内生真菌感染对干旱胁迫下黑麦草生长的影响

 内生真菌是生活在健康植物的茎叶内，形成不明显感染的一类真菌。以黑麦草（Lolium perenne L.）为实验材料，研究在不同强度的干旱胁迫下内生真菌（Neotyphodium lolii）侵染对其叶片延伸生长、分蘖数和生物量的影响。结果表明，与非感染种群相比，内生真菌感染对黑麦草叶片延伸速率无明显促进作用；内生真菌感染种群具有明显较多的分蘖数；在重度胁迫并经过恢复期后，内生真菌感染种群具有较高的根冠比。因而内生真菌可能通过提高植物的分蘖能力和促进有机物向根系的分配来促进宿主植物的营养生长并提高其抗旱性

EFFECTS OF ENDOPHYTE INFECTION ON THE GROWTH OF LOLIUM PERENNE L. UNDER DROUGHT STRESS

Endophytes are fungi that form inapparent infection within leaves and stems of healthy plants. Endophytes or endophytic fungi exist widely in the higher plants and are generally considered as mutual symbiotes to the host plants. The present study examined the association of an endophyte (Neotyphodium lolii) with its host plant, Lolium perenne cv. Pinnacle. Both endophyte status and drought stress level were considered. Endophyte-free (EF) plants were obtained by a mild heat treatment while endophyte-infected (EI) plants were germinated directly. After transplantation and four weeks of growth in pots, EF and EI plants were subjected to drought stress of different water status in the soil; soil moisture was maintained at 20% to 40%, 40% to 60%, 60% to 80%, and over 80% of the field capacity. Leaf extension rate and tiller numbers were measured during drought stress, and biomass was determined after recovery stage. Our objective was to determine the influence of endophyte infection on growth characteristics and drought resistance of the host plants. Leaf extension of Lolium perenne shifted during drought stress, while no significant superiority was found in EI plants as compared with EF plants. The EI plants tended to produce more tillers than the EF plants during drought stress. After severe stress and recovery stage, the EI populations had a significantly higher root/shoot ratio than the EF populations, while there was no significant difference in total biomass between EI and EF populations. Our results indicated that endophyte infection might enhance the drought resistance of the host plant by enhancing its tiller production during drought stress and its photosynthate allocation to roots between stress periods.