Pathogenicity analysis and construction of CgBASP2 knockout mutant of Colletotrichum gloeosporioides infecting Hevea brasiliensis

Key words: 
• Colletotrichum gloeosporioides /
• Hevea brasiliensis /
• CgBASP2

Abstract: Based on the prediction result of secreted proteome of Colletotrichum gloeosporioides infecting rubber tree（ Hevea brasiliensis）,one of the candidate genes was cloned by RT-PCR and named as Biotrophy- associated Secreted Protein 2 of C. gloeosporioides（ CgBASP2）. This gene was sequenced and found to encode 100 amino acids with a relative molecular weight of about 9. 85 1. 2 × 10³. Bioinformatics analysis showed that the gene contains an 18 aa signal peptide at N terminal,but without any transmembrane domain. Alignment analysis showed that the amino acid sequence of the gene CgBASP2 from H. brasiliensis is 100%,90%,87%,87% and 67%similar to that of the CgBASP2 from Colletotrichum gloeosporioides Nara gc5,Colletotrichum orbiculare MAFF,Colletotrichum graminicola,Colletotrichum higginsiaum and Magnaporthe oryzae 70-15,respectively. The CgBASP2 gene knockout mutant strain ΔCgBASP2 was constructed by using homologous recombination to study its biological functions. This ΔCgBASP2 mutant strain inoculated onto the leaves of rubber tree was found to lose pathogenicity while the wild type strain had good pathogenicity. This result implied that the CgBASP2 gene might probably play an important role in the pathogenicity of C. gloeosporioides.