QTL mapping of panicle architecture and yield-related traits between two US rice cultivars 'LaGrue' and 'Lemont'

Grain yield is a quantitative trait, which is determined by several agronomic traits. Unfortunately, there is little information about the genetics behind yield components in US rice cultivars. The objectives of the present study were to (1) conduct a QTL study to identify chromosome (chr. hereafter) regions associated with yield traits in two U.S.-developed rice cultivars and (2) identify candidate genes in major QTL regions related to yield traits. Four rice cultivars were evaluated in summer 2017 at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC) at Stuttgart, AR. for 15 agronomic traits associated with yield. Of the four cultivars, "LaGrue" had a higher number of seeds/panicle, number of primary panicle branches/panicle, and number of seeds/plant and "Lemont," despite having longer panicles and higher 100 seed weight/panicle, produced the least number of seeds among the cultivars. A bi-parental population was developed from a cross between LaGrue and Lemont for QTL analysis. A set of 322 F 2:3 lines were evaluated in a randomized complete block design (RCBD) for several agronomic traits at two locations with three replications for each line. A total of 17 major QTL were detected, including two major QTL for plant height on chr. 1 and two major QTL for flag leaf length and panicle length on chr. 8 with seven candidate genes found in these regions. The results from the study would be useful for marker-assisted selection in rice breeding.