Cellular patterns and metabolic changes during tepal development in Lilium tsingtauense

Abstract

: Lilium tsingtauense is an endangered bulb plant in China that has curved leaves and orange flowers. Little is known about theopening of the L. tsingtauense flower. In this paper, the blooming process of L. tsingtauense flowers was sampled in five stages accordingto characteristic tepal morphology. The center of the tepal has an increasing elongation rate compared with the upper and lower parts.Tepal growth from closed buds at the greenish tepal stage (CBS) to the completely opened buds at the horizontal tepal stage is mainlydue to cell division, cell elongation, and obvious longitudinal cellular growth. The fructose and glucose levels increased as the floweropened; however, the sucrose levels remained constant. The ultrastructure of different flowering stages implies that starch grains weremainly concentrated in the early flowering stage, and the cell wall was thicker in the fully opened flowers in the unhorizontal tepal stagecompared with CBS and the completely opened bud in the reflexed tepal stage. Quantitative reverse transcriptase PCR showed thatcell expansion and hormone-related genes were correlated with flower opening. These results clearly illustrate the patterns of tepal cellexpansion and the changes in metabolites during L. tsingtauense flower opening