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Effects of rinsing and chilling on germination and expression of dormancy-associated genes in seeds of 'Hokimomo' peach (Prunus persica (L.) Batsch)

Worarad, K., Suzuki, T., Rumainum, I., Yamane, K.
Acta horticulturae 2017 no.1167 pp. 413-418
Prunus persica, abscisic acid, breeding, cold treatment, dehydrins, gene expression, genes, germination, ornamental trees, peaches, seed dormancy, seed treatment, seedling growth, seeds, sowing, tap water, water stress
Ornamental peaches can be propagated from seed. Efficient seed treatments for early germination and seedling growth can help to shorten nursery and breeding periods. In order to find key genes associated with dormancy release, we analyzed the expression of certain genes previously found to be related to seed dormancy. Seeds of 'Hokimomo' peach were rinsed for 2 or 7 days under running tap water at 15°C and chilled at 5°C. Chilling (stratification) for periods of 6 or 8 weeks were found to be suitable for germination and growth of seedlings with resulting heights between 15-20 cm at 35 days after sowing. Seeds rinsed for 2 days showed a higher germination rate than those rinsed for 7 days when the chilling period was 6 or 8 weeks. In contrast, the germination rate of seed rinsed for 7 days was better than those rinsed for 2 days when the chilling period was 4 weeks. In this study, the expression of genes NCED1, ABA 8'-hydroxylase and GA2-oxidase tended to decrease after seeds were rinsed for 7 days and chilled for 4 weeks. Transcript levels of LEA-D34 or dehydrin, a gene that is associated with drought stress was significantly higher before seeds were rinsed compared to its levels following rinsing and chilling of seeds. Our findings provide useful information for understanding the molecular mechanism(s) of seed dormancy and the development of methods to shorten the breeding period in various ornamental trees.