Occurrence of 2 n 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

GARCÍA, A. V.; ORTIZ, A. M.; SILVESTRI, M. C.; CUSTODIO, A. R.; MORETZSOHN, M. C.; LAVIA, G. I.

CROP SCIENCE

CROP SCIENCE SOC AMER

Año: 2020 vol. 60 p. 2420 - 2436

0011-183X

Unreduced (2n) gametes are the driving force that leads to polyploidization ofplants in nature and an important tool for ploidy breeding. Peanut (Arachishypogaea L., Leguminosae) seems most likely to have originated by sexualpolyploidization through interspecific hybridization between the wild diploidrelatives?A. duranensis Krapov. & W.C. Greg. and A. ipaënsis Krapov. & W.C.Greg?and subsequent binding of the unreduced gametes in the hybrid. Therefore,aiming to contribute to understanding the event of polyploid origin of thisimportant crop, we made diploid hybrids between A. duranensis and A. ipaënsisand then investigated the production of unreduced gametes in the hybridsby analyzing the size range of pollen, the constitution of the sporads, and themicrosporogenesis process. The meiotic abnormalities found, such as persistentbridges, tripolar spindles, and cytomixis processes, would lead to the formationof restitution nuclei in both the first and second meiotic division. These failuresin the regularity of meiosis lead to the formation of dyads and triads, andconsequently to 2n pollen grains. These findings constitute the first evidence ofthe formation of unreduced gametes in intergenomic hybrids obtained betweenthe wild progenitors of A. hypogaea and enable us to propose a model of originof the crop through sexual polyploidization.