Broussonetia papyrifera (B. papyrifera) is an allergenic plant in the mulberry family that grows at varied elevations and climatic conditions worldwide. In northern Pakistan, B. papyrifera is abundant and it produces a substantial amount of pollen that disperses in the air causing allergies in some humans. Climate change affects pollen production. To investigate potential changes in pollens development and potential allergenicity, B. papyrifera pollens were collected in summer and in spring from different regions in Pakistan. Study samples were subjected to morphological analysis, Fourier Transform Infrared Spectroscopy (FTIR) analysis for biochemical differences, and Liquid Chromatography-Mass Spectrometry (LCMS) for metabolome analysis. Morphological studies of the dried pollen by light microscopy showed seasonal and regional differences in pollens size and exine morphology. FTIR analysis showed inter-regional and inter-seasonal differences in the metabolome of the pollen. Differences in lipid and protein functional groups of pollen from different regions showed variation in the FTIR spectra. These differences in FTIR spectra correlated with the changing climatic conditions. Metabolome analysis of targeted pollen samples identified 33 organic compounds of seven different groups. Four unsaturated fatty acids were identified that have a potential role in allergic responses. The findings in this study are unique in demonstrating climatic variables that effect B. papyrifera pollen physiology (FTIR analysis) which also confirms differences in pollen-associated lipid metabolites identified by LCMS analysis. These results demonstrate information that may be used to predict potential changes in allergy risks from pollens of B. papyrifera in the future. The findings may provide a model for predicting variation in pollen structure and associated allergies in response to climate changes for other species.

Broussonetia papyrifera (B. papyrifera) is a tree producing allergenic pollen that grow at varied climatic conditions worldwide. The tree pollen disperse in the air causing allergies in susceptible humans. The study investigates climate change variable’s impact on B. papyrifera pollen’s composition, pollen metabolome, pollen allergenicity and their occurrence in the upcoming years. The tree pollens were collected in summer and spring from different regions in Pakistan. Pollens were subjected to morphological analysis, Fourier Transform Infrared Spectroscopy (FTIR), Liquid Chromatography-Mass Spectrometry (LCMS), and immunoblotting. The tree future-growth invasion was predicted through MaxEnt modeling. Light microscopy and FTIR showed seasonal and regional differences in pollen-morphology and pollen-metabolome that correlated to weather conditions’ shift. LCMS analysis detected four allergenic lipids having a potential role in allergies. Pollen protein immunoblotting-studies identified putative 15 kDa novel allergen, and verified previously known 40 kDa, 33 kDa, and 10 kDa allergens. B. papyrifera MaxEnt modeling through ACCESS1­0 and CCSM4 under 2-greenhouse gas emissions scenarios {representative concentration pathway (RCP) 4.5 and 8.5} projected the tree invasion by the years 2050 and 2070. The study findings demonstrate that climatic variables differences affect B. papyrifera-pollen physiology. The study discovered allergenic lipids and a 15 kDa potential novel allergen in B. papyrifera-pollen protein extracts, and predicted the tree invasion in future. These results predict potential changes in B. papyrifera-pollen allergy risks in the future and provide a model system for studying pollen morphology, plant invasion, and associated allergies in response to climate changes for other species.