Cytological studies of Saccharum and allied genera. VIII. F2 and BC1 progenies from 112- and 136-chromosome S. officinarum x S. spontaneum hybrids
Bot Gaz 124(3): 186-190
Pollen mother cells of 112-chromosome (2n + n) Saccharum officinarum X S. spontaneum hybrids usually showed 56II or 55II + 2I. Trivalents also occurred. Pollen mother cells of 136-chromosome (2n + n) S. officinarum X S. spontaneum hybrids showed a range of 66II + 4I to 61II + 14I. Chromosome numbers in an F2 progeny from a 112-chromosome F1 ranged from 2n = 109 to 113. Chromosome numbers in BC1 progenies from S. officinarum X 112-chromosome F1 hybrids ranged from 2n =120 to 141. Chromosome numbers in F2 progenies from 136-chromosome F1 hybrids ranged from 2n = 109 to 139. One BC1 plant from S. officinarum X 136-chromosome F1 had 2n = 144. These results show that, upon self-pollination, F1 (2h + n) hybrids transmitted variable chromosome numbers to the F2. The variable numbers can be explained by ordinary meiotic irregularities. Upon being pollinated by F1 (2n + n) hybrids, S. officinarum transmitted 80 chromosomes, its somatic chromosome number, to its progenies. In the same crosses, the F1 hybrids transmitted chromosome numbers that varied within limits explainable by ordinary meiotic irregularities.