Selection and regeneration of Vitis vinifera Chardonnay hydroxyproline-resistant calli.

Proline (Pro) accumulation protects plant cell under abiotic stress. Hydroxyproline (Hyp) as selection agent is a toxic analog of proline and promotes Pro overaccumulation. In this study, Chardonnay calli were firstly irradiated with different dosages of 60Co and then cultured on a Hyp-added medium. Finally, some stable hydroxyproline-resistant (HR) calli were obtained. When calli were cultured on 4 mM Hyp medium for 7 days, intracellular Pro content of the HR calli was five times higher than that detected in the normal calli. The regeneration of HR calli into plantlets was much slower than that of normal ones. When cultured on woody plant medium (WPM) containing 10 mM NaCl for 14 days, HR plantlets still grew well with lower Pro than withered normal plantlets. qRT-PCR results of Pro biosynthesis-related genes in HR plantlets showed that three genes VvP5CS, VvOAT, and VvP5CDH were conducive for Pro accumulation. These results confirmed that HR plantlets acquired salt tolerance ability. We prospect that this procedure to obtain salt-tolerant plants may be valuable to breed programs and improve grapevine genotypes with increased tolerance to salt and other abiotic stresses.