A Novel R2R3-MYB Gene LoMYB33 From Lily Is Specifically Expressed in Anthers and Plays a Role in Pollen Development

Abstract

Lily (Lilium spp.) is an important commercial flower crop, but its market popularity and applications are adversely affected by severe pollen pollution. Many studies have examined pollen development in model plants, but few studies have been conducted on flower crops such as lily. GAMYBs are a class of R2R3-MYB transcription factors and play important roles in plant development and biotic resistance; their functions vary in different pathways, and many of them are involved in anther development. However, their function and regulatory role in lily remain unclear. Here, the GAMYB homolog LoMYB33 was isolated and identified from lily. The open reading frame of LoMYB33 was 1620 bp and encoded a protein with 539 amino acids localized in the nucleus and cytoplasm. Protein sequence alignment showed that LoMYB33 contained a conserved R2R3 domain and three BOX motifs (BOX1, BOX2, and BOX3), which were unique to the GAMYB family. LoMYB33 had transcriptional activation activity, and its transactivation domain was located within 90 amino acids of the C-terminal. LoMYB33 was highly expressed during the late stages of anther development, especially in pollen. Analysis of the promoter activity of LoMYB33 in transgenic Arabidopsis revealed that the LoMYB33 promoter was highly activated in the pollen of stage 12 to 13 flowers. Overexpression of LoMYB33 in Arabidopsis significantly retarded growth; the excess accumulation of LoMYB33 also negatively affected normal anther development, which generated fewer pollen grains and resulted in partial male sterility in transgenic plants. Silencing of LoMYB33 in lily also greatly decreased the amount of pollen. Overall, our results suggested that LoMYB33 might play an important role in the anther development and pollen formation of lily.

Transcriptomic analysis reveals candidate genes associated with anther development in Lilium Oriental Hybrid ‘Siberia’

“…To address this issue by molecular breeding requires elucidation of the mechanisms involved in anther development and identification of the key genes that regulate pollen abortion or anther dehiscence. In recent years, several genes, such as LoPIPI2 ( Tong et al., 2013 ), LoMYB80 ( Sui et al., 2015 ), LoAMS ( Sui et al., 2020 ), and LoMYB33 ( Liu et al., 2021 ), have been cloned and indicated to regulate different stages of anther development. Nevertheless, the delimitation of developmental stages and roles of additional genes in the regulatory mechanism require further study.…”

“…Previous studies on the mechanism of anther development in lily have isolated and cloned several genes, which have been functionally analyzed. The transcription factors LoAMS , LoMYB80 , and LoMYB33 play important roles in anther development and the pollen maturation of lily ( Sui et al., 2015 ; Sui et al., 2020 ; Liu et al., 2021 ). Lily PLASMA MEMBRANE INTRINSIC PROTEIN 2 (LoPIP2) is involved in desiccation induced anther dehiscence ( Tong et al., 2013 ).…”

Comparative transcriptome analyses reveal insights into catkin bloom patterns in pecan protogynous and protandrous cultivars

“…MYB genes have been shown to function in the formation of male flowers in other plant species. In other plant species, the MYB genes are involved in a transcriptional cascade that mediates stamen and pollen maturation [ 26 – 29 ]. The expression of these genes is mostly confined to sporophytic tissues of the stamen.…”

Comparative analysis of the MYB gene family in seven Ipomoea species

“…The 2R-MYB genes, named R2R3-MYB, were usually the largest MYB gene subfamily in green plants ( Martin and Paz-Ares, 1997 ). They play essential roles in plant lifetime, including (1) primary and secondary metabolites, such as phenylpropanoid metabolism ( Liu et al., 2015 ; Tang et al., 2021 ), flavonoid biosynthesis ( Czemmel et al., 2012 ; Lin et al., 2021 ; Zhao et al., 2022b ), anthocyanin biosynthesis ( Naing and Kim, 2018 ; Upadhyaya et al., 2021 ; Wang et al., 2022c ), chlorogenic acid biosynthesis ( Tang et al., 2021 ), indolic and aliphatic glucosinolate biosynthesis ( Gigolashvili et al., 2009 ), and apigenin biosynthesis ( Wang et al., 2022b ); (2) cell fate and identity, for instance, epidermis and root formation ( Du et al., 2009 ); (3) developmental processes, like embryogenesis ( Wang et al., 2009 ), pollen development ( Liu et al., 2021 ), male sterility ( Yu et al., 2021 ), and plant trichome development ( Shangguan et al., 2021 ); and (4) responses to biotic and abiotic stresses, including diseases ( Shen et al., 2017 ; Gu et al., 2020 ; Hawku et al., 2022 ), high salinity ( Wang et al., 2021a ; Du et al., 2022 ), cold ( Dong et al., 2021 ), heat ( Wu et al., 2021b ), and drought ( Lv et al., 2021 ; Wu et al., 2021a ).…”