Artemisinin, a sesquiterpene lactone containing an endoperoxide bridge, has been isolated from the aerial parts of Artemisia annua L. plants. It is effective against both drug-resistant and cerebral malaria-causing strains of Plasmodium falciparum. The relatively low yield (0.01 - 0.8 %) of artemisinin in A. annua is a serious limitation to the commercialization of the drug. Therefore, the enhanced production of artemisinin either in cell/tissue culture or in the whole plant of A. annua is highly desirable. It can be achieved by a better understanding of the biochemical pathway leading to the synthesis of artemisinin and its regulation by both exogenous and endogenous factors. Furthermore, genetic engineering tools can be employed to overexpress gene(s) coding for enzyme(s) associated with the rate limiting step(s) of artemisinin biosynthesis or to inhibit the enzyme(s) of other pathway competing for its precursors. These aspects which may be employed to enhance the yield of artemisinin both in vitro and in vivo are discussed in this review.

This study was conducted to characterize and explore the endophytic fungi of selected plants from the Western Himalayas for their bioactive potential. A total of 72 strains of endophytic fungi were isolated and characterized morphologically as well as on the basis of ITS1-5.8S-ITS2 ribosomal gene sequence acquisition and analyses. The fungi represented 27 genera of which two belonged to Basidiomycota, each representing a single isolate, while the rest of the isolates comprised of Ascomycetous fungi. Among the isolated strains, ten isolates could not be assigned to a genus as they displayed a maximum sequence similarity of 95% or less with taxonomically characterized organisms. Among the host plants, the conifers, Cedrus deodara, Pinus roxburgii and Abies pindrow harbored the most diverse fungi, belonging to 13 different genera, which represented almost half of the total genera isolated. Several extracts prepared from the fermented broth of these fungi demonstrated strong bioactivity against E. coli and S. aureus with the lowest IC₅₀ of 18 μg/ml obtained with the extract of Trichophaea abundans inhabiting Pinus sp. In comparison, extracts from only three endophytes were significantly inhibitory to Candida albicans, an important fungal pathogen. Further, 24 endophytes inhibited three or more phytopathogens by at least 50% in co-culture, among a panel of seven test organisms. Extracts from 17 fungi possessed immuno-modulatory activities with five of them showing significant immune suppression as demonstrated by the in vitro lymphocyte proliferation assay. This study is an important step towards tapping the endophytic fungal diversity from the Western Himalayas and assessing their bioactive potential. Further studies on the selected endophytes may lead to the isolation of novel natural products for use in medicine, industry and agriculture.

Brassinosteroid hormones (BRs) multitask to smoothly regulate a broad spectrum of vital physiological processes in plants, such as cell division, cell expansion, differentiation, seed germination, xylem differentiation, reproductive development and light responses (photomorphogenesis and skotomorphogenesis). Their importance is inferred when visible abnormalities arise in plant phenotypes due to suboptimal or supraoptimal hormone levels. This group of steroidal hormones are major growth regulators, having pleiotropic effects and conferring abiotic stress resistance to plants. Numerous abiotic stresses are the cause of significant loss in agricultural yield globally. However, plants are well equipped with efficient stress combat machinery. Scavenging reactive oxygen species (ROS) is a unique mechanism to combat the deleterious effects of abiotic stresses. In light of numerous reports in the past two decades, the complex BR signaling under different stress conditions (drought, salinity, extreme temperatures and heavy metals/metalloids) that drastically hinders the normal metabolism of plants is gradually being untangled and revealed. Thus, crop improvement has substantial potential by tailoring either the brassinosteroid signaling, biosynthesis pathway or perception. This review aims to explore and dissect the actual mission of BRs in signaling cascades and summarize their positive role with respect to abiotic stress tolerance.

Artemisinin is frequently used in the artemisinin-based combination therapy to cure drug-resistant malaria in Asian subcontinent and large swath of Africa. The hairy root system, using the Agrobacterium rhizogenes LBA 9402 strain to enhance the production of artemisinin in Artemisia annua L., is developed in our laboratory. The transgenic nature of hairy root lines and the copy number of transgene (rol B) were confirmed using polymerase chain reaction and Southern Blot analyses, respectively. The effect of different concentrations of methyl jasmonate (MeJA), fungal elicitors (Alternaria alternate, Curvularia limata, Fusarium solani, and Piriformospora indica), farnesyl pyrophosphate, and miconazole on artemisinin production in hairy root cultures were evaluated. Among all the factors used individually for their effect on artemisinin production in hairy root culture system, the maximum enhancement was achieved with P. indica (1.97 times). Increment of 2.44 times in artemisinin concentration by this system was, however, obtained by combined addition of MeJA and cell homogenate of P. indica in the culture medium. The effects of these factors on artemisinin production were positively correlated with regulatory genes of MVA, MEP, and artemisinin biosynthetic pathways, viz. hmgr, ads, cyp71av1, aldh1, dxs, dxr, and dbr2 in hairy root cultures of A. annua L.