Core Collection Screening Of A Germplasm Population And Evaluation Of Salt And Drought Tolerance At The Germination Stage In Jute(Corchorus Spp.)

Jute,including white jute(C.capsularis)and dark jute(C.olitorius),is not only an important bast fiber crop in the world,but also an important salt-tolerant economic crop that can be planted along the beaches and in saline areas.The construction of core collections of plants and evaluation of specific traits are the basic work for the improvement of varieties.In this study,screening of core SSR primers and core germplasm resources from 300 different original accessions as well as evaluation of salt and drought resistance at the germination stage in jute were conducted.The results of the study are as follows:1.To select the core SSR primers for classification of jute germplasm resources,1188 pairs of SSR primers developed by the research team were evaluated by using 24 strains of jute cultivars(lines)with obvious genetic differences.747 pairs of primers(62.96%)were amplified with good polymorphism.The primary core SSR primers were screened again according to the published genetic map with the distribution on the 7 linkage groups.And 44 pairs of core primers were finally determined.The genetic diversity of 24 jute germplasms was analyzed using the core primers.A total of 92 polymorphic loci were obtained and the PIC values varied from 0.1254 to 0.8679 with an average of 0.6092.There is no significant difference between cluster analysis and progeny information of these accessions,indicating the validity of 44 pairs of core primers.From this point,these core primers can be used inconstruction of the core germplasm and genetic diversity of jute.2.In order to select the core germplasm of jute,11 agronomic traits were identified in the 300accessions from 11 countries and regions including India,Bangladesh and China.The coefficient of variation varied from 13.06%to 84.87%,indicating a rich genetic diversity.The results of principal component analysis showed that the first four principal components were:fiber yield factor,stress factor,growth stage factor and psedo-qualitytraitss factor,and the cumulative variation contribution of these four factors were 67.217%.The clustering results of geographical origin did not show any regularity,indicating that there were homonyms or heteronyms in jute germplasm resources.The clustering analysis of agronomic traits showed that the jute germplasm was divided into 46 groups while the jute germplasm was divided into 10 groups based on the clustering analysis of molecular markers.Combining the two cluster analyses,geographic location,and growth habits of these jute accessions,a preselected core collection including 108 accessions was established.Furthermore,44 pairs of core primers were used to analyze the genetic differences.The 108 varieties were divided into white jute and dark jute at the genetic similarity coefficient of 0.65.According to the analysis of genetic differences,genetic redundancy with genetic similarity greater than or equal to 0.85 was excluded and 84 core collections were obtained.By comparison with the coefficient of variation and the number of alleles between 84 jute core collections and 300 germplasms,it was found that there was no significant difference between them,indicating that the 84 jute core collections could represent the genetic diversity of 300 jute germplasm resources to the maximum extent.3.In order to evaluate the salt-tolerance and drought-resistance characteristics of the core germplasm of jute,salt-tolerant and drought-resistant extreme materials were selected to evaluate the salt-tolerance and drought-resistance characteristics at the germination stage.In this study,120 mMNaCl solution and 15%PEG-6000 solution were used to compare the relative germination rates of 46 jute core collections and 300 germplasms under salt and drought tolerance conditions,and the salt-tolerant and drought-resistant characteristics were classified.The results showed that the stress of 120 mMNaCl solution and 15%PEG-6000 solution was a suitable concentration for screening the salt and drought resistance of jute.Among them,136 are high salt-tolerant materials,92 are medium salt-tolerant materials,and 72 are salt-sensitive materials.The best representative materials for salt tolerance areZijinhuangma,Qiongyueqing and Fuhuangma No.3,and the representative material with the lowest salt tolerance is MinmaNo.429.There were 72 high drought tolerance materials,95 moderately drought tolerance materials and 133 drought sensitive materials.The most representative drought-resistant material is Funong No.2,Guangbaai and Tianma.The representative material with the worst drought resistance is Yuanzima.These materials are the basis of further researches on dissecting of the genetic and molecular mechanisms of salt tolerance and drought resistance in jute.