Date of Award:

1-1-1984

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Advisor/Chair:

William F. Campbell

Abstract

Cotyledonal- or transverse-cracking (TVC) in certain cultivars of snapbeans, Phaseolus vulgaris ~. seeds, clearly evident during germination, seriously places affected seedlings at a competitive disadvantage. TVC is an inherited trait and occurs across cell walls of cotyledons rather than along cell walls. Thus, it might be hypothesized that internal pressure resulting from swelling of storage proteins during imbibition might account for cellular rupture. To further elucidate this possibility, experiments were designed to compare electrophoretic patterns of storage proteins from seeds of snapbeans resistant and susceptible to TVC, and to correlate the different patterns of polyacrylamide gel el ectrophoretograrns of these proteins to TVC.

One hundred seeds were selected randomly from a bulk sample of 225 g from each of 17 seed lots representing 15 cultivars, seed coats removed and cotyledons finely ground (60 mesh). Seed flours were defatted twi ce with hexane (50 ml / g) at 4°C and defatted flours reground with a mortar

and pestle. Seed proteins were extracted in 0.5 M NaCl (solvent to four ratio of 10:1) at pH 7.5 for 1 h at 4oc with centrifugation at 10,000 g for 30 min. Separated proteins were subjected to electrophoresis under denaturing and non-denaturing conditions and molecular weight of different protein brands determined. Different protein banding patterns were identified and correlated to the TVC phenomenon. The data showed visual differences between banding patterns of resistant and susceptible cultivars.

While the electrophoretic technique shows observable differences in cultivars expressing differential TVC, it is not clear which protein bands are associated with the TVC phenomenon. For plant breeders to employ this tool in screening for TVC resistant snapbean cultivars, further requirements are needed.

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