盐胁迫下泛菌属内生细菌对杂交狼尾草发芽及生理的影响

内生细菌作为一种宝贵的天然微生物资源,在植物防病、杀虫、促生、耐盐及耐干旱能力等方面具有广阔的应用前景。本研究分析了泛菌属内生细菌(Pantoea sp.)PP04对不同盐浓度胁迫下杂交狼尾草(Pennisetum americanum×P.purpureum)种子萌发及幼苗生长的影响。结果表明,该内生细菌在低(100mmol·L~(-1))、中(200mmol·L~(-1))度盐浓度下,对杂交狼尾草种子的萌发率、发芽指数及胚芽长度都有明显增益作用,增幅分别达10.75%、28.57%和300%。进一步研究发现,在不同浓度的盐胁迫下,内生细菌PP04通过诱导杂交狼尾草不同的抗氧化保护酶活性,从而减少膜脂过氧化作用,降低丙二醛(MDA)的含量。在低、中浓度盐胁迫下,PP04能显著提高杂交狼尾草超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸酶(APX)的活性。其中SOD和POD活性在低盐胁迫下增幅最高,可达64.17%和73.14%;而CAT和APX酶活性在高盐(300 mmol·L~(-1))胁迫下增幅最大,可达160.57%和73.38%。说明该内生细菌菌株可通过缓解氧化胁迫对植物造成的损伤,显著提高植物对盐胁迫的耐受性,具有良好的开发应用前景。

Endophytic bacteria can mitigate salinity stress on seed germination and physiology in hybrid Pennisetum

Endophytic bacteria have a broad spectrum of applications such as in plant disease prevention,pest insect suppression,plant growth promotion,and plant salt and drought tolerance;they,therefore,provide a valuable natural resource.This investigation was conducted to determine the influence of the endophytic bacterium Pantoea sp.PP04 on seed germination and seedling growth of hybrid Pennisetum under low (100 mmol· L-1),medium (200 mmol · L-1),and high (300 mmol· L-1) salinity stress.The analysis showed that the endophyte PP04 had a significant positive impact on seed germination rate,germination index,and lengths of embryos under low and medium salinity stress,which would enhance their germination rate at 10.75％,28.57％,and 300％,respectively.We also found that under different levels of salinity stress,this endophytic bacterium reduced lipid peroxidation of cell membranes in hybrid Pennisetum by inducing different antioxidant protective enzyme activities.As a consequence,the content of malondialdehyde (MDA) decreased.Under low and medium salinity stress,the endophytic bacterium significantly increased activity of superoxide dismutase (SOD),peroxidase (POD),catalase (CAT),and ascorbate peroxidase (APX) in hybrid Pennisetum.The greatest increases in SOD (64.17％) and POD (73.14％) activities occurred under low salinity stress.The largest increases in CAT (160.57％) and APX (73.38％) occurred under high salinity stress.Our results indicated that the endophyte PP04 significantly mitigated the damage caused by oxidative stress from salinity and improved the tolerance of plants to a salt stress environment.These results suggest that the endophyte PP04 has promising characteristics for future applications.