Molecular characterization of tea mosquito bug from tea growing regions of India.

The tea mosquito bug, Helopeltis (Hemiptera: Miridae), is an insidious pest that poses a significant economical threat to tea plantations. As a basic first step to control this pest is authentic identification, but the inability to determine morphological characters of Helopeltis species makes this process very difficult. DNA barcoding is a reliable alternative to traditional morphological identification of this pest. Since tea is cultivated in different parts of the country, an attempt was made to molecular characterization of Helopeltis. This is the first report on molecular identification and diversity characterization of Helopeltis collected from tea growing regions of southern and north India, using cytochrome c oxidase subunit I (COI) gene of mitochondrial (mt) DNA. Beginning with the molecular identification of this pest is essential to start an effective pest management strategy, and will provide basic information for diffusion pattern, population dynamics and chemical application.

Metabolite profiling and characterization of somaclonal variants in tea (Camellia spp.) for identifying productive and quality accession.

A study has been undertaken to characterize 15 field grown somaclonal variants derived from cotyledonary tissues of UPASI-10 using morphological, physiological and biochemical characters. Although variants were derived from UPASI-10, a very few variants possessed unique "Chinery" characters while others exhibited "Assam" characters. However, no variant showed identical morphological characters aligning with the parent. Somaclonal variants showed distinct variation in terms of photosynthetic carbon assimilation, stomatal conductance and diffusion resistance. Proline accumulation and water use efficiency showed marginal variations among the variants. SE 8 and SE 10 recorded higher values of membrane stability index denoting their tolerant nature against stress. Class interval analysis based on physiological parameters grouped these plants into three clusters. Three variants grouped under good category representing higher values of productivity index followed by five variants under moderate category. Green leaf constituents and quality profile of made tea produced with crop shoots of variants exhibited wide variation. Center point radar graph analysis of quality constituents grouped these plants into three clusters. Variants SE 2 and SE 13 were segregated distinctly representing their black tea characters. When considering both the quality and productivity indices, SE 3 and SE 7 fall under moderate category and in future these two variants may be subjected to further quality tests for commercial exploitation.

Genetic integrity of somaclonal variants in tea (Camellia sinensis (L.) O Kuntze) as revealed by inter simple sequence repeats.

Adoption of inter simple sequence repeats (ISSR) technique to analyze the genetic variability of somatic embryo derived tea plants was evaluated. Morphological characterisation of the field grown plants revealed no identical character aligning with the parent, UPASI-10. Out of 40 primers, 15 exhibited concurrent polymorphism were selected for the study. Genetic variability of somaclones derived from single line cotyledonary culture ranged from 33.0 to 55.0%. A unique fragment of 1.2Kb was visible in majority of the accessions whereas the fragments below the length of 0.6Kb were noticed only in 50% of the variants. Out of 120 interactions attempted using Pearson's coefficient correlation, only 9.2% of somaclones exhibited significant similarity at genetic level. Dendrogram constructed based on simple matching coefficient revealed a distance of 2.257-3.317 between the final clusters. This strengthens the existence of wide genetic variation among the somaclones.

Genetic diversity of UPASI tea clones (Camellia sinensis (L.) O. Kuntze) on the basis of total catechins and their fractions.

Tea leaf catechins and the ratio of dihydroxylated to trihydroxylated catechin fractions were analysed to identify the genetic diversity of 26 UPASI released tea clones. Principal component analysis (PCA) based on regression factor separated tea clones into five groups according to their jats (Jats are region based rays for e.g., Assam, China and Cambod origin) as well as their quality constituents (such as total polyphenols, total catechins, amino acids in the green leaves and liquor characteristics of black tea), particularly the catechins. Group 1 represented medium quality (quality of the final produce) clones, such as UPASI-10, UPASI-12 and UPASI-15 and drought tolerant clones like UPASI-1, UPASI-2, UPASI-9 and UPASI-10. Group 2 contained purely "China" cultivars while group 3 possessed high quality tea cultivars. "Assam" (group 5) teas had the lowest ratio of dihydroxylated to trihydroxylated catechin fractions (1:4) than the "Chinery" (group 2) teas (1:5). This biochemical differentiation indicated that there is a vast genetic diversity in UPASI released tea clones in terms of catechin fractions, even though the majority of them were selected from one tea estate located in the Nilgiris.