疏水表面诱导橡胶树炭疽菌侵染结构的发育分化过程

为了解橡胶树2种炭疽病菌的侵染结构发育分化过程,采用平板菌落生长速率法测定了3株胶孢炭疽菌Colletotrichum gloeosporioides和3株尖孢炭疽菌C.acutatum的菌丝生长速率,测量其分生孢子大小,显微观察2种炭疽菌在疏水表面诱导下侵染结构的发育分化过程。结果表明,胶孢炭疽菌菌丝生长速率为0.96~1.36 cm/d,显著高于尖孢炭疽菌的菌丝生长速率0.72~0.89 cm/d,但二者分生孢子大小无显著差异。在疏水表面诱导下,2种炭疽菌分生孢子在接种2~6 h后开始萌发,12 h孢子萌发率为71.70%~88.05%,13~16 h开始分化附着胞,24 h附着胞形成率为48.99%~70.74%,36 h菌丝诱发形成大量附着枝,48 h后分生孢子产生的次生菌丝也可诱发形成附着枝,附着枝呈圆形、姜瓣形、梨形或不规则形。分生孢子极易产生,可在菌丝顶端成簇或菌丝侧面排列产生,也可由分生孢子形成的芽管产生,或在芽管分化附着胞过程分枝形成分生孢子;附着胞多着生于芽管顶端,少数附着胞顶端可继续萌发类似短芽管结构,再次分化形成可黑色化的次级附着胞。表明橡胶树2种炭疽菌不同菌株间分生孢子萌发时间、孢子萌发率、附着胞形成时间和形成率有一定差异,但种间无明显差异;橡胶树炭疽菌分生孢子极易形成,在疏水表面容易分化形成附着胞和附着枝,说明具有极强的适生性。

Development and differentiation of infection structures of Colletotrichum spp. from the rubber tree Hevea brasiliensis on hydrophobic surfaces

In order to investigate the development and differentiation of the infection structures of Colletotrichum spp. from the rubber tree Hevea brasiliensis, the colony growth rate and conidial size were tested, and sporulation, conidium germination and appressorium formation induced on hydrophobic surfaces were observed under microscope for three strains of C. gloeosporioides and three strains of C. acutatum from H. brasiliensis. The results showed that the average colony growth rate of C. gloeosporioides strains was 0.96-1.36 cm/d, significantly faster than that of C. acutatum (0.72-0.89 cm/d). There was no significant difference in the conidial size between the two species. The conidia of all tested strains were germinated between 2-6 hours after inoculation (hai) and reached 71.70%-88.05% germination rate at 12 hai. Spherical or ovoid appressoria formed at the ends of germ tubes between 13-16 hai and reached 48.99%-70.74% formation rate at 24 hai. Hyphopodia were easy to produce at 36 hai from mycelia induced by hydrophobic surfaces and at 48 hai from hyphae germinated by conidia, and hyphopodia were ovate, lobed or irregular. The conidia were easily produced from the conidiophores that formed from hyphal tip or sides, and secondary conidia were also produced from germ tubes that accompanied appressorium formation. Moreover, the secondary appressorium formed on the top of appressorium were firstly observed in this study. The results indicated that the initial time of conidial germination and appressoria formation or rates of germination and appressorium formation were different between different strains, but there was no statistical difference between the two Colletotrichum species from H. brasiliensis. Conidia, appressoria and hyphopodia were easy to produce on the hydrophobic surfaces, suggesting that the two Colletotrichum species were highly adaptable.