The three main germplasm resource bases used for genetic diversity in disease resistance are commercial varieties, landraces and wild ancestral species. Cultivar mixtures with landraces have traditionally been used by subsistence farmers to keep disease epidemics at low levels. These subsistence farmers live mainly in developing countries and produce up to 20% of the world's food. Landraces have been a valuable source of disease resistance to them because of their already high adaptations in appropriate agronomic backgrounds. Mixtures with improved varieties are now being advocated as an alternative strategy for disease control in many crops. Wild germplasm are also being used to transfer new and valuable genes of disease resistance to cultivated crops. Continuous efforts are being directed at broadening the genetic base of crops by a search for sources of disease resistance, which remain the most practical and environmentally sound means for the control of most major diseases in agricultural crops.
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References
1.
LenneJ.M.WoodD., ‘Plant diseases and the use of wild germplasm’, Annual Review of Phytopathology, Vol 29, 1991, pp 35–63.
2.
SegalA.ManisterskiJ.FischbeckG.WahlI., ‘How plant populations defend themselves in natural ecosystems’, in HorsfallJ.G.CowlingE.B., eds, Plant Disease, NY Academic, New York, 1980, pp 75–102.
3.
WitcombeJ.R.ErskineW., eds, Genetic Resources and their Exploitation — Chickpea, Faba Beans and Lentils, Martinuus Nijhoff, The Hague, 1984.
4.
LenneWood, op cit, Ref 1.
5.
BurdonJ.J., Diseases and Plant Population Biology, Cambridge University Press, 1987.
6.
Segal, op cit, Ref 2.
7.
SegalA.DorrK.H.FischbeckG.ZoharyD.WahlI., ‘Genotypic composition and mildew resistance in a natural population of wild barley, Hordeum spontaneum’, Plant Breeding, Vol 99, 1987, pp 118–127.
8.
FrankelO.H.HawkesJ.G., eds, Crop Genetic Resources for Today and Tomorrow, Cambridge University Press, Cambridge, 1975.
9.
LenneWood, op cit, Ref 1.
10.
FrankelHawkes, op cit, Ref 8.
11.
StalkerH.T., ‘Utilization of wild species for crop improvement’, Advances in Agronomy, Vol 33, 1980, pp 111–147.
12.
MamlukO.F.van SlagerenM.W., ‘Resistance to common bunt, yellow rust, leaf rust and Septoria tritici blotch in wild einkorn and wild emmer wheat’, Phytopathologica Mediterranea, Vol 32, 1993, pp 14–19.
13.
FeuersteinU.BrownA.H.D.BurdonJ.J., ‘Linkage of rust resistance genes from wild barley (Hordeum spontaneum) with isozyme markers’, Plant Breeding, Vol 104, 1990, pp 318–324.
14.
MosemanJ.G.BaenzigerP.S.KilpatrickR.A., ‘Genes conditioning resistance of Hordeum spontaneum to Erysiphe graminis f.sp. hordei’, Crop Science, Vol 21, 1981, pp 229–232.
15.
AbbottD.C.BrownA.H.D.BurdonJ.J., ‘Genes for scald resistance from wild barley (Hordeum vulgare ssp. spontaneum) and their linkage to isozyme markers’, Euphytica, Vol 61, 1992, pp 225–231.
16.
SinghK.B.ReddyM.V., ‘Sources of resistance to ascochyta blight in wild Cicer species’, Netherlands Journal of Plant Pathology, Vol 99, 1993, pp 163–167.
17.
Porta-PugliaA.InfantinoA.CrinoP.FedericoR.AngeliniR.VenoraG.BragaloniM.FalchettiM.L.MosconiC., ‘Ascochyta blight and Fusarium wilt diseases in chickpea: Host–pathogen interaction’, in New Perspectives for an Ancient Species: The Chickpea in the Economy and Diet of Mediterranean Peoples, Proceedings of ‘La Sapienza’ University Conference, Rome, December 1995, pp 45–54.
18.
InfantinoA.Porta-PugliaA.SinghK.B., ‘Screening wild Cicer species for resistance to Fusarium wilt’, Plant Disease, Vol 80, 1996, pp 42–44.
19.
KaiserW.J.Alcala-JimenezA.R.Hervas-VargasA.Trapero-CasaJ.L.Jimenez-DaizR.M., ‘Screening of wild Cicer species for resistance to races 0 and 5 of Fusarium oxysporum f.sp. ciceris’, Plant Disease, Vol 78, 1994, pp 962–967.
20.
Di VitoM.SinghK.B.GrecoN.SaxenaM.C., ‘Sources of resistance to cyst nematode in cultivated and wild Cicer species’, Genetic Resources and Crop Evolution, Vol 43, 1996, pp 103–107.
