Flowering habit of two bamboo species, Phyllostachys meyeri and Shibataea chinensis, analyzed with flowering gene expression

Two bamboo species, Phyllostachys meyeri McClure and Shibataea chinensis Nakai, which each originated from one clone cultivated in the Fuji Bamboo Garden, Japan, exhibited single-genet flowering and temporal changes in flowering and the regeneration process were investigated from 2004 to 2008 and from 2004 to 2011 in P. meyeri and S. chinensis, respectively. The clump of P. meyeri flowered when most mother culms were dead, followed by recovery with seedlings and survived rhizome system and a few culms continued to flower during 5 years, whereas S. chinensis flowered with mother culms alive, and most of the culms continued flowering in each spring until 2011. These processes were analyzed using expression levels of flowering promoting gene FLOWERING LOCUS T (FT) homologues and flowering repressing gene TERMINAL FLOWER 1/CENTRORADIALIS (TFL1/CEN) homologues by the quantitative real-time reverse transcription polymerase chain reaction method. The expression level of FT homologues was highest in the leaves during full bloom in both species, decreased gradually over the next 2 years and vanished in 5 years in P. meyeri, but remained high for 3 years in S. chinensis. These results suggest that the expression level of FT homologues was related to flowering, irrespective of flowering behavior. Simultaneous expression of both genes was detected only in the inflorescences. The relationship between expression balance and flowering habit and inflorescence architecture is discussed.