Phenotypic Comparison of CaDXS and CaPDS Gene Silencing in Capsicum annuum L.

Purpose To silence the CaDXS and CaPDS gene of chili pepper, and to compare and analyse the differences of photobleaching phenotypes, finding new silent marker genes in capsicum.

Methods The silencing vectors of CaDXS and CaPDS gene were constructed by double restriction endonuclease digestion. The chili pepper were infected by Agrobacterium tumefaciens-mediated transformation, and the silencing phenotypes of chili pepper were observed. The silence efficiency of CaDXS and CaPDS gene was detected by real-time fluorescence quantitative PCR.

Results At 21 days after infection of A. tumefaciens, the leaves of CaDXS gene silenced chili pepper turned chlorotic; the leaves of CaPDS gene silenced chili pepper began to appear photobleaching. About 30 days after infection of A. tumefaciens, the leaves of CaDXS gene silenced chili pepper showed obvious photobleaching; the photobleaching degree of CaPDS gene silenced chili pepper leaves intensified, and the new leaves were almost photobleaching. Compared with the CaDXS gene, the silencing of CaPDS gene resulted in a more obvious and efficient photobleaching phenotype in chili pepper. The expression levels of CaDXS and CaPDS gene in silenced chili pepper leaves were significantly decreased (P<0.05), and the silence efficiency reached 86.80% and 93.08%, respectively, which further indicated that CaDXS and CaPDS gene in chili pepper were silenced successfully.

Conclusion  CaDXS gene can also be used as a visual marker gene in chili pepper, but CaPDS gene is a more suitable visual marker gene than CaDXS gene in chili pepper for the photobleaching phenotype appears earlier and more obviously.