[Transmission and genetic effect of ting chromosome in cross progenies from octoploid Tritileymus with 4D nullisomic]

A pair of ting chromosomes (ti) added to 72180 4D nullisomic was subcentral centromere chromosome and was about 1/3-1/4 the size of a chromosome on the average length. It's chromosome configuration was 19.59" (18-20) + 0.46' (0-4) + 0.99" (0-1) + 0.96ti" (0-1) + 0.08ti' (0-2) at PMC MI. The cells with ring ti" account for 96.19%, of which 82.38% were free on each side of the equatorial plane. ti chromosome paired in advance, defered segregation and had no synapsis with a chromosome. When the cross progenies from 72180 4D nullisomic with octoploid Trilileymus were backcrossed to the 4D nullisomic used as the male, the transmitting rate of 2ti chromosome was six times higher than that where the nullisomic was used as the female. The transmitting and loss rates of ti chromosome were 50.38% and 18.34% respectively, and averagely each plant has 0.72 ti chromosome in the cross generations. The appearing rate of ti chromosome was 43.18% in root tip cell and 8.16% in PMC MI of the plants without ti chromosome. When the number of a chromosome was less than 42, the genetic effect of ti chromosome on the quantitative character was significant, while the number of a chromosome was 42, the genetic effect was not apparent.