Mutagenesis in gynomonoecious spinach (Spinacia oleracea L.) plants and selection of low oxalate variants
2006
Hata, N.(Okayama Univ. (Japan)) | Murakami, K. | Yoshida, Y. | Masuda, M. | Tanaka, A. | Shikazono, N. | Hase, Y.
This study was conducted to evaluate mutagenesis in gynomonoecious spinach (Spinacia oleracea L.) plants for inducing low oxalate variants. Gamma-ray and ion beams of 220 MeV 12C5+ and 50 MeV 4He2+ were used as mutagen in seed irradiation. Optimum dosages for irradiation were determined to be about 100Gy, 15-20 Gy and 150-200 Gy in gamma-ray, 12C5+ and 4He2+, respectively. In M2 generation, there was one line segregating albino seedlings, one line segregating xantha seedlings and two lines segregating viridis seedlings, which indicates that recessive mutation could be expressed in M2 generation due to the capacity for self-fertilization of gynomonoecious plants in an otherwise dioecious spinach. To save on labor and time for analysis, selection of low oxalate variants in M2 generation was conducted by a two-step selection which consisted of the first analysis of bulked leaves from 2 plants as one specimen followed by the second analysis of selected individual plants. In the first analysis of 813 specimens, we selected 13 specimens as low and 9 specimens as high in oxalate content. In the second analysis, there was consistency in the distribution of low and high oxalate content corresponding to the first screening, indicating that selection of low oxalate variants could be achieved by this two-step selection with half the labor and time for analysis as compared to non-bulked method. There were no clear differences in distribution of oxalate content between M3 progenies of plants selected as low or high oxalate content, suggesting that the low oxalate content in plants isolated in M2 generation was not of a genetic origin. From these results, it seems to be necessary to explore a variant with obvious deviation from the continuous variation of oxalate content in the M2 generation.
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