Meiotic behaviour and pollen fertility of F₁, F₂ and BC₁ progenies of Iris dichotoma and I. domestica

Abstract

Pollen characteristics are very important for Iris interspecific hybridisation. In this study, the pollen viability and male meiosis were studied in yellow-flowered Iris dichotoma (Y2), I. domestica (S3) and their hybrids F1, F2 and BC1 (BC1-Y and BC1-S). The BC1-Y hybrids showed higher pollen viability than that of F1, F2 and BC1-S hybrids, which were between I. dichotoma (26.1%) and I. domestica (35.1%). Two sterile hybrids, F2-1 and BC1-S-1, exhibited more meiotic abnormalities (57.3% and 58.7%) than other individuals. During the first meiotic division, a diffuse diplotene stage was observed for the first time in the genus Iris. The meiotic abnormalities included non-congressed chromosomes, chromosome bridges, lagging chromosomes, unequal division, abnormally oriented spindle fibres, nonsynchronous division and polyad, and resulted in reduced pollen fertility. The relatively high frequency of 2n pollen grains was found in hybrids of BC1-Y-2, BC1-Y-1, BC1-S-2, BC1-S-3 and BC1-S-4. Our research provides a new resource for meiotic behaviour and pollen fertility of the genus Iris.

Exploiting Unreduced Gametes for Improving Ornamental Plants

“…The occurrence in 2 n pollen is associated with the presence of monads, dyads, or triads during microsporogenesis ( Negri et al, 1995 ; Fernandez et al, 2010 ; Chung et al, 2013 ; Nakato and Masuyama, 2021 ; Xu et al, 2021 ; Zhang et al, 2021 ) except 2 n gamete formation that is the result of pre- or post-meiotic restitution. Analysis of microsporogenesis may therefore provide an alternative method to identify 2 n pollen, but this method does not provide any information about pollen viability.…”