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1. Exosymbiotic microbes within fermented pollen provisions are as important for the development of solitary bees as the pollen itself

   https://doi.org/10.1002/ece3.8788  

   Dharampal, Prarthana S.; Danforth, Bryan N.; Steffan, Shawn A. (April 2022, Ecology and Evolution)
2. Disruption of pollen tube homogalacturonan synthesis relieves pollen tube penetration defects in the Arabidopsis O-FUCOSYLTRANSFERASE1 mutant

   https://doi.org/10.1007/s00497-023-00468-5  

   Robichaux, Kayleigh J.; Smith, Devin K.; Blea, Madison N.; Weigand, Chrystle; Harper, Jeffrey F.; Wallace, Ian S. (April 2023, Plant Reproduction)

   During angiosperm sexual reproduction, pollen tubes must penetrate through multiple cell types in the pistil to mediate successful fertilization. Although this process is highly choreographed and requires complex chemical and mechanical signaling to guide the pollen tube to its destination, aspects of our understanding of pollen tube penetration through the pistil are incomplete. Our previous work demonstrated that disruption of the Arabidopsis thaliana O-FUCOSYLTRANSFERASE1 (OFT1) gene resulted in decreased pollen tube penetration through the stigma-style interface. Here, we demonstrate that second site mutations of Arabidopsis GALACTURONOSYLTRANSFERASE 14 (GAUT14) effectively suppress the phenotype of oft1 mutants, partially restoring silique length, seed set, pollen transmission, and pollen tube penetration deficiencies in navigating the female reproductive tract. These results suggest that disruption of pectic homogalacturonan (HG) synthesis can alleviate the penetrative defects associated with the oft1 mutant and may implicate pectic HG deposition in the process of pollen tube penetration through the stigma-style interface in Arabidopsis. These results also support a model in which OFT1 function directly or indirectly modifies structural features associated with the cell wall, with the loss of oft1 leading to an imbalance in the wall composition that can be compensated for by a reduction in pectic HG deposition. 

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3. Airborne sub-pollen particles from rupturing giant ragweed pollen

   https://doi.org/10.1007/s10453-021-09702-x  

   Stone, Elizabeth A.; Mampage, Chamari B.; Hughes, Dagen D.; Jones, Lillian M. (September 2021, Aerobiologia)

   Abstract Ragweed pollen is a prevalent allergen in late summer and autumn, worsening seasonal allergic rhinitis and asthma symptoms. In the atmosphere, pollen can osmotically rupture to produce sub-pollen particles (SPP). Because of their smaller size, SPP can penetrate deeper into the respiratory tract than intact pollen grains and may trigger severe cases of asthma. Here we characterize airborne SPP forming from rupturing giant ragweed ( Ambrosia trifida ) pollen for the first time, using scanning electron microscopy and single-particle fluorescence spectroscopy. SPP ranged in diameter from 20 nm to 6.5 μm. Most SPP are capable of penetrating into the lower respiratory tract, with 82% of SPP < 1.0 μm, and are potential cloud condensation nuclei, with 50% of SPP < 0.20 μm. To support predictions of the health and environmental effects of SPP, we have developed a quantitative method to estimate the number of SPP generated per pollen grain ( $${n}_{\mathrm{f}}$$ n f ) based upon the principle of mass conservation. We estimate that one giant ragweed pollen grain generates 1400 SPP across the observed size range. The new measurements and method presented herein support more accurate predictions of SPP occurrence, concentration, and air quality impacts that can help to reduce the health burden of allergic airway diseases. Graphic abstract Rupturing ragweed pollen releasing cellular components (right), viewed by an inverted light microscope. 

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4. Cannabis pollen dispersal across the United States

   https://doi.org/10.1038/s41598-024-70633-x  

   Nimmala, Manu; Ross, Shane D; Foroutan, Hosein (September 2024, Scientific Reports)

   For the recently legalized US hemp industry (Cannabis sativa), cross-pollination between neighboring fields has become a significant challenge, leading to contaminated seeds, reduced oil yields, and in some cases, mandated crop destruction. As a step towards assessing hemp cross-pollination risk, this study characterizes the seasonal and spatial patterns in windborne hemp pollen dispersal spanning the conterminous United States (CONUS). By leveraging meteorological data obtained through mesoscale model simulations, we have driven Lagrangian Stochastic models to simulate wind-borne hemp pollen dispersion across CONUS on a county-by-county basis for five months from July to November, encompassing the potential flowering season for industrial hemp. Our findings reveal that pollen deposition rates escalate from summer to autumn due to the reduction in convective activity during daytime and the increase in wind shear at night as the season progresses. We find diurnal variations in pollen dispersion: nighttime conditions favor deposition in proximity to the source, while daytime conditions facilitate broader dispersal albeit with reduced deposition rates. These shifting weather patterns give rise to specific regions of CONUS more vulnerable to hemp cross-pollination. 

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5. Direct analysis of pollen fitness by flow cytometry: implications for pollen response to stress

   https://doi.org/10.1111/tpj.14286  

   Luria, Gilad; Rutley, Nicholas; Lazar, Itay; Harper, Jeffery F.; Miller, Gad (March 2019, The Plant Journal)