IMPF: 01.55The most important evolutionary event in the success of commercial tea cultivation outside China in ca. 30 countries came about by the origin of India hybrid tea in India, derived from the extensive spontaneous hybridization that took place between the Assam type tea growing in the forest regions of Assam, North-East India and China type tea introduced from China in ~1875 to many regions of North-East India. The release of an enormous pool of vigorous and highly variable plants of India hybrid tea in North-East India was a significant step forward for the origin and evolution of tea as a highly successful crop plant. The 1,644 accessions and clones of India hybrid tea, representatives of known 15 morphotypes, were screened by 412 AFLP markers amplified by 7 AFLP primer pair combinations. All the 412 genetic loci were polymorphic across the 1,644 accessions and clones. The analysis was done with distance (PCoA and NJ) methods, and the STRUCTURE (Bayesian) model. Both PCoA and NJ analysis clustered 1,644 tea accessions and clones into six major groups with one group in each, constituted mostly by China hybrid, Assam China hybrid and Assam hybrid morphotypes, of distinct genetic identity. No group was exclusive for any particular morphotype. The accessions and clones belonging to morphotypes, Assam type, Assam hybrid, China hybrid and China Cambod were distributed in all the groups. It is the Assam type/Assam hybrid morphotypes which exhibit much broader genetic variability than in China type/China hybrid/Cambod type/Cambod hybrid morphotypes. The STRUCTURE analysis inferred 16 populations (K = 16), for which the greatest values of probability were obtained. Nine of the 16 clusters were constituted by the tea accessions and clones of ?pure? ancestry. The remaining clusters were of ?mixed? ancestry. This analysis provides evidence that the accessions and clones of the same morphotype are not always of same genetic ancestry structure. The tea accessions and clones obtained from outside North-East India shared the same groups (distance method) and clusters (STRUCTURE model) which were constituted by North-East India accessions. The present study also demonstrates very narrow genetic diversity in the commercial tea clones vis-a-vis the profound genetic diversity existing in the tea accessions. These clones were distributed in hardly two of the six groups in NJ tree. The identified 105 core accessions and clones, capturing 98% diversity, have their origin from almost all groups/subgroups of NJ tree.Peer reviewe

Understanding of mechanistic details of Mediator functioning in plants is impeded as the knowledge of subunit organization and structure is lacking. In this study, an interaction map of Arabidopsis Mediator complex was analyzed to understand the arrangement of the subunits in the core part of the complex. Combining this interaction map with homology-based modeling, probable structural topology of core part of the Arabidopsis Mediator complex was deduced. Though the overall topology of the complex was similar to that of yeast, several differences were observed. Many interactions discovered in this study are not yet reported in other systems. AtMed14 and AtMed17 emerged as the key component providing important scaffold for the whole complex. AtMed6 and AtMed10 were found to be important for linking head with middle and middle with tail, respectively. Some Mediator subunits were found to form homodimers and some were found to possess transactivation property. Subcellular localization suggested that many of the Mediator subunits might have functions beyond the process of transcription. Overall, this study reveals role of individual subunits in the organization of the core complex, which can be an important resource for understanding the molecular mechanism of functioning of Mediator complex and its subunits in plants.

IMPF: 01.55Seabuckthorn, a non-leguminous nodule bearing dioecious shrub, is a storehouse of neutraceutical, pharmaceutical and cosmetic usage. The 348 genotypes of Hippophae rhamnoides ssp. turkestanica, H. salicifolia and H. tibetana were collected from 194 locations at 46 major sites across 1,500km from north-east to north-west Himalayas, harboring one of the most harsh, highly variable climatic and ecological conditions and rugged rocky terrain in the range of 3,000?5,000 metres altitude. Amplified fragment length polymorphism (AFLP) and selective amplification of microsatellite polymorphic loci (SAMPL) DNA markers were utilized to assess the genetic diversity of total spectrum of Himalayan germplasm resources and interrelationships among Hippophae taxa. A total of 151, 50, and 41 AFLP loci were detected in Hippophae rhamnoides ssp. turkestanica, H. salicifolia and H. tibetana respectively; of these, 92.6, 30.6 and 25.1% were polymorphic. For SAMPL, the number of markers and polymorphism for these species were respectively, 77 (77.7%), 41 (41.4%), and 23 (23.2%). Nei?s genetic diversity and Shannon?s information index values revealed that populations of H. rhamnoides ssp. turkestanica in Sumur and Raling in Ladakh and Lahaul-Spiti, respectively, were the most diverse. In H. salicifolia and H. tibetana, the populations in Changu, and Takcha and Guling in Spiti valley, were the most diverse. In H. rhamnoides ssp. turkestanica, high levels of interpopulation genetic diversity with little intra-population diversity was accompanied by very low gene flow (Nm) range, estimated by AFLP (0.571?0.943) and SAMPL (0.321?0.726) markers. In H. rhamnoides ssp. turkestanica, the genotypes collected from Uttaranchal were found to be the least diverse. The exclusive characteristics of the nuclear genome in the Uttaranchal genotypes warrant new species rank closer to H. salicifolia rather than to H. rhamnoides ssp. turkestanica. The present results also provide explicit evidence to suggest that both H. salicifolia and H. tibetan deserve species rank.Peer reviewe

No abstract

No abstract