K. Devi

Light and temperature regulated terpene biosynthesis: hepatoprotective monoterpene picroside accumulation in Picrorhiza kurrooa

Picrorhiza (Picrorhiza kurrooa) is an endangered medicinal plant with well-known hepatoprotective activity attributed to monoterpenoid picrosides. The present article details on regulatory genes of terpenoid metabolism, 3-hydroxy-3-methylglutaryl coenzyme A reductase (pkhmgr) and 1-deoxy-D-xylulose-5-phosphate synthase (pkdxs) from picrorhiza. Since no molecular information was available, these genes were cloned to full-length by degenerate primers and rapid amplification of cDNA ends, followed by cloning of the upstream sequences that showed the presence of core sequences for light and temperature responsiveness. Electrophoretic mobility shift assay confirmed binding of protein to these motifs. Expression of pkhmgr and pkdxs was up-regulated at 15°C as compared to at 25°C as well as under light as compared to dark conditions. Picrosides content exhibited the trend similar to gene expression. To rule out the possible limitation of carbon pool under dark condition, plantlets of picrorhiza were raised in vitro in Murashige and Skoog medium supplemented with 3% sucrose. Results showed similar up-regulation of both the genes and the higher picrosides content in in vitro raised plantlets in the presence of light. Data suggested the important roles played by light and temperature in regulating pkhmgr and pkdxs, and the picrosides level in picrorhiza.

State of Art of Saffron (Crocus sativus L.) Agronomy: A Comprehensive Review

Saffron (Crocus sativus L.) is the most expensive spice of the world, and it is one of the 85 members of the genus Crocus. It is native of Asia Minor, and it is cultivated in Mediterranean countries. Saffron predominantly contains certain chemical constituents that are responsible for imparting colour, flavour, and aroma. Some of its components have cytotoxic, anti-carcinogenic and anti-tumor properties. Since, saffron is a triploid (2n = 3x = 24) plant and fails to produce seed upon selfing or crossing, so it is propagated through corms. The growing area for saffron is not extensive, although its demand in the international market is increasing. Research activities have been initiated to develop new production technologies of this spice in many countries. Saffron grows best in friable, loose, low-density, well-watered, and well-drained clay calcareous soils. Besides, climate and soil, planting time, seed/corm rate, planting depth, corm size/weight, crop density, nutrient management, weed management, growth regulators, harvest, and post-harvest management also influence saffron quality and quantity. In this paper, an attempt has been made to compile the recent agronomic research on saffron for commercial flower and corm production.

In vitro cormlet production and growth evaluation under greenhouse conditions in saffron (Crocus sativus L.) – A commercially important crop

The present study describes the effects of season on initial bud sprouting, direct shoot regeneration from the base of the sprouted bud, and cormlet production from multiple shoots, and provides growth evaluation of in vitro produced cormlets under greenhouse conditions. Initial sprouting of buds from corm segments was previously described in medium supplemented with 2,4‐dichlorophenoxyacetic acid (2,4‐D, 9.05 μM) and 6‐benzylaminopurine (BAP, 26.64 μM). Maximum bud sprouting (90%) was observed during November and December. Direct multiple shoot primordia were initiated from the base of these sprouted buds on BAP (26.64 μM). Multiplication of shoots was achieved in BAP (26.64 μM) and α‐naphthalene acetic acid (1.0 and 5.0 μM). Growth retardants (chlorocholine chloride and paclobutrazol) were used for cormlet production from multiple shoots, and paclobutrazol (1.7 μM) evinced maximum cormlet production (86.07%). Growth of these in vitro‐produced cormlets was evaluated under greenhouse conditions, and 91.66% sprouting was observed. An increase in cormlet weight (66.88%) was also observed under in vivo conditions.

Propagation of Picrorhiza kurroa Royle ex Benth: An important medicinal plant of Western Himalaya

This study is aimed at developing propagation methods and ex situ conservation for Picrorhiza kurroa, an endangered medicinal plant of western Himalaya. Regeneration using leaves from mature plant of characterized germplasm is beneficial because the source plant is not damaged. A regeneration protocol was standardized by using leaves from aseptic shoot cultures, raised from ex vitro leaves. Maximum regeneration percent (94.33) and significantly higher shoot number (38.0) was evident in middle portion of leaf at 2.32 µM of kinetin (Kn). Abaxial surface that was in touch with the medium was more responsive as compared to adaxial surface. The time of exposure to thidiazuron (TDZ) was emphasized as 15 days interval, gave the best response in terms of shoot number (42.0). For shoot multiplication, Kn at 2.32 µM was optimum. Microshoots with well developed root system were obtained in MS basal medium after 4 weeks. Incubation of cultures at low temperature (15°C) for ten days enhanced the survival percent under green house conditions and could be correlated with the development of thick cuticle and well differentiated leaf tissues (palisade and spongy parenchyma). Flow cytometric analysis was performed to check the genetic stability of in vitro plantlets. In a parallel study, seed progenies of these germplasm were raised under ex situ conditions. Its reproductive cycle was also studied for successful domestication.

