Physiological and Molecular Changes during Lily Underground Stem Axillary Bulbils Formation

Abstract

Lily is regarded as one kind of the most economically important cut flowers in China. In this paper, lily cultivar ‘Aladdin’ (Lilium longiflorum × Lilium asiatic) was chosen as experimental material for its distinct high propagation coefficient in nature and three main conclusions were achieved. Firstly, our observation results revealed that the noticeable propagation coefficient of ‘Aladdin’ depended on strong capacity to form many underground stem axillary bulbils positioned on underground node of plant after 70 days of cultivation and having 1 cm flower buds. Secondly, in terms of physiological changes, zeatin riboside (ZR) relative concentration, soluble sugar and starch content peak when and where such bulbils are forming. Finally, two KNOX family Lilium genes were sequenced completely and one BELL family gene was sequenced partly; besides, there might be an interaction between KNOX-2 and BELL protein to accomplish their functions in bulbils organogenesis according to qRT-PCR results. As far as we know, it is the first time to study the formation mechanism of lily underground stem axillary bulbils. We illustrated physiological and molecular profiles, as well as offered a new prospect to lily molecular breeding in the future.