Isolation and characterization of ripening-related expansin cdna from tomato^†

Among different ripening-related genes, expansins are unique due to their non-enzymatic nature and their ability to stimulate cell wall disassembly by reversible disruption of hydrogen bonds at cellulose-hemicellulose interface. In the present study, LeExp1 cDNA from an Indian tomato cv Pusa Sheetal has been cloned and sequenced. The LeExp1 gene expression was analyzed in vegetative tissues, flowers and fruit tissues at different stages of ripening. The gene was found to express only in fruit tissues from breaker stage onwards. The transcript level progressively increased beyond the breaker stage and achieved a maximum level at the pink and red ripe stages of fruit development. The nucleotide and predicted amino acid sequences of the LeExp1 cDNA were compared with ripening-related expansins from others species and revealed high degree of conservation.