Effect of pollination time on the frequency of 2n+n fertilization in apomictic buffelgrass
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Fertilization of an unreduced egg (2n + n) increases ploidy level and creates a new hybrid. It occasionally occurs in apomictic species but at a frequency too low to be a reliable method for genetic improvement. This investigation was undertaken to determine if 2n + n fertilization could be increased by early pollination. Six buffelgrass, Pennisetum ciliare (L.) Link [syn. Cenchrus ciliaris L.], accessions, five apomicts and one sexual, were self-pollinated and cross-pollinated with birdwoodgrass, P. ciliare (L.) Link var. setigerum (Vahl.) Leek, at 3, 2, 1, and 0 d before anthesis. The 2u + n progeny were identified by flow cytometry. DNA content (pg 2C-1) was determined for 1962 self-pollinated and 3072 cross-pollinated plants. Twenty-eight self- and 80 cross-pollinated plants had a higher DNA content and were products of 2u + n fertilization. The overall frequency of 2u + n fertilization when self- and cross-pollinated was 1.4 and 2.6%, respectively. For all protogynous intervals, the frequency ranged from 0 to 5.2% for self-pollinated plants and 0 to 8.2% for cross-pollinated plants. When self-pollinated, there was no correlation between time of pollination and recovery of 2n + n hybrids. When cross-pollinated, there was a linear relationship between time of pollination and number of 2n + n hybrids recovered. More 2n + n hybrids were recovered from crosses made 2 or 3 d before anthesis. Thus in apomictic buffelgrass, the frequency of 2n + n fertilization can be increased by pollinating early, and in apomictic species where sexual germplasm is not available, this approach has potential to produce new apomictic hybrids.
author list (cited authors)
Burson, B. L., Hussey, M. A., Actkinson, J. M., & Shafer, G. S.
complete list of authors
Burson, BL||Hussey, MA||Actkinson, JM||Shafer, GS