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Cytology of 2n Pollen Formation in Diploid Crested Wheatgrass, Agropyron cristatum
Author(s) -
Ray Ian M.,
Tokach Mary K.
Publication year - 1992
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1992.0011183x003200060011x
Subject(s) - pollen , biology , ploidy , agropyron cristatum , meiosis , microspore , botany , anaphase , hybrid , paspalum , chromosome , genetics , stamen , gene
Hybrids between induced tetraploids of diploid crested wheatgrass, Agropyron cristatum (L.) Gaertn. (2 n = 2 x = 14), and tetraploid crested wheatgrass, A. desertorum (Fisch. ex Link) Schult. (2 n = 4 x = 28), have provided improved germplasm with unique agronomic traits. Introgression from diploids to tetraploids would be simplified if diploids that produce 2 n gametes (gametes with the sporophytic chromosome number) could be identified. This study was initiated to determine if 2 n pollen is produced in diploid crested wheatgrass and to determine the cytological mechanisms of 2 n pollen formation. Pollen diameters were investigated by measuring 60 pollen grains from each of 600 diploid and 100 tetraploid genotypes. Pollen diameters averaged 37.9 μm (SE = 0.17) and 41.1 μm (SE = 0.33) for diploid and tetraploid genotypes, respectively, with a range of 35.3 to 41.3 μm among the diploids, and 39.7 to 46.8 μm among the tetraploids. Approximately 16% of the diploid genotypes produced some pollen grains with twice the mean volume of n pollen. Cytological analyses of 17 individuals that produced variable‐sized pollen indicated that 2 n pollen was produced via restitution at the second meiotic division. Meiotic abnormalities that could give rise to 2 n microspores include i) arrest at metaphase II, ii) lack of sister chromatid movement in anaphase II, iii) movement of all or most sister chromatids to a single pole in anaphase II, and iv) abnormal cytokinesis after telophase II. The formation of 2 n pollen in diploid crested wheatgrass should facilitate efficient transfer of germplasm from diploids to tetraploids within the genus Agropyon .