Document Type

Thesis - University Access Only

Award Date

1997

Degree Name

Master of Science (MS)

Department / School

Plant Science

First Advisor

Jackie C. Rudd

Abstract

Drought is the most common environmental stress, affecting every aspect of wheat (T. aestivum L.) growth from seed germination to seed set. Abscisic acid (ABA) insensitivity in wheat has been reported to confer post-anthesis heat and drought tolerance. The report inspired this research to investigate the effectiveness of ABA as a selection agent in wheat anther culture medium to rapidly select for ABA insensitivity. Two ABA-insensitive wheat lines were crossed with three ABA-sensitive lines. Anthers of the parents and their F 1 hybrids were cultured on WI 4 media containing ABA of different concentrations. Abscisic acid significantly inhibited callus induction of all ABA-sensitive parents, even at 1. 0 μM. However, 1. 0 μM ABA did not significantly decrease the induction rate of the ABAinsensitive parents. For each of the crosses chosen, H2 regenerants, natural F2 population, and their parents were evaluated by using an ABA seedling leafbioassay. This bioassay measures chlorophyll retention after 48 hours at 30.0 μM ABA and 32-34°C. In terms of frequency distribution and average adjusted green leaf score, anther culture without ABA in the callus induction medium did not alter the ABA sensitivity. No effect of selection against the ABA sensitive genotype was found at the low concentration of ABA. However, the application of ABA at the high concentration greatly enriched the fraction of ABA-insensitive plants in the population. The consistency between sensitivity and in vitro responses of parents to ABA, and the results of testing the H2 regenerants all suggest that ABA could be introduced into anther culture medium for in vitro selection of ABA insensitivity in wheat. This study also indicated that there is no linkage between the ABA sensitivity and the spring wheat type.

Library of Congress Subject Headings

Wheat -- Drought tolerance. 
Abscisic acid. 
Wheat -- Varieties.      

Publisher

South Dakota State University

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Rights Statement

In Copyright