Variation in the Rusts of Cereals1

Johnson, T.

doi:10.1111/j.1469-185x.1953.tb01373.x

Cited by 20 publications

(6 citation statements)

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“…The specific determination has a demonstrable genetic basis, resistance or susceptibility to a particular clone of the parasite depending often upon a single gene. Virulence and avirulence in the parasite also have a genetic basis (: 3), so that the susceptibility of a potential host plant must be defined in terms of the genotype of the par asite. The significance of the host-gene: parasite-gene relationship for suscep tibility is emphasized by the findings of Flor, whose careful and extensive studies with flax rust (Melampsora lini) have shown that for each pair of alleles controlling resistance and susceptibility in the host there is a corre sponding gene pair controlling virulence and avirulence in the parasite (14 to 17).…”

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Physiological Aspects of Fungus Diseases of Plants

Allen¹

1954

Annu. Rev. Plant. Physiol.

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The present review will be concerned with the inception and results of diseases of higher plants caused by obligately parasitic fungi. The term "ob ligate parasite" refers to those fungi which have not yet been cultured even in their vegetative phase except on a living host plant and whose nutrient re quirements and physiology are therefore largely unknown. Particular em phasis will be placed on diseases caused by rusts (Uredinales) and powdery mildews (Erysiphaceae), but occasional reference will also be made to other obligate parasites, particularly the downy mildews (Peronosporaceae) .Some physiological aspects of these diseases are included in recent re views (1, 2), and the literature on variation in rusts has been reviewed by Johnson (3). Gaumann's Pjlanzliche Infektionslehre (4) is an extensive and provocative collation of many aspects of plant diseases, and is available in English translation (5) , and in a second edition in German (6) . In a mono graph on The Cereal Rusts, Chester has presented a comprehensive sur vey and analysis of the litereature on stem rust of wheat and some allied diseases (7), and Volume VII of Buller's Researches on Fungi, published posthumous ly, has many interesting observations on certain aspects of the biology of the Uredinales (8). A monograph in Russian is concerned primarily with the au thor's investigations on the metabolism of plants infected with obligate par asites (9).The terminology used to describe attributes of host and parasite has been reduced to a minimum for purposes of this review. "Susceptibility" and "re sistance" will be used to designate conditions of the host which, respective ly, favor or do not favor development of a parasite. Plants showing extremes of these conditions will sometimes be referred to as "congenial" and "im mune," respectively. "Virulence" and "avirulence" will designate the com plementary conditions of the parasite. The term "infection" will be used to designate the penetration of a host cell and whatever subsequent progress the parasite makes.The literature on these diseases will be considered in three sections cor responding to three aspects of the origin and development of disease: (a) the inception of disease, (b) environmental factors affecting the host's suitability as a substrate for development of the parasite, and (c) changes in host phys iology resulting from infection. THn INCEPTION OF DISEASEGenetic basis of host restriction.-A given plant species is liable to attack only by certain parasites, but these parasites may come from the most di verse groups of the plant and animal kingdoms. A particular species of par-225 Annu. Rev. Plant. Physiol. 1954.5:225-248. Downloaded from www.annualreviews.org Access provided by Tufts University on 12/01/14. For personal use only.Quick links to online content Further ANNUAL REVIEWS

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Physiological Aspects of Fungus Diseases of Plants

Allen¹

1954

Annu. Rev. Plant. Physiol.

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“…Extensive studies of the theoretical and experimental aspects are required as is the monitoring of the situation in commercial crops. However, the following can be concluded from the studies mentioned above: ( 1 ) A stable equilibrium of the host-pathogen population, if it exists, can be reached only after an impractically long time; (2) the frequency of susceptible host genotypes required to keep the race frequency unchanged, if such a frequency exists, is very large; and (3) varieties with specific resistance are always eventually broken down in monoculture conditions.…”

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“…Investigations from such a standpoint were carried out by M~d e ,~-~ Leonard,G-R and Kiyosawa and YabukLg! lo Mode 3 developed equations to specify the gene frequencies at equilibrium in a host-pathogen system where ( 1 ) both the host and pathogen mate at random with respect to a single locus in the host and two independent loci in the pathogen, and where (2) there is a Flor-type complementary genetic system. He assumed that the fitness of the host in a particular host-pathogen combination varies inversely as the fitness of the pathogen.…”

Section: Population-genetic Approachmentioning

confidence: 99%