Comparative metabolomic analysis of unreleased and released pollen from Putranjiva roxburghii Wall.

•Unreleased pollen contained more glucose and fructose, whereas released pollen contained more sucrose.•Proline, kinetin and salicylic acid are essential for pollen development, maturity and viability.•Cadaverine, spermine, and spermidine were found in higher concentrations in unreleased pollen, whereas putrescine was found in higher concentrations in released pollen.•Accumulated 12-Octadecadienoic acid, together with palmitic acid and stearic acid has been identified to be crucial component for pollen.