The variability in grape (Vitis vinifera L.) proanthocyanidin content is largely attributable to viticultural and environmental conditions. However, the particular effect temperature has on proanthocyanidin biosynthesis is poorly understood. The aim of the present study was to ascertain the magnitude of the effect of temperature on proanthocyanidin biosynthesis in Cabernet Sauvignon grape berries cultured in vitro. In addition, the effects of temperature on global gene transcription were evaluated, and the microarray data were later validated by quantitative real-time PCR (qPCR). The grape berries used in this research were sampled 3-4 weeks after full bloom and cultured in vitro either under a low (20 °C) or high (30 °C) temperature treatment for 15 days (d) with sampling occurring every five days. The proanthocyanidin content was higher in the skin and seeds of grape berries cultured at a low temperature compared with a high temperature. However, overall proanthocyanidin composition between the treatments was not significantly affected. Microarray data revealed a total of 1298 genes with ≥ 3.5-fold expression differences under high temperature conditions. High temperature also inhibited the expression level of key genes involved in proanthocyanidin biosynthesis, anthocyanidin reductase (ANR) and leucoanthocyanidin reductase-1 (LAR-1) within the berry skin. However, the transcriptomic accumulation of transcription factors, such as VvMybPAs, VvMyb5a and VvMyb5b, was barely influenced during the peak expression of ANR and LAR-1. Thus, the present study revealed that temperature has a significant effect on proanthocyanidin biosynthesis in grape during berry development through enhancing the expression of key biosynthetic genes.
Keywords: Grape; Microarray; Proanthocyanidins biosynthesis; Temperature effect.