Abstract
Improved imaging procedures were developed and employed for the construction of a quantitative chromosome map based on condensation pattern. The condensa-tion pattern is uneven condensation along a chromosomal axis resulting from differential condensation of chromatin fibers at prometaphase appearing commonly in small plant chromosomes, represented by the genus Brassica. Brassica chromosomes have distinct condensation patterns at the prometaphase stage. The procedures for quantitative mapping are divided into six parts: (i) capture of images, (ii) adjustment of light distortion, (iii) measurements of an image parameter, CP, or density profiles and length of chromosomal arms, (iv) gray value adjustments between homologous chromosomes, (v) adjustment of chromosomal lengths and obtaining the standard CP, or graygram, and (vi) thresholding graygram for a quantitative chromosome map or an idiogram. The quantitative chromosome map shows well the characteristics of the Brassica chromosomes. The series of imaging procedures enable construction of quantitative chromosome maps and can be employed for a wide range of species having various chromosome numbers. The quantitative chromosome map constructed by the improved imaging currently developed is an aid to cytogenetical and genome analysis of plant species.
