Tea is the world's most popular non-alcoholic beverage. China and India are known to be the largest tea producing countries and recognized as the centers for the domestication of the tea plant ...(Camellia sinensis (L.) O. Kuntze). However, molecular studies on the origin, domestication and relationships of the main teas, China type, Assam type and Cambod type are lacking.
Twenty-three nuclear microsatellite markers were used to investigate the genetic diversity, relatedness, and domestication history of cultivated tea in both China and India. Based on a total of 392 samples, high levels of genetic diversity were observed for all tea types in both countries. The cultivars clustered into three distinct genetic groups (i.e. China tea, Chinese Assam tea and Indian Assam tea) based on STRUCTURE, PCoA and UPGMA analyses with significant pairwise genetic differentiation, corresponding well with their geographical distribution. A high proportion (30%) of the studied tea samples were shown to possess genetic admixtures of different tea types suggesting a hybrid origin for these samples, including the Cambod type.
We demonstrate that Chinese Assam tea is a distinct genetic lineage from Indian Assam tea, and that China tea sampled from India was likely introduced from China directly. Our results further indicate that China type tea, Chinese Assam type tea and Indian Assam type tea are likely the result of three independent domestication events from three separate regions across China and India. Our findings have important implications for the conservation of genetic stocks, as well as future breeding programs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Tea is the most popular non-alcoholic beverage worldwide and is one of the most important tree cash crops in East Africa. However, no comprehensive study has been carried out on the genetic structure ...and diversity of tea germplasm for this region to date. In the present study, 193 tea accessions held at the ex situ Germplasm Bank of the Tea Research Institute (TRI), Kenya, were analysed using genetic data from 23 polymorphic simple sequence repeat (SSR) loci. A total of 266 alleles were detected with the number of alleles per locus ranging from 4 to 19 with an average of 7.88. Genetic clustering by STRUCTURE was used to correct misidentified accessions based on morphological characters. After reassignment of the tea accessions, Camellia assamica exhibited the lowest genetic diversity (Hs = 0.648) despite being the most widely cultivated tea type in the East African region. C. assamica subsp. lasiocalyx showed the highest genetic diversity (Hs = 0.76), which supported its origin by hybridization among tea types. Tea cultivars cultivated across the region exhibited lower genetic diversity (Hs = 0.661) compared to material held at the ex situ Germplasm Bank of TRI. Tea accessions clustered in the neighbour-joining tree on the basis of geographical origin, pedigree and leaf pigmentation, indicating their common origin. Our results indicated further that East African tea germplasm has a complex breeding history with a majority of the hybrids being F2 generation and backcross plants. C. assamica contributed significantly more genetic materials in the tea breeding programmes in East Africa. This study highlights the importance of ex situ germplasm banks to conserve the highest genetic diversity, which is an important resource for future tea crop improvements in East Africa.
A Tea is the most popular non-alcoholic beverage in the world. Asia accounts for 85% of the global tea production. Comprehensive studies on the genetic diversity and origin of domestication of tea ...plant are scarce, while the studies carried out to date also used fewer number of markers narrowing down its scope. Genotyping by Sequensing (GBS) is a novel next generation sequensing technique which generates large amounts of Single Nucleotide Polymorphysms (SNPs) that are vital for modern genetic analysis. Therefore, 114 wild, landraces and cultivated tea samples collected across 14 countries in Asia were subjected to GBS analysis to study the genetic relationships and origin of domestication of tea plant in Asia. A set of 247,760 high quality SNPs were generated and used for the genetic analysis of 112 samples. Multiple analysis with SNPs revealed three independent domestication events for cultivated tea confirming the results of simple sequence repeat analysis. Most of the wild species clustered together while few species/samples clustered differently showing their gene flow with the cultivated tea or possible hybrid origins. Structure and neighbour joining tree analysis clearly showed a differential clustering of Assam tea collected from India, Sri Lanka and other South Asian countries with the Assam tea collected from China and neighbouring countries in East Asia. Future studies with the recently published tea genome possibly identify differentially selected genes/biochemical pathways during tea domestication. Based on the findings of this most comprehensive study done on tea plant to date, incorporation of Chinese Assam tea germplasm into the breeding programmes in India, Sri Lanka and other South Asian countries is recommended.
Tea is the world's most popular non-alcoholic beverage. China and India are known to be the largest tea producing countries and recognized as the centers for the domestication of the tea plant ...(Camellia sinensis (L.) O. Kuntze). However, molecular studies on the origin, domestication and relationships of the main teas, China type, Assam type and Cambod type are lacking. Twenty-three nuclear microsatellite markers were used to investigate the genetic diversity, relatedness, and domestication history of cultivated tea in both China and India. Based on a total of 392 samples, high levels of genetic diversity were observed for all tea types in both countries. The cultivars clustered into three distinct genetic groups (i.e. China tea, Chinese Assam tea and Indian Assam tea) based on STRUCTURE, PCoA and UPGMA analyses with significant pairwise genetic differentiation, corresponding well with their geographical distribution. A high proportion (30%) of the studied tea samples were shown to possess genetic admixtures of different tea types suggesting a hybrid origin for these samples, including the Cambod type. We demonstrate that Chinese Assam tea is a distinct genetic lineage from Indian Assam tea, and that China tea sampled from India was likely introduced from China directly. Our results further indicate that China type tea, Chinese Assam type tea and Indian Assam type tea are likely the result of three independent domestication events from three separate regions across China and India. Our findings have important implications for the conservation of genetic stocks, as well as future breeding programs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Banana is the fourth most important food crop worldwide. However, its production has been threatened by banana streak disease, caused by banana streak virus (BSV). Despite this situation, little is ...known about the inter-relationships between symptom severity and cultivar/virus genotypes. Symptom severity assessment for sixty five symptomatic samples was carefully done. The rolling circle amplification technique was used to identify the virus species (isolate) infecting each sample. The Mysore virus isolates (BSMysV) and the banana cultivars containing the balbisiana (B) component were associated with the most severe banana streak disease symptoms.
Most of the published methods for DNA isolation from vectors (insects) are not always effective in mealy-bugs, aphids and leafhoppers because they have high amount of polyphenols in their body ...systems. A simple, rapid, reliable labor-effective and carcinogenic compound-free salting out method for isolation of high molecular DNA from these insects is described. The ratio of OD sub(260)/OD sub(280) ranged between 1.8 to 2.0. The method was successfully applied to Rolling Circle Amplification and in restriction analysis, indicating the removal of the common inhibitors.
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