Articles
Seed and protocorm development by in vitro ovary culture at the fertilization phase in Cymbidium
Article number
1262_19
Pages
141 – 148
Language
English
Abstract
In Cymbidium, the period from pollination to fertilization is about 3 months and the period from pollination to mature seed is about 10 months.
It is difficult to observe sequential changes in fertilization and seed development because sufficient developing ovaries are needed.
Often, the fruit abscises, and several ovaries are lost.
Because the low viability of the pollinia was considered one of the causal factors of the abscission of the ovaries, mixed pollination of Cymbidium eburneum with the pollinia of three other species, C. floribundum, C. devonianum, and C. eburneum, was performed to produce the required number of ovaries.
Pollinated pistils were collected every two weeks, sterilized, and sliced off horizontally.
The column side was placed into fixing solution and the basal side was placed on 0.3% gellan-gum solidified MS medium supplemented with 5% sucrose, 10 mg L‑1 picloram and 1 mg L‑1 benzyl aminopurine.
The initial developing ovules were observed in ovaries collected 4 weeks after pollination.
In the ovaries collected 6 weeks after pollination, a pollen tube was observed near the ovule.
The number of developing ovules and pollen tubes increased over the weeks.
Nine months after pollination, the cultured ovaries were browning and splitting, and seeds were observed.
Surviving seeds from the cultured ovaries started 7 weeks after pollination were found by FDA staining, and a few protocorms were obtained from the ovary culture started 6 weeks after pollination.
The number of protocorms increased over the weeks.
When C. lowianum were used as seed parents, protocorms were found from the ovary cultures started 10 weeks after pollination.
These results suggest that the timing of ovule development and fertilization might not synchronize in the same ovary.
Moreover, fertilized ovules might continue to develop into seeds in these ovary cultures.
It is difficult to observe sequential changes in fertilization and seed development because sufficient developing ovaries are needed.
Often, the fruit abscises, and several ovaries are lost.
Because the low viability of the pollinia was considered one of the causal factors of the abscission of the ovaries, mixed pollination of Cymbidium eburneum with the pollinia of three other species, C. floribundum, C. devonianum, and C. eburneum, was performed to produce the required number of ovaries.
Pollinated pistils were collected every two weeks, sterilized, and sliced off horizontally.
The column side was placed into fixing solution and the basal side was placed on 0.3% gellan-gum solidified MS medium supplemented with 5% sucrose, 10 mg L‑1 picloram and 1 mg L‑1 benzyl aminopurine.
The initial developing ovules were observed in ovaries collected 4 weeks after pollination.
In the ovaries collected 6 weeks after pollination, a pollen tube was observed near the ovule.
The number of developing ovules and pollen tubes increased over the weeks.
Nine months after pollination, the cultured ovaries were browning and splitting, and seeds were observed.
Surviving seeds from the cultured ovaries started 7 weeks after pollination were found by FDA staining, and a few protocorms were obtained from the ovary culture started 6 weeks after pollination.
The number of protocorms increased over the weeks.
When C. lowianum were used as seed parents, protocorms were found from the ovary cultures started 10 weeks after pollination.
These results suggest that the timing of ovule development and fertilization might not synchronize in the same ovary.
Moreover, fertilized ovules might continue to develop into seeds in these ovary cultures.
Publication
Authors
J. Kato, R. Hirai, K. Iguchi, A. Iwata, S. Ichihashi
Keywords
Cymbidium, fertilization, mature-like seed, ovary culture, picloram
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