Evaluation Of Drought Resistance And Expression Analysis Of AhPLP Gene Family In Peanut (Arachis Hypogaea L.)

Peanut is one of the most important oil crops in the world.China is the largest producer and consumer of peanut in the world,peanut plays an important role in guaranteeing national grain and oil security,and agricultural trade.Peanut is mainly planted in arid and semi-arid hilly areas in China,and is susceptible to drought stress of different degrees during the whole growth and development period,which seriously affects the yield and quality.Therefore,it is of great significance to select peanut varieties with high drought resistance and study drought resistance mechanism for guiding peanut production.The PLP family plays an important role in the regulation of plant stress tolerance,but the identification and functional studies of this gene family in peanut are rarely reported.In this study,11 peanut varieties(lines)with different drought resistance were selected,and three schemes were set at seedling stage to treat them with drought stress,to study the changes of plant agronomic traits,physiological and biochemical indexes,and to evaluate the drought resistance ability of peanuts by comprehensive membership function method.The whole genome of AhPLP gene family was identified and the expression under drought stress was analyzed.The main results are as follows:1.After treatment with 15% PEG6000 solution for 7 days,the morphological indexes of main stem height,main root length,fresh plant weight and dry plant weight of 11 peanut varieties(lines)were significantly reduced compared with CK.The results showed that Hua708,Nongdahei7572 and A.mon had strong drought resistance,while Baisha1016 and ZP08 had weak drought resistance.After treatment with 20% PEG6000 solution for 72 h,SOD,POD,CAT activities and MDA content of 11 peanut varieties(lines)were significantly increased.The results showed that ZP06 and Hua708 had strong drought resistance,while Nongdahua107,ZP08 and Baisha1016 had weak drought resistance.After natural drought treatment,ZP08 had the shortest drought tolerance days,while Hua814 had the longest drought tolerance days.The content of proline,water content and chlorophyll SPAD value in leaves changed significantly.The results showed that ZP06,Hua814 and Hua708 had strong drought resistance,while Baisha1016 and Nongdahua201 had weak drought resistance.The results showed that Hua708 had the strongest drought resistance,Nongdahei7572,A.mon,ZP06 and Nongdahua108 had strong drought resistance,ZP08 and Baisha1016 had the weakest drought resistance,and other peanut varieties(lines)had medium drought resistance.2.A total of 26 PLP family members were identified,with amino acid sequence length ranging from 220 to 812 AA,molecular weight ranging from 23.59 to 89.86 k D and isoelectric point ranging from 4.68 to 8.74.The PLP family members were unevenly distributed on 10 chromosomes and divided into two subfamilies in phylogenetic tree.The promoters of AhPLP gene family members have elements that respond to hormone and stress induction,such as abscisic acid response element and drought induction response element.RNA-seq data showed that different genes had specific expressions under different temporal and spatial conditions.AhPLP1,AhPLP10 were highly expressed in all tissues,AhPLP4 was specifically expressed in seeds and fruit pericarps,and AhPLP23,AhPLP26 were specifically expressed in nodule and roots.AhPLP21 was highly expressed in nodule,pistil and fruit pericarps.q RT-PCR results showed that AhPLP1,AhPLP10 and AhPLP13 were all expressed in roots,stems,leaves,flowers and seeds.AhPLP4 was highly expressed in leaves,pericarps and stamens,AhPLP5 was highly expressed in leaves and stamens,and AhPLP9 was highly expressed in stamens,seeds and stems.The data were basically consistent with RNA-seq data.3.According to the results of AhPLP gene family identification,combined with promoter elements and tissue expression characteristics,AhPLP1,AhPLP10,AhPLP23 and AhPLP26 were screened as candidate genes to analyze the response of the four genes under drought stress.Four peanut varieties(lines)with different drought resistance ability were selected,which were Nongdahua108,Hua708,A.mon and ZP08.The peanut seedlings were treated with 20%PEG6000 solution stress,and the expression levels of four genes in roots,stems and leaves were determined and analyzed under different treatment time.With the extension of drought stress treatment time,the expression levels of the four genes in different peanut seedlings increased first and then decreased,and the expression level of AhPLP1 in ZP08 increased the most,and maintained high expression level at different treatment time.The expression of AhPLP10 in Hua708 increased significantly,and maintained a high expression level during the whole treatment period.The expression level of AhPLP23 in the stems of the four peanut varieties(lines)was relatively low,but the expression level of AhPLP23 in the roots was high,and the expression level of AhPLP23 in the roots of ZP08 increased the most.The expression level of AhPLP26 in the stems of the four peanut varieties(lines)was low,but it always maintained a high expression level in the leaves,and the expression level of AhPLP26 in ZP08 increased greatly.The results showed that AhPLP1,AhPLP10,AhPLP23 and AhPLP26 genes were sensitive to drought stress and showed different responses.