Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/1997
Publication Date: N/A
Interpretive Summary: Seed abortion and non-fertilization are two of the main barriers to breeding of desirable characteristics found in wild, uncultivated species into cultivated peanuts. We made crosses between the closest wild species relative to the cultivated peanut and four selected cultivated-types. We found that the time when fertilization occurs varied in wild- and cultivated-types, and that in the various crosses, the female parent most influenced the timing of fertilization. Abortion of embryos occurred in hybrids (crosses of wild- and cultivated-types) both as the peanut peg elongated and after the peg tip entered the soil. Abortions in the self pollinated peanuts were highest after the pegs entered the soil. The data allow us to understand when some of the problems occur, and the information should be useful in knowing when to examine biochemical and morphological factors that affect these phenomena. This reproductive development data also provided further information about the potential genetic background and relationship of various wild- and cultivated-types, which furthers the total understanding of breeding within and among the types.
Technical Abstract: Wild species of Arachis encompass a large number of diploid and species which can provide valuable genetic resources for improving A. hypogaea, the domesticated peanut. A. monticola is the only species which which is both compatible with A. hypogaea and at the same ploidy level. An evaluation of reproductive efficiency in crosses between A. hypogaea and dA. monticola was conducted to better understand the potential for utilization of this germplasm. A significant maternal effect was observed among selfs and hybrids for timing of fertilization. Selfs of Florunner and NM Valencia C initiated fertilization by 1 d after pollination, whereas syngamy did not occur in NC 6, Argentine or A. monticola until after day 1. Fertilization approached 100% in A. monticola and A. hypogaea genotypes except for NM Valencia C. which only had 70%. 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. A. monticola selfs and hybrids most closely followed the pattern of reproductive development of cultivar Argentine, which lends support to the theory that the species is a weedy derivative of the cultivated peanut.