Study Of Arbuscular Mycorrhiza Fungi (AMF) Regulating Cd Accumulation And Quality In Panax Notoginseng

Panax notoginseng(Bur K.)F.H.Chen,also known as Tianqi,is a perennial herb of the genus Ginseng in the Araliaceae Juss,and is a traditional valuable Chinese herb with important medicinal and economic values in China.However,with the increasing market demand and planting area,the high geological background of heavy metals,application of a large amount of pesticides and fertilizers,and frequent land replacement resulted from continuous cropping obstacles make P.notoginseng vulnerable to heavy metal pollution during the planting process.Arbuscular mycorrhizal fungi(AMF)can form symbiotic relationships with a variety of plants and play important roles in promoting plant growth and development,enhancing plant antioxidant defense mechanisms,and regulating heavy metal uptake and transport.However,whether AMF is involved in the regulation of Cd accumulation and quality of P.notoginseng is unclear.In this research,five different AMFs were inoculated with P.notoginseng under Cd stress:Claroideoglomus etunicatum(Ce),Rhizophagus intraradices(Rin),Rhizophagus irregularis(Rir),Funneliformis mosseae(Fm),and Glomus versiforme(Gv)and the AMF colonization rate,photosynthesis,antioxidant system activity,mineral element content,Cd content,and saponin content of P.notoginseng were comprehensively evaluated..The main findings were as follows:(1)All five AMFs were able to form a symbiotic relationship with P.notoginseng,and their colonization rates were in the following order:Ce>Rin>Rir>Fm>Gv;the colonization rates ranged from 11%to 34%;after forming a symbiotic system with P.notoginseng,AMFs could improve the dry weight,fresh weight and root activity of P.notoginseng roots under Cd stress.Among them,inoculation of Ce had the most significant effect on dry weight,fresh weight and root activity of P.notoginseng.(2)Inoculation with AMF increased chlorophyll a,b and total content in P.notoginseng leaves under Cd stress;and increased its net photosynthetic rate(P_n),stomatal conductance(Gs)and transpiration rate(Tr).Among them,inoculation with Rin had the most significant effect on chlorophyll content and photosynthesis of P.notoginseng.(3)Inoculation with AMF significantly increased the activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)as well as the content of reduced glutathione(GSH)and ascorbic acid(As A)and reduced the content of malondialdehyde(MDA)in P.notoginseng under Cd stress.Among them,inoculation with Rir had the most significant effect on the antioxidant enzyme activity of P.notoginseng,while inoculation with Rin had the most significant effect on the non-enzymatic antioxidant content of P.notoginseng.(4)Inoculation with AMF significantly increased the contents of nitrogen(N),phosphorus(P),potassium(K),magnesium(Mg),and calcium(Ca)of P.notoginseng under Cd stress,increased the saponin content and reduced the Cd content,and improved the yield and quality of P.notoginseng.Among them,inoculation with Rir had the most significant effect on the mineral nutrient content of P.notoginseng,while inoculation with Rin had the most significant effect on promoting the accumulation of P.notoginseng saponin and reducing the Cd content of P.notoginseng.By analyzing the effects of the five AMFs on the colonization of P.notoginseng roots,the abatement of heavy metal Cd,the repair of antioxidant system,and the enhancement of yield and quality,a comprehensive comparison showed that Rin>Rir>Ce>Fm>Gv.