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.

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.

An rt-PCR method was employed to clone S-adenosylmethionine (SAM) synthetase gene from tea plant (Camellia sinensis) and a eDNA sequence with 805-bp probably encoding SAM synthetase was obtained. The eDNA and its reversed complement sequence showed a high homology (81-85%) with SAM gene from many other plant species. The gene product translated from the reversed complement of the eDNA sequence was found to have 75-76% identity with the known S-adenosylmethionine synthetase from 9 plant species, indicating its mostly function as S-adenosylmethionine synthetase in tea plant.

The colour differences in terms of △L, △a, △b and △E between distilled water and infusions of 29 green teas, 16 black teas and 13 oolong teas and their correlation with sensory quality attributes of tea were investigated. The results showed that the △L value decreased but the △a, △b and △E increased with the degree of fermentation of the three kinds of tea. The △L was positively correlated to quality attributes of green tea and oolong tea but negatively correlated to those of black tea. The △a of tea infusions is a reliable descriptor to differentiate among green and black teas. The regression of total quality score of green tea (TQSg) upon the △a was TQSg=−2.26△a+77.2 (R2=0.22, p <0.01), that of total quality score of black tea (TQSb) upon △b was TQSb=0.70△b+44.6 (R2=0.31, p<0.05) and that of total quality score of oolong tea (TQSo) upon △L was TQSo=1.09△L+94.5 (R2=0.75, p<0.01). Because the infusion colour difference indicators of △a, △b and △L can be done rapidly, it could be very useful for on-site or on-line quality monitoring during tea manufacture and storage.