Occurrence of 2n microspore production in diploid interspecific hybrids between the wild parental species of peanut (Arachis hypogaea L., Leguminosae) and its relevance in the genetic origin of the cultigen

A V GARCÍA; AM ORTIZ; MC SILVESTRI; A CUSTODIO; MORETZSOHN ; GI LAVIA

CROP SCIENCE

CROP SCIENCE SOC AMER

Lugar: Baltimore; Año: 2020 vol. 60 p. 2420 - 2436

0011-183X

Unreduced (2n) gametes are the driving force that leads to polyploidization of plants in nature and an important tool for ploidy breeding. Peanut (Arachis hypogaea L.,Leguminosae) is assumed to have been originated by sexual polyploidization through interspecific hybridization between the wild diploid relatives -A. duranensis and A. ipaënsis-, and subsequent binding of the unreduced gametes in the hybrid. Therefore, aiming to contribute to the understanding the event of polyploid origin of this important crop, we made diploid hybrids between A. duranensis and A. ipaënsis, and then investigated the production of unreduced gametes in the hybrids by analyzing the size range of pollen, the constitution of the sporads, and the microsporogenesis process. The meiotic abnormalities found, such as persistent bridges, tripolar spindles and cytomixis processes, would lead to the formation of restitution nuclei in both the first and second meiotic division. These failures in the regularity of meiosis lead to the formation of dyads and triads, and consequently to 2n pollen grains. These findings constitute the first evidence of the formation of unreduced gametes in intergenomic hybrids obtained between the wild progenitors of A. hypogaea and enable us to propose a model of origin of the crop throughsexual polyploidization.