study, we observed that expression of AcFT2 decreased by 0.25 fold at bulbing stage but started increasing afterwards till 75DAT.…”

“…In long day onion, expression of AcFT2 was severely reduced in 60 and 70 DAT but the expression of AcFT3 exhibited somewhat increased expression in stage 3 (75 DAT) emphasizing that the role of AcFT3 may be more in maintaining bulb formation. Dalvi et al (2016) observed that the expression of AcFT4 remained high till 60 days and then decreased indicating that this gene may be involved in vegetative growth and not in bulbing. In our studies also, we found that AcFT4 increased in its expression at 60 DAT, which was the stage for bulb initiation, and then started decreasing in expression indicating that this gene may be involved in vegetative growth.…”

“…Our results were contrary to these observations as expression of all these three genes was downregulated in long day variety at bulbing stage. Dalvi et al (2016) studied the expression of six genes (AcFT1 to 6) in short day tropical onion. They observed that expression of AcFT1 gene was low until 70 DAT after which it started to increase indicating that in the short day onion, AcFT1 may not be responsible for bulb initiation.…”

“…Rashid et al (2016) did not detect AcFT2 and observed that AcFT3 shared 83% identity with AcFT5 and concluded that FT-like protein 1 and FTlike protein 2 genes, similar to AcFT6 and AcFT5, might have influence on bulb formation. In short day onion, Dalvi et al (2016) reported that AcFT6 expression level was high during bulb initiation stage and suggested that it might be involved in bulb initiation. Our aim was to investigate the differential expression of six FT genes involved in bulb formation of long day and short day genotypes under tropical Indian conditions.…”