Abstract
Background and Aims Arachis batizocoi is a wild relative of cultivated peanut (A. hypogaea), an allotetraploid with an AABB genome. Arachis batizocoi was once considered the ancestral donor of the peanut B genome, but cytogenetics and DNA phylogenies have indicated a new genome classification, ‘K’. These observations seem inconsistent with genetic studies and breeding that have shown that A. batizocoi can behave as a B genome.Methods The genetic behaviour, genome composition and phylogenetic position of A. batizocoi were studied using controlled hybridizations, induced tetraploidy, whole-genome in situ fluorescent hybridization (GISH) and molecular phylogenetics.Key Results Sterile diploid hybrids containing AK genomes were obtained using A. batizocoi and the A genome species A. duranensis, A. stenosperma, A. correntina or A. villosa. From these, three types of AAKK allotetraploids were obtained, each in multiple independent polyploidy events. Induced allotetraploids were vigorous and fertile, and were hybridized to A. hypogaea to produce F1 hybrids. Even with the same parental combination, fertility of these F1 hybrids varied greatly, suggesting the influence of stochastic genetic or epigenetic events. Interestingly, hybrids with A. hypogaea ssp. hypogaea were significantly more fertile than those with the subspecies fastigiata. GISH in cultivated × induced allotetraploids hybrids (harbouring AABK genomes) and a molecular phylogeny using 16 intron sequences showed that the K genome is distinct, but more closely related to the B than to the A genome.Conclusions The K genome of A. batizocoi is more related to B than to the A genome, but is distinct. As such, when incorporated in an induced allotetraploid (AAKK) it can behave as a B genome in crosses with peanut. However, the fertility of hybrids and their progeny depends upon the compatibility of the A genome interactions. The genetic distinctness of A. batizocoi makes it an important source of allelic diversity in itself, especially in crosses involving A. hypogaea ssp. hypogaea.
Highlights
The genus Arachis is endemic to South America, found over a wide area and in diverse environments
Estimated pollen viability using acetic carmine staining of wild parents, cultivated peanut and induced allotetraploids plants ranged from 89Á7 to 98Á8 %, and showed little variation regardless of the accession, cultivar or allotetraploid (v2 1⁄4 2637Á1, d.f. 1⁄4 24, P < 0Á001) (Fig. 4). These results suggest that estimated pollen viability is not the major contributor to differences in success of F1 production
The K genome is closer to the B than the A genome: phylogenetic, genome in situ fluorescent hybridization (GISH) and genetic evidence
Summary
The genus Arachis is endemic to South America, found over a wide area and in diverse environments It contains 81 described species, assembled into nine taxonomical sections, according to their morphology, geographic distribution and cross-compatibility (Krapovickas and Gregory, 1994; Valls and Simpson, 2005; Valls et al, 2013). The allotetraploids, the wild A. monticola and the cultivated peanut A. hypogaea are very closely related and belong to the same biological species. Arachis batizocoi was once considered the ancestral donor of the peanut B genome, but cytogenetics and DNA phylogenies have indicated a new genome classification, ‘K’. These observations seem inconsistent with genetic studies and breeding that have shown that A. batizocoi can behave as a B genome
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
