SEQUENCE CHARACTERISATION OF beta-1,3-GLUCANASE GENE FROM HEVEA BRASILIENSIS THROUGH GENOMIC AND cDNA CLONING

摘要

Accumulation of different isoforms of beta-1,3-glucanase gene has been reported in various plant species in response to pathogen infection and other forms of stress.Although their major role is in disease resistance,they are also involved in various developmental and physiological processes.The genomic and cDNA sequences encoding beta-l,3-glucanase gene in Hevea brasiliensis were amplified with gene specific primers,which were designed based on the available cDNA sequence and conserved amino acid domains of different plant p-l,3-glucanases.Under optimal PCR conditions a 968 bp DNA fragment was amplified from genomic DNA.Reverse transcription and amplification of the cDNA also yielded a similar 968 bp fragment.These bands were cloned and sequenced.Both PCR and RT-PCR products were the same and showed homology with the previously reported sequences.No intron was present in the coding region of 316 amino acid final functional protein.Southern hybridisation confirmed the presence of a low copy number gene with no difference among the Phytopththora tolerant and susceptible H.brasiliensis clones studied.Northern hybridisation and RT-PCR analysis showed higher expression of beta-l,3-glucanase in latex than in leaves.The possible roles of beta-l,3-glucanase gene in combating the abnormal leaf fall disease in Heven and its likely involvement in somatic embryogenesis are also discussed.