Liquid Culture Systems for in vitro Plant Propagation

Chapter 24
Development of photoautotrophy in Coffea somatic
embryos enables mass production of clonal transplants
F. Afreen, S.M.A. Zobayed 1 & T. Kozai
Department of Bioproduction Science, Chiba University, Matsudo Chiba 271-8510, Japan.
1
Present address: Department of Plant Agriculture, University of Guelph, Guelph Ontario
N1G 2W1, Canada.
Corresponding author: T. Kozai, Department of Bioproduction Science, Chiba University,
Matsudo, Chiba 271-8510, Japan. E-mail: kozai@faculty.h.chiba-u.jp
Abstract: Somatic embryogenesis offers the promise of a cost-effective, large-scale
propagation method and is considered as a unique alternative technique to overcome some of
the limitations of conventional clonal propagation methods. Production of somatic embryos
from cell, tissue and organ cultures may occur directly which involves the formation of an
asexual embryo from a single cell or a group of cells on a part of the explant tissue without an
intervening callus phase. In this study, the photosynthetic ability of different stage coffee
(Coffea arabusta) somatic embryos and the development of photoautotrophy are reported.
Results revealed that cotyledonary and converted somatic embryos have the ability to
photosynthesise and can be grown under photoautotrophic conditions (with no supply of
sugar from the culture medium). The development of photosynthetic ability can be
accelerated by placing the somatic embryos in a photosynthetic photon flux of 100 µmol m -2 s -1
for at least 14 days. Cotyledonary stage somatic embryos were cultured under photoautotrophic
conditions in three different growing systems to develop an optimized protocol
for a large-scale embryo-to-plantlet conversion and propagation system. Our results
demonstrated that the use of a newly developed temporary root zone immersion bioreactor is
effective for the embryo-to-plantlet conversion and enhanced growth under photoautotrophic
conditions.
Key words: bioreactor, CO 2 enrichment, embryo-to-plantlet conversion, photoautotrophy,
photosynthesis, somatic embryo, stomata
Abbreviations: Fm: maximal fluorescence; Fo: minimal fluorescence; Fs: fluorescence value
at steady state condition; PPF – photosynthetic photon flux; PS II – photosystem II
323
A.K. Hvoslef-Eide and W. Preil (eds.), Liquid Culture Systems for in vitro Plant Propagation, 323–335.
© 2005 Springer. Printed in the Netherlands.