Determination of chromosomal ploidy in Agave ssp.
Chromosome observation is necessary to elucidate the structure, function and organization of Agave plants’ genes and genomes. However, few researches about chromosome observation of Agave ssp. were done, not only because their chromosome numbers are large, but also because their ploidies are complicated. The root tips of 19 Agave ssp. germplasms were used as materials for determining their chromosomal ploidies. Through normal pre-treatment, fixation, digesting and Giemsa staining, the glass slides with expelled cells on them were obtained. Observed with a light microscope, the results showed that 10 germplasms are diploids, including 4 wild species and a local variety which are good parents for cross-breeding. The main cultivar in China A.hybrid cv NO 11648 is also a diploid. A. cantala Roxb used as parent for disease-resistant breeding is a triploid. A. hybrid cv nanya NO.1 and A. hybrid cv nanya NO.2 are tetraploids. The other germplasms belong to polyploids. Although three germplasms’ ploidies were reported before, the other 16 germplasms’ were first reported in this paper. These results will provide theoretical basis for cross-breeding.