Similarities and differences in the genetic and physiological control of resistance to stemphylium leafspot in winter-active and semi-dormant lucernes
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Published:1999
Issue:3
Volume:39
Page:301
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ISSN:0816-1089
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Container-title:Australian Journal of Experimental Agriculture
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language:en
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Short-container-title:Aust. J. Exp. Agric.
Author:
Irwin J. A. G.,Bray R. A.
Abstract
Previously, it has proven difficult to improve resistance to some biotypes of
Stemphylium vesicarium in selections from lucerne cv.
Sequel (highly winter active) in contrast to selections from cv. Trifecta
(semi-winter dormant). Stemphylium leafspot is a disease of the cooler months,
and there are 2 possible explanations for the differing reactions: either the
winter-active genetic backgrounds do not contain the requisite resistance
genes, or the winter-active lines are physiologically disadvantaged through
their winter activity. A diallel cross was made between clones from Trifecta
and Sequel representing a range of disease reactions. Progeny were grown
either under summer or winter conditions before inoculation. For both
environments, variation was entirely additive. There was no interaction
between crosses (or parents) and the 2 environments, and there was a close
relationship (r = 0.93) between the breeding
values (gi) of parents in the 2 environments. The data
indicated that variation in both backgrounds was entirely additive, although
there were indications that phenotypic expression of resistance was stronger
in clones from the Trifecta background. To increase resistance in
winter-active material, it would be necessary to introgress the resistance
genes from non-winter-active material.
Publisher
CSIRO Publishing
Subject
General Agricultural and Biological Sciences