Rong Yu

Document Type

Dissertation - University Access Only

Award Date

1995

Degree Name

Doctor of Philosophy (PhD)

Department / School

Plant Science

First Advisor

Chen H. Chen

Second Advisor

Fred A. Cholick

Abstract

A culture filtrate of South Dakota Isolate 9 of the tan spot pathogen Pyrenophora tritici-repentis, or a proteinaceous toxin (MW @14 kD) purified from the filtrate was introduced into W14 anther culture medium as an agent for in vitro disease resistance selection. Anthers of F1 hybrids between cultivars carrying the contrasting characters resistant and susceptible were cultured. Capacities of callus/embryoid initiation in cultured anthers were significantly impaired, and the rate of initiation was generally inversely related to filtrate/toxin concentration in medium. Toxin infiltration testing on pollen plants revealed that toxin or culture filtrate at a dilution of 5x10-3 exerted an effective selection pressure on cultures for microspores of insensitive genotypes, resulting in many more toxin-insensitive than toxin-sensitive regenerants. The progeny of each toxin-insensitive pollen plant was uniformly insensitive, indicating that the H1 plants were truly doubled haploid. Plants regenerated from F1 anthers cultured on W14 medium, free of toxin or culture filtrate,-showed a gametic segregation ratio of 1 toxin-sensitive to 1 toxin-insensitive, suggesting that toxin sensitivity within these spring wheat cultivars tested was governed by one pair of genes. All F2 populations showed a segregation ratio of 3 sensitive to 1 insensitive, further implying that sensitiveness was dominant over insensitiveness. This in vitro screening system may recover ample disease resistant doubled haploid plants enough for further rapid selection for other desirable agronomic traits. It has been suggested that the efficiency of doubled haploid recovery may be further improved by treating surviving calli/embryoids with 50-100 mg/L colchicine in differentiation medium prior to plant regeneration.

Library of Congress Subject Headings

Wheat -- Disease an pest resistance
Wheat speckled leaf blotch
Wheat -- Varieties

Format

application/pdf

Publisher

South Dakota State University

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Rights Statement

In Copyright