Expression quantitative trait loci (eQTL) analysis of Brassica rapa under varying soil phosphorus (P) supplies

ABSTRACT: The aim of this study was to identify eQTL in Brassica rapa grown under altered soil phosphorus (P) supply, to understand better the genetic architecture of P-use efficiency (PUE) in plants. Recombinant inbred lines (RILs) of the BraIRRI mapping population were grown at adequate and growth-limiting soil P. Variation in leaf gene expression was quantified using an Agilent Brassica 95k oligonucleotide array. Informative gene expression markers (GEMs) were used to map eQTL and PUE-related QTL. Gene expression was highly dependent on soil P supply. However, the altered expression of many genes, including known P-responsive genes, was highly heritable. Interval mapping using P supply as a covariate revealed 18,876 eQTL, representing 15,912 unique probes. Notable trans-eQTL hotspots occurred on chromosomes A06 and A01; these were enriched with protein modification and phosphorus metabolism-related (A06), as well as chloroplast and photosynthesis-related (A01) transcripts. Regulatory loci and genes associated with P-use efficiency identified through eQTL analysis are potential targets for further characterisation and may have potential for crop improvement. Availability of the annotated B. rapa genome sequence will facilitate their study, including the separation of cis- and trans- effects. The experiment was designed to identify expression QTL associated with availability of phosphorus in Brassica rapa. Seventy-eight informative lines from the “BraIRRI” mapping population of Brassica rapa L. (2n = 2x = 10; A-genome) and the two parent lines (IMB211, female; R500, male) were selected for study. The establishment of the BraIRRI population is described by Iniguez-Luy et al. (2009). Plants were grown from seed in compost, under two [P]ext treatments of 9 mg L-1 (low) or 30 mg L-1 (optimal) Olsen extractable P. RNA was extracted from leaf samples from one experimental run (78 lines at low and optimal [P]ext, with one line duplicated i.e. 158 samples), and from leaf samples from the parent lines at low and optimal P in all three experimental runs (12 samples) using a modified TRIzol extraction method (Hammond et al., 2006).

ORGANISM(S): Brassica rapa

SUBMITTER: John Hammond 

PROVIDER: E-GEOD-27052 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress