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Title: GENETIC CONTROL OF O3 SENSITIVITY IN A CROSS BETWEEN TWO SNAPBEAN CULTIVARS

Author
item Reinert, Richard
item EASON, GWEN - NCSU PLANT PATHOLOGY DEPT

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/20/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Two snap bean cultivars (one sensitive to ozone and one insensitive to ozone) were crossed to determine the inheritance of sensitivity to ozone. Six populations of plants were studied including: the two parents, the first generation from the cross, the second generation from the cross, and two generations which were developed by backcrossing individual plants from the first generation with each of their parents. The results showed how sensitivity to ozone varied within each of these generations. Ozone sensitivity of the first generation of plants was more like the ozone-sensitive parent, whereas the sensitivity to ozone of the second generation was different from both parents. The backcross generations were more like the parent to which they were crossed. Bean selections with minimal sensitivity to O3 can be developed with several generations of screening and selection under ambient ozone concentrations.

Technical Abstract: A cross was made between two cultivars of snap bean (Phaseolus vulgaris L.), 'Oregon 91' (P1) and 'Wade Bush' (P2), an O3-sensitive and O3- insensitive cultivar, respectively, to identify the genetic control of O3 sensitivity. Ten genetic populations (generations), 'Oregon 91' (P1), 'Wade Bush' (P2), their F1, F2, backcrosses (F1 x P1 and F1 x P2) and reciprocal crosses were field planted each of two summers and evaluated for injury to O3. When components of genetic variation were estimated, additive genetic variance was the most important component in the total variance. Dominance variance was also a significant component of the genetic variation, but was not as strong a contributor as additive variance. There was an inconsistency in the magnitude and the direction of the factors contributing to the dominance effects and also a large environmental component making up the phenotypic variance. Estimates of broad sense heritability and narrow sense heritability were 60% and 44%, respectively. This study showed that O3-sensitive and -insensitive selections could be screened and evaluated in an ambient O3 environment. Several generations will be necessary, however, to develop Bush Blue Lake type selections that vary only in sensitivity to O3.