Based upon the morphological characteristics, tea is classified botanically into 2 main types i.e. Assam and China, which are morphologically very distinct. Further, they are so easily pollinated among themselves, that a third category, Cambod type is also described. Although the general consensus of origin of tea is India, Burma and China adjoining area, yet specific origin of China and Assam type tea are not yet clear. Thus, we made an attempt to understand the origin of Indian tea through the comparative analysis of different chloroplast (cp) genomes under the Camellia genus by performing evolutionary study and comparing simple sequence repeats (SSRs) and codon usage distribution patterns among them. The Cp genome based phylogenetic analysis indicated that Indian Tea, TV1 formed a different group from that of China tea, indicating that TV1 might have undergone different domestications and hence owe different origins. The simple sequence repeats (SSRs) analysis and codon usage distribution patterns also supported the clustering order in the cp genome based phylogenetic tree.

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Grafting of fresh cuttings using drought-susceptible and low-yielding clones as scions on drought-tolerant clones as rootstocks offers the possibility of raising composite plants with improved productivity and drought tolerance. Hence, the study was aimed to widen the choice of compatible composites and to delineate the underlying factors responsible for productivity and drought tolerance in grafted plants. One year-old composite plants of TRF-1, TRF-2 and UPASI-28 cleft-grafted on the rootstocks of UPASI-2, UPASI-9, ATK-1 and TRI-2025 were field planted along with their respective controls and evaluated. The results indicated that productivity and drought tolerance of scion clones varied significantly with the rootstocks used. Significant increases in yield and yield components were noted in the following graft combinations compared with their corresponding self-rooted scion clones: TRF-1 grafted on UPASI-9 and ATK-1, TRF-2 grafted on all four rootstocks, and UPASI-28 grafted on UPASI-9, TRI-2025 and UPASI-2. The findings clearly emphasize the scion–rootstock interaction as the critical determinant of productivity in grafted plants compared with vigour, drought tolerance and yield potential of scion and rootstock clones. Further, high-yielding capacity of grafts over the ungrafted scions and rootstocks was largely dependent on the yield potential of the scion clone and the degree of scion–rootstock compatibility. Higher field survival and enhanced yield observed during the drought period in the compatible grafts demonstrated their better drought tolerance compared with their respective self-rooted scions.

Camellia assamica L. (O). Kuntze. var. TV-1 from Assam, India is one of the most important tea cultivar of Indian Tea Industry which botanically belongs to Assam type and has distinct morphological as well as chemical constituent in leaf than China type of tea. We here present the first draft genome sequence of TV-1, assembled in 2.93 Gb size comprising of 14,824 scaffolds and covering 97.66% of the predicted genome size (3.0 Gb) as determined by flow cytometry. The N50 value, longest and average contig size for this draft genome was found to be as 538.96 Kb, 3.64 Mb and 197.99 Kb, respectively. There were 495,747 SSRs (Di-to Hexa-mers) in the genome and the repeat contents accounted for 71.87% of the genome. About 94.40% genome completeness was predicted with BUSCO, maximum among the published and reported tea genomes. The clustering of the assembled genome with Hi-C data resulted in 15 clusters ranging from the size of 631.46 Mb to 14.39 Mb and accounting 99.32% of assembled genome. This data will act as the starting point for unravelling the important genes and differentiating Indian tea from other commercially available tea varieties. 2