Precocious flowering and seeding behaviour in tissue-cultured bamboos

Abstract

BAMBOO flowers only once during its lifetime, dying at the end of its first fruiting season. This monocarpic flowering is intriguing not only in that it occurs after a lapse of 12 to 120 years, but because it is 'gregarious', local populations of bamboo flowering together and then dying. New bamboo plants are produced either by vegetative subdivision or from seed. Breeding of bamboo, however, has proved to be extremely difficult: seed production depends on unpredictable circumstances and events¹, and the basis of gregarious flowering, and the causes of death and flowering, are not known. Flowering in vitro has previously been studied by culturing expiants of stem tips, mature stems, roots, petioles, leaves, inflorescences, flowers and so on^2–5. Although bamboo plantlets have been formed by means of organogenesis and embry-ogenesis^6–8, in vitro flowering has not previously been reported for bamboo. We now report on an in vitro system in which we could consistently induce flowering in the two species of bamboo Bambusa arundinacea Willd and Dendrocalamus brandisii Kurz. Inflorescence expiants containing a panicle of spikelets gave rise to several viable inflorescences on subculture; fertile seeds were also produced. Further refinements to this system could lead to the introduction of breeding programmes to improve bamboo, and to the production of perennial seeds for bamboo, as well as to a better understanding of the physiology underlying flowering behaviour in bamboo.