PALD encoding a lipid droplet-associated protein is critical for the accumulation of lipid droplets and pollen longevity in Arabidopsis

Pollen longevity is critical for plant pollination and hybrid seed production, but few studies have focused on pollen longevity. In this study, we identified an Arabidopsis thaliana gene, Protein associated with lipid droplets (PALD), which is strongly expressed in pollen and critical for the regulation of pollen longevity. PALD was expressed specifically in mature pollen grains and the pollen tube, and its expression was upregulated under dry conditions. PALD encoded a lipid droplet (LD)-associated protein and its N terminus was critical for the LD localization of PALD. The number of LDs and diameter were reduced in pollen grains of the loss-of-function PALD mutants. The viability and germination of the mature pollen grains of the pald mutants were comparable with those of the wild-type, but after the pollen grains were stored under dry conditions, pollen germination and male transmission of the mutant were compromised compared with those of the wild-type. Our study suggests that PALD was required for the maintenance of LD quality in mature pollen grains and regulation of pollen longevity.

Automated summary

In this study, a gene called PALD was identified in Arabidopsis thaliana and found to play a critical role in pollen longevity. PALD is expressed specifically in mature pollen grains and the pollen tube, and its expression is upregulated under dry conditions. The protein encoded by PALD is associated with lipid droplets (LDs), and the presence of PALD is important for maintaining LD quality and regulating pollen longevity. The study also showed that loss-of-function PALD mutants had reduced LDs in pollen grains and compromised pollen germination and male transmission after being stored under dry conditions.