Photoautotrophic culture of Coffea arabusta somatic embryos: photosynthetic ability and growth of different stage embryos
C. arabusta somatic embryos were cultured and development of stomata, rate of CO2 fixation or production, chlorophyll content and chlorophyll fluorescence were studied in embryos at different stages of development. Cotyledonary and germinated embryos have photosynthetic capacity, although pretreatment at a high photosynthetic photon flux (PPF) (100 Amol m-2 s-1) for 14 days increased photosynthetic ability. Except in a very small number of cases, stomata did not develop fully in precotyledonary stage embryos and were absent in torpedo stage embryos. Low chlorophyll content (90-130 Ág g-1 fresh mass) was noted in torpedo and precotyledonary stage embryos compared with cotyledonary and germinated embryos (300-500 Ág g-1 fresh mass). Due to the absenceof stomata and low chlorophyll content in the torpedo and precotyledonary stage embryos, the photosynthetic rate was low and, in some cases, CO2 production was observed. These data suggest that the cotyledonary stage is the earliest stage that can be cultured photoautotrophically to ensure plantlet development. When grown photoautotrophically (in a sugar-free medium with CO2 enrichment in the culture headspace and high photosynthetic photon flux), torpedo and precotyledonary stage embryos lost 20-25 percent of their initial dry mass after 60 days of culture. However, in cotyledonary and germinated embryos, the dry mass of each embryo increased by 10 and 50 percent, respectively. By using a porous supporting material, growth (especially root growth) was increased in cotyledonary stage embryos. In addition, photoautotrophic conditions, high PPF (100-150 Amol m-2 s-1) and increased CO2 concentration (1100 Amol mol-1) were found to be necessary for the development of plantlets from cotyledonary stage embryos.
| Main Authors: | , , |
|---|---|
| Format: | biblioteca |
| Published: |
2002
|
| Subjects: | COFFEA ARABICA, DIOXIDO DE CARBONO, ENRIQUECIMIENTO EN GAS CARBONICO, CLOROFILAS, CAFE, COTILEDONES, CONTENIDO DE MATERIA SECA, FLUORESCENCIA, GERMINACION, CRECIMIENTO, CULTIVO IN VITRO, MICROPROPAGACION, FOTOSINTESIS, RAICES, EMBRIOGENESIS SOMATICA, EMBRION, ESTOMA, CULTIVO DE TEJIDOS, |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|