AUTHOR=Kurokawa Kana , Kobayashi Junya , Nemoto Keiichirou , Nozawa Akira , Sawasaki Tatsuya , Nakatsuka Takashi , Yamagishi Masumi 

TITLE=Expression of LhFT1, the Flowering Inducer of Asiatic Hybrid Lily, in the Bulb Scales

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.570915

DOI=10.3389/fpls.2020.570915

ISSN=1664-462X

ABSTRACT=<p>Asiatic hybrid lily leaves emerge from their bulbs in spring, after cold exposure in winter, and the plant then blooms in early summer. We identified four <italic>FLOWERING LOCUS T</italic> (<italic>FT</italic>)-like genes, <italic>LhFT1</italic>, <italic>LhFT4</italic>, <italic>LhFT6</italic>, and <italic>LhFT8</italic>, from an Asiatic hybrid lily. Floral bud differentiation initiated within bulbs before the emergence of leaves. <italic>LhFT</italic> genes were mainly expressed in bulb scales, and hardly in leaves, in which the <italic>FT-like</italic> genes of many plants are expressed in response to environmental signals. <italic>LhFT1</italic> was expressed in bulb scales after vernalization and was correlated to flower bud initiation in two cultivars with different flowering behaviors. <italic>LhFT8</italic> was upregulated in bulb scales after cold exposure and three alternative splicing variants with a nonsense codon were simultaneously expressed. <italic>LhFT6</italic> was upregulated in bulb scales after flower initiation, whereas <italic>LhFT4</italic> was expressed constantly in all organs. <italic>LhFT1</italic> overexpression complemented the late-flowering phenotype of <italic>Arabidopsis ft-10</italic>, whereas that of <italic>LhFT8</italic> did so partly. <italic>LhFT4</italic> and <italic>LhFT6</italic> overexpression could not complement. Yeast two-hybrid and <italic>in vitro</italic> analyses showed that the LhFT1 protein interacted with the LhFD protein. LhFT6 and LhFT8 proteins also interacted with LhFD, as observed in AlphaScreen assay. Based on these results, we revealed that <italic>LhFT1</italic> acts as a floral activator during floral bud initiation in Asiatic hybrid lilies. However, the biological functions of <italic>LhFT4</italic>, <italic>LhFT6</italic>, and <italic>LhFT8</italic> remain unclear.</p>