Ribosome binding of phasiRNA precursors accelerates the 24-nt phasiRNA burst in meiotic maize anthers

Area of Science:

• Plant molecular biology
• RNA biology
• Plant reproductive development

Background:

• Reproductive phased, secondary, small interfering RNAs (phasiRNAs) are vital for plant anther development.
• PHAS transcripts are known to bind ribosomes on the endoplasmic reticulum in maize, but the functional significance is unclear.

Purpose of the Study:

• To investigate the role of ribosome binding to PHAS transcripts in phasiRNA biogenesis during maize anther development.
• To elucidate the mechanism by which ribosome binding influences the production of 24-nt phasiRNAs.

Main Methods:

• Ribosome profiling across 10 developmental stages of maize anthers.
• Analysis of short open reading frames (sORFs) within ribosome-bound regions of PHAS transcripts.
• Genetic manipulation of sORFs and ribosome-binding regions in specific PHAS loci.

Main Results:

• Ribosome binding patterns on 24-PHAS transcripts correlated with phasiRNA production timing and abundance.
• Conserved ribosome enrichment upstream of miR2275 target sites across maize inbred lines.
• sORFs were identified in ribosome-binding regions, but peptide production was not detected; deletion of these regions reduced phasiRNA production.

Conclusions:

• Short open reading frames (sORFs) facilitate ribosome binding to 24-PHAS transcripts.
• Ribosome binding, mediated by sORFs, is essential for efficient 24-nt phasiRNA biogenesis in developing maize anthers.