Abstract
Italian ryegrass (Lolium multiflorum Lam.) is widely cultivated in temperate regions owing to its excellent producibility and digestibility. Nitrogen is an essential nutrient for plant growth; however, the overuse of nitrogen fertilizers can lead to excessive accumulation of nitrate-nitrogen in Italian ryegrass, which can prove to be lethal for ruminants. To study the genetic control of the nitrate-nitrogen content in Italian ryegrass, an Italian ryegrass line LNG8 (with low 0.12% dry matter (DM) of nitrate-nitrogen) and a second line JFIR12 (with a “normal” 0.20% DM of nitrate-nitrogen) were pair-crossed and 190 F2 individuals derived from these were used to construct an SSR-based linkage map for conducting QTL analysis. A linkage map was constructed based on 212 Lolium SSR markers. The female parental map consisted of seven linkage groups (LGs) and had a total length of 714.1 cM with 178 loci and an average map density of 4.0 cM. The male parental map consisted of 7 LGs and had a total length of 737.4 cM with 199 loci and an average map density of 3.7 cM. We measured the nitrate-nitrogen content of the mapping population in three replicates (including the main stem and two tillers separated from the main stem) at the six-leaf stage. The nitrate-nitrogen content of the mapping population followed a normal distribution with a marginal skewness toward the lower parent. Our analysis revealed the presence of six QTLs on three LGs. A major QTL on LG1 was detected in all three replicates in both two-parental maps, which could explain 19.4%–29.9% of the phenotypic variation. Furthermore, based on the information of model plant species such as rice and Arabidopsis, we cloned six nitrogen metabolism-related genes and attempted to locate these on our linkage maps; however, none of these six genes were located in the demarcated QTL regions. These results will be useful for understanding the genetic bases of nitrate-nitrogen content in Italian ryegrass and the molecular cloning of QTLs for determination of nitrate-nitrogen content. The flanking markers of the QTLs will be helpful for breeding Italian ryegrass with low nitrate-nitrogen content.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
