Finally, the Cross That Made Arachis Monticola Krapov. & Rigoni And/Or

Finally, the Cross that Made Arachis monticola Krapov. & Rigoni and/or Arachis hypogaea L. C.E. SIMPSON*. Texas A&M AgriLife Research. Texas A&M AgriLife Research and Extension Center. Texas A&M University System. Stephenville, Texas 76401-8992. Much has been said and written about what were the progenitors of the cultivated peanut (Arachis hypogaea L.). Early in the career of this author, the only non-A, i.e., did not have the small “A pair” of chromosomes, was A. batizocoi Krapov. & W.C. Greg. This information was published by Dr. Joe Smartt, Dr. W.C. Gregory and Dr. M.P. Gregory in the mid-1970’s. At that time I was working on transferring resistance to leaf spot (Early, Cercospora arachidicola S. Hori and Late, Cercosporidium personatum (Berk. & M.A. Curtis) Deighton) from A. cardenasii Krapov. & W.C. Greg. and A. chacoensis nom. nud. (later it was realized that this was A. diogoi Hoehne), but I was having serious sterility problems in making the transfer. After the Smartt, et al. paper I incorporated A. batizocoi into the program and had immediate success in making the transfer. This same introgression pathway was used to transfer resistance to two of the root knot nematode species (Meloidogyne arenaria (Neal) Chitwood and M. javanica (Treub) Chitwood) into the cultigen. With this success, these species were included in discussions of the origin of the cultivated peanut. During the 1980’s much cytological data was accumulated that did not support the cross I made as being the progenitors of peanut. As the molecular era began to work into the peanut research field, Dr. G. Kochert asked about getting some materials to do molecular studies. From that beginning of identifying A. duranensis as the A genome donor and A. ipaёnsis as the probable B genome donor to the cultigen, adding in Dr. J.G. Seijo’s, Dr. M.D. Burow’s and others work, we now have a reasonably good foundation to indicate that these two are in fact the donors. However, molecular studies also confirm that A. duranensis was the female of the original cross(es). Herein has been the problem. This author has attempted the cross, A. duranensis X A. ipaёnsis, literally hundreds of times without success, as have others, reporting the same results. The reciprocal cross is easily accomplished, and Dra. A.P. Fávero reported the reciprocal cross as part of her PhD research project. She made the cross, doubled the progenies and made numerous crosses with the several varieties of A. hypogaea. Fávero did not compare her progenies to A. monticola (personal communication) so we do not know if what she crossed was A. monticola or A. hypogaea, or something else she may have created with the reciprocal cross, to the peanut cultivars. Recently, one of Dr. G. Seijo’s students reported that the A genome donor to A. hypogaea most probably came from the valley of the Rio Seco in northwest Argentina. Upon this revelation, I decided to use some of these materials and try the cross again, and much to my delight, I was successful in obtaining seeds from the elusive cross. With the chromosomes doubled we have now harvested 14 seeds and will begin a comparison of these progenies to various A. monticola accessions as well as representatives of the botanical varieties of A. hypogaea. From these efforts I hope to be able to make a definitive answer to the question: did the Arachis duranensis X Arachis ipaёnsis cross produce, when doubled, Arachis monticola, or Arachis hypogaea? .

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