2022 Volume 104 Issue 3 Pages 176-181
We attempted to select heterozygous plus-trees to study a male sterility gene in the Japanese hinoki cypress (Chamaecyparis obtusa (Sieb. et Zucc.) Endl.), which is one of the primary tree species that cause pollinosis. Hence, we produced self-pollinated families derived from eight plus-trees. We observed pollen dispersal at the age of 8 years and pollen cell at the age of 9 years. Male sterile trees were found in two self-pollinated families of “Tanzawa 6” and “Tanzawa 7,” at proportions of 22.2％ and 25.0％, respectively. This indicated that these two clones have a male-sterile gene in heterozygotes. All the confirmed male-sterile individuals had no transition from the pollen mother cell stage to the next stage of pollen development. Two self-pollinated male sterile trees in “Tanzawa 7” exhibited normal seed germination, which indicated that they were not female-sterile. These results suggested that these trees are useful for male sterile breeding in Japanese hinoki cypress. However, the seed germination rate and early growth of self-pollinated individuals were inferior to those of other cross-pollinated individuals. Because of the possibility that selfing could also affect pollen cell development, it is essential to perform additional observation using backcross families.
