Document Type

Dissertation - Open Access

Award Date

2016

Degree Name

Doctor of Philosophy (PhD)

Department

Agronomy, Horticulture, and Plant Science

First Advisor

Karl Glover

Keywords

allopurinol, chlorosis, lesion mutant, number of lesions, number of seeds, yield

Abstract

A mutant wheat (Triticum aestivum L.) genotype can constitutively produce hypersensitive-like flecks in the absence of any pathogen. The lesions of the mutant are thought to be the result of Reactive Oxygen Species (ROS), which are similarly implicated in hypersensitive reactions to fungal pathogens. Allopurinol can suppress ROS. Consequently, allopurinol was applied to a wheat lesion mutant to test the hypothesis that the same ROS are involved, regardless of the presence of the pathogen. ‘Ning7840’, a lesion mutant and ‘Alsen’, a related genotype that does not express the mutant phenotype were treated with different concentrations of allopurinol under controlled conditions in a greenhouse. The results reveled significant genotype × allopurinol interaction effects on grain yield, grain number, and chlorophyll content. Up to the application of 50μM allopurinol, there was a significant increase in grain yield and grain number; whereas any increase above 50μM allopurinol reduced grain yield and grain number compared to the check treatment. Allopurinol reduced hypersensitive reaction-like symptoms in Ning7840, with the highest concentration resulting in the lowest leaf chlorosis. However, there was a decline in chlorophyll content, with allopurinol levels above 25μM applied in Ning7840. The results suggest that higher levels of allopurinol were effective in suppressing hypersensitive reaction-like symptoms in Ning7840, but the treatment impacts grain yield beyond 50μM level. New races of sunflower rust (Puccinia helianthi) can overcome R-genes in sunflower (Helianthus annuus L.) resulting in significant yield losses. Allopurinol has effectively reduced rust-disease symptoms in other crops but has not been applied in to sunflower. Different concentrations of allopurinol were applied as a soil drench to sunflower and the concentrations of allopurinol reduced the symptoms, but genotypes did not react differently. There was a reduction in spike area, number of seeds, weight of seeds and weight of biomass with an increase in allopurinol concentrations. Allopurinol reduced rust symptoms, but this did not result in an increase in grain yield in comparison to the control.

Library of Congress Subject Headings

Wheat -- Disease and pest resistance.

Sunflowers -- Disease and pest resistance.

Rust diseases.

Allopurinol.

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

277

Publisher

South Dakota State University

Rights

Copyright © 2016 Thumbiko W.G. Mkandawire

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