Functional Studies on the LiAG1 Gene of Lilium 'Ice Pink Queen' in Flower Development

Lily (Lilium Asiatica Hybrida) is a globally known perennial herbaceous bulbous flower, popular for its large, colourful flowers and high economic and ornamental value. However, pollen generation is a severe issue that reduces the cosmetic value of lilies. In this study, the MADS transcription factor LiAG1 was isolated and identified from the Lilium Asiatica Hybrida 'Ice Pink Queen', a male-sterile variety obtained through several years of hybridisation in our laboratory. qRT-PCR revealed that LiAG1 expression was greater in lily anthers, especially during the half-opening stage. The transient expression in tobacco demonstrated that LiAG1 was located in the nucleus. In the 'Ice Pink Queen' lily, suppression of LiAG1 using TRV-VIGS (tobacco-rattle-virus-mediated virus-induced gene silencing) resulted in the disappearance of most of the tapetum layer and the absence of the microsporangia. Overexpression of LiAG1 in transgenic Arabidopsis and tobacco resulted in narrower and more involute leaves, plant dwarfing, earlier blooming, and better pollen viability. Overall, our results suggested that LiAG1 might play an important role in flower development, especially anther development, of Lilium Asiatica Hybrida 'Ice Pink Queen'.