余庆县茶叶斑病致病菌Pestalotiopsis trachicarpicola鉴定及其生物学研究

Studies on the identification and biology of the pathogenic fungi Pestalotiopsis trachicarpicola of tea leaf spot in Yuqing County

为有效控制贵州省余庆县茶叶斑病的发生及为害,从该区域茶树叶部病害样品中分离纯化多个菌株,并对其中多个形态相似的分离物进行菌落形态、子实体、产孢细胞、分生孢子的形态观察。测定了核糖体转录间隔区(ITS)、微管蛋白(TUB2)和翻译延长因子1-α(TEF-1α)等核酸序列,采用PAUP软件及最大简约法,进行了多基因系统发育树分析。依据柯赫氏法则,在室内和田间条件下,研究了代表性菌株GZYQ2018YQX001a对茶树叶片的致病性及其在PDA、OA和MEA3种培养基上的生长速率、菌落形态和生物学特性。结果表明,代表性菌株GZYQ2018YQX001a的菌落形态、子实体、产孢细胞和分生孢子等形态与Pestalotiopsis trachicarpicola一致。其子实体呈黑色,半嵌入培养基内,球形,直径130~440μm。产孢细胞梭形,淡蓝色,较短,细胞壁较薄。分生孢子呈纺锤形、薄壁,具横隔,成熟分生孢子平均大小为(23.56±2.89)μm×(6.3±0.75)μm,由5个细胞构成,基底细胞和顶端细胞呈透明状,中间3个细胞均为橄榄色。多基因系统发育树表明代表性菌株GZYQ2018YQX001a与P. trachicarpicola MFLUCC 12-0264聚为一支,自举支持率为100%。致病性分析表明,代表性菌株GZYQ2018YQX001a可导致茶树叶片产生病斑,病斑后期可产生子实体。生物学特性研究表明,代表性菌株GZYQ2018YQX001a在PDA培养基上生长最快,生长速率为(1.45±0.03)cm/d,生长速率显著快于菌株在OA、MEA培养基上的生长速率(P<0.05)。

To control the occurrence and damage of tea leaf spot effectively, we isolated and purified several fungal strains from the tea leaf disease samples in Yuqing County, Guizhou Province, and observed the morphology of the colony, fruiting body, conidiomata, conidiogenous cells, and conidia of the strains with similar morphology. The region of the internal transcribed spacer(ITS), β-tubulin2(TUB2), and translation elongation factor(TEF-1α) were sequenced, and the phylogenetic tree of polygenes was analyzed by PAUP software and maximum parsimony method. According to Koch’s rule, the pathogenicity test of the representative strain GZYQ2018 YQX001 a was conducted under the condition of laboratory and field. Meanwhile, the radial growth rates, colonial morphology, and biological characteristics of the representative strain were studied by incubation on PDA, OA, and MEA medium. The results showed that the colony, fruiting bodies, conidiogenous cells, and conidia of the representative strain GZYQ2018 YQX001 a were similar to Pestalotiopsis trachicarpicola.The fruiting body of this strain was black which was semi-immersed in medium. The conidiomata were globose, 130~440μm in diameter. The conidiogenous cells were fusiform, hyaline, short, and thin-walled. The conidia were fusiform, thinwalled, with septa. The matured conidia were(23.56 ± 2.89) μm×(6.3 ± 0.75) μm that contained five cells, the basal cell and apical cell were transparent, and the middle three cells were olive color. The phylogenetic tree analysis showed that the representative strain GZYQ2018 YQX001 a and P. trachicarpicola MFLUCC 12-0264 were clustered into one clade and their bootstrap support rate was 100%. The pathogenicity test indicated that the representative strain GZYQ2018 YQX001 a could induce the lesion of tea leaf, and the fruiting body was formed on the lesion during the last stage of inoculation. The study of biological characteristics showed that the representative strain GZYQ2018 YQX001 a grew fastest on PDA medium, and the growth rate was 1.45 ±0.03 cm/d, which was significantly higher than that on OA and MEA medium(P<0.05).