Inhibitory effect of StCYP707A1 gene on tuberization in transgenic potato

Tuber formation of potato is a complex biological process and is regulated by many factors including phytochrome, hormones, transcription factors, RNAs, microRNAs, etc. In our previous study, CYP707A1, an ABA 8′-hydroxylase gene, was down-regulated in the StCOL antisense transgenic potato stolons, but its relation with potato tuberization has not been studied yet. In this study, to investigate the role of this gene in potato tuberization, we cloned a CYP707A1 gene from potato cultivar Desiree and constructed the StCYP707A1 over-expression and anti-sense potato lines by Agrobacterium-mediated transformation. In total, four over-expression transgenic lines and nine anti-sense transgenic lines were confirmed by PCR analysis. Semi-quantitative RT-PCR and qRT-PCR analysis showed that the level of StCYP707A1 transcripts was significantly higher in the over-expression lines (A7 and A9) and lower in the anti-sense lines (F2 and F8), compared to the wild-type control. We further analyzed tuber formation in the transgenic lines and the wild-type control. The result showed that tuber yield per plant and average tuber weight were decreased in A7 and A9 and increased in F2. We also measured the content of ABA and GA3 in transgenic lines. ABA level was reduced in A7 and A9 and increased in F2. Contrariwise, the concentration of GA3 was higher in A7 and A9, and lower in F2 than in wild-type control. These results indicate that StCYP707A1 negatively affects potato tuberization through ABA regulation on gibberellic acid concentration.