Wheat gene bank accessions as a source of new alleles of the powdery mildew resistance gene Pm3: a large scale allele mining project.
BACKGROUND
In the last hundred years, the development of improved wheat cultivars has led to the replacement of landraces and traditional varieties by modern cultivars. This has resulted in a decline in the genetic diversity of agriculturally used wheat. However, the diversity lost in the elite material is somewhat preserved in crop gene banks. Therefore, the gene bank accessions provide the basis for genetic improvement of crops for specific traits and and represent rich sources of novel allelic variation.


RESULTS
We have undertaken large scale molecular allele mining to isolate new alleles of the powdery mildew resistance gene Pm3 from wheat gene bank accessions. The search for new Pm3 alleles was carried out on a geographically diverse set of 733 wheat accessions originating from 20 countries. Pm3 specific molecular tools as well as classical pathogenicity tests were used to characterize the accessions. Two new functional Pm3 alleles were identified out of the eight newly cloned Pm3 sequences. These new resistance alleles were isolated from accessions from China and Nepal. Thus, the repertoire of functional Pm3 alleles now includes 17 genes, making it one of the largest allelic series of plant resistance genes. The combined information on resistant and susceptible Pm3 sequences will allow to study molecular function and specificity of functional Pm3 alleles.


CONCLUSIONS
This study demonstrates that molecular allele mining on geographically defined accessions is a useful strategy to rapidly characterize the diversity of gene bank accessions at a specific genetic locus of agronomical importance. The identified wheat accessions with new resistance specificities can be used for marker-assisted transfer of the Pm3 alleles to modern wheat lines.
Bhullar
Navreet K
NK
Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, 8008 Zurich, Switzerland. bkeller@botinst.uzh.ch
Zhang
Zhiqing
Z
Wicker
Thomas
T
Keller
Beat
B
D000483:Alleles; D001203:Ascomycota / Q000472:pathogenicity; D001483:Base Sequence; D018744:DNA, Plant / Q000235:genetics; D057225:Data Mining; D017343:Genes, Plant; D007113:Immunity, Innate; D008969:Molecular Sequence Data; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics* / Q000276:immunology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014908:Triticum / Q000235:genetics* / Q000276:immunology
D018744:DNA, Plant
Plant Cell. 2006 Aug;18(8):2082-93
16844906
Theor Appl Genet. 2008 Feb;116(3):417-25
18092148
Plant J. 2004 Apr;38(2):215-26
15078326
Plant Cell. 2002 Aug;14(8):1903-17
12172030
Mol Biol Evol. 2005 Dec;22(12):2444-56
16120808
Plant Cell. 2003 Mar;15(3):732-44
12615945
Proc Natl Acad Sci U S A. 1999 May 25;96(11):5937-43
10339521
Plant Physiol. 2003 Feb;131(2):558-67
12586880
Plant J. 2009 Mar;57(5):846-56
18980638
Theor Appl Genet. 2008 Jun;117(1):135-42
18392800
Proc Natl Acad Sci U S A. 2004 Jun 29;101(26):9885-90
15161968
Theor Appl Genet. 2006 Dec;114(1):165-75
17063340
Mol Plant Pathol. 2009 Jul;10(4):449-57
19523099
Nucleic Acids Res. 1997 Dec 15;25(24):4876-82
9396791
Plant Cell. 2001 Feb;13(2):337-50
11226189
Mol Plant Microbe Interact. 2010 Apr;23(4):497-509
20192836
Genetics. 2004 Mar;166(3):1517-27
15082565
Genetics. 2007 Oct;177(2):1207-16
17720914
Plant J. 2001 Feb;25(3):335-48
11208025
Plant Cell. 1999 Mar;11(3):495-506
10072407
Plant J. 2004 Feb;37(4):528-38
14756761
Proc Natl Acad Sci U S A. 2009 Jun 9;106(23):9519-24
19470492
Science. 1997 Aug 22;277(5329):1063-6
9262467
Plant Physiol. 2005 Oct;139(2):885-95
16183849
Plant Cell. 2004 Nov;16(11):2870-94
15494555
Plant J. 2006 Jul;47(1):85-98
16740148
Cell. 1997 Dec 12;91(6):821-32
9413991
Genetics. 2006 Apr;172(4):2449-63
16415370
Plant J. 1999 Dec;20(5):541-52
10652126
Nucleic Acids Res. 1994 Nov 11;22(22):4673-80
7984417
J Exp Bot. 2009;60(9):2541-52
19451185