AUTHOR=Yang Changfu , Zhang Fan , Jiang Xueqian , Yang Xijiang , He Fei , Wang Zhen , Long Ruicai , Chen Lin , Yang Tianhui , Wang Chuan , Gao Ting , Kang Junmei , Yang Qingchuan 

TITLE=Identification of Genetic Loci Associated With Crude Protein Content and Fiber Composition in Alfalfa (Medicago sativa L.) Using QTL Mapping

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.608940

DOI=10.3389/fpls.2021.608940

ISSN=1664-462X

ABSTRACT=Crude protein content and fiber composition are critical factors affecting alfalfa quality. In order to explore the genetic basis of alfalfa quality-related traits, we conducted quantitative trait loci (QTL) mapping based on quality-related phenotypic data obtained from an F1 population, consisting of 392 individuals derived from a cross between Cangzhou and Zhongmu No.1. The content of crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and lignin were measured in the F1 progenies. The phenotypic results demonstrated that four quality-related traits had significant correlation with forage quality over three different growth years. According to the QTL mapping, a total of 78 QTLs associated with the quality traits were identified at one location over three years, with the contribution of each QTL to the phenotypic variation ranging from 1.45-14.35%. Among these QTL, four QTLs (qNDF1C, qCP5A, qADF7D, qNDF8B) have been previous reported by others and five QTLs (qADF1C-1, qNDF5B, qNDF6D, qNDF8B, qADF8B) were detected repeatedly by using the BLUP values of each trait. Furthermore, we found 12 regions where co-localized quality-related QTLs are mapped onto chromosomes 1, 4, 5, 6, 7 and 8. One of these regions, containing three QTL (qNDF1C, qADF1C-2, qlignin1C-2), was detected on the linkage map 1C (86.5-89.5 cM) of both the male and female parents in 2019. By analyzing the marker sequences of this region, several genes related to fiber synthesis were found to be analogous with the Medicago truncatula genome (26.7-31.1 Mb). These results could facilitate the identification of candidate genes related to alfalfa quality and be utilized in marker-assisted selection for favorable alleles in breeding programs of alfalfa quality improvement.