植物内生肠杆菌对狗牙根耐盐性的调控研究

以从海滨雀稗中分离得到的内生肠杆菌为材料，采用种子萌发与盆栽试验两种方式研究植物内生细菌对狗牙根耐盐性的影响。通过对狗牙根种子和幼苗接种单一内生细菌和混合内生细菌，并测定种子发芽率、苗长、根长、生物量等生长指标与叶绿素含量、相对含水量、相对电导率和叶片中钠离子、钾离子的含量综合评价植物内生细菌对狗牙根耐盐能力的调控。结果表明，在150 mmol·L^-1盐胁迫下处理14 d后，接种混合菌液B3014比接种单一菌液B30更能提升狗牙根种子的萌发率、对盐胁迫下胚根及胚芽长度的增长也较显著（P<0.05）。在成坪期，与空白对照相比，接种内生细菌可以提升200 mmol·L^-1盐胁迫下狗牙根的成坪质量，增加地上、地下生物量的积累、苗长与根长生长量，并提升植株叶绿素含量与叶片相对含水量，降低细胞膜破损程度。在接种内生细菌处理中，接种混合菌液B3014可以使狗牙根在盐胁迫下受到的损伤显著低于（P<0.05）接种单一菌液B30。与此同时，接种混合菌液B3014对狗牙根叶片中钠离子含量降低程度高于接种单一菌液B30，同样，接种混合菌液B3014也能更好地积累盐胁迫下狗牙根叶片内钾离子含量，增加盐胁迫下狗牙根的耐盐能力。因此，接种混合菌液B3014对盐胁迫下狗牙根种子的萌发和成坪后的耐盐能力的提升高于接种单一菌液B30。探讨植物内生细菌对狗牙根耐盐能力的调控，为提高草坪草在盐碱环境中的应用提供了新思路。

An evaluation of the effects of the plant endophyte Enterobacter on the salt tolerance of bermudagrass

Endogenous Enterobacter species were isolated from Paspalum vaginatum and were then used to study the influence of plant endophytic bacteria on the salt tolerance of bermudagrass in two methods of seed germination and pot experiment. In pot experiments germinating bermudagrass seeds and seedlings forming miniature turves in pots 10 cm×10 cm×9 cm were inoculated with a single species of endophytic bacterium （Enterobacter ludwigii） or with a mixture of two endophytic bacterial species （E. ludwigii+Enterobacter bugandensis）. The experiments also included blank controls （CK）. Seed germination rate， shoot length， root length and biomass growth indexes， chlorophyll content， relative water content， relative electrical conductivity and leaf contents of sodium and potassium ions were determined to provide a comprehensive evaluation of effects of endophytic bacteria on bermudagrass salt tolerance. It was found that when germinating bermudagrass seeds under 150 mmol·L^-1 NaCl stress were assessed after 14 days， germination， radicle length and plumule length each ranked B3014>B30>CK （P<0.05）. For potted plants subjected to 200 mmol·L^-1 NaCl stress that had formed turves， inoculation with endophytic bacteria enhanced turf quality， shoot length， root growth， shoot and root biomass， chlorophyll content and relative water content of leaves， and also reduced cell membrane electrolyte leakage and these effects were more pronounced for B3014 than for B30 （P<0.05）. In addition the endophytic bacteria facilitated reduction of Na⁺ and increase in K⁺ concentrations in tissues of inoculated plants， with these effects again more pronounced in the B3014 treatment than in the B30 treatment. In summary， inoculation with Enterobacter improved seed germination and salt tolerance of bermudagrass seedlings under salt stress， and B3014 was more effective than B30 alone. Enhancement of the salt tolerance of bermudagrass by inoculation with endophytic bacteria provides a new method for improving the performance of turfgrass in saline alkali environments.