Determination Of Epidermal Wax Content In Wheat Leaves And Analysis On Its Effect On Photosynthetic And Agronomic Traits

The wax layer covered on the surface of the plant plays an important role in droughtresistance, high temperature, radiation resistance and disease resistance. In order to ascertainthe relationship between epidermal waxes and their effects on physiology and agronomictraits in wheat, the influence of leaf epidermal wax content on chlorophyll content, water useefficiency (WUE), net photosynthetic rate, stomatal conductance and other physiologicalcharacteristics and its correlation with biomass, economic yield, harvest index(HI) wereinvestigated by using the progeny lines derived from crosses between parents with high andlow wax content. The main results are as follows:1. The offspring groups which established by hybrid parent of high wax content line andlow wax content varieties were used as materials, which analyzed the correlation of thecuticular wax content by traditional weight method and GC gas chromatographydetermination, to explore the relationship between the parameters of the canopy spectralreflectance and wax content of wheat leaves, while screening and establishing the predictionmodel of the cuticular wax content of wheat leaves. The results indicated that:(1) Traditionalweight method and GC gas chromatography both measuring method can more accuratelyreflect the cuticular wax content of wheat, and their overall correlation were highly significant,which the correlation coefficient is0.481.(2) The mainly blade wax components of highwaxy materials were diketone, which exceeded the proportion of50%, and extremelysignificant correlation between wax content and diketone content.(3) There are differencesbetween different wax content of spectral reflectance in wheat leaves.(4) There were highercorrelation between the wax content of wheat blade and the parameters R550/(R550-R675) and(R350-R700) which were proposed in this study, the fitting equation can be used as a rapidusing spectral reflectance model to estimate leaf wax content, while the fitting equation can beused as a rapid model to use the reflection spectrum estimating the wax content of the leaves.2. Results of the correlation analysis between blade wax and diketone content of theoffspring groups used the traditional weight method and GC gas chromatography, thephysiological trait like net photosynthetic rate, stomatal conductance, intercellular CO2concentration, transpiration rate, water use efficiency (WUE), and the agronomic trait likebiomass, economic yield and harvest index show that:(1)The relationship between the wheat epidermal wax contents which utilized traditional weight method and GC gas chromatographyand physiological indexes, yield indexs are consistent.(2)Wax content had a significantpositive correlation to net photosynthetic rate, water use efficiency, biomass and harvestindex(HI), while showed a significant negative correlation with the transpiration rate, whichproved that the epicuticular wax has a positive meaning for crop drought resistance.3、This study used the method of homologous cloning and electronic cloning whichreferenced from the ECR (enoyl-CoA reductase) gene of Brachypodium distachyon to clone agene of functional similarity with Cer10from Arabidopsis thaliana, which namedTaCer10.The sequence length is3018bp, which the genetic similarity were90%,88%and87%from the ECR gene of Brachypodium distachyon, SC2gene of corn, and the associatedgene of Oryza sativa. The length of CDS is930bp, which encoding309amino acids. TheCDS have four conservative domains of Steroid_dh, PLN02392, Tsc13_N and PLN02560respectively; while PLN02560is the function structure domain of ECR (enoyl-CoAreductase). This study hypothesizes that the gene plays an important role in synthetic pathwayof wax from VLCFAs C24extend to C26, which laid a certain foundation in the directionalimprovement of wheat traits by genetic transformation after constructing expression vector.