An HPLC method has beem used to separute and determine quality-related chemieal componentsin Zhenong-xiangya and Zhenong-cuiliu, two special green teas from Zhejiang, China. Secenteen or eighteem amino aeids and five cateclhins were detected. Theamine was the major amino aeid by far, its coutent eadhing 37.7% and 54% of the total amino aeids in these teas, respectively. The catechin convem was 154-4mgg-1 in Zhenong-xiangya, and 170-7mgg-1 in Zhenong-cuilin. Caffeine contemts in the teas studied were all above 75mgg-1 which was much higher than those previously reported in green teas. The ouamin C.comtems were all about 2mgg-1, Seven peaks were resolved in the HPLC profiles of the flavonoid exvraets of the two reas and three of them were identified as rwlin, mvricerin and quercetin using reference compounds.

Scanning electron microscopy was used to investigate the ultrastructure of trichomes on Maofeng, a special Chinese green tea. The trichomes were cylindrical in appearance with a length of 0.61mm, wall thickness of 0.2-0.3/tm and a mid-point diameter of 9-10/tm. The angles between the trichomes and the leaf under-surface were below 30 in Maofeng tea though they were 45-75 in flesh green leaf. The trichome wall consisted mainly of fibre and its outer-surface was unevenly covered with waxy ubstances and striped. The trichome joint, by which the trichome was attached to the leaf lower epidermis, was expanded and filled with essential oil droplets. The undeveloped trichomes assumed a flattened form because of the action of pressing during rolling and shrank during the tea drying process. During the Maofeng tea processing, trichome shedding was caused by disruption of its expanded joint structure and breakdown at the cylindrical wall above the expanded joint.

The effect of gibberellins on tea leaf chemical composition and quality was investigated. The results showed that application of gibberellins was beneficial to green tea quality. Content of amino acids increased by 9-8% and that of vitamin C by 17.8% and tea catechins index increased by 12.9%. The content of tea polyphenols and ratio of tea polyphenols to amino acids decreased by 9.9% and 11.5%, respectively. Differences of all the indicators were statistically significant (P<0.05). Quality scores of the treated leaf increased significantly (P<0.05). It was also revealed that tea plant response to gibberellins was dependent not only on genetics, but also on shoot development stage.

The achievements in the 20th century and the future development trend of tea breeding and tea cultivation in China were described in the present paper. China, with 1,076,220 ha tea field, is now one of the major tea producing and tea exporting countries in the world and its tea field area ranked the first in the world. Chinese tea industry has been greatly developed in the 20th century because of the development of tea breeding and cultivation techniques. The development of tea breeding in China was benefited from the techniques of vegetable propagation, cross breeding, chemically and physically induced mutation as well as bio-technique and molecular biological technique. There were five stages in the development of tea breeding in China, i.e. the non-organized stage, clonal tea breeding stage, yield breeding stage, quality breeding stage and resistance breeding stage. The tea production in China has been fast developed in the 20th century, especially in the last 50 years. It was mainly benefited from the increase of planting density, the popularization of improved tea cultivars, the manuring technique, the efficient and low-cost cultivation technique. The development trend in Chinese tea breeding will be pest-resistance breeding, high quality breeding and breeding of some special use tea cultivars such as those with high content of catechins, low content of caffeine and low activity of polyphenol oxidase. Intensive management, low-cost and sustainable production will be the important research topics in Chinese tea cultivation in the early decades of the 21st century.

Bt gene expressive vector was constructed and transformed into tea plant in order to raise new tea cultivars with pest resistance. The Bt gene DNA was inserted into vector pCAMBIA2301. The constructed plasmid with Bt gene, intron-GUS gene and NPTⅡgene was transformed into Escherichia coli and ntroduced into Agrobacterium stains LB4404, EHA105 and pRil5834 by triparental cross method. The Bt gene was then transformed into leaves and callus of tea by Agrobacterium-mediated methods. Transient expression of the GUS gene was successful in both callus and leaves of tea plant. Screening agent testing showed that hygromycin was a more effective callus screening agent compared to kanamycin and its optimum concentration was 20μgml-1. Kanamycin was effective in screening for tea leaf and its optimum concentration was 50μgml-1.