Optical Techniques to Measure Genetic Instability in Cell and Tissue Cultures

Abstract

Biotechnology has great potential in forestry, particularly in plantation forestry, where rapid reforestation is financially and ecologically imperative, and especially in situations where the desirable species grows well in an exotic environment but does not reproduce there. The potential benefits of biotechnology include: rapid multiplication of selected genotypes; cloning; somatic hybridization; increased disease, insect, and herbicide resistance; germplasm preservation; triploid production; rapid haploid and pure line production; somatic embryogenesis; and somaclonal variation (see Berlyn et al. 1986a; Bajaj 1986). However, there are potential problems which include: low yield of somatic embryos, especially in conifers; inability to regenerate almost all forest trees from protoplasts, which prevents application of somatic hybridization; delayed expression of undesirable traits; morphological incompatibility of plant organs in genetically engineered plants; out-of-phase development, that alters timing mechanisms such as bud flushing, dormancy induction, initiation of earlywood and latewood formation and reproductive development; and genetic instability of regenerated plantlets and consequent inability to regenerate true to type. As has been documented, high levels of auxins employed in plant tissue culture for root initiation and organogenesis can cause DNA content polymorphisms (Renfroe and Berlyn 1985; Berlyn et al. 1987). These effects are probably deleterious, especially in conifers, but the long-term significance of these changes is not well understood.