Distribution Of Specialized Epidermal Cells And Stomatal Development In Wheat

Stomatal development requires a series of asymmetrical and symmetrical division from protodermal cell,and many cell fate determination and differentiation.For decades,the crop scientist all over the world has been committed to raise high yield of food crops through the improvement of plant stomatal number,however,know little about the mechanism of gramineae stomatal development.In order to further study the monocot stomatal development and its regulation mechanism,in this study,we analyzed the cell types of wheat leaf abaxial epidermis,the stomatal development regulation,stomatal development process and molecular regulation of mechanism stomatal development.Through continuous exploration and research,we found a set of methods for the first time for making the impression of the leaves can be used to observe different periods of developmental stages.The samples are clear,easy to operate,economic and secure using this method.These methods lay an important foundation for our future research on specialized cell types and stomata development in wheat leaf abaxial epidermis..Through the observation of wheat leaf abaxial epidermis,we found six kinds of cells:long cells,stomata,trichome,silicide cells,cork cell and side thorn.And silicide cells and cork cell together are called short cells.Stomatal neatly arranged on both sides of the leaf vein;Silica body are sporadically distributed in epidermis,especially in the parts covered with leaf vein,but it is hard to find silicide cells and cork cell in the second leaf as previously reported.So we observed the first leaf of wheat,the third leaf,flag leaf,flag leaf-1,flag leaf-2,and found that silicide cells and cork cells could be identified more on the higher positioned leaves,and the form of trichome is also different from lower positioned leaves.After clarfying cell types and characteristics,we then counted stomatal density and index of fourteen wheat varieties.The results showed that under the same growth environment,different varieties of wheat shows apparent difference in stomata density and index,which are most likely caused by the internal reasons in stomata development.And we observe the whole stomatal development process successfully in wheat for the first time.The most important difference between wheat and Arabidopsis in stomatal development is the development of subsidiary cells.Wheat subsidiary cells were recruited from cells next to stomatal lineage,and the process requires highly polarized cell division dedicated toward the GMC.After forming a GMC,SMC divides asymmetrically to produce small subsidiary cells next to GMC.And in order to study the development of subsidiary cells in grasses,we cloned genes TaRac3 from wheat by using homology cloning based on the sequences of the reported gene OsRac3.We also analyze the gene sequences,protein sequences,conservative domain structure characteristics using bioinformatics methods,and predict the biological functions of TaRac3.We constructed plant expression vector pGwb6-TaRac3 through the Gateway recombinant cloning technology,and obtained the transgenic Arabidopsis plants harboring TaRac3 genes by the Agrobacterium-mediated transformation.Our study builded the foundation for elucidating the functions of TaRac3 in abiotic stresses responses and morphological development,and provided candidate genes for the genetic improvement of wheat stress resistance.