The Stomatal Adaptation And Expression Regulation Mechanisms Of Related Gene For Three Life-form Aquatic Plant

As one of the most critical innovations,the stomata plays an important role when plants adapt to terrestrial environment.With the evolution of plants and their adaptation to the environment,the stomata characteristics of different plant taxon appear different,and at the same time imply different expression regulation mechanisms.Compared with terrestrial plants,there are few studies on the stomatal of aquatic plants,and many problems remain unclear.Therefore,studying the stomatal characteristics of aquatic plants and their expression regulation mechanisms is of great significance for understanding the adaptive evolution of plants in aquatic and terrestrial environment.The related studies have shown that different kinds of life-form aquatic plants have different stomatal characters,the stomata of aquatic plants is mainly distributed on the contact surface of the leaves and air,such as the upper and lower epidermis of the aerial leaves,the upper epidermis of the floating leaves,and the submerged leaves always have no stoma.In this study,three kinds of life-form aquatic plants,the submerged plant Potamogeton pectinatus,the heterophylly plant Potamogeton octandrus,and the amphibious plant Isoetes sinensis,combined with aquatic and terrestrial habitats,were used to compare the stomatal morphology by a variety of ways.At the same time,using RNA-Seq technology to obtain transcriptome data of Potamogeton pectinatus.Combined with transcriptome data of Potamogeton octandrus and Isoetes sinensis obtained before,the stomatal homologous genes of three life-form aquatic plants were detected by using bioinformatic methods and by align with the nucleotide sequence and protein sequence of published stomatal genes in the database.And by reference the model species Arabidopsis thaliana which has bene studied the development of stomatal genes,we analyzed the expression of stomatal developmental homologous genes to explore the regulation mechanism of stomatal development.We can obtain the following results and conclusions:1.The stomatal adaptability characteristics of three life-form aquatic plants:The submerged plant Potamogeton pectinatus has paraytic stomata,which suggests that submerged plants may have the potential ability to form stomata.The stomata density is gradually decreased from the leaf tip to the leaf base,and the stomata density of the upper epidermis was larger,and the stomata of the leaf tip was smaller than that of the leaf blade.This distribution pattern is more conducive to promote the exchange between plants and environment,also can promote stomatal movement.The heterophylly plant Potamogeton octandrus has paraytic stomata,which is mainly distributed on the upper epidermis.This may due to the uniform light of the upper surface of the floating leaf and the equal opportunity to exchange gas with the environment.There is no stomata on the submerged leaves.The amphibious plant Isoetes sinensis has paraytic stomata,which are arranged symmetrically in two longitudinal regions close to the leaf edge.The stomata of the terrestrial leaves are mostly open,and the stomata of the aquatic leaves are more closed state,the stomatal density gradually decreases from the leaf tip to the leaf base.2.The stomatal expression regulation mechanism of three life-form aquatic plants(1)The characteristics of transcriptome data of Potamogeton pectinatusA total of 40,331 unigenes were assembled by De novo.By align with 7 large databases(NR,Swiss-Prot,GO,COG,KOG,eggNOG4.5,KEGG),a total of 24,842 unigenes were annotated.When align with the NR database,most of the homologous sequences are from Elaeis guineensis and Phoenix dactylifera,which both belong to monocot,and the annotations align with other databases are mainly concentrated on the basic functional metabolism.In the GO annotation,the number of unigenes belong to metabolic process is the highest.In the KOG annotation,the number of unigenes classified into general functional prediction is the highest.Under the KEGG annotation,the number of unigenes classified into metabolism is the highest,which indicating that the active metabolic activity in the leaf of Potamogeton pectinatus,and it is essential for maintaining the normal life of this plants.(2).The stomatal development homologous genes and the gene expressionA total of 18 stomatal development homologous genes were detected in submerged plant Potamogeton pectinatus,which indicating that some key genes of stomatal development are retained in Potamogeton pectinatus.These may be the key functional genes for inducing stomata in submerged plants.There may also have been lost some key genes,as some individual species make changes for better adapt to the living environment.A total of 30 stomatal development homologous genes were detected in heterophylly plant Potamogeton octandrus.The results of gene expression analysis showed that both in juvenile leaves and adult leaves,two positive regulatory factors FAMA and EPFL9 were up-regulated and two negative regulatory factors ERECTA and SDD1 were down-regulated in the floating leaves when compared with the submerged leaves.In addition,there were three genes down-regulated in juvenile floating leaves and one in adult floating leaves when compared with submerged leaves,which indicating that stomatal development regulation is more active in juvenile leaves,and the differential expression of these genes may be one of the reasons for stomatal induction of floating leaves and stomatal inhibition of submerged leaves.A total of 13 stomatal development homologous genes were detected in amphibious plant Isoetes sinensis.The results of gene expression analysis showed that one gene(SCRM)was up-regulated in terrestrial leaves while one gene(SPCH)was down-regulated when compared with aquatic leaves.The regulatory pathway which these genes involved in may be necessary for stomatal development when Isoetes sinensis adapt to aquatic and terrestrial environments.