Green tea is a popular drink used for therapeutic purposes to mitigate the consequences of diabetes. In this study, we aimed at evaluating the potential of green tea infusion to ameliorate structural and enzymatic damages caused by hyperglycemia in the testis and epididymis of Wistar rats. For that, nondiabetic and streptozotocin-induced diabetic rats (negative control and diabetes control, respectively) received 0.6 mL of water by gavage. Another set of diabetic animals received 100 mg/kg of green tea infusion diluted in 0.6 mL of water/gavage (diabetes + green tea) daily. After 42 days of treatment, the testes and epididymides were removed and processed for histopathological analysis, micromineral determination, and enzymatic assays. The results showed that treatment with green tea infusion preserved the testicular and epididymal histoarchitecture, improving the seminiferous epithelium and the sperm production previously affected by diabetes. Treatment with green tea reduced tissue damages caused by this metabolic condition. Given the severity of hyperglycemia, there was no efficacy of the green tea infusion in maintaining the testosterone levels, antioxidant enzyme activity, and microminerals content. Thus, our findings indicate a protective effect of this infusion on histological parameters, with possible use as a complementary therapy for diabetes.

The jungles of Linyun and Longlin Autonomous Prefecture, located in the heart of the southwestern Guangxi Zhuang Autonomous Region of China, are home to the oldest tea trees (Camellia sinensis) in the world. In the absence of regular annual rings, radiocarbon (14C) dating is one of the most powerful tools that can assist in the determination of the ages and growth rates of these plants. In this work, cores were extracted from large ancient tea trees in a central Longlin rain forest; extraction of carbon was performed with an automated sample preparation system. The 14C levels in the tree cores were measured using accelerator mass spectrometry (AMS) at the University of Tsukuba. These measurements indicated that contrary to conventional views, the ages of trees in these forests range up to ~700 years, and the growth rate of this species is notably slow, exhibiting a long-term radial growth rate of 0.039±0.006 cm/yr. It was demonstrated that 14C analyses provide accurate determination of ages and growth rates for subtropical wild tea trees.

Scirtothrips dorsalis Hood is a polyphagous species and an important sucking pest of tea (Camellia sinensis) (Theaceae). The fitness traits of S. dorsalis on two alternative host plants: Capsicum annuum L. (chilli) (Solanaceae) and Ricinus communis (castor oil plant) (Euphorbiaceae) and on C. sinensis and corresponding levels of defence enzymes was studied. The study revealed that C. sinensis is the more suitable host of S. dorsalis based on faster development (13.6 days) compared to the alternative hosts, C. annuum (15.5 days) and R. communis (16.7 days), a higher fecundity (C. sinensis: 11.4 eggs; C. annuum: 9.7 eggs; R. communis: 8.6 eggs), and superior egg hatchability (C. sinensis, 92.6%; C. annuum: 82.5%; and R. communis: 74.6%). The host-based variation in the fitness traits of S. dorsalis corroborated in light of differential activity of three major detoxifying enzymes, such as the general esterases (GEs), glutathione S-transferases (GSTs), and cytochrome P450 mediated monooxygenases (CYPs). Densitometric analysis of GEs showed five esterase isozymes (EST I–V) with retardation factor (Rf) values of 0.17, 0.22, 0.27, 0.35 and 0.52, respectively. The pixel density, and accordingly the profile height, varied in different host-specific S. dorsalis. A significant variation of the quantity of these enzymes was also apparent in the insect when reared on the three hosts. A 2.4 and 2.7, 1.6 and 2.0, and 2.0 and 2.3-fold higher GEs, GSTs and CYPs activity on the two non-tea hosts possibly signify a predisposition of the species for higher tolerance to insecticides, enabling the pest to switch to tea where synthetic insecticides are routinely used.

The invasive orange spiny whitefly (OSW) Aleurocanthus spiniferus has extended its distribution to non-native areas since the early 20th century. In a similar manner, the invasive tea spiny whitefly (TSW) A. camelliae has been expanding over East Asia in recent decades. In this study, the genetic diversity of OSW and TSW and of their important parasitoid wasp Encarsia smithi was investigated in China and Japan to enable more efficient biological control policies. We detected two phylogenetic groups (haplogroups A1 and A2) in OSW and three phylogenetic groups (haplotypes B1 and B2, and haplogroup B3) in TSW in China; however, only a single haplotype was detected in each whitefly species in Japan. Based on historical records and molecular data, OSW was considered to be native to China whereas TSW has probably expanded to China from a more southern location in the last 50 years; China appears to be the source region for OSW and TSW invading Japan. In E. smithi, two phylogenetic groups were detected in Japan: haplotype I, associated with OSW, and haplogroup II mostly associated with TSW, except in two locations. These data support the hypothesis that E. smithi parasitizing TSW in Japan did not originate from the existent population parasitizing OSW but was newly imported into Japan following the invasion of its host.

