Study On The Formation And Mechanism Of Abnormal Stomata In Wheat

Stomata surrounded by two guard cells is the special pore on the plant surface.Based on the shape of the guard cells,it can be divided into two types i.e.kidney shaped and dumbbell shaped stomata.Stomata mediate the transpiration and photosynthesis by aperture control,thereby affect the growth and development of the plants.Wheat is an important cereal crop whose guard cells are dumbbell-shaped.However,in this study,abnormal stomata with single subsidiary cell were found on the coleoptile and first leaf of wheat.To clarify the distribution and functional mechanism of abnormal stomata,we conducted this study and the main findings list as follows.1.Scanning electron microscopy was used to investigate the stomata in various organs of wheat.Dumbbell-shaped stomata were found in both wheat leaves and panicle tissues.For the first time,dumbbell-shaped stomata were detected on the seed coat during grain filling stage,and stomata still exist after seed dormancy.Exclusively,abnormal stomata were found on the tips of coleoptile and the first leaf,but not in the middle and base of these organs.2.The function of abnormal stomata was determined by the bioassay system.The results showed that the aperture of abnormal stomata in wheat was significantly lower than that of normal stomata.Abnormal stomata appeared to be no obvious response to ABA treatment,whereas normal stomata aperture decreased significantly after challenged with ABA.In addition,the dynamic monitoring of stomata after ABA treatment showed that the abnormal stomata are insensitive to ABA,while the normal stomata gradually closed after application of ABA,indicating that the abnormal stomata have ABA response defects.3.Under abiotic stress factors such as Na Cl,drought and high temperature treatments,abnormal stomatal density and stomatal index decreased and the development of abnormal stomata was inhibited.While high humidity treatment promoted abnormal stomatal development,indicating that abnormal stomata development is closely related to the environmental factors.4.Results based on seven wheat cultivars(lines)showed that the abnormal stomata distributed in the coleoptile and the first leaf of each material,which proved the wide existence of abnormal stomata in wheat.And abnormal stomata density in coleoptile is significantly higher than those of the first leave in all varieties used.The high-throughput transcriptome sequencing on the coleoptiles and the first leaf of Chinese Spring and Lunxuan987 with distinguished stomatal phenotype was carried out.The resulted revealed that there are 18701 differentially expressed genes in the coleoptile,and 17051 in the first leaf.106 paralogous genes of 23 stomatal development-related genes reported were used for the intersection analysis and 10 candidate genes were identified finally as abnormal stomata determining genes.In summary,we found the abnormal stomata in wheat for the first time and clarify the mechanism underlying the biological functions.The findings obtained from this study will enrich the fundamental theories of wheat stress responses and provide great reference for relevant studies in other crops.