Coordinated accumulation of (+)-delta-cadinene synthase mRNAs and gossypolin developing seeds of Gossypium hirsutum and a new member of the cad1 family from G-arboreum

A new member of the (+)-delta-cadinene synthase (CAD1) family was isolated from a Gossypium arboreum cDNA library. This cDNA encodes a protein that sh owed 97.3%, 96.9%, and 79.2% sequence identities with the proteins encoded by previously isolated cDNAs of cad1-C1, cad1-C14, and cad1-A, respectively . It may be grouped into the cad1-C subfamily as cad1-C2. Seeds of a glande d cotton cultivar, G. hirsutum cv. Sumian-6, were collected at different in tervals during maturation, and the cad1 mRNA levels were analyzed by quanti tative RT-PCR. The transcripts could be detected in seeds of 27 DPA (days p ostanthesis) and increased dramatically along with the seed maturation, whi ch coordinated with an increase in sesquiterpene cyclase activities and sub sequently the accumulation of gossypol. The transcription level detected wi th primers specific to cad1-C (including at least C1, C14, and cdn1) was hi gher than that detected with primers specific to cad1-A, and mRNA was detec ted also with cad1-C2-specific primers. This investigation indicates that, in developing seeds of the glanded cotton cultivar, genes of both the CAD1- C and CAD1-A subfamilies are expressed and there is an active biosynthesis of cadinene-type sesquiterpenes.