BIII progeny (2n + n) from apomictic Paspalum notatum obtained through early pollination

MARTÍNEZ, ERIC J.; ESPINOZA, FRANCISCO; QUARIN, CAMILO L.

JOURNAL OF HEREDITY

The American Genetic Association. Oxford University Press

Lugar: 200 Madison Avenue, New York, NY 10016; Año: 1994 vol. 85 p. 295 - 297

0022-1503

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB;} @page Section1 {size:595.3pt 841.9pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> An apomictic tetraploid (2n = 4x = 40) cytotype of Paspalum notatum (Bahiagrass) was emasculated and pollinated from 1 to several days prior to anthesis (DPA). Two pollen sources were used: the tetraploid (4x) cytotype and a diploid (2x) variety (Pensacola Bahiagrass). Spikelets pollinated with pollen of the 4x plant at 1 DPA gave rise to only 4x seedlings, indicating a 2n + 0 parthenogenetic origin. When pollination was achieved 2 DPA, 46% of recovered seedlings were considered to be BIII progenies produced through fertilization of the unreduced egg cell of an aposporous embryo sac with a reduced sperm nucleus (2n + n = 40 + 20 = 60).  Few seedlings were recovered from 3 DPA, and all were tetraploid, originated through parthenogenesis (2n + 0).  When diploid Pensacola Bahiagrass was the pollen donor, all seedlings from 1 DPA were parthenogenetic tetraploids (2n + 0), whereas most from 2 or 3 DPA were BIII progenies (2n + n) and had 50 chromosomes (2n = 40 + n = 10).  Control seedlings, from pollinations at anthesis time, were all tetraploid (2n + 0), as expected. These results indicate that time of pollination may be manipulated in an apomictic species to increase the production of BIII progenies.  Early pollinations, in some cases, prevent parthenogenetic development of the unreduced egg cell in an aposporous embryo sac, allowing its fertilization.