B chromosome in a rice aneuploid variation

An awned rice plant was discovered among the progeny of the triploid Zhongx ian 3037. Cytological investigation showed that this awned plant was a vari ation with extra chromosomes. Based on the properties of the extra chromoso mes during both meiosis and mitosis - e.g., short stature, darkly staining, instability in chromosome number, and lack of synapsis with A chromosomes - they could be considered to be B chromosomes in rice. The B chromosome(s) in both asexual and sexual progenies exhibited a unique segregation that i s different from that of telotrisomics and other aneuploids. Moreover molec ular marker analysis detected no dosage effects between the B-chromosome pl ant and the normal diploid of Zhongxian 3037, indicating that the B chromos omes might not be directly derived from any A-chromosome fragments in rice.