The Genetic Analysis Of Root System Under Two Potassium Levels In Brassica Napus

Potassium(K)efficiency is associated with plant growth and development,means that it is important for improvement-breeding in Brassica napus.As the complex quantitative genetic characters,root related traits are controlled by multiple factors.And different roots would have different potassium efficiency.In this study,RIL population,a double haploid population derived from a cross between ZS11 and NO.73290,and association population(280),were used in hydroponic experiments.We investigate biomass,root traits,K accumulation and K efficiency with hydroponics at low K(KS)and normal K(CK)experiments.Genetic analysis for these traits were conducted,quantitative trait loci(QTL)and association analysis for these traits were mapped on the RIL map and SNP arrays severally.The main results are as follows:1.The most appropriate K concentration was 0.05mmol/L to conduct the low K experiment in Brassica napus,at which the plant appeared obvious changes in root and showed phenotype lacking of potassium.2.The KS treatment significantly decreased the values of biomass,K accumulation and significantly increased the values of PRL,RSRD,RSRF in three hydroponic experiments.KEC and [K]a had significant correlation with root traits.Highly significant differences were existed among KEC and [K]a with PRL under KS treatment,but no significant differences were observed between them under CK treatment.Meanwhile,compared with the KEC out door,the KEC indoor were much lower.Hence,we guess that potassium efficiency might be closely related to the PRL,and at the same time,influenced by genetic and environmental factors both.3.A total of 134 significant QTL were detected for the fourteen traits at KS and CKtreatments in three environments,and most of them were environmental dependent.An individual QTL explained between 6.35 to 23.71% of the observed phenotypic variation.The interval 45-60.1cM in chromosome A2,61.8-75.7cM and 90.7-106.3cM in chromosome A7 were distributed by abundant QTL which were detected under both KS and CK conditions.4.There were 15 important signals including 4 significant signals were detected through Genome-wide association analysis in all.Based on the result of QTL,we find a overlap between Bn-A07-p16461287 with Bn-A07-p18230931,which is likely to be a important region to control the development of root system and may contain the key genes.