The effectiveness of insect-pollination test to evaluate the level of self-incompatibility and their genetic analysis in radish (Raphanus sativus L.)

Abstract

We have tried an insect-pollination self-incompatibility (SI) test to strictly evaluate the level of SI as a model for the actual F(1) seed production field using radish as experimental material. Twelve inbred lines, homozygous for the S-alleles, were used in the artificial self-pollination and the insect-pollination SI test. There was a positive correlation ( r = 0.606) between the results by these two methods. Some lines showed a low level of SI in the insect-pollination test despite showing a high level of SI in the artificial self-pollination test. On the other hand, no lines showing a low level of SI in artificial self-pollination had a high level of SI in insect-pollination. These results show that the insect-pollination SI test can be considered to be a more reliable and stricter method than the artificial self-pollination test with respect to an evaluation of SI levels. We have raised and analyzed an F(2) population and F(3) lines derived from an F(1) cross between a line showing a high level of SI (R00-04) and one showing a low level. The rate of self-seed settings of the F(2) population showed a binomial distribution. There were 39 high-level SI plants to 15 low-level SI plants. This result and F(3) progeny tests suggested that the high level of SI which R00-04 showed is controlled by a dominant gene.

Diallel Analysis of the Level of Self-incompatibility Evaluated by Insect-pollination in Brassica rapa L.

“…On the other hand, we used the IPI test, which can more precisely evaluate the level of SI, so the results of our genetic analyses are more reliable. In future, it will be interesting to analyze the differences in function among HLSI-1 of R. sativa (Horisaki et al 2003), and putative genes controlling the high level of SI genes identified in this study.…”

“…The IPI test was performed according to the methods of Horisaki et al (2003). In brief, seeds of the 15 F 1 crosses and the parents were sown on 6 December 2002 in a greenhouse of the Tohoku Seed Co. in Utsunomiya, Tochigi, Japan.…”

“…So we contrived a new method for evaluating the level of SI, the insect-pollination-incompatibility (IPI) test, which is performed in actual F 1 seed production fields (Horisaki et al 2003). In a comparison between the artificial self-pollination test and the IPI test in B. rapa and radish (Raphanus sativa L.), most of the parental lines showed a higher rate of pod set by the IPI test than by the artificial self-pollination test, and lines evaluated by the artificial selfpollination test as having high levels of SI were shown by the IPI test to have a widely ranging from the high level to the low level of SI.…”

“…In a comparison between the artificial self-pollination test and the IPI test in B. rapa and radish (Raphanus sativa L.), most of the parental lines showed a higher rate of pod set by the IPI test than by the artificial self-pollination test, and lines evaluated by the artificial selfpollination test as having high levels of SI were shown by the IPI test to have a widely ranging from the high level to the low level of SI. Thus, the IPI test is a more reliable method of evaluating the level of SI than the artificial selfpollination test (Horisaki et al 2003, Horisaki andNiikura 2004). Moreover, genetic analysis of the level of SI by the IPI test indicated the existence of a single dominant gene, HLSI-1 (High Level of Self-Incompatibility), which governs the level of SI and is independent of the S-locus in R. sativa (Horisaki et al 2003).…”

“…Thus, the IPI test is a more reliable method of evaluating the level of SI than the artificial selfpollination test (Horisaki et al 2003, Horisaki andNiikura 2004). Moreover, genetic analysis of the level of SI by the IPI test indicated the existence of a single dominant gene, HLSI-1 (High Level of Self-Incompatibility), which governs the level of SI and is independent of the S-locus in R. sativa (Horisaki et al 2003). Here we reveal the mode of inheritance of the level of SI in B. rapa by diallel analysis using the IPI test, and discuss the selection of the level of SI.…”