蟠桃褐腐病原菌生物学特性及细胞壁降解酶活性

由桃褐腐病原菌(Monilinia fructicola)引起的蟠桃褐腐病是蟠桃采后主要的病害,造成水果采后损失严重。同时,M.fructicola引起果实采后疾病的发生,因宿主不同,其致病性也不尽相同。以M.fructicola为对象,研究其在不同环境条件(温度、pH值、光照条件)下的生物学特性和不同培养条件(温度、pH值、培养时间)对M.fructicola自身产生的细胞壁降解酶活性的影响。结果表明:M.fructicola孢子萌发和芽管延长的最适pH值为5.0,且偏弱酸性环境更适宜其生长,但是过酸环境其孢子萌发率明显降低;菌落生长的最适温度范围为20~28℃,高于36℃,则菌不能正常生长;温度会影响菌落形态,温度不同,则菌落形态不同;光照对菌落生长影响甚微;内切葡聚糖酶(endoglucanase,EG)、β-葡萄糖苷酶(β-glucosidase,BG)、果胶甲基半乳糖醛酸酶(polymethylgalacturonase,PMG)、多聚半乳糖醛酸酶(polygalacturonase,PG)活力均在28℃条件下最高;pH 6.0时EG、BG酶活力均达到最高;PMG、PG酶活力在pH 7.0时达到最高;EG、BG、PMG、PG在培养5 d时的酶活力最高;在各pH值、温度、培养时间条件下,BG酶活力高于EG酶活力,PG酶活力高于PMG酶活力。

Biological Characteristics and Cell Wall Degrading Enzyme Activities of Flat Peach Brown Rot Pathogen

Brown rot disease caused by Monilinia fructicola is one of the major postharvest diseases of flat peach, whichcauses serious postharvest loss. Meanwhile, the pathogenicities of M. fructicola for different fruit hosts are different. Inthis investigation, we studied the biological characteristics of M. fructicola under different culture conditions includingtemperature, pH, and light, and we also examined the impacts of culture temperature, pH and time on the activities ofcell wall degrading enzymes. The results showed that the optimum pH for spore germination and germ tube extension ofM. fructicola was 5.0 and it grew well in a weak acidic environment, while the spore germination rate was significantlylower in an excessively acidic environment. The optimum temperature for colony growth was in the range of 20?28 ℃,and the pathogen could not grow normally at a temperature above 36 ℃. Temperature affected colony morphology, and atdifferent temperatures, the colony morphology characteristics were different. Light had little effect on the hyphal growth.The activities of the cell wall degrading enzymes endoglucanase (EG), β-glucosidase (BG), polymethylgalacturonase (PMG),and polygalacturonase (PG) were the highest at 28 ℃. The activities of EG and BG reached the highest values at pH 6.0,while the activities of PMG and PG reached the highest values at pH 7.0. The activities of these four enzymes were thehighest after cultivation for 5 days. Regardless of changes in pH, temperature and incubation time, BG activity was higherthan EG activity and PG activity was higher than PMG activity.