QTL architecture of reproductive fitness characters in Brassica rapa

Abstract

BackgroundReproductive output is critical to both agronomists seeking to increase seed yield and to evolutionary biologists interested in understanding natural selection. We examine the genetic architecture of diverse reproductive fitness traits in recombinant inbred lines (RILs) developed from a crop (seed oil) × wild-like (rapid cycling) genotype of Brassica rapa in field and greenhouse environments.ResultsSeveral fitness traits showed strong correlations and QTL-colocalization across environments (days to bolting, fruit length and seed color). Total fruit number was uncorrelated across environments and most QTL affecting this trait were correspondingly environment-specific. Most fitness components were positively correlated, consistent with life-history theory that genotypic variation in resource acquisition masks tradeoffs. Finally, we detected evidence of transgenerational pleiotropy, that is, maternal days to bolting was negatively correlated with days to offspring germination. A QTL for this transgenerational correlation was mapped to a genomic region harboring one copy of FLOWERING LOCUS C, a genetic locus known to affect both days to flowering as well as germination phenotypes.ConclusionsThis study characterizes the genetic structure of important fitness/yield traits within and between generations in B. rapa. Several identified QTL are suitable candidates for fine-mapping for the improvement of yield in crop Brassicas. Specifically, brFLC1, warrants further investigation as a potential regulator of phenology between generations.

Genome-Wide Association Mapping of Fertility Reduction upon Heat Stress Reveals Developmental Stage-Specific QTLs in Arabidopsis thaliana

“…Li et al, 2014). Fruit length is considered to be a suitable trait to select for in B. napus (Samizadeh et al, 2010) because high heritability is observed for this trait, which is less sensitive to GxE than, for example, the total number of fruits per plant (Chay and Thurling, 1989;Dechaine et al, 2014). In this experiment, high heritability was also observed for silique length (Table 3).…”

“…Total yield is determined by several plant traits, such as total fruits per plant, seed weight, seeds per fruit, and fruit length. The last three are correlated and many coinciding QTLs have been reported (Alonso-Blanco et al, 1999;Dechaine et al, 2014;N. Li et al, 2014).…”

Using RNA-seq for genomic scaffold placement, correcting assemblies, and genetic map creation in a commonBrassica rapamapping population

“…Individual replicates of each RIL were sown into peat pots filled with field soil and topped with 1 cm LP5 potting soil (Sun Gro Horticulture, Agawam, MA). Seeds were planted in the first week of June 2011, and pots were transplanted to the field 2.5 wk later following established protocols (Dechaine et al 2014). One biological replicate of each genotype was planted into each of five fully randomized blocks.…”

“…For this study, we utilized an existing RIL population of B. rapa that has been used extensively for QTL mapping of physiological, developmental, and evolutionarily important traits [BraIRRi; Baker et al 2015;Brock et al 2010;Dechaine et al 2007Dechaine et al , 2014Edwards et al 2011;Iniguez-Luy et al 2009;Lou et al 2011Lou et al , 2012. Recently, we completed deep RNA-Seq of the parents of the BraIRRi population, providing a large SNP set and improved gene annotation information (Devisetty et al 2014).…”

Natural variation in growth and physiology under salt stress in rice: QTL mapping in aHorkuch×IR29mapping population at seedling and reproductive stages

“…QTL co-localization has been reported for traits that are strongly correlated (Dechaine et al , 2014). Many clustered, putatively pleiotropic QTL have been found that affect various life history and fitness characters, especially those that are related to yield, in rice, wheat, pea and rapeseed (Burstin et al , 2007; Quarrie et al , 2006; Shi et al , 2009; Xue et al , 2008).…”