Cloning and Expression Analysis of Chalcone Synthase and Chalcone Isomerase Encoding Genes in Gossypium hirsutum

In this study,chalcone synthase and chalcone isomerase encoding genes（ GhCHS and GhCHI） were cloned from upland cotton（ Gossypium hirsutum）cultivar HM-40,and analyzed bioinformatically. Their functions were analyzed through virus induced gene silencing（ VIGS）. The results showed that GhCHS gene has an open reading frame（ ORF） of 1 170 bp and encodes a protein of 389 amino acids. Many phosphorylation sites were detected in GhCHS protein,suggesting that it may be involved in kinase phosphorylation. The deduced GhCHS protein was most closely related to Theobroma cacao CHS protein according to phylogenetic analysis. The GhCHI ORF was 630 bp and encoded a protein of 209 amino acids. Many phosphorylation sites were found in GhCHI protein,indicating that it may be related to kinase phosphorylation. The GhCHI protein was most closely related to Hibiscus cannabinus CHI protein according to phylogenetic analysis. Quantitative PCR（ q PCR） showed that GhCHS and GhCHI were rapidly activated after inoculation with Verticillium dahliae VD07,and then their expression levels kept increasing over time,indicating that the two genes might play an important role in the defense response against Verticillium wilt. Virus induced gene silencing（ VIGS） was used to silence endogenous GhCHS and GhCHI genes in upland cotton plants before VD07 was inoculated to identify disease resistance. The results showed that the disease index of plants untreated with Agrobacterium tumefaciens was 31. 2,and that of the plants inoculated with empty vector was 30. 0. The disease index of GhCHS-silenced plants was 72. 5,and that in GhCHI-silenced plants was 67. 5. These results confirmed that GhCHS and GhCHI may play an important role in defense response of upland cotton to Verticillium wilt.