Study Of The Variation Of Tea Cell Wall Infected With Tea Brown Blight Based On Confocal Raman Spectroscopy

Tea is one of the important cash crops of our country. We produce, export and consume of large amounts of tea every year. However, the tea tree disease has seriously affected the quality and quantity of tea, bringing significant economic losses. This paper was aiming at tea brown blight, one of the three most serious tea tree disease, for an in-depth study. Confocal Raman microscopy was first applied to study the outward appearance information, internal chemical composition and cellular structure of healthy and infected tea leaves of Longjing43in a non-destructive way. Combining with Raman spectrum unfolding method, data digging technology, chemical imaging tool and plant pathology knowledge, the variation of tea cell wall under tea brown blight infection was revealed. The main results are as follows:(1) Aiming at the prevalence problem of cosmic rays and fluorescence background in Raman spectrum, a kind of automatic identification of cosmic rays method was put forward.(2) Study of the Raman spectral responses and features of Colletotrichum camelliae Massee. Finding that the most significant Raman characteristic peak of the pathogen was1622cm"1and this Raman peak was coming from chitin. Then chemical image of chitin was drawn based on the Raman shift of1620-1625cm-1, visually showing the distribution regularity of chitin on the surface of the hyphae.(3) Study of the Raman spectral responses and features of healthy tea cell wall and infected tea cell wall. Distinctly differences of Raman peaks were finding between these two types of cell walls. Three biopolymers of pectin, cellulose and lignin were discovered to have the most significant variation in Raman intensities. Results showed that the content of these three biopolymers all decreased after infection.(4) Study of the Raman spectral responses and features of the cell wall of vascular bundle in two different infection stages. Distinctly differences of Raman peaks were finding between the different infection stages. By analysing the typical Raman spectra of cell wall in vascular bundle, characteristic peaks of lignin and cellulose were found. By comparing the two spectra of different infection, it was found that with the deepening of the infection, the content of lignin and cellulose were continuous declining in vascular bundle, but the content of lignin decreased even more.