Chromosomal Location of HCA1 and HCA2, Hybrid Chlorosis Genes in Rice

Many postzygotic reproductive barrier forms have been reported in plants: hybrid weakness, hybrid necrosis, and hybrid chlorosis. In this study, linkage analysis of the genes causing hybrid chlorosis in F2 generation in rice, HCA1 and HCA2, was performed. HCA1 and HCA2 are located respectively on the distal regions of the short arms of chromosomes 12 and 11. These regions are known to be highly conserved as a duplicated chromosomal segment. The molecular mechanism causing F2 chlorosis deduced from the location of the two genes was discussed. The possibility of the introgression of the chromosomal segments encompassing HCA1 and/or HCA2 was also discussed from the viewpoint of Indica-Japonica differentiation

Studies on the multivariate statistics oriented genetic parameters and their uses

Typescript (photocopy).Multivariate statistical methods have rarely been used in the plant breeding field. Their intricate theories have made themselves unappealing to most experimentalists. However, recent advancements of electronic computers virtually eliminate the problems associated with complicated calculations required to execute a multivariate analysis. Therefore, in this study, attention is paid primarily to the evaluation of one of the multivariate statistical methods, Factor Analysis, as a new breeding tool. A new concept of hereditary parameters and a new index were proposed. As the proposed method is intended for the supplement of a Smith-Hazel selection index, the efficiency and the consistency of the selection index were also examined. The Smith-Hazel selection index constructed for maize demonstrated its efficiency and pronounced robustness under the violation of one of the hypotheses--correct parameters must be known. For the evaluation of the multivariate analysis oriented method, two sets of paired sorghum subpopulations as well as their original mother population were analyzed by a factor analysis method and heritability like parameter vectors were derived from their factor scores for each population. ..