Inheritance of Drought Tolerance During Germination and Early Growth in a Multiparental Population of Common Bean (Phaseolus vulgaris L.)

Resumen

Objective: (1) Estimate the genetic variables related to drought tolerance during germination of F₃ from a MAGIC common bean population, and (2) Classify the F₃ as tolerant or susceptible to drought at an early stage.

Design/methodology/approach: Seeds from 200 F₃ of a MAGIC common bean population (designed as L-1, L-2, L-3… L-200) and their eight parents (R-bufa-80, R-bufa-60, T-negro, T-amarillo, PS-AZH-15-1, P-saltillo, USPT-WM-1 and Salinas) were used. A bioassay was established in the Plant Biophysics and Physiology Laboratory of the Colegio de Postgraduados, Montecillo, Mexico in July 2023. Seeds were germinated in Petri dishes at 27 ºC in a growth chamber. The experimental design was a simple lattice with two replications. The evaluated treatment consisted of germination in a PEG-6000 solution at -0.49 MPa for 72 h. The parents R-bufa-80, R-bufa-60, T-negro and T-amarillo were used as tolerant controls. Germination was quantified 24, 48 and 72 h after the establishment of the bioassay.

Results: At 24 h, the germination percentage exhibited high heritability; however, it did not a quantitative inheritance pattern. For germination at 48 and 72 h, heritability was moderate, and for total length it was low. Neverthless, these traits displayed a phenotypic distribution consistent with quantitative inheritance. F₃ L-184 appeared to exhibit transgressive segregation for germination at 24 h and for total length at 72 h. The evaluation of the complete multiparental population allowed the selection of F₃ with the best and worst response to water deficit, based on their germination and early growth under PEG-6000 induced osmotic stress.

Limitations on study/implications: Due to seed availability, the F₃ were not evaluated under control (water) conditions; therefore, their response were compared with those of the parents previously characterized for drought tolerance.

Findings/conclusions: Germination percentage and total length exhibited quantitative inheritance, except for germination at 24 h. F₃ L-184, L-198, and L-106 can be classified as drought tolerant, whereas L-69 and L-182 can be classified as susceptible. This MAGIC population and their parents can be incorporated into breeding programs due to the range of identifiable responses.