Ti:sapphire-pumped deep-infrared femtosecond optical parametric oscillator based on CdSiP2

We report on a femtosecond optical parametric oscillator (OPO) for the deep-infrared (deep-IR) based on the Kerr-lens-mode-locked Ti:sapphire laser as the pump source. By deploying a novel cascaded intracavity arrangement, comprising a femtosecond OPO based on the nonlinear crystal, CdSiP2, synchronously pumped internal to a MgO:PPLN femtosecond OPO, we have generated broadly tunable radiation across 5958-8117 nm using rapid static cavity delay tuning, with a maximum power of 64 μW at 6791 nm, limited by the absorption in mirror substrates as well as polarization-dependent intracavity losses. The deep-IR idler power exhibits excellent passive stability of better than 1.1% rms over 2 h, with a spectral bandwidth as large as ∼650 nm at ∼6800 nm. The demonstrated concept is generic and can be similarly deployed in other operating time scales and wavelength regions, also using different laser pump sources and nonlinear materials.

Yb-fiber-laser-based, 1.8 W average power, picosecond ultraviolet source at 266 nm.

We report a compact, stable, high-power, picosecond ultraviolet (UV) source at 266 nm based on simple single-pass two-step fourth-harmonic generation (FHG) of a mode-locked Yb-fiber laser at 79.5 MHz in LiB3O5 (LBO) and β-BaB2O4. Using a 30-mm-long LBO crystal for single-pass second-harmonic generation, we achieve up to 9.1 W of average green power at 532 nm for 16.8 W of Yb-fiber power at a conversion efficiency of 54% in 16.2 ps pulses with a TEM00 spatial profile and passive power stability better than 0.5% rms over 16 h. The generated green radiation is then used for single-pass FHG into the UV, providing as much as 1.8 W of average power at 266 nm under the optimum focusing condition in the presence of spatial walk-off, at an overall FHG conversion efficiency of ∼11%. The generated UV output exhibits passive power stability better than 4.6% rms over 1.5 h and beam pointing stability better than 84 μrad over 1 h. The UV output beam has a circularity of >80% in high beam quality with the TEM00 mode profile. To the best of our knowledge, this is the first report of picosecond UV generation at 266 nm at megahertz repetition rates.

Fiber-laser-based green-pumped continuous-wave singly-resonant optical parametric oscillator

Stable, high-power, second-harmonic-generation (SHG) of a compact CW Ytterbium (Yb) fiber laser at 1064 nm into the green and its use as a pump source for CW singly-resonant optical parametric oscillator (SRO) is demonstrated. Using a simple single-pass SHG configuration in MgO:sPPLT, as much as 9.6 W of single-frequency green radiation at 532 nm is generated from 30 W of fundamental power at a conversion efficiency of 32.7% in a Gaussian spatial profile with a beam quality factor of M2 < 1.3. Thermal effects have been investigated at different fundamental power levels and various thermal management schemes are employed to maximize the second-harmonic power. The green source is successfully deployed to pump a CW SRO tunable over 855–1408 nm, generating up to 2.1 W of idler at 1168 nm. The peak-to-peak idler power stability is better than 10.7% over 40 min, with beam quality factor M2 < 1.26 for the idler and M2 < 1.52 for the signal.

Picosecond difference-frequency-generation in orientation-patterned gallium phosphide

We report the first picosecond mid-infrared source based on OP-GaP using single-pass DFG, providing tunable radiation across 3040–3132 nm, with 57 mW of average-power at 3044 nm, 3.2% rms stability over 1h, in good beam-quality.

Advances in Bamboo Biotechnology: Present Status and Future Perspective

Bamboo, the most important natural and renewable resource of the world, has always been an integral part of the social and economic life of many Asian countries. Therefore, the annual demands for bamboos have already outcrossed the annual yields across the world. Increasing population pressure; indiscriminate exploitation by paper, pulp and fuel industry; and insufficient attempts to replenish and cultivate bamboos are further widening the gap between demand and supply. This has forced scientists to pay greater attention towards employment of advanced biotechnological tools for understanding, generating and improving bamboos. As a result, new insights into bamboos were gained through genomics, proteomics, nanotechnology and transgenic technology. The findings show the way for better utilization of improved bamboos in meeting the future needs of the world. The achievements highlighted in the present review pave the way for the betterment of bamboos for the next millennium.

Mid-infrared picosecond difference frequency generation in orientation-patterned gallium phosphide

We report the first picosecond mid-infrared source based on OP-GaP using single-pass DFG, providing tunable radiation across 3040–3132 nm, with 57 mW of average-power at 3044 nm, 3.2% rms stability over 1h, in good beam-quality.