Effects of CO2 on transplantation of grape plantlets cultured in vitro by promoting photosynthesis

Abstract

Abstract Plantlet in vitro is an indispensable step in micropropagation and breeding of grape (Vitis vinifera L.). However, the plantlets rely on the artificially controlled micro-environment, which is difficult to adapt to the field acclimation and transplantation, resulting in low survival rate and qualified plantlets rate. Studying the photosynthetic and growth characteristics of plantlets cultured with CO2 and sucrose as carbon sources presents important references for the acclimation and transplantation. In this context, Pinot Noir plantlets in vitro were cultured with S1: medium with 2% sucrose, normal carbon dioxide (CO2) concentration (380 μmol•mol−1), CS: medium with 2% sucrose, high CO2 concentration (1000 μmol•mol−1), C0: medium without sucrose, high CO2 concentration (1000 μmol•mol−1) and S0: medium without sucrose, normal CO2 concentration (380 μmol•mol−1). The results indicated that the growth status and survival rate (an average increase of 19.4%) of plantlets were significantly improved by high concentration CO2 treatments. The photosynthetic parameters of high-concentration CO2 treatments had a positive effect on photosynthetic products, which were consistent with the up-regulated trend of the relative expression of related synthesis and transport genes. Interestingly, the sugar content of photosynthetic products in leaves showed a trend from high to low at different carbon treatment stages, but the opposite trend was observed in stems. What s more, the main photosynthetic parameters of high concentration CO2 treatments were significantly increased, especially the photosynthetic fluorescence parameters of CS were the highest, and the relative expression of photosynthesis related genes were significantly up-regulated during acclimation and transplantation. Comprehensive principal component analysis method speculated that exogenous CO2 mainly laid a good foundation for the acclimation and transplantation by promoting the photosynthesis of plantlets and adjusting the source-sink relationship of leaf and stem photosynthetic products.