Changes in the levels of mRNAs for putative cell growth-related genes in the albedo and flavedo during citrus fruit development.

Changes in mRNA levels for the seven gene homologues to endoxyloglucan transferase-related protein, expansin, extensin, β-1,3 glucanase, glycine-rich protein, pectinacetylesterase and pectinesterase, which were obtained by random sequencing studies, were investigated in relation to rind development in citrus (Citrus unshiu Marc.) fruit. Expression patterns in the albedo and flavedo were classified into four types: Type-I, transcript levels low in early fruit development but increased at the ripening stage; Type-II, transcript levels high until mid-development and then decreased towards ripening; Type-III, detectable transcript limited to fruitlets at 26 days after flowering (DAF); Type-IV, ubiquitous during the development. Based on the expression patterns, we discuss the possible roles of these genes in rind development.