S11 - Session P4 - Differential expression of gene and transcription factor associated abscisic acid biosynthesis and signaling in two Capsicum annuum genotypes differing in chilling sensitivity

Authors: Jieun Seo *, Eun Jin Lee, Jeong Gu Lee

Chilling injury causes quality loss in Capsicum annuum fruit during cold storage after harvest. Seed browning is the most visible chilling symptom of pepper fruit during cold storage and transportation. Chilling sensitivity of peppers varies according to genotypes, it was classified into two groups: chilling-sensitive with severe seed browning and chilling-insensitive with non-severe seed browning. In our transcriptomic data comparing chilling-sensitive and chilling-insensitive pepper fruit, 25 differentially expressed genes were mainly associated to abscisic acid (ABA). Green mature pepper fruit of chilling-sensitive 'Gyeonggiyangpyung' and chilling-insensitive 'Takanotsume' were stored at 2 ℃ and seed browning rates were observed for 21 days. The chilling injury index (CI index) was ranged from 0 (none) to 4 (severe) according to the degree of seed browning. Chilling-sensitive 'Gyeonggiyangpyung' showed 3.09 CI index for 21 days but chilling-insensitive 'Takanotsume' was 0.5, respectively. DCFH-DA was used to investigate reactive oxygen species (ROS) production in embryo of pepper seeds. The fluorescence intensity of 'Gyeonggiyangpyung' was two-times higher that of 'Takanotsume'. The relative gene expressions of NCED3 and ZEP involved in ABA biosynthesis pathway and the gene expressions of PYL8 , ABAR , RCAR1 in ABA signaling clearly increased in chilling-insensitive 'Takanotsume' after chilling treatment. They significantly increased for 10 h after chilling treatment and declined. In contrast to chilling-insensitive 'Takanotsume', the relative expressions of NCED3 , ZEP, PYL8, and RCAR1 did not significantly changed in chilling-sensitive 'Gyeonggiyangpyung'. These results indicate that increased expressions of genes involved in ABA biosynthesis and signaling might be reduced chilling sensitivity of pepper fruit after harvest.