Anther-specific expression of MsMYB35 transcription factor in alfalfa
(Medicago sativa L.) and its crucial role in pollen development
Abstract
Alfalfa ( Medicago sativa L.) is a high-quality forage crop and
an essential resource for livestock. Understanding the molecular
mechanisms underlying male sterility in alfalfa is pivotal for the
development of superior forage varieties. Despite the critical role of
anther development in plant reproduction, its molecular
regulation—particularly the involvement of transcription factors in M.
sativa—remains insufficiently explored. This study bridges this gap by
isolating and characterizing an R2R3-MYB transcription factor,
MsMYB35, and unveiling its regulatory role in anther development.
Quantitative RT-PCR (qRT-PCR) revealed that MsMYB35 is
predominantly expressed during early anther development and is
homologous to AtMYB35. MsMYB35 was found to localize in
both the cytoplasm and nucleus. DNA affinity purification sequencing
(DAP-seq) identified 3,647 target genes of MsMYB35, with
enrichment analysis uncovering three recognition motifs. Integrated
DAP-seq and RNA-seq analyses revealed that MsMYB35 directly
regulates two key anther development-related genes. Functional analyses
showed that overexpression of MsMYB35 promotes anther
development, while silencing MsMYB35 leads to defective anther
sacs and wrinkled pollen grains. Proper MsMYB35 expression
ensures the formation of viable and fertile pollen grains, solidifying
its role as a critical regulator of anther development. These findings
provide a novel perspective on the molecular mechanisms regulating
anther development in M. sativa and offer valuable insights for
improving molecular breeding and hybrid seed production strategies. By
advancing the fundamental understanding of transcriptional regulation in
anther development, this study sets the stage for innovative approaches
to alfalfa crop improvement.