21.
BayaaB.ErskineW.HamdiA., ‘Evaluation of a wild lentil collection for resistance to vascular wilt’, Genetic Resources and Crop Evolution, Vol 42, 1995, pp 231–235.
22.
IqbalS.M.BakhshA.MalikB.A., ‘Identification of resistant sources to ascochyta blight in lentil’, LENS Newsletter, Vol 17, 1990, pp 26–27.
23.
BayaaB.ErskineW.HamdiA., ‘Response of wild lentil to Ascochyta fabae f.sp. lentis from Syria’, Genetic Resources and Crop Evolution, Vol 41, 1994, pp 61–65.
24.
ZadoksJ.C., ‘The biotic environment of plants’, Structure and Functioning of Plant Populations, Vol 70, No 11, pp 299–315.
25.
van LeurJ.A.G.CeccarelliS.GrandoS., ‘Diversity for disease resistance in barley landraces from Syria and Jordan’, Plant Breeding, Vol 103, 1989, pp 324–335.
26.
CeccarelliS.GrandoS.van LeurJ.A.G., ‘Genetic diversity in barley landraces from Syria and Jordan’, Euphytica, Vol. 36, 1987, pp 389–405.
27.
JanaS.PietrzakL.N., ‘Comparative assessment of genetic diversity in wild and primitive cultivated barley in center of diversity’, Genetics, Vol 119, 1988, pp 981–990.
28.
Segal, op cit, Ref 2.
29.
Ceccarelli, op cit, Ref 26.
30.
Van Leur, op cit, Ref 25.
31.
PyndjiM.M.TrutmannP., ‘Managing angular leaf spot on common bean in Africa by supplementing farmer mixtures with resistant varieties’, Plant Disease, Vol 76, 1992, pp 1144–1147.
32.
RobertsonL.D.SinghK.B.ErskineW.MoneimA.M., ‘Useful genetic diversity in germplasm collections of food and forage legumes from West Asia and North Africa’, Genetic Research and Crop Evolution, Vol 43, 1996, pp 447–460.
33.
AkandaS.I.MundtC.C., ‘Effect of two-component cultivar mixtures and yellow rust on yield and yield components of wheat’, Plant Pathology, Vol 46, 1997, pp 566–680.
34.
Ibid.
35.
MundtC.C., ‘Use of host genetic diversity to control cereal diseases: Implications for rice blast’, in LeongS.A.ZeiglerR.S.TengP.S., eds, Rice Blast Disease, CAB International, Wallingford, pp 293–307.
TrutmannP.VossJ.FairheadJ., ‘Management of common bean diseases by farmers in the Central African highlands’, International Journal of Pest Management, Vol 39, 1993, pp 334–342.
38.
Mundt, op cit, Ref 35.
39.
Burdon, op cit, Ref 5.
40.
BarreraJ.A.S.FrederiksenR.A., ‘Evaluation of hybrid sorghum mixtures for controlling sorghum leaf blight’, Phytopathology, Vol 78, 1994, pp 499–503.
41.
ChinK.M.WolfeM.S., ‘Selection on Erysiphe graminis in pure and mixed stands of barley’, Plant Pathology, Vol 33, 1984, pp 535–546.
42.
WolfeM.S.McDermottJ.M., ‘Population genetics of plant pathogen interactions: The example of the Erysiphe graminis-Hordeum vulgare pathosystem’, Annual Review of Phytopathology, Vol 32, 1994, pp 89–113.
43.
WolfeM.S., ‘The current status and prospects of multilines, cultivars and varietal mixtures for disease resistance’, Annual Review of Phytopathology, Vol 23, 1985, pp 251–273.
44.
WolfeM.S., ‘Trying to understand and control powdery mildew’, Plant Pathology, Vol 33, 1984, pp 451–466.
45.
HuangR.KranzJ.WelzH.G., ‘Selection of pathotypes of Erysiphe graminis f.sp. hordei in pure and mixed stands of spring barley’, Plant Pathology, Vol 43, 1994, pp 458–470.
46.
McDonaldB.A.AllardR.W.WebsterR.K., ‘Effect of two-, three-, and four-component barley mixtures to a variable pathogen population’, Crop Science, Vol 28, 1988, pp 447–452.
47.
AkandaMundt, op cit, Ref 33.
48.
NtahimperaN.DillardH.R.CobbA.C.SeemR.C., ‘Anthracnose development in mixtures of resistant and susceptible dry bean cultivars’, Phytopathology, Vol 86, 1996, pp 668–673.
49.
ErskineW., ‘Lessons for breeders from land races of lentil’, Euphytica, Vol 93, 1997, pp 107–112.