Nucleopolyhedrovirus (NPV) was isolated from infected Hyposidra talaca (Walker) caterpillars. This defoliating pest was sampled from the Terai and Dooars tea plantations along the foothills of Darjeeling, India. Phase contrast and transmission electron microscopy revealed polyhedral occlusion bodies (OBs) typical of NPVs. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis showed that the molecular weight of the major protein of the OBs is 32.17 kDa. Dose–mortality bioassays conducted for OBs on the second instar caterpillars of H. talaca resulted in a median lethal concentration (LC50) of 2.8 × 103 OBs/ml. The median lethal time (LT50) was 5.45 days for 1 × 104 OBs/ml, 4.15 days for 1 × 105 OBs/ml and 4.05 days for 1 × 106 OBs/ml concentrations. These results indicate the potential of using this NPV as a microbial pesticide against H. talaca.

Genetic diversity and genetic variation of 240 adult plants of four tea populations in Hunan – Camellia sinensis var. sinensis, C. sinensis var. assamica cv. Duntsa, C. ptilophylla and C. sinensis var. assamica cv. Jianghua – were studied by rapid amplification of polymorphic DNA (RAPD) markers. The results showed 226 loci using 21 random primers (10 bp), of which 201 (88.9%) were polymorphic. The genetic diversity analysis indicated that Shannon's index was 0.43; 74.7% of which was within-population genetic diversity while 25.3% was among-population variation. The gene diversity indexes of total populations (HT), within populations (HS) and among populations (HST) were, respectively, 0.37, 0.28 and 0.09. The coefficient of gene differentiation (GST) among populations was 0.23, indicating a 76.7% variation within populations and 23.3% among populations. These results displayed a rich within-population genetic variation, as in Shannon's diversity index. Interpopulation gene flow (Nm) was 0.74, which indicates the limited genetic exchange between populations.

Seed development of tea was studied to identify the maturity index and the optimal time of seed collection. After harvest, the moisture content (28–30%fresh weight basis) of mature seeds, which germinated 100%, declined progressively (19% moisture content) after shedding, with a decrease in seed germination and viability. However, this viability loss could be prevented to some extent by storing seeds within intact fruits. The maximum rate of seed dry matter accumulation coincided with the accumulation of starch in the embryos and seeds at stage 8, the embryo maturation phase. Although the embryo abscisic acid (ABA) content was highest at stage 8, free ABA declined in the tea embryos throughout the remainder of the seed maturation cycle.

The osmotin gene was introduced into tea [Camellia sinensis (L.) O. Kuntze] somatic embryos at the globular stage of development via microprojectile bombardment, to determine the effects of this stress-tolerance-related gene on the accumulation of storage reserves and acquisition of desiccation tolerance during embryo maturation. Changes in total soluble sugars, starch and proteins in response to osmotin were estimated in the stably transformed embryos, using standard biochemical and histochemical methods, after the globular embryos had matured to the heart stage of development. These changes also were compared with two types of controls, comprising (1) untransformed embryos and (2) embryos that were bombarded without osmotin DNA. The control embryos showed poor reserve accumulation and negligible germination but, in contrast, the embryos bombarded with the osmotin gene showed a several-fold increase in storage reserves, normal maturation and 57–63% germination. When these transformed embryos were desiccated to 15.5% moisture content, only 40% germinated, although a further increase in the accumulation of storage reserves occurred. In contrast, the control embryos became necrotic and failed to germinate. This study demonstrates the use of somatic embryogenesis as a tool for understanding seed recalcitrance in tea, and suggests that transformation with stress-tolerance genes can overcome the developmental problems associated with recalcitrant seeds.

Euproctis latifascia Walker is an important pest attacking old leaves of tea bushes and mother leaves of nursery cuttings in Darjeeling foothills, Terai and Northeast India. Laboratory experiments were designed to assess the effect of an artificial diet and a natural diet, i.e. tea leaves, Camellia sinensis, on life history traits like development time, survival and fecundity of E. latifascia. In addition, the maintenance cost as well as the nutritional and production indices were estimated for each substrate (diet) using the gravimetric (dry mass) methods. On the natural (tea leaves) and artificial diets, the total development periods were 78.4 and 68.6 days, fecundity 248.8 and 230.3 eggs/female; in the final caterpillar stage (VI), the relative consumption rates were 0.8 and 0.6, relative growth rates 0.05 and 0.07, maintenance costs 5.1 and 2.9 and production index 0.1 and 0.2, respectively. The fifth instar larvae also showed similar differences in their nutritional indices. Based on these parameters it appears that the artificial diet is more suitable for laboratory rearing of E. latifascia than the natural tea-leaf diet.