Reproductive Efficiency in Reciprocal Crosses of Arachis monticola with A. hypogaea Subspecies1

Abstract

Abstract Wild species of Arachis encompass a large number of species which can provide valuable genetic resources for improving A. hypogaea L., the domesticated peanut. Arachis monticola Krapov. and Rig. is the only species which is both cross compatible with A. hypogaea and at the same ploidy level. An evaluation of reproductive efficiency in crosses between A. hypogaea and A. monticola was conducted to better understand the potential for utilization of this germplasm. This study documents the reproductive efficiency of A. monticola in reciprocal crosses with A. hypogaea subsp. hypogaea var. hypogaea cvs. Florunner and NC 6; A. hypogaea subsp. fastigiata var. vulgaris cv. Argentine; and A. hypogaea subsp. fastigiata var. fastigiata cv. New Mexico Valencia C by using selfs as controls. A significant maternal effect was observed among selfs and hybrids for timing of fertilization. Selfs of Florunner and New Mexico Valencia C initiated fertilization by 1 d after pollination, whereas syngamy did not occur in selfs of NC 6, Argentine or A. monticola until after day 1. Fertilization approached 100% in A. monticola and A. hypogaea genotypes except for New Mexico Valencia C, which only had 70% of the eggs fertilized. Embryo abortion was observed in both selfs and interspecific hybrids, with the highest rates in selfs after the pegs entered the soil; but in hybrids abortion also occurred as the peg elongated. Crosses were generally more successful when A. hypogaea was the female parent, and developing cultivars with A. monticola cytoplasm will be difficult. Sixty to more than 90% of growing ovules aborted in different interspecific crosses. Arachis monticola selfs and hybrids most closely followed the pattern of reproductive development of A. hypogaea cv. Argentine, which lends support to the theory that A. monticola is a weedy derivative of the cultivated peanut.