R2R3-type LoMYB21 affects jasmonate-regulated development and dehiscence of anthers in lily (Lilium oriental hybrids)

Lilies are widely cultivated for cut flowers, but their large anthers carry a considerable amount of colored pollen that is dispersed easily. Studying the molecular mechanism of anther development and dehiscence could help solve this problem. LoMYB21, encoding a putative R2R3 v-myb avian myeloblastosis viral oncogene homolog (MYB) transcription factor, was identified from oriental lilies (Lilium ‘Siberia’). Real-time quantitative PCR analysis showed that LoMYB21 was mainly expressed in the anther, filament and stigma and had high expression during the late stages of lily anther development. LoMYB21 had transactivation activity and was located in the nucleus through yeast one-hybrid assays and transient expression in Nicotiana benthamiana. Suppression of LoMYB21 by virus-induced gene silencing (VIGS) in Lilium ‘Siberia’ led to anther indehiscence and reduced the expression of genes related to Jasmonate acid (JA) biosynthesis and signal transduction. Induction of LoMYB21 in DEX::LoMYB21 transgenic Arabidopsis caused procumbent inflorescences that became infertile, accompanied by higher expression of JA biosynthetic and signaling genes. These results demonstrated that JA content and signaling were abnormal in silenced lily and transgenic LoMYB21 Arabidopsis, which affected anther development. Our study indicated that LoMYB21 could regulate lily anther dehiscence through JA biosynthesis and signaling during the late stages of anther development.