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

Abstract

Elucidating the biochemical and metabolic adaptations of unreleased and released pollen provides more insights into pollen development, maturation, and vitality. Hence, in the present investigation, Putranjiva roxburghii Wall. was selected to critically examine the biochemical and metabolite profiling of released and unreleased pollen states. Metabolomic profiling revealed 276 metabolites from the unreleased pollen and 271 metabolites from the released pollen, falling into 12 different categories. The levels of auxin family hormones like indole-3-acetic acid and 1-naphthalene acetic acid, along with other biomolecules like glucose, fructose, proline, 12-Octadecadienoic acid (C18:2 w6c), cadaverine, spermine and spermidine were higher in the unreleased pollen suggesting their functional significance in the pollen maturation. Whereas, the levels of kinetin, gibberellic acid, salicylic acid, sucrose, lipid, 12-Octadecadienoic acid were higher in the released pollen compared to unreleased pollen. Furthermore, the metabolites like lysophosphatidylinositol, phosphatidylglycerol, lysophosphatidic acid, linoleic acid and its derivatives, phosphatidylcholine, monoacylglycerol, sphingosine-1-phosphate and oleacein were found unique in released pollen, indicating these metabolites may participate to complete the pollen development. Among the carbohydrates, sucrose accumulation was higher in released pollen, signifying it to be a potent source of energy reservoir for future tube growth and germination processes. Additionally, increased fatty acid levels in the released pollen may act as a structural component preventing pollen from adverse environmental conditions for their viability and fertility. Thus, the current study unraveled the metabolic pathways associated with released pollen revealing the metabolic activities. This is the first study done on the wind pollination pollen in Putranjiva roxburghii Wall.