title: Genetic analysis of tolerance to the root lesion nematode Pratylenchus neglectus in the legume Medicago littoralis.
abstract: BACKGROUND
  The nematode Pratylenchus neglectus has a wide host range and is able to feed on the root systems of cereals, oilseeds, grain and pasture legumes. Under the Mediterranean low rainfall environments of Australia, annual Medicago pasture legumes are used in rotation with cereals to fix atmospheric nitrogen and improve soil parameters. Considerable efforts are being made in breeding programs to improve resistance and tolerance to Pratylenchus neglectus in the major crops wheat and barley, which makes it vital to develop appropriate selection tools in medics.
  
  
  RESULTS
  A strong source of tolerance to root damage by the root lesion nematode (RLN) Pratylenchus neglectus had previously been identified in line RH-1 (strand medic, M. littoralis). Using RH-1, we have developed a single seed descent (SSD) population of 138 lines by crossing it to the intolerant cultivar Herald. After inoculation, RLN-associated root damage clearly segregated in the population. Genetic analysis was performed by constructing a genetic map using simple sequence repeat (SSR) and gene-based SNP markers. A highly significant quantitative trait locus (QTL), QPnTolMl.1, was identified explaining 49% of the phenotypic variation in the SSD population. All SSRs and gene-based markers in the QTL region were derived from chromosome 1 of the sequenced genome of the closely related species M. truncatula. Gene-based markers were validated in advanced breeding lines derived from the RH-1 parent and also a second RLN tolerance source, RH-2 (M. truncatula ssp. tricycla). Comparative analysis to sequenced legume genomes showed that the physical QTL interval exists as a synteny block in Lotus japonicus, common bean, soybean and chickpea. Furthermore, using the sequenced genome information of M. truncatula, the QTL interval contains 55 genes out of which five are discussed as potential candidate genes responsible for the mapped tolerance.
  
  
  CONCLUSIONS
  The closely linked set of SNP-based PCR markers is directly applicable to select for two different sources of RLN tolerance in breeding programs. Moreover, genome sequence information has allowed proposing candidate genes for further functional analysis and nominates QPnTolMl.1 as a target locus for RLN tolerance in economically important grain legumes, e.g. chickpea.
authors.affiliation: South Australian Research and Development Institute, Plant Genomics Centre, Waite Campus, Urrbrae, SA 5064, Australia. klaus.oldach@sa.gov.au.
authors.forename: Klaus H
authors.initials: KH
authors.lastname: Oldach
authors.forename: David M
authors.initials: DM
authors.lastname: Peck
authors.forename: Ramakrishnan M
authors.initials: RM
authors.lastname: Nair
authors.forename: Maria
authors.initials: M
authors.lastname: Sokolova
authors.forename: John
authors.initials: J
authors.lastname: Harris
authors.forename: Paul
authors.initials: P
authors.lastname: Bogacki
authors.forename: Ross
authors.initials: R
authors.lastname: Ballard
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D000818:Animals; D018533:Biomass; D001947:Breeding; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D008040:Genetic Linkage; D005819:Genetic Markers; D029902:Medicago / Q000235:genetics*; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics* / Q000469:parasitology*; D018517:Plant Roots / Q000235:genetics* / Q000469:parasitology*; D018520:Plant Shoots / Q000235:genetics; D040641:Quantitative Trait Loci / Q000235:genetics; D015203:Reproducibility of Results; D012639:Seeds / Q000235:genetics; D014431:Tylenchoidea / Q000502:physiology*
chemical_list: D005819:Genetic Markers
references.citation: Trends Plant Sci. 2002 Jul;7(7):293-6
references.pmid: 12119165
references.citation: Theor Appl Genet. 2004 Feb;108(3):414-22
references.pmid: 13679975
references.citation: Plant Physiol. 2006 May;141(1):188-95
references.pmid: 16514014
references.citation: Fungal Genet Biol. 2006 Oct;43(10):707-14
references.pmid: 16784880
references.citation: BMC Plant Biol. 2013 Mar 27;13:54
references.pmid: 23531152
references.citation: Plant Cell Physiol. 2010 Apr;51(4):585-95
references.pmid: 20203239
references.citation: Ann Bot. 2008 May;101(7):997-1005
references.pmid: 18310158
references.citation: Phytopathology. 2014 Feb;104(2):174-87
references.pmid: 24047251
references.citation: J Nematol. 2000 Dec;32(4S):591-9
references.pmid: 19271014
references.citation: Plant Cell. 1998 Aug;10(8):1307-19
references.pmid: 9707531
references.citation: Plant J. 2002 Jul;31(2):127-36
references.pmid: 12121443
references.citation: Plant J. 2000 Sep;23(5):567-76
references.pmid: 10972883
references.citation: Mamm Genome. 1999 Apr;10(4):327-34
references.pmid: 10087288
references.citation: Nature. 2011 Nov 16;480(7378):520-4
references.pmid: 22089132
references.citation: Theor Appl Genet. 2002 Apr;104(5):874-879
references.pmid: 12582649
references.citation: Plant Physiol. 2005 Apr;137(4):1189-96
references.pmid: 15824281
references.citation: Annu Rev Plant Physiol Plant Mol Biol. 1996 Jun;47:627-654
references.pmid: 15012303
references.citation: Proc Natl Acad Sci U S A. 2004 Oct 26;101(43):15289-94
references.pmid: 15489274
references.citation: J Nematol. 1973 Jul;5(3):225-6
references.pmid: 19319337
references.citation: Plant J. 2003 May;34(3):327-38
references.pmid: 12713539
references.citation: Plant Cell. 2011 Jun;23(6):2422-39
references.pmid: 21685259
references.citation: Plant Mol Biol. 2014 Feb;84(3):329-44
references.pmid: 24085708
references.citation: Nat Biotechnol. 2013 Mar;31(3):240-6
references.pmid: 23354103
references.citation: Theor Appl Genet. 2011 May;122(7):1321-30
references.pmid: 21298411
references.citation: J Cell Sci. 2012 Oct 1;125(Pt 19):4423-33
references.pmid: 23132929
references.citation: Genetics. 2006 Apr;172(4):2541-55
references.pmid: 16489220
references.citation: Curr Biol. 1996 Jun 1;6(6):634-7
references.pmid: 8793280
references.citation: Theor Appl Genet. 2005 Dec;112(1):30-40
references.pmid: 16228189