title: High-throughput root phenotyping screens identify genetic loci associated with root architectural traits in Brassica napus under contrasting phosphate availabilities.
abstract: OBJECTIVE
  Phosphate (Pi) deﬁciency in soils is a major limiting factor for crop growth worldwide. Plant growth under low Pi conditions correlates with root architectural traits and it may therefore be possible to select these traits for crop improvement. The aim of this study was to characterize root architectural traits, and to test quantitative trait loci (QTL) associated with these traits, under low Pi (LP) and high Pi (HP) availability in Brassica napus.
  
  
  METHODS
  Root architectural traits were characterized in seedlings of a double haploid (DH) mapping population (n = 190) of B. napus ['Tapidor' × 'Ningyou 7' (TNDH)] using high-throughput phenotyping methods. Primary root length (PRL), lateral root length (LRL), lateral root number (LRN), lateral root density (LRD) and biomass traits were measured 12 d post-germination in agar at LP and HP.
  
  
  RESULTS
  In general, root and biomass traits were highly correlated under LP and HP conditions. 'Ningyou 7' had greater LRL, LRN and LRD than 'Tapidor', at both LP and HP availability, but smaller PRL. A cluster of highly significant QTL for LRN, LRD and biomass traits at LP availability were identified on chromosome A03; QTL for PRL were identified on chromosomes A07 and C06.
  
  
  CONCLUSIONS
  High-throughput phenotyping of Brassica can be used to identify root architectural traits which correlate with shoot biomass. It is feasible that these traits could be used in crop improvement strategies. The identification of QTL linked to root traits under LP and HP conditions provides further insights on the genetic basis of plant tolerance to P deﬁciency, and these QTL warrant further dissection.
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Shi
authors.forename: Taoxiong
authors.initials: T
authors.lastname: Shi
authors.forename: Martin R
authors.initials: MR
authors.lastname: Broadley
authors.forename: Philip J
authors.initials: PJ
authors.lastname: White
authors.forename: Yan
authors.initials: Y
authors.lastname: Long
authors.forename: Jinling
authors.initials: J
authors.lastname: Meng
authors.forename: Fangsen
authors.initials: F
authors.lastname: Xu
authors.forename: John P
authors.initials: JP
authors.lastname: Hammond
mesh_terms: D018533:Biomass; D029688:Brassica napus / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D002874:Chromosome Mapping; D005838:Genotype; D010641:Phenotype; D010710:Phosphates / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D018517:Plant Roots / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D040641:Quantitative Trait Loci / Q000235:genetics*; D036226:Seedlings / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D010710:Phosphates; D010758:Phosphorus