Cytological mechanism of 2n pollen formation and unilateral sexual polyploidization inLolium
✍ Scribed by C. A. Sala; E. L. Camadro; M. T. Salaberry; A. O. Mendiburu
- Publisher
- Springer
- Year
- 1989
- Tongue
- English
- Weight
- 452 KB
- Volume
- 43
- Category
- Article
- ISSN
- 0014-2336
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✦ Synopsis
Plants of Lolium perenne, L . multiflorum and L. hybridum (331, 51 and 18, respectively) were screened for 2n pollen production . The screening was based on the size differences that are expected to be found between n and 2n pollen of a plant . It was found that 28 plants of perennial ryegrass -belonging to 13 cultivarsproduced pollen grains of heterogenous size (big and small) . The estimated frequency of big pollen grain production was higher than 10% in ten out of 28 plants and in three of them it reached a value of 100% . Eight plants obtained from two 4x x 2x crosses, in which the male parent had been previously identified as producing pollen grains of heterogenous size, was tetraploid . The cytological mechanism of big pollen grain formation observed in three plants consists in the lack of spindle formation and, consequently, of chromosome migration in anaphase II . From these breeding and cytological results, it was concluded that the big pollen grains observed were viable 2n pollen grains . The nuclei of the 2n pollen grains produced by this mechanism are genetically equivalent to those formed by the restitution of the second meiotic division . The value of these gametophytes in a breeding program of Lolium is discussed .