Recently, the Fruit Postharvest Disorder and Disease Team at the Institute of Pomology, CAAS, discovered that AbLac4 is involved in the growth, development, and pathogenic process of the postharvest pathogenic fungi Athelia bombacina in pears. The related findings have been published in Food Microbiology.

Athelia bombacina is a newly discovered and important post-harvest fruit pathogen. We previously found that it exhibited a strong ability to produce laccase, an important pathogenic factor of various pathogens and a major enzyme that destroys the host's first line of defense. However, it remains unclear whether the Lac genes, which are significantly up-regulated during the interaction between A. bombacina and its host, play a role in regulating the growth, development and pathogenicity of A. bombacina.

Based on this, this study observed the key core gene AbLac4 in the Lac genes family was identified and characterized through bioinformatics analysis based on transcriptome data. The absence of AbLac4 inhibited colony growth, reduced biomass, slowed down apical growth, and caused "U"-shaped structures in A. bombacina.

In addition, the absence of AbLac4 down-regulated the expression of the key genes related to sporulation (abaA-1, abaA-2 and abaA-3), reduced sporulation, with no effect on spore germination rate. The ΔAbLac4 was more sensitive to cell wall stress and temperature stress. The absence of AbLac4 also reduced the pathogenicity of A. bombacina in 'Huangguan' pears. Furthermore, the absence of AbLac4 significantly reduced Lac activity in the early culture environment and disrupted the pH balance. Additionally, the contents of oxalic acid and soluble sugar were significantly reduced, and the activities of hemicellulase and pectinase were decreased significantly on the 5th day of culture. Extracellular enzyme-related genes (EpgA, EpgB, PG, EngA, EngB, ExgA and ExgB) in A. bombacina were also down-regulated.

In summary, this study not only revealed AbLac4 exhibited a positive correlation with the growth, development, and pathogenic capability of A. bombacina, but also identified that there is a synergistic relationship between AbLac4 and oxalic acid, which jointly regulate the pathogenic process of A. bombacina.

This study was supported by projects such as the Science and Technology Innovation Project of the CAAS (CAAS-ASTIP-RIP), and China Agriculture Research System - Pear (CARS-28).

Link:https://doi.org/10.1016/j.fm.2025.104924

(By Xiaohui Jia, jiaxiaohui@caas.cn)