Genome-Wide Association Studies of Root-Related Traits in Brassica napus L. under Low-Potassium Conditions

Abstract

Roots are essential organs for a plant’s ability to absorb water and obtain mineral nutrients, hence they are critical to its development. Plants use root architectural alterations to improve their chances of absorbing nutrients when their supply is low. Nine root traits of a Brassica napus association panel were explored in hydroponic-system studies under low potassium (K) stress to unravel the genetic basis of root growth in rapeseed. The quantitative trait loci (QTL) and candidate genes for root development were discovered using a multilocus genome-wide association study (ML-GWAS). For the nine traits, a total of 453 significant associated single-nucleotide polymorphism (SNP) loci were discovered, which were then integrated into 206 QTL clusters. There were 45 pleiotropic clusters, and qRTA04-4 and qRTC04-7 were linked to TRL, TSA, and TRV at the same time, contributing 5.25–11.48% of the phenotypic variance explained (PVE) to the root traits. Additionally, 1360 annotated genes were discovered by examining genomic regions within 100 kb upstream and downstream of lead SNPs within the 45 loci. Thirty-five genes were identified as possibly regulating root-system development. As per protein–protein interaction analyses, homologs of three genes (BnaC08g29120D, BnaA07g10150D, and BnaC04g45700D) have been shown to influence root growth in earlier investigations. The QTL clusters and candidate genes identified in this work will help us better understand the genetics of root growth traits and could be employed in marker-assisted breeding for rapeseed adaptable to various conditions with low K levels.

Morpho-physiological, Genomic, and Transcriptional Diversities in Response to Potassium Deficiency in Rapeseed (Brassica napus L.) Genotypes

“…In the previous study aforementioned, several QTLs for rapeseed low K resistance were identified on the chromosomes of A2, A4, A5, A7, and A9. 24 Prior to our current study, several researches were conducted to identified the key genes responsible for low K resistance in different rapeseed genotypes, 21,24,19 most of which focused on the dry biomasses or root morphology as the observed phenotype but failed to investigate the differential K + profiling among rapeseed genotypes. Although some genes were assumed to be involved in the regulation of low K resistance, a few of them have been verified to play key roles in the responses of rapeseed plants to low K stresses.…”

“…Genetic variations in the sensitivity to K deficiency found in rapeseed genotypes highlight the complex regulatory mechanisms . However, previous studies have mainly focused on the morpho-physiological and transcriptomic responses of single rapeseed genotype to K deficiency, ,, or rough mapping of some QTLs for rapeseed low K resistance . Few of the previous studies have integrated morpho-physiological responses, genomic variations, and transcriptional profiling into the dissection of differential low K resistance among rapeseed genotypes.…”

“…24 However, previous studies have mainly focused on the morpho-physiological and transcriptomic responses of single rapeseed genotype to K deficiency, 51,36,26 or rough mapping of some QTLs for rapeseed low K resistance. 19 Few of the previous studies have integrated morpho-physiological responses, genomic variations, and transcriptional profiling into the dissection of differential low K resistance among rapeseed genotypes. In this study, based on the initial assessment of low K resistance variations among a rapeseed panel comprising 259 accessions, two genotypes with differential low K resistance were identified and characterized.…”

“…18 Oilseed rape (Brassica napus L., A n A n C n C n , 2n = 4x = 38) is the world's third-largest oilseed crop, after soybean and palm oil. 19 B. napus is a crop that originated from interspecific crosses between the diploid ancestors B. rapa (A r A r , 2n = 2x = 20) and B. oleracea (C o C o , 2n = 2x = 18), resulting in an allopolyploid species. 20 The sustainable development of rapeseed production has been limited by the discrepancy between the high demand for K and insufficient K input.…”

“…Oilseed rape (Brassica napus L., A n A n C n C n , 2 n = 4 x = 38) is the world’s third-largest oilseed crop, after soybean and palm oil B.…”