TY - CONF

T1 - The influence of folded relief of guard cell surface on stomatal movements

AU - Паутов, Анатолий Александрович

AU - Бауэр, Светлана Михайловна

AU - Иванова, Ольга Викторовна

AU - Крылова, Елена Геннадьевна

AU - Сапач, Юлия Олеговна

N1 - Conference code: 50th

PY - 2022

Y1 - 2022

N2 - Stomata are structural elements of plant epidermis. They are composed of two guard cells divided by a stomatal pore.Stomata control transpiration and gas exchange. Their guard cells are capable of reversible deformation. As a result ofthis deformation, the stomatal pore opens or closes. The structural features of the guard cells responsible for theirdeformation are still under debate. It is believed that stomatal movements depend mainly on turgor pressure in the guardcells and on the structure of the guard cell walls, including their uneven thickness.All guard cells have outer ledges formed by cuticle and located on their upper sides not far from the stomatal pore. Theguard cells can also bear folds that surround stomatal ledges forming marginal stomatal rings. Typically, the rings resultfrom the folding of the cuticle itself. The subcuticular space of such folds can be filled with pectin or with fibrous wall-like materials. To elucidate the role of the rings, we have applied dynamic modeling using the finite element method.The data on the shape of the guard cells, on uneven thickness of their walls, on localization and relative sizes ofstomatal ledges and rings were accurately reproduced during model stoma construction. Turgor pressure was simulatedby creating the load distributed over the inner surfaces of the guard cells. Stomata with marginal rings are located on thesubsidiary cells. The dynamic modeling has shown that the marginal stomatal rings are able to influence the movementsof the guard cells. The turgid guard cells without outer ledges and marginal stomatal rings bulge above the leaf surface.The wide opening pore between such guard cells moves in the same direction and rises above the leaf surface as well.The outer ledges prevent wide opening of the stomatal pore and cause its sinking below the leaf surface. Stomatal ringscan enhance this effect. The influence of marginal rings on stomatal movements depends on the mechanicalcharacteristics of the rings, namely on their rigidity and squeezing of stoma by them. The formation of rigid rings orrings squeezing the stoma in addition to rigid ledges leads to the deepest sinking of the open pore below the leafsurface.The methods of light, scanning and transmission electron microscopy have shown that a stoma can bear not only one,but many folds which either form several stomatal rings, or intertwine with each other, forming massive compoundstomatal rings. In some plant species, stomata are surrounded by peristomatal rims tightly pressed against the marginalstomatal rings. Unlike the stomatal rings, the peristomatal rims are located not on the stomata, but on the cells aroundthem. It has also been established that stomatal rings can be induced by undulate morphology of the cellulose cell walls.Taking into account all these data allows to adjust simulation results and reveals a stronger influence of stomatal ringson the movements of the guard cells. Marginal stomatal rings have been found in plants that occupy different positionsin the APG IV taxonomic system, in both archaic and evolutionarily advanced plant groups. This indirectly indicates theessential role of these structures.The research was carried out with the support of the Russian Science Foundation grant No. 22-24-00572,https://rscf.ru/en/project/22-24-00572 /.

AB - Stomata are structural elements of plant epidermis. They are composed of two guard cells divided by a stomatal pore.Stomata control transpiration and gas exchange. Their guard cells are capable of reversible deformation. As a result ofthis deformation, the stomatal pore opens or closes. The structural features of the guard cells responsible for theirdeformation are still under debate. It is believed that stomatal movements depend mainly on turgor pressure in the guardcells and on the structure of the guard cell walls, including their uneven thickness.All guard cells have outer ledges formed by cuticle and located on their upper sides not far from the stomatal pore. Theguard cells can also bear folds that surround stomatal ledges forming marginal stomatal rings. Typically, the rings resultfrom the folding of the cuticle itself. The subcuticular space of such folds can be filled with pectin or with fibrous wall-like materials. To elucidate the role of the rings, we have applied dynamic modeling using the finite element method.The data on the shape of the guard cells, on uneven thickness of their walls, on localization and relative sizes ofstomatal ledges and rings were accurately reproduced during model stoma construction. Turgor pressure was simulatedby creating the load distributed over the inner surfaces of the guard cells. Stomata with marginal rings are located on thesubsidiary cells. The dynamic modeling has shown that the marginal stomatal rings are able to influence the movementsof the guard cells. The turgid guard cells without outer ledges and marginal stomatal rings bulge above the leaf surface.The wide opening pore between such guard cells moves in the same direction and rises above the leaf surface as well.The outer ledges prevent wide opening of the stomatal pore and cause its sinking below the leaf surface. Stomatal ringscan enhance this effect. The influence of marginal rings on stomatal movements depends on the mechanicalcharacteristics of the rings, namely on their rigidity and squeezing of stoma by them. The formation of rigid rings orrings squeezing the stoma in addition to rigid ledges leads to the deepest sinking of the open pore below the leafsurface.The methods of light, scanning and transmission electron microscopy have shown that a stoma can bear not only one,but many folds which either form several stomatal rings, or intertwine with each other, forming massive compoundstomatal rings. In some plant species, stomata are surrounded by peristomatal rims tightly pressed against the marginalstomatal rings. Unlike the stomatal rings, the peristomatal rims are located not on the stomata, but on the cells aroundthem. It has also been established that stomatal rings can be induced by undulate morphology of the cellulose cell walls.Taking into account all these data allows to adjust simulation results and reveals a stronger influence of stomatal ringson the movements of the guard cells. Marginal stomatal rings have been found in plants that occupy different positionsin the APG IV taxonomic system, in both archaic and evolutionarily advanced plant groups. This indirectly indicates theessential role of these structures.The research was carried out with the support of the Russian Science Foundation grant No. 22-24-00572,https://rscf.ru/en/project/22-24-00572 /.

UR - http://apm-conf.spb.ru/program/

UR - http://apm-conf.spb.ru/wp-content/uploads/2022/06/Abstracts_APM_2022.pdf

M3 - Abstract

SP - 67

Y2 - 20 June 2022 through 24 June 2022

ER -