| Peanut is an important economic and oil crop,which is widely cultivated in the world with high diversity.Accurate identification and classification of germplasm resources is the basis of germplasm utilization,mining key genes control important agronomic traits,and breeding.Abiotic stress is the main factor limiting the yield of peanut.The screening of salt tolerant germplasm materials,the excavation of key genes for salt tolerance and the functional research are the basis of breeding novel salt tolerant peanut varieties.In this study,more than 200 peanut germplasm resources preserved in the laboratory had been identified.These germplasm resources were divided into varieties according to morphological indexes.The botanic classification is consistent with the clustering analysis for most individuals.There were 64 aquaporin genes identified in peanut.Salt induced AhTIP3;1 had high water permeability.AhTIP3;1 overexpressed yeast lines were more sensitive to salt stress.However,the germination rate enhanced in AhTIP3;1overexpressed Arabidopsis lines under salt stress.(1)A total of 203 peanut germplasm resources were investigated in three different of experimental sites in two years.The important agronomic characters,such as plant height,branch number,flowering habit,pod and seed size,and quality characteristics were counted.Based on previous studies,the key to peanut varieties classification was rearranged,and these resources were divided into two subspecies and five varieties.The differences of flowering habit,branch number,plant type index,seed number,kernel characteristics and seed oil content among varieties were compared.Some specific resources were identified.For instance,germplasms with plant high less than 30 cm and oleic acid content lower than oleic acid content were identified.Correlation analysis of different traits showed that 1)the correlation rate(r2)between seed weight and seed length,and width is 0.63 and 0.65,respectively;2)there was a significant negative correlation between oleic acid content and linoleic acid content in kernels(P < 0.0001).The morphological classification was further confirmed by cluster analysis of 203 peanut samples at the whole genome level by using genome resequencing data(15x).(2)Aquaporins constitute a multiple member family in higher plants,which play a key role in regulating plant water balance under abiotic stresses.In order to completely understand the function of peanut aquaporins,their family members were identified in the whole genome,and their phylogeny,gene structure,and conserved sequences were analyzed in this study.A total of 64 aquaporin members were identified in tetraploid peanut genome.Based on phylogenetic analysis and selective filtration structure,it is suggested that NIPs(nodulin 26 like intrinsic proteins)should be divided into NIP1 s and NIP2 s,instead of the previous seven group classifications.Furthermore,the expression pattern of peanut aquaporin gene under salt stress was analyzed based on previous studies.It was found that members of TIP3 s were specifically induced under salt stress.AhTIP3;1 had high water transport activity when expressed in Xenopus oocyte system and AhTIP3;1overexpressed yeast lines showed NH3 and boron transport activity.Through genetic transformation and heterologous expression,it was found that AhTIP3;1overexpressed yeast lines were more sensitive to salt stress,while the AhTIP3;1overexpressed Arabidopsis thaliana had a higher germination rate under salt stress than the wild type.This work laid a foundation for the classification,identification and utilization of the increasing peanut germplasm resources,and provided a variety of materials with various plant height,branch number,fruit characteristics and fatty acid content for the diversity of breeding goals.This study provides a comprehensive overview of MIP(major intrinsic protein)superfamily and its expression and function under salt stress,which will favor to understand the role of aquaporins in plants under salt stress. |
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