Analysis of genes preferentially expressed in early stage of pollinated and parthenocarpic fruit in eggplant

To isolate genes preferentially expressed at early stages of fruits in eggplant (Solanum melongena L., var. Senryo No. 2), subtractive hybridization was used on cDNAs from pollinated fruits and poly(A)+RNA from unpollinated fruits at 3 days after anthesis. In this way, 8 cDNA clones were isolated from a cDNA library constructed from pollinated fruits at 3 days after anthesis, and were designated EEF13, 20, 22, 26, 38, 45, 48, and 53, respectively. Expression patterns of EEF genes in pollinated fruit were similar to those in 4-chlorophenoxyacetic acid (4-CPA)-treated fruit by Northern blot analyses. During development of pollinated and 4-CPA-treated fruit, the transcription patterns of EEF genes were classified into three types. EEF20 and EEF38 genes whose products are highly similar to histones, were expressed abundantly on the day of anthesis and continued to be expressed during the early stages of fruit development (Type 1). Transcription of five genes was at higher level from 2 to 4 days after anthesis (Type 2), and the encoded products of EEF22 and EEF26, showed high similarity with calreticulin and polyphenol oxidase, respectively. Another gene, EEF48 (Type 3), showed high and continuous expression from 2 to 20 days after anthesis and was almost restricted to fruits. Deduced amino acid sequence of EEF48 showed high similarity with a cell wall protein.