Response Of Allium Senescens Seedling To Drought Stress

Allium senescens Linn is a perennial herb of the family Liliaceae and Allium with many values for food,medicinal use,feeding,and ornamental use.In recent years,the demand for A.senescens as a food resource has been increasing,and wild A.senescens resources have been in short supply;at the same time,as an excellent ornamental plant,A.senescens has increased in demand in urban and landscape afforestation.Therefore,it is necessary to continuously expand the cultivated area and the growth range of the A.senescens.However,most of the areas in China are in arid and semi-arid regions,and the water resources are very limited.To study the physiological response of A.senescens seedlings,the anatomical structure of leaves,and the response of differentially expressed genes under Drought Resistance and Drought Stress of A.senescens Seedlings,and to screen and cultivate allium plants with strong drought tolerance,and expand the range of A.senescens cultivation and enhancement.Water use efficiency,reducing the cost of cultivation and maximizing the ecological and economic benefits of A.senescens have theoretical guidance and practical significance.The study was conducted in May 2016 to July 2017 at Hebei University using outdoor pots and natural drying methods to simulate drought stress.A total of four treatments were conducted.The relative soil moisture content(percentage of the maximum water holding capacity in the field)was 80%-85%(normal,control),60%-65%(mild stress),40%-45%(moderate stress),and 20%-25%(severe stress),respectively,at 20 days of drought stress The growth indexes,physiological indexes,and anatomical structures of A.senescens seedlings were measured and the transcriptomes were sequenced.(1)Under severe drought stress,the above-ground biomass and plant height were reduced by 44.6% and 25.1% respectively compared to the control treatments of A.senescens seedling.The above-ground biomass and plant height were affected by drought stress to less than about 60% and 70% respectively Plants,it's show that has strong drought resistance of A.senescens seedling.(2)A.senescens seedlings could increase their ability to adapt to drought stress by increasing chlorophyll content under moderate drought stress(P<0.05);valine played an important role in maintaining the stability of protein structure and maintaining cell membrane integrity role;SOD enzymes play an important role in antioxidation during moderate drought stress,and POD enzymes play an important antioxidant role in severe drought stress.(3)With the increase of drought stress,the ratio of palisade tissue and spongy tissue thickness in leaves of A.senescens seedlings was significantly increased(P<0.05),indicating that A.senescens seedlings can resist drought by increasing the palisade tissue thickness and reducing the thickness of spongy tissue.(4)The differentially expressed genes in A.senescens were mainly concentrated in cell wall tissue or biogenesis,glycosaminoglycans decomposition,aminopolysaccharide metabolism,catabolism of carbohydrate derivatives,and catabolism of organic nitrogen compounds.Significant differentially expressed genes were mainly concentrated in amino acids.There are seven metabolically significant pathways,including sugar and nucleotide sugar metabolism,RNA trafficking,linoleic acid metabolism,dislocation repair,mRNA surveillance pathways,plant-pathogen interactions,and splicing.