Involvement of both subgroups A and B of expansin genes in kiwifruit fruit ripening

Abstract

Two complementary DNA fragments encoding expansin genes Ad-EXP1 and Ad-EXP2 were isolated from ripening kiwifruit (Actinidia deliciosa cv. Bruno) by reverse transcription-polymerase chain reaction amplification using a pair of degenerate primers. The homology between these two expansin family members was 50% in nucleotide sequence and 74% in amino acid sequence. It was revealed that Ad-EXP1 and Ad-EXP2 belong to subgroups A and B of an expansin gene family respectively. However, gene expression of these two members shared similar patterns. Both were upregulated by ethylene treatment and downregulated by acetylsalicylic acid treatment. The study suggests that members of both subgroups A and B of the expansin family are involved in kiwifruit fruit ripening.