In Response To Drought And Low Temperature Stress Induced By Piriformospora Indica

A.andraeanum andraeanum is a perennial semi-epiphytic herb,which is native to the tropics and demands warm and humid.It is sensitive to temperature and moisture and afraid of drought.It is easy to cause cold damage,when the growth temperature is above 15 ? or below 12 ?.Low temperature and drought are important abiotic factor that limits the growth and development of andraeanum.Piriformospora indica is an endophytic fungus that can colonize the roots of a variety of host plants.Its function is similar to that of Arbuscular Mycorrhizal Fungi(AMF),which can colonize the roots of plants,promote its growth,improve the ability of plants to absorb minerals and enhance the resistance of plants.In this paper,three andraeanum varieties "Pink Champion","Sierra" and "Vito" were used as experimental materials to study the influence of low temperature stress and drought stress on the relative conductivity,malondialdehyde(MDA)content and antioxidant enzyme activity of andraeanum and the effects of P.indica on its cold resistance and drought resistance,and discuss the effects of P.indica on andraeanum under low temperature stress and drought stress,which provides a theoretical basis for selecting varieties of andraea4num and enhancing its stress resistance by P.indica.The main results are as follows:1.With the extension of low temperature stress time,the relative conductivity and MDA content of different varieties of andraeanum increased.The change trend of chlorophyll content was complex,showing a trend of increasing first,then decreasing and then increasing again.And the change of antioxidant enzymes was not regularly.'Sierra'had the strongest cold tolerance,the increase of its relative conductivity and MDA content was small,and cell membrane permeability was stable.After 72 h of low temperature stress,the relative conductivity and MDA content of 'Sierra' increased by 128.2%and 39.28%respectively,while the relative conductivity and MDA content of' Vito' increased significantly compared with 'Sun',which was 152.18%and 54.09%respectively.Under low temperature stress,the activity of SOD of 'Sierra'was higher,the activity of CAT and POD was stable,the ability of scavenging reactive oxygen species was stronger,and the content of chlorophyll was higher,showing strong cold tolerance.'Vito' had a higher degree of cell membrane lipid peroxidation,low chlorophyll content and POD activity,large fluctuations in CAT and SOD activity,and the least resistance to cold,followed by 'Pink Champion'.2.With the prolongation of drought stress,the relative conductivity and MDA content of different varieties of andraeanum increased,and the change trend of total chlorophyll was complex,showing a trend of increasing first,then decreasing and then increasing again.The increase of relative conductivity and MDA content of 'Pink Champion' was less under drought stress,and its relative conductivity and MDA content increased by 65.48%and 27.01%respectively at 72h.The relative conductivity of 'Vito' was significantly higher than the 'Pink Champion',with increase of 166.27%.Under drought stress,CAT and POD activities of 'Pink Champion'were higher,SOD activity was more stable,the ability of scavenging reactive oxygen species was stronger,chlorophyll content was higher,showeing strong drought tolerance.The chlorophyll content of' Vito'decreased greatly,the activity of CAT and POD fluctuated greatly,the degree of cell membrane lipid peroxidation in the body was heavier,and the drought resistance was the worst,followed by 'Sierra'.3.The system was established.P.indica can promote the growth and development of roots significantly,increase the growth of the aboveground of andraeanum and have obvious promoting effect.The fresh weight of the aboveground and roots of the andraeanum inoculated with P.indica were increased significantly,and the total root length,root surface area,total volume and number of root tips and root branches of different varieties of andraeanum were highly significant increased.4.The cell membrane stability of Andraeanum-P.indica symbiosis plants was significantly enhanced,the increase of relative conductivity and MDA content under low temperature stress was inhibited,and the degree of declining of chlorophyll content was decreased.P.indica can enhance the activity and stability of antioxidant enzymes in the leaves of andraeanum,maintaine the balance between defense system and reactive oxygen species,and avoid the low temperature exacerbation of plant metabolism disorders.P.indica can induce the improvement of cold resistance of andraeanum,especially in the variety 'Vito' with poor cold tolerance.5.Andraeanum-P.indica symbiosis plants enhanced the cell membrane stability of andraeanum under drought stress,inhibited the relative conductivity and MDA content of andraeanum.And the chlorophyll content of different varieties of andraeanum within 3-9 days of drought stress increased in some extent.P.indica can enhance the activity and stability of antioxidant enzymes in different varieties of andraeanum,reduce the degree of membrane lipid peroxidation in andraeanum,and induce the improvement of drought resistance of andraeanum,especially in the variety ' Vito' with poor drought tolerance.