Pollens are powdery substance consisting of pollen grains. Pollen grain has male macrogametophyte that produces male gametes. The male gamete is protected by hard pollen coat made up of sporopollenin during pollination process. Pollen growth, development and dispersal study is termed as palynology and has applications in archaeology, forensics and pollen associated allergies. Pollens are produced in large quantities during flowering time of plants, having size from 10-100µm, and are light in weight that can be easily carried away by wind. Dispersion of pollen through air takes place through long distances and introduce pollens to region where natural growth of these plants may not be present. They remain in air for longer time, and are inhaled during breathing process. Some of the pollens cause immune system exacerbations or allergic reactions in susceptible populations.
Pollens are rich in nutrient and proteins. Plants in response to environmental stresses (both biotic and abiotic) modify their protein content. Structural changes in the protein content due to these stresses cause some of the proteins to invoke immune system and cause allergies. Pollens of Broussenetia papyrifera (Paper mulberry), Phleum pratense (Timothy grass), Parthenium hysterophorous, Artemisia vulgaris, etc. have been studied to cause allergies. These proteins due to their allergy causing nature are called as allergens. Many plants pollens have been identified to carry allergens and cause allergies. Pollen allergies are termed as pollinosis. Pollinosis can be rhinitis, rhino-conjunctivitis, asthma and dermatitis. Apart from allergens, lipid contents in pollens also play role in pollen allergies. These lipid contents in general are termed as phyto-prostanes. Additionally, pollens being rich in nutrients, support microbial growth and also serve as a carrier of these microbes during pollen dispersal. Human beings may expose to pollens and associated bacteria during inhalation of pollen in breathing. State-of-the-art Identification and characterization of such pollens responsible for causing allergies is in progress.
Pollens are reproductive organs and rich in nutrient sources to support reproduction process of plant. They provide rich nutrient sources for bacterial growth, and carry bacteria to long distances during pollen dispersal process. Both gram-positive and gram-negative bacteria are found on pollens. Pollens and bacteria, being small in size and difficult to obtain pollen and study them like other particles, the exact role of pollen associated microbiome has not been fully explored. However, some of the bacteria found on pollens are associated with lung diseases or pollen allergies. Pollens studied in this project have discovered that pollens of Parthenium hysterophorous colonize Pantoea dispersa, Pinus colonizes Brevibacterium epidermitis and Pantoea agglomerans, Broussenetia papyrifera colonizes Brachybacterium fresconis and Staphylococcus sciuri. Pantoea dispersa, Pantoea agglomerans and Brevibacterium epidermitis have roles in lung diseases. Identification and characterization of such bacteria responsible for causing allergies in association with pollens is in progress.
Pollens being rich in nutrient sources also support growth of fungal spores. Fungal spores have size and shape similar to pollens, and are therefore sometimes difficult to distinguish between pollens and spores. It has been found that fungal spores of Alternaria alternata, Aspergillus fumigatus, Aspergillus niger, Aspergillus tubingensis, Cladosporium herbarum and Penicillium chrysogenum are abundantly found on allergenic pollens. These spores being small in size and light weight, disperse easily in air. Human beings are exposed to these spores frequently during blooming season of plants and exposure to these pollens has been found to cause diseases like asthma, rhinitis and sinusitis in humans. Identification and characterization of such spores is in progress
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