Download or read book Dissecting the Genetic Basis of Various Adaptation Traits in Alfalfa Using QTL Mapping written by Laxman Adhikari and published by . This book was released on 2018 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fall dormancy (FD) and winter hardiness (WH) influence seasonal yield, stand persistence, and latitudinal adaptation of alfalfa (Medicago sativa L.). Selection of dormant alfalfa genotypes with higher WH has been a common practice. This research was carried out to dissect the genetic basis of FD and WH through quantitative trait loci (QTL) mapping and explore the potential of incorporating WH in non-dormant alfalfa. Other traits, including time of flowering (TOF), spring yield (SY), cumulative summer biomass (CSB), and leaf rust resistance were also evaluated. An F1 population was derived for linkage analysis and QTL mapping by crossing a dormant winter-hardy cultivar (3010) with a non-dormant cold-sensitive cultivar (CW 1010) Genotyping-by-sequencing was used for single nucleotide polymorphism (SNP) marker discovery. Dormancy and WH were evaluated according to NAAIC protocols. We mapped 45 FD and 35 WH QTLs on the genetic linkage maps of both parents. More than 70% of the FD QTLs did not share genomic locations with WH QTLs, suggesting that the two traits are inherited separately. This study also showed that using late autumn to early winter regrowth height is more reliable than early autumn in estimating alfalfa dormancy in southern environments with mild-winters. The QTL markers with higher phenotypic effects (R2) can be used in marker-assisted selection (MAS) of non-dormant alfalfa with improved WH. Incorporating WH in non-dormant alfalfa can ensure forage production in late autumn and early winter to minimize the forage gaps. In this research, we mapped a total of 25 QTLs for TOF, 17 QTLs for SY, six QTLs for CSB, and eight QTLs for leaf rust resistance in the same alfalfa population. Four TOF QTLs were detected in corresponding genomic positions of flowering QTLs of M. truncatula reported previously. The multiple QTLs detected for leaf rust resistance suggests that alfalfa resistance to the rust pathogen is polygenic. The QTL markers identified in this study constitute an important addition to alfalfa genomic resources and can be validated in populations with diverse genetic backgrounds and in multiple environments for potential use in MAS.