Successful crosses between fungal-resistant wild species of Arachis (section Arachis) and Arachis hypogaea

Abstract

Peanut (Arachis hypogaea) is the fifth most produced oil crop worldwide. Besides lack of water, fungal diseases are the most limiting factors for the crop. Several species of Arachis are resistant to certain pests and diseases. This study aimed to successfully cross the A-genome with B-K-A genome wild species previously selected for fungal disease resistance, but that are still untested. We also aimed to polyplodize the amphihaploid chromosomes; cross the synthetic amphidiploids and A. hypogaea to introgress disease resistance genes into the cultivated peanut; and analyze pollen viability and morphological descriptors for all progenies and their parents. We selected 12 A-genome accessions as male parents and three B-genome species, one K-genome species, and one A-genome species as female parents. Of the 26 distinct cross combinations, 13 different interspecific AB-genome and three AA-genome hybrids were obtained. These sterile hybrids were polyploidized and five combinations produced tetraploid flowers. Next, 16 combinations were crossed between A. hypogaea and the synthetic amphidiploids, resulting in 11 different hybrid combinations. Our results confirm that it is possible to introgress resistance genes from wild species into the peanut using artificial hybridization, and that more species than previously reported can be used, thus enhancing the genetic variability in peanut genetic improvement programs.

Identifying Arachis Amphidiploids Resistant to Foliar Fungal Diseases

“…Some genotypes were not evaluated in all 3 yr due to limited seed supply. Our best amphidiploids resulted from the hybridization of these accessions, corroborating the results of Fávero et al (2015a). It is believed that the value found for the Runner IAC 886 cultivar for resistance to early leaf spot is due to an artifact caused by the interaction with late leaf spot.…”

“…Field trials were conducted during the 2010-2011, 2011-2012 and 2012-2013 seasons, in Pólo Centro Norte, Agência Paulista de Tecnologia dos Agronegócios, in Pindorama, São Paulo, Brazil, using a randomized block design with four replications with five plants per plot. Based on previous results of leaf diseases resistance of wild accessions and interspecific hybrids (Michelotto et al, 2015), and the development of synthetic amphidiploids (Fávero et al, 2006(Fávero et al, , 2015a(Fávero et al, , 2015b, we evalu- protection. The reactions of the wild species accessions and amphidiploids should not be compared with this cultivar because it dies before the end of cycle of the other accessions.…”

Recombinants from the crosses between amphidiploid and cultivated peanut (Arachis hypogaea) for pest-resistance breeding programs

“…It is common in these crosses the presence of abortions of “peg” that did not develop seeds, developed seeds that did not germinate and germinated seeds that did not had the vigor to survive in pots [21, 22, 23]. Further, greater number of abortions was due to interspecific hybrids with difference between genomes.…”

Organography of greenhouse and field accessions of wild Arachisspecies (section Arachis)

“…Principal component analysis showed that 10 morphological descriptors were important in explaining the distribution of accessions (in order of importance): length (n + 1), number of flowers, height of main stem (n), right apical leaflet length, right apical leaflet width, diameter (n), seed length, anthocyanin pigmentation of branches, bristles on rachis, and standard petal base color. In fact, several studies have shown that characters such as branch length, leaflet length, and leaflet width are important in discriminating accessions of Arachis species (Veiga et al 2001;Castro et al 2007;Fávero et al 2015a, Fávero et al 2015b). For instance, Costa (2012) 4 examined six floral structures in several wild Arachis species, all of which were also evaluated in this study except for A. villosa and A. ipaënsis, and found significant differences in all floral structures for all species.…”

“…Wild Arachis species can be used as animal forage and for landscaping, and have proved useful as an important source of genes for peanut breeding (Oliveira and Valls, 2002;Assis et al 2013;Santos et al 2013;Fávero et al 2015a).…”