PROPAGATION OF PLANTS BY SOMATIC EMBRYOGENESIS

The in vitro culture of plants offers many advantages over conventional propagation but its wider commercial application is largely limited by high labour costs. These would be reduced by utilising the phenomenon of somatic embryogenesis for plant regeneration (Jones, 1984, Biochem. Soc. Symp. 98: 222-232). Although many publications describe how mbryogenesis may be induced in particular cases (reviewed by Williams and Maheswaran, 1986, Ann. Bot. 57: 449-462), the underlying mechanisms controlling it remain elusive; a clearer understanding is required for its widespread use to become established (Krikorian, 1982, Biol. Rev. 57: 151-218). The work described here is chiefly concerned with experiments investigating the induction of somatic embryos in tissue cultures of four very different important crop species (coffee, kiwi-fruit, banana and pineapple). Large numbers of embryos of coffee were produced; alterations in the pattern of this regeneration under different cultural conditions were explored. Particular attention was given to speeding up the process of embryo differentiation while keeping the necessary labour inputs as low as possible. The secondary proliferation of coffee embryos was examined in a range of bioreactors. The design of these structures was found to have effects on growth as profound as the composition of the culture medium. From kiwi-fruit leaf explants a number of morphologically distinct types of callus were induced by different synthetic auxins. These types were modified when grown in different vessels. Subculture of callus resulted in root or shoot formation but no somatic embryos were produced. Multifactorial experiments were used to determine the conditions under which callus growth from explants of banana and pineapple could be initiated. Discrete nodules developed from banana callus in liquid medium from which roots grew - no shoots, however, arose and the structures did not appear to be embryos. Examination of the intracellular free 2,4-D concentration showed this to peak in correlation with coffee embryogenesis after several months on growth regulator-free medium. Differences were found in the amounts of free and conjugated polyamines in normally and abnormally developing somatic embryos. SDS-PAGE showed no cellular proteins to be specific to embryogenic coffee tissues. Variation was, however, found in both the total and glycoproteins secreted into liquid medium by proliferating embryos and non-embryogenic cells. Further work to explore such biochemical phenomena may enable somatic embryogenesis to be realised in crops at present recalcitrant in this respect.

Name dc:type.qualificationname

PhD

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

De Montfort University

Year dc:date.issued

1992

Author dc:creator

• RAYNS, FRANCIS WILLIAM

Licence

• https://dora.dmu.ac.uk/bitstreams/b8ed4150-1bcc-4247-b13f-a0b61d824e41/download