REGENERATION AND AGROBACTERIUM- MEDIATED TRANSIENT EXPRESSION OF TWO CHILI PEPPER (CAPSICUM SPP. L.) CULTIVARS

Abstract

Chili pepper is a staple crop for humans. We tried to develop an efficient tissue-culture and transient gene expression system in two pepper genotypes, A108 and Hab51p2-1. Using MS agar supplemented with 2mg/L of Zeatin, 0.5mg/L of BA, Kinetin, and IAA, we succeeded in regenerating these two chili pepper cultivars. When we used cotyledons, the induction percentages of callus for A108 and Hab51p2-1 were 96.6 and 100, respectively. The simultaneous induction percentage for both shoot and root for A108 was 10.3 and that for Hab51p2-1 was 5.8. When we used hypocotyls, the induction percentages of callus for A108 and Hab51p2-1 were 95.8 and 96.2, respectively. In addition, we developed a transient gene expression system for A108 and Hab51p2-1 peppers using two strains of Agrobacterium tumefaciens, AGL-1 and GV3101 transformed with the CGEL21 vector harboring the EGFP and GUS genes to establish a pepper transformation system by agroinfiltration. Expression of both reporter genes was detected using fluorescence microscopy, PCR, histochemical GUS assay, and quantitative real-time PCR. Using quantitative real-time PCR, we demonstrated that the AGL-1 strain showed better performance in the transformation system for A108 pepper with a normalized transient GUS gene expression level of 2.03359±0.54354, compared to the GV3101 strain with a transient expression level of 0.79618±0.28541. For transformed Hab51p2-1 pepper, we detected transient expression of GUS gene in all transformed groups, although the expression level was relatively lower than that of the A108 transformed groups, suggesting that more studies are needed to validate the reason for the low transient expression level in the Hab51p2-1 pepper genotype.