A review of wheat leaf rust research and the development of resistant cultivars in Canada

Figures & data

Fig. 1 Distribution of wheat varieties in Western Canada in 1956. Reprinted from Searle Grain Company Limited Annual Variety Survey Report 1956.

Fig. 2 Relationship between year of release and average leaf rust (% of flag leaf coverage) severity over the period of 2008–2010 at Carman, Manitoba for 45 Canadian wheat cultivars. From Martens et al. (2014).

Table 1. Near-isogenic lines of the wheat cultivar Thatcher with unique leaf rust resistance genes developed in Canada.

Gene	RL number	Pedigree
Lr1	RL6003	Thatcher*6/Centenario
Lr2a	RL6016	Thatcher*6/Webster
Lr2b	RL6019	Thatcher*6/Carina
Lr2c	RL6047	Thatcher*6/Brevit
Lr3a	RL6002	Thatcher*6/Democrat
Lr3bg	RL6042	Bage/8*Thatcher
Lr3ka	RL6007	Thatcher*6/Klein Anniversario
Lr9	RL6010	Transfer (Aegilops umbellulata)/6*Thatcher
Lr10	RL6004	Thatcher*6/Exchange
Lr11	RL6053	Thatcher*6//E-1/Hussar
Lr12	RL6011	Exchange/6*Thatcher
Lr13	RL6001	Prelude*6/Loros
Lr14a	RL6013	Selkirk/6*Thatcher
Lr14b	RL6006	Thatcher*6/Maria Escobar
Lr15	RL6052	Thatcher*6/W1483
Lr16	RL6005	Thatcher*6/Exchange
Lr17a	RL6008	Klein Lucero/6*Thatcher
Lr18	RL6009	Thatcher*7/Africa 43
Lr19	RL6040	Thatcher*7/Translocation 4 (Lr19 derived from Agropyron elongatum)
Lr20	RL6092	Thatcher*6/Timmo
Lr21	RL6043	Thatcher*6/RL5406(Tetra Canthatch/Aegilops squarrosa var meyeri-RL5289)
Lr22a	RL6044	Thatcher*7/RL5404(Tetra Canthatch/Aegilops squarrosa var strangulata-RL5271)
Lr22b	Thatcher	Marquis/Iumillo Durum//Marquis/Kanred
Lr23	RL6012	Lee 310/6*Thatcher
Lr24	RL6064	Thatcher*6/3/Agent//2*Prelude/8*Marquis
Lr25	RL6084	Thatcher*7/Transec
Lr26	RL6078	Thatcher*6/St-1–25
Lr28	RL6079	Thatcher*6/C-77–1
Lr29	RL6080	Thatcher*6//CS7D/Ag#11
Lr30	RL6049	Thatcher*6/Terenzio
Lr32	RL6086	Thatcher*6/3/Thatcher/Aegilops squarrosa//Mq(K)
Lr33	RL6057	Thatcher*6/PI58548
Lr34	RL6058	Thatcher*6/PI58548
Lr35	RL5711	Marquis-K*8//RL5344/RL5346 (Triticum monococcum)
Lr37	RL6081	Thatcher*8/VPM
Lr38	RL6097	Thatcher*6/T7Kohn
Lr44	RL6147	Thatcher*6/Triticum speltoides 7831 85GN 438
Lr45	RL6144	Thatcher*6/St-1
Lr52	RL6107	Thatcher*6/V336
Lr60	RL6172	Thatcher*3/V860
Lr63	RL6137	Thatcher*6/TMR5-J14-12-24
Lr64	RL6149	Thatcher*6/8404
Lr67	RL6077	Thatcher*6/PI250413

Table 2. Leaf rust resistance genes discovered in whole or in part by Canadian researchers.

