The Effects Of Amf On Cell Membrane Endogenous Polyamines And Salicylic Acid In Citrus Under Drought Stress

Arbuscular mycorrhizas(AM) are mutualistic symbioses that form between arbuscular mycorrhazal fungi(AMF) in soil and the roots of host plants,the symbioses are characterized by bi-movement of nutrients where carbon flows to the symbioses and inorganic nutrients or water move to the plants,thereby becoming a transported cartier between soil and the roots of host plants.The present study is to evaluate the effects of water status on AM development,and the effects of AMF on growth,cell membrane, endogenous polyamines and salicylic acid of trifoliate orange(Poncirus trifoliate(L.) Raf.) and red tangerine(Citrus tangerine Hort.ex Tanaka) inoculated with Glomus mosseae(G.m) under well-watered and drought stress conditions.That how drought resistance of citrus are enhanced by the endogenous growth matters with AMF is the main work in this study.The main contents and results in the present study are as follows:1 The effects of water status on AM development.Drought-stress significantly decreased the mycorrhizal infection of two citrus roots,with treatment days increasing, mycorrhizal colonizaion rates increased under well-watered and drought stress conditions. Sporulations were relatively accelerated under well-watered condition,and increased with prolonged periods of the treatment,while they were accelerated in a certain extent under the beginning of drought stress,but the increase of spore numbers relatively fell later. Glomalin was observed in rhizospher of two citus seedlings,and increased under drought stress condition.2 The effects of AMF on growth and development in citrus under well-watered and water stress conditions.Drought-stress could obviously decrease the growth of two citrus seedlings,but AMF-inoculation could alleviate the effect.AMF-inoculation increased plant height,stem diameter,leaf number,leaf area and dry matter weight(shoot dry matter weight,root dry matter weight and plant total dry matter weight).AM dependency and contribution of trifoliate orange under drought stress condition was lower than well-watered condition.Leaf relative water content of two citrus seedlings decreased under water stess condition,but were more enhanced by AMF inoculaion under well-watered condition.3 The effects of AMF on cell membrane and lipid peroxidation in citrus under well-watered and drought stress conditions.Drougt-stress brought damages that showed differences by different species and treatment days to the two citrus leaves,cell membrane permeability increased.The damages to cell membrane permeability in trifoliate orange under drought stess condition were up to the top on 20 days after treatment,while AMF-inoculation alleviated damages in a certain extent which showed the most signicant differences on the same day.Under drought stress condition,along with treatment days increasing,the damages to red tangerine reached the highest value on 40 days after treatment.The leaf relative electronic conductivity in red tangerine was lower than that in trifoliate orange.Whether leaves or roots,MDA contents which were always higher in leaves than in roots in trifoliate orange and red tangerine under drought stress condition markedly increased.MDA contents in leaves and roots of trifoliate orange decreased by G.m inoculation,and the effect was most signicant on 20 days after treatment.4 The effect of AMF on endogenous polyamines and salicylic acid in citrus under well-watered and drought stress conditions.Drought-stress could obviously accelerated accumulations of three free polyamines and total polyamines in both two citrus seedlings. Whether well-watered or drought stress conditions,free putrescine and spermidine contents markedly decreased by G.m inoculation,but spermine increased,and upper (Spd+Spm) /Put ratio was retained in trifoliate orange.Salicylic- acid accumulations of leaves in trifoliate orange and red tangerine(both free and conjunct state) increased under drought stess condition,and came to max on 20 days after treatment,which decreased by AMF inoculaion comparing with the non-inoculation.