禾本科植物内生真菌研究3:产生子座而无有性孢子的Neotyphodium属内生真菌-拂子茅属植物新共生体

2006年5月在南京市南郊发现了着生内生真菌子座的禾本科植物。子座长47.5~165.0mm,白色,包裹其宿主植物的旗叶叶鞘;于4月下旬形成,7月中旬完全崩溃;在自然条件下、人工交配试验中,子座上均未形成有性生殖结构。宿主植物直立,高90~120cm,有丰富的根状茎;连续2个花期均无抽穗。根据植物外部特征、叶表皮微形态特征以及rDNA-ITS序列的分析结果,将这种不抽穗的禾本科植物鉴定为拂子茅属植物(Calamagrostis sp.)。从29株着生子座的植株和87株不着生子座的植株中全部检出了内生真菌,从中分离得到了20个菌株。根据分生孢子、分生孢子梗的形态特征,分离菌株被鉴定为Neotyphodium属内生真菌。宿主植物的特殊性和菌株的子座形成能力显示了这是一个禾本科植物-内生真菌的新组合。这个组合是产生子座而不形成有性世代的第3例,并且这3例组合的宿主都是翦股颖族植物。

Grass endophyte researches 3:a new grass-endophyte association developed from Calamagrostis sp.and Neotyphodium sp.producing stromata without sexual spores

In May 2006,we observed stromata producing gramineous plants in the Southern Suburb Nanjing.Stromata surrounded the flag leaf sheathes,white,as long as 47.5-165.0 mm.From its appearance in late April until crash in middle July,no mature sexual structures were either observed in nature or conducted by artificial mating tests.These plants were upstanding and 90-120 cm in height with aggressive stolons,but did not produce inflorescences during the two heading periods.Mainly based on morphology,leaf epidermis micromorphology and rDNA-ITS phylogenetic analysis,the non-flowering host plant was identified as Calamagrostis sp..Twenty-nine plants with stroma and 87 plants without stroma collected were detected to be all infected by endophytes,and 20 fungal isolates were isolated and selected from these samples.Basing on the morphological properties of asexual structures,the isolates were identified as Neotyphodium sp..The botanical properties of the host plant and the endophyte stromata without sexual structures indicate that this symbiotum should be a brand new host-endophyte association.This combination is the 3rd example on the development of sexual structure non-producing stromata,and more surprisingly,the host plants of all the 3 such examples came out from tribe Agrostideae.