Gene(s)	Common wheat or alien source of resistance gene	Chromosome location in common wheat	Thatcher isoline	Citation
Lr2a	Webster (T. aestivum L.)	2DS	RL6016	Dyck and Samborski (1968)
Lr2b	Carina (T. aestivum L.)	2DS	RL6019	Dyck and Samborski (1974)
Lr2c	Brevit (T. aestivum L.)	2DS	RL6047	Dyck and Samborski (1974)
Lr3a	Democrate (T. aestivum L.)	6BL	RL6002	Dyck and Samborski (1968)
Lr3bg	Bage (T. aestivum L.)	6BL	RL6042	Haggag and Dyck (1973)
Lr3ka	Klein Anniversario (T. aestivum L.)	6BL	RL6007	Haggag and Dyck (1973
Lr12	Opal (T. aestivum L.)	4BL	RL6011	Dyck et al. (1966)
Lr13	Frontana; Manitou (T. aestivum L.)	2BS	RL4031	Dyck et al. (1966)
Lr14a	Selkirk (T. aestivum L.)	7BL	RL6013	Dyck and Samborski (1970)
Lr14b	Rafaela; Maria Escobar (T. aestivum L.)	7BL	RL6006; RL6056	Dyck and Samborski (1970)
Lr16	Exchange; Selkirk (T. aestivum L.)	2BS	RL6005	Dyck and Samborski (1968)
Lr17a	Klein Lucero; Rafaela, EAP (T. aestivum L.)	2AS	RL6008; RL6054; RL6055	Dyck and Samborski (1968)
Lr18	Africa 43; Sabikei (T. aestivum L.)	5BL	RL6009	Dyck and Samborski (1968)
Lr19	Thinopyrum ponticum (Podp.) Barkworth & D.R. Dewey	7DL	RL6040; RL6085	Sharma and Knott (1966)
Lr21	Ae. squarrosa L. var meyeri	2DS	RL6043	Rowland and Kerber (1974)
Lr22a	Ae. squarrosa L. var strangulata	2DS	RL6044	Rowland and Kerber (1974)
Lr22b	Canthatch (T. aestivum L.)	2DS	Thatcher	Dyck (1979)
Lr23	Gaza (T. turgidum L. var. durum)	2BS	RL6012	McIntosh and Dyck (1975)
Lr30	Terenzio (T. aestivum L.)	4AL	RL6049	Dyck and Kerber (1981)
Lr32	Ae. squarrosa L.	3DS	RL6086	Kerber (1987), Kerber (1988)
Lr33	PI58548; PI268454; PI268316 (T. aestivum L.)	1BL	RL6057	Dyck et al. (1987)
Lr34	PI58548; Frontana; Chinese Spring, Terenzio, Bezostaja (T. aestivum L.)	7DS	RL6058; RL6091; RL6106; RL6159	Dyck (1987)
Lr35	Ae. speltoides Tausch.	2BS	RL6082	Kerber and Dyck (1990)
Lr36	Ae. speltoides Tausch.	6BS	N/A^1	Dvorak and Knott (1990)
Lr44	Triticum spelta L.	1BL	RL6147	Dyck and Sykes (1994)
Lr52	V336; V618 (T. aestivum L.)	5BS	RL6107	Hiebert et al. (2005)
Lr53	Triticum dicoccoides L.	6BS	N/A	Marais et al. (2005)
Lr56	Ae. sharonensis Eig.	6AL	N/A	Marais et al. (2006)
Lr59	Ae.peregrina (Hackel in J. Fraser)	1AL	N/A	Marais et al. (2008)
Lr60	V860 (T. aestivum L.)	1DS	RL6172	Hiebert et al. (2008)
Lr62	Ae. neglecta Req. ex Bertol.	6AS	N/A	Marais et al. (2009)
Lr63	T. monococcum L.	3AS	RL6137	Kolmer et al. (2010)
Lr64	T. turgidum L.	6AL	RL6149	Dyck et al. (1994)
Lr67	PI250413 (T. aestivum L.)	4DL	RL6077	Hiebert et al. (2010b)
Lr70	KU3198 (T. aestivum L.)	5DS	N/A	Hiebert et al. (2014)

¹Not available. A ‘Thatcher’ isoline was not developed for the Lr gene at the time of publication.

Fig. 3 Virulence frequency to leaf rust resistance genes Lr2a, Lr9, Lr16, Lr17, Lr21 and Lr24 in the Canadian Puccinia triticina population 2000–2013. Data from McCallum & Seto-Goh 2003, 2004, 2005, 2006a, 2006b, 2008, 2009; McCallum et al. 2010, 2011b, 2013, and B. McCallum (unpublished data).

Table 3. Frequency (%) of predominant P. triticina virulence phenotypes in Canada from 2000 to 2013.

Virulence	Year
Phenotype^a	2000	2001	2002	2003	2004	2005	2006	2007	2008	2009	2010	2011	2012	2013
MBDS	54.1^b	18.5	30.2	13.4	10.0	4.0	1.4	1.3	0.5	0.3	0	1.4	6.4	12.1
MBTN	0	0	0	0	0	0	0	0	1.0	0	2.8	4.2	4.3	8.6
MFDS	0	0	0	0	0	0.2	5.1	0.8	5.7	1.0	0.5	0.7	0	0.8
MFPS	0	0	0	0	0	5.7	4.8	3.9	4.9	4.5	3.5	6.0	3.0	6.3
MLDS	0	0	0.7	0	0	0	1.4	8.4	18.9	20.6	26.1	7.4	2.6	7.8
TBBG	0	0	0	0	14.8	10.2	1.7	0	0.2	0	4.5	8.5	19.2	11.7
TBBJ	0.6	1.7	9.9	57.0	41.2	7.1	3.4	0	0.2	0.3	1.3	0.7	0.9	0.8
TDBG	0	0	0	0	0.3	44.5	50.1	54.3	22.9	15.8	11.8	9.5	2.6	2.0
TDBJ	0.3	0	0	0	0.6	8.6	16.7	16.5	23.1	28.1	22.8	13.0	6.4	7.0
TGBJ	21.6	39.5	22.0	3.1	3.3	0.7	0	0	0	0	0	0	0	0
THBJ	5.7	14.6	1.4	0	0	0	0	0	0	0	0	0	0	0
TNBG	0	0	0	0	0	0	0.3	0	0	0	1.0	2.1	14.5	10.5
Others	17.7	25.6	35.8	26.5	29.7	19.0	15.0	14.7	22.6	29.4	25.7	47.9	46.4	44.5
Number of isolates	366	362	295	97	330	420	353	381	104	310	399	284	234	265
Number of virulence phenotypes	23	41	40	23	46	39	31	22	48	39	41	72	54	37

^aThe first three letters of the virulence phenotype determined according to Long & Kolmer (1989), Set 4 [subsequently added]: LrB, Lr10, Lr14a and Lr18.

^bData from McCallum & Seto-Goh 2003, 2004, 2005, 2006a, 2006b, 2008; McCallum et al. 2010, 2011b, 2013; and B. McCallum (unpublished data).

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