The Malus carotenoid cleavage dioxygenase 7 is involved in stress response and regulated by basic pentacysteine 1

Abstract

Strigolactones have multiple roles for plants, including repression of the development of lateral buds and lateral roots, and improvement of stress tolerance, while the knowledge about the regulation of strigolactone synthesis is rare. The Malus genus is important resource of apple’s rootstocks, thus study on strigolactone synthesis in Malus is helpful to realize the signal communication between apple scion and rootstock. Here, we detected the strigolactone contents of seven Malus species and confirmed the synthesis of strigolactones widely existed in Malus. Then the putative strigolactone synthesis gene, carotenoid cleavage dioxygenase 7 (CCD7), and its promoter sequence were cloned. The sequences were quite conserved and some stress responsive cis-acting elements were predicted in the promoters. The CCD7’s expressions and its promoter's activity decreased under drought, waterlogging or methyl jasmonate (MeJA) treated conditions. By yeast one-hybrid screening, it was found that one transcriptional factor (TF) basic pentacysteine 1 (BPC1) had the ability of binding to CCD7’s promoter. Transient overexpression of BPC1 repressed the activity of CCD7 promoter. The expressions of BPC1 were increased when Malus suffered from the stresses, and it was believed that BPC1 was one of the potential regulator of CCD7’s expression and strigolactone synthesis.