印度梨形孢真菌对干旱胁迫下紫花苜蓿生长及抗旱性的影响

以紫花苜蓿为材料,通过盆栽砂培的方法,设置接种(40 mL 含有印度梨形孢菌丝体的菌剂)+干旱(土壤含水量为田间最大持水量的15%~20%)、未接种(40 mL无菌水)+干旱、接种+正常供水(土壤含水量保持在田间持水量的75%~80%)、未接种+正常供水4个处理,研究印度梨形孢真菌与紫花苜蓿共生对干旱胁迫下紫花苜蓿生长及抗旱性的影响。结果表明,印度梨形孢真菌在紫花苜蓿根部定殖率较高,达87.4%;与未接种+干旱处理相比,接种印度梨形孢对干旱胁迫下紫花苜蓿地上部和根系有明显影响,其中,地上部鲜重、干重、叶绿素含量、叶片相对含水量及叶片数分别比未接种处理显著增加了63.4%,69.2%,12.5%,17.1%和5.7片,根系鲜重、干重、主根长及侧根数分别增加了33.3%,57.1%,5.1 cm和5条(P<0.05);与未接种+干旱处理相比,接种后的紫花苜蓿叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、脯氨酸(Pro)和可溶性糖(SS)含量明显增强,分别是未接种处理的1.71,1.27,1.22,1.49和1.48倍(P<0.05),而超氧阴离子()与丙二醛(MDA)含量大幅度降低。因此,印度梨形孢真菌与紫花苜蓿共生可以促进干旱胁迫下紫花苜蓿生长,主要是通过刺激抗氧化酶活性和渗透调节物质的累积来抵抗干旱逆境。而在正常供水条件下,接种印度梨形孢没有明显的促进生长的作用。

Effects of Piriformospora indica fungus on growth and drought resistance in alfalfa under water deficit stress

Pot experiments were conducted to evaluate the growth and drought resistance of alfalfa (Medicago sativa )seedlings colonized by Piriformospora indica fungus.The experiment comprised a 2×2 factorial com-bination of inoculation (inoculated,I,or un-inoculated,NI)and drought (droughted,D or not,ND)treat-ments,giving 4 combinations:I-D,I-ND,NI-D (reference),and NI-ND.For the inoculated plants,40 mL of inoculant with P .indica mycelium was applied,and for control plants,40 mL of sterile water was added.Soil water content was 75% -80% of field capacity for the normal irrigation treatment and 15% -20% for the drought treatments.Fresh shoot and root weights,root length,dry shoot and root weights,chlorophyll
(SPAD),relative water content (RWC),antioxidase enzyme activity,O2 - ,methane dicarboxylic aldehyde (MDA)and osmolytes were determined for all treatments.The fungus strongly colonized the roots of alfalfa, infecting 87.4% of seedlings.When the colonized plants were exposed to drought stress,the fresh shoot weight,dry shoot weight,chlorophyll,relative water content and the number of leaves per plant were promo-ted significantly by 63.4%,69.2%,12.5%,17.1% and 5.7,respectively.In addition the fresh root weight, dry root weight,length of taproot and number of lateral roots were improved significantly by 33.3%,57.1%, 5.1 cm and 5 roots,respectively,compared to the reference plants (NI-D).Furthermore,the activities of su-per-oxide,peroxidases,catalases,and the levels of proline and of soluble sugar in the leaves increased by 1.71, 1.27,1.22,1.49 and 1.48 times,respectively,and the contents of O2 - and MDA decreased significantly.In summary,P .indica fungus enhanced the growth and drought tolerance of alfalfa in the seeding stage by stim-ulating the activity of antioxidant enzymes and the content of osmolytes,while under normal irrigation,the fungus had no significant effect on the growth of alfalfa.