Functional Analysis Of White Collar-1 Bcwc1 In Botrytis Cinerea

Botrytis cinerea is an important plant pathogenic fungus that can cause field and postharvest diseases of fruits and vegetables. The production and postharvest supply of fruits and vegetables usually suffers from huge losses due to it. This work used Botrytis cinerea as the object to study the regulation mechanisms of white collar-1 in growth, development, resistance to ultraviolet (UV) and virulence of the fungus. It can provide some theoretical reference for the control of post harvest diseases of fruits and vegetables based on this study.Light is one of the most important environmental factors. The light can regulate various activities including vegetative growth and development, biological clocks entrainment, gene expression and so on. Our previous work have found that the B. cinerea was light responsive in growth patterns, and the formation of spores and the generation of melanin were inhibited by blue light, meanwhile the pathogenicity of B. cinerea was effected by illumination. The basic mechanism for light sensing in fungi is due to the role of photoreceptors. In the genome database of B.cinerea, three photoreceptors sensing blue light in database were searched out by Blastp. They are Bcwcl,Bcwc2,Vivid,their expression are regulated by light by the test of Semi-quantitative RT-PCR. Among these photoreceptors, BcWC1 is predicted to be the key member, with a LOV domain sensing blue light and a zinc finger domain regulating downstream photoresponsive gene expression. Through homologous recombination, two knock-out mutant strains of Bcwclnamed ABcwc1-59(WC1-59) and ΔBcwcl-64 (WC1-64)were obtained. The mutants showed slower growth rate than the wild type in different media through the analysis of the phenotype. However, the mutant strain got stronger spore production rate and melanin accumulation than the wild type strain. We also found that resistance to UVstress of the mutants was reduced. Moreover, the mutant had defect in pathogenicity on hot tissues through the pathogenic experiment analysis. In order to make it clear that the cause of the pathogenicity deficiency, we studied some virulence factors of B. cinerea including appressorium formation,cell wall degrading enzyme secretion and reactive oxygen species(ROS) accumulation. The results showed that the mutant strains could produce normal appressorium but took longer time. The secretion of three major hydrolase, polygalacturonase, protease, cellulasein mutant was the same as the wild type but not the use of nutrients secretion, resulting in slow growth. It was also found that the mutants lost secretion ability of ROS. This all results indicate that Bcwcl is an important factor in regulating the growth and development, resistance to UV and virulence in B. cinerea.