Identification of QTLs for shoot and root growth under ionic–osmotic stress in Lotus, using a RIL population

Abstract

The genusLotusincludes a group of forage legume species including genotypes of agronomic interest andmodel species. In this work, an experimental hydroponic growth system allowed the discrimination of growth responses toionic–osmotic stress in a population of recombinant inbred lines (RILs) developed fromL. japonicus L. burttiiand theidentification of the associated quantitative trait loci (QTLs). The analyses led to the identification of eight QTLs: three forshoot growth localised on chromosome 3, 5 and 6; one for root growth on chromosome 1; three for total growth onchromosome 1, 4 and 5; and one associated with shoot/root ratio on chromosome 3. An interaction of QTL stress conditionwas established and the effect of the environment quantified. In summary, it was established that the allele fromL. burttiiexplained most responses to osmotic stress, while the alleles ofL. japonicusexplained the responses related to ionic stressconditions. Of 49 markers linked to all QTLs identified, 41 expressed superiority of theL. burttiiparental allele in theosmotic stress condition, but when an iso-osmotic concentration of NaCl was applied,L. burttiilost superiority in 21 ofthese markers. This shows the superiority of theL. japonicusparental allele in ionic stress conditions. This study is thefirst report in which a RIL population of lotus is analysed with the aim of providing molecular markers associated withplant responses to ionic or osmotic stress.