Maize Anther Development Involves Translated Open Reading Frames From 3' Untranslated Regions

Few studies have explored the functions of peptides encoded by open reading frames (ORFs) in annotated noncoding regions, particularly the 3' untranslated regions (3' UTRs). Although translated ORFs in 5' UTRs (5' ORFs) have been shown to inhibit translation of their corresponding main ORFs (mORFs), the roles of 3' ORFs remain poorly understood. This study analyzes translational regulation across ten developmental stages of maize (Zea mays) anthers and finds that peptides translated from 5' or 3' ORFs can represent misidentified isoforms, with 3' ORFs potentially linked to anther sterility. Notably, the cloned APV1 locus, whose mutation causes male sterility, exemplifies this relationship. Genome-wide translation profiles further reveal enrichment of photosynthesis-related genes during Phase III (the binucleate microspore stage). The presence of stomata and the observed low electron transport rate and net photosynthetic rate suggest that anthers assimilate CO₂ with limited photosynthetic efficiency via a pathway distinct from typical C₄ photosynthesis. Overall, this study identifies 3' ORFs as potential targets for generating male-sterile maize lines and provides new insights into anther photosynthetic activity.