Plant Recovery of Selfs and Interspecific Hybrids of Arachis by In Vitro Culture of Peg Tips

Embryo abortion is a barrier to interspecific hybridization between cultivated and wild species of Arachis L., and in vitro culture of embryos prior to abortion is potentially useful for overcoming this problem. In Arachis, the peg tips encase the embryos as they move from above to below ground. The objectives of this research were to enhance the in vitro techniques to rescue selfed embryos of Arachis species and to apply this technique to obtain hybrid plants. Arachis hypogaea L. and four diploid wild species—A. glandulifera Stalker, A. duranensis Krapov. and W.C. Gregory, A. batizocoi Krapov. and W.C. Gregory, and A. valida Krapov. and W.C. Gregory—which have different degrees of compatibility with A. hypogaea were used. Ten-day-old peg tips were cultured on the combined MS and B5 media with 1-naphthaleneacetic acid (NAA), gibherellic acid (GA₃), and and 6-benzylaminopurine (BAP) for 90 d. In vitro-developed ovules, embryos, or seeds were subcultured to regenerate plants. The results indicated that A. hypogaea had higher frequencies of pod and seed production than the wild species. Arachis glandulifera produced more pods and seeds than the other three wild species, and no significant difference in pod and seed production was found among A. duranensis, A. valida, and A. batizocoi. Selfed plants were recovered from all live species. In vitro development of hybrid embryos to the cotyledonary stage was observed in all eight interspecific crosses among A. hypogaea and the four Arachis dipioids. Mature hybrid plants were recovered from seven of eight combinations. This is in contrast to plants recovered from five of eight hybrid combinations (including reciprocals) when pods were left on the plant. Arachis glandulifera × A. hypogaea hybrids which previously had been attempted, but not obtained, were recovered through peg tip culture followed by somatic embryogenesis. This study demonstrated that Arachis hybrid proembryos can be rescued through peg tip culture.