Fertility, Cytological Stability, and Phenotypic Traits of Backcross Progeny of an Arachis Amphiploid 1

Abstract

The possibility of introgressing Arachis spegazzinii Krap. & Greg. nom. nud. (GKP 10038, PI 262133) into three botanical varieties of A. hypogaea L. was examined. Ease of crossing, chromosome number segregation, and the penetrance and segregation of morphological characters are reported. The amphiploid (A. spegazzinii ✕ A. hypogaea) (6x) was backcrossed to three cultivars representing three botanical varieties of peanut. Ease of crossing with the amphiploid plant was successively less from A. vulgaris Hartz (spanish) to A. fastigiata Waldron (Valencia) to A. hypogaea L. (Virginia). Variations in crossing success were also found among plants within a cultivar. Most of the backcross progeny had 50 chromosomes, but aneuploids were also identified. Second-generation hybrid progenies from the first backcross (BC1F2) varied in chromosome number from 41 to 57, and the BC1F3 plants varied from 40 to 58. No BC1F2 plants had a stable chromosome number. Plant type, flower color, and fruit form gave evidence for the presence of exotic germplasm. Agronomically desirable fruit characters were found in BC1F3 plants.