Sporopollenin-inspired design and synthesis of robust polymeric materials

Abstract

Sporopollenin is a mechanically robust and chemically inert biopolymer that constitutes the outer protective exine layer of plant spores and pollen grains. Recent investigation of the molecular structure of pine sporopollenin revealed unique monomeric units and inter-unit linkages distinct from other previously known biopolymers, which could be harnessed for new material design. Herein, we report the bioinspired synthesis of a series of sporopollenin analogues. This exercise confirms large portions of our previously proposed pine sporopollenin structural model, while the measured chemical, thermal, and mechanical properties of the synthetic sporopollenins constitute favorable attributes of a new kind of robust material. This study explores a new design framework of robust materials inspired by natural sporopollenins, and provides insights and reagents for future elucidation and engineering of sporopollenin biosynthesis in plants.

Imaging plant cell walls using fluorescent stains: The beauty is in the details

“…138 Although the exact chemical structure of sporopollenin is still unknown, it has been suggested that it is mainly comprised of aliphatic polyketide-derived polyvinyl alcohol units crosslinked by p-coumaryl-substituted fatty acid-derived C16 aliphatic units via acetal linkages. 139 A lot of interest currently lies in obtaining the precise structure of pollen coat and sporopollenin for the biotechnological purpose of designing new polymers of different properties, as well as in imaging pollen coat and sporopollenin using highresolution microscopy. Two fluorescent brighteners, FB-52 and FB-184, were identified and used together with the above-described BF stain to image at a high resolution and distinguish the pollen coat and the exine structures in the pollen of oilseed rape (Brassica napus), Chinese ash (Fraxinus chinensis), Calystegia hederacea and petunia (Petunia hybrida).…”

“…These processes involve lipids, phenols and polysaccharide metabolisms in the tapetum, as well as the transport of sporopollenin precursors 138 . Although the exact chemical structure of sporopollenin is still unknown, it has been suggested that it is mainly comprised of aliphatic polyketide‐derived polyvinyl alcohol units crosslinked by p‐coumaryl‐substituted fatty acid‐derived C16 aliphatic units via acetal linkages 139 . A lot of interest currently lies in obtaining the precise structure of pollen coat and sporopollenin for the biotechnological purpose of designing new polymers of different properties, as well as in imaging pollen coat and sporopollenin using high‐resolution microscopy.…”

Why cutting respiratory CO2 loss from crops is possible, practicable, and prudential

“…Removing CO 2 from the atmosphere in a permanent or long‐term way, that is, carbon capture and storage (CCS), has shot to the top of engineering, agriculture/forestry and synthetic biology research agendas 76,77 . Increased net photosynthesis (i.e., photosynthesis minus respiration) 78 and increased deposition in crop roots of recalcitrant (i.e., biodegradation‐resistant) forms of carbon such as suberin or sporopollenin 79,80 are seen as attainable, scalable and low‐cost ways to support CCS. Moreover, implementing CCS in agricultural systems (carbon farming) is viewed as a promising new source of farm income from sale of carbon offsets 81 .…”