Objective The glycoside hydrolase gene LtGH88 of Lasiodiplodia theobromae was cloned to study the mechanism of canker in Cinnamomum camphora, which is the major pathogen that causes the disease.
Methods The LtGH88 encoding sequence was cloned by PCR from tissues of C. camphora infected by L. theobromae to determine the characteristics and functions of the protein by bioinformatic methods. Expression of the gene was detected by real-time quantitative PCR, and functions analyzed using the Agrobacterium tumefaciens mediated transient transformation in Nicotianaben thamiana.
Results The full open reading frame of LtGH88 was 1 152 bp with a molecular weight of 42.8 kDa and a theoretical isoelectric point of 4.56. The predicted secondary structure of the protein consisted of 49.09% α helix, 11.23% extended chain, and 34.99% random coil. A signal peptide of 1-18 amino acids was located at the N terminus. The protein belonged to the glycoside hydrolase family 88 (GH88) capable of degrading pectin. LtGH88 was significantly expressed in the early stage of the infection. It did not cause cell necrosis in the leaf of N. thamiana but was able to inhibit the hypersensitive response (HR) induced by Bax.
Conclusion It was postulated that LtGH88 in L. theobromae inhibited the immune response of C. camphora facilitating the pathogenic invasion and colonization on the host plant.
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