Cytological studies on sugarcane and its relatives I. Hybrids between Saccharum officinarum, Miscanthus japonicus and Saccharum spontaneum
Li, H.W.; Loh, C.S.; Lee, C.L.
Bot Bull Acad Sinica 2(3): 147-160
Crossing P.O.J. 2725 with M. japonicus gave 2 types of seedlings: an intermediate type characterized by a slender cane, narrower leaves and a lower sugar content, with the reduced gametes of both parents. The normal type characterized by a larger cane, wider leaves and a higher sugar content, resembling the female parent, with the unreduced gamete from the female parent and the reduced gamete from the male. Meiosis for all the parents and the hybrids was studied. One of the intermediate types was crossed with Saccharum spontaneum, and a tri-hybrid was obtained. It contained the unreduced female gamete and the reduced male gamete. S. spontaneum and S. officinarum, both with a higher order of polyploidy, had chromosomes mostly, if not exclusively, bivalents; rarely were a few multivalents found. Sometimes pseudo-multivalents were formed by having chromatic threads joining bivalents together to form chains in prophase, metaphase,and even persisted to anaphase in the 1st meiotic mitosis. In the hybrids involving reduced chromosomes, auto-syndetic pairing resulted. Chromosomes of Miscanthus behaved similarly, but were inconsistent. Noble cane vars. were hypothesized to be derived from the doubling of the amphidiploid which would be formed by the natural hybridization of 2 spp. of Saccharum, each with the basic number of 10 chromosomes, but of unlike genomatic constitution. "Nobilization" was defined as the union of the unreduced noble cane gamete used as the female parent, with any reduced or unreduced male gamete from noble cane, wild spp. of Saccharum. or other related genera. The process of "nobilization" could not be indefinite, because the increment of chromosomes would be limited by the nucleo-cytoplasmic ratio.