Prem L. Uniyal

Host Generated siRNAs Attenuate Expression of Serine Protease Gene in Myzus persicae

Background Sap sucking hemipteran aphids damage diverse crop species. Although delivery of ds-RNA or siRNA through microinjection/feeding has been demonstrated, the efficacy of host-mediated delivery of aphid-specific dsRNA in developing aphid resistance has been far from being elucidated. Methodology/Principal Findings Transgenic Arabidopsis expressing ds-RNA of Myzus persicae serine protease (MySP) was developed that triggered the generation of corresponding siRNAs amenable for delivery to the feeding aphids. M. persicae when fed on the transgenic plants for different time intervals under controlled growth conditions resulted in a significant attenuation of the expression of MySP and a commensurate decline in gut protease activity. Although the survivability of these aphids was not affected, there was a noticeable decline in their fecundity resulting in a significant reduction in parthenogenetic population. Conclusions/Significance The study highlighted the feasibility of developing host based RNAi-mediated resistance against hemipteran pest aphids.

Aphid resistance in Brassica crops: challenges, biotechnological progress and emerging possibilities.

Aphids, (Hemiptera: Aphidoidea) a nefarious insect pest of Brassicaceae members including major vegetable and oilseed crops have coevolved with their host plant and emerged as most economically important insect pest of crop Brassicas. Their atypical feeding mechanism and unusual reproductive biology made them intractable to control below economic threshold level of damage to the crops. To a large extent aphid infestation is controlled by spraying agrochemicals of systemic mode of action and rarely by biological control. Use of systemic insecticides is highly cost intensive as well poses bigger threat of their incorporation in dietary chain. Breeding for genetic resistance against aphids has not been possible owing to the non-availability of resistance source within the crossable germplasms and lack of knowledge of the genetics of the trait. Genetic engineering with insect resistant transgenes seems to be the only potential avenue to address this difficult-to-accomplish breeding objective. Some success had been achieved in terms of developing aphid resistant cultivars through genetic engineering however, commercial utilization of such crops are still awaited. Thus protection of crops against aphids necessarily requires more research to identify either more effective insecticidal transgenes or biological phenomenon that can usher to new mechanism of resistance. The present review is an attempt to highlight the current status and possible avenues to develop aphid resistance in Brassicaceae crops.

Effects of paraquat on lipid peroxidation and antioxidant enzymes in aquatic fern Azolla microphylla

Paraquat is most extensively used methyl viologen herbicide to control weeds in the rice-Azolla ecosystem. The effects of different paraquat (PQ) dosages on growth, lipid peroxidation, and activity of antioxidant enzymes of Azolla microphylla Kaul. were investigated. The results indicated that Azolla fronds survived only at the concentrations of 2–6 μM PQ. Frond fragmentation and browning occurred after 24 h at 8 μM PQ. At 24 h, the amount of proteins decreased by 48.7 % in Azolla fronds exposed to 10 μM PQ than that in control fronds. The supplementation of 10 μM PQ increased the activities of superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), and ascorbate peroxidase (APX) by 2,4-, 1,8-, 3,0-, and 2,2-fold, respectively, as compared with control. The content of PQ and activities of SOD, CAT, GPX, and APX were found to be positively correlated. Our study showed that PQ (2–6 μM) caused ROS overproduction in Azolla fronds, which were scavenged by induced activities of antioxidant enzymes.

In vitro germination and seedling development of Dalzellia zeylanica (Gardner) Wight (Podostemaceae)

Abstract Seeds were germinated aseptically on thermocole cubes in 1/5 strength Murashige and Skoogs (1962) liquid medium (MS). The mature embryo has two well-developed cotyledons but lacks a plumule and a distinct radicle. The embryo emerges from the seed by the elongation of cotyledons and hypocotyl. The epidermal cells at the radicular pole elongate to form rhizoids. Proliferation of cells of the plumular pole gives rise to six to eight leaf primordia. An endogenously formed protuberance in the hypocotyledonary region develops into a green, dorsiventral thallus. The margins of the thallus also bear leaves. The presence of a band of small meristematic cells (five or six layers thick) below the apical mantle of large irregular cells has been seen in paradermal sections of thallus tips. Presumably they participate in the growth of the thallus. A vertical section of the thallus shows parenchymatous ground tissue and a strand of vascular tissue in the middle of the thallus which divides to supply the branches of the thallus. Tracheary elements have spiral/annular thickenings. Sieve elements showed callose when stained with aniline blue and viewed under a fluorescence microscope.

Studies on Indotristicha tirunelveliana Sharma, Karthik. & Shetty (Podostemaceae): An endemic, rare and enigmatic taxon

Summary The Podostemaceae are remarkable for their morphological, ecological and evolutionary interest and present a challenging system to study these phenomena. Indotristicha tirunelveliana , a member of the Podostemaceae, is an unique, rare, endemic and submerged haptophyte that grows in a rapidly flowing waterfall in Tamil Nadu, India. The plant body consits of 7–25 em long, suberect rhizome, attached to rocks with the help of haptera. The rhizome bears densely crowded shoots with four rows of spirally arranged leaves which completely cover the dorsal surface of the rhizome. Floral shoots arise as buds on the rhizome but flower development occurs only when the plants are 10–15 cm below the water level. Anthesis occurs only when the flowers are exposed to air. Fruit is a 9-ribbed capsule, opens by means of 2–3 septicidal slits. Large number of seeds in groups together with placentae and fruit valves are dispersed on the crevices of rock and germinate when they get first showers of monsoon. The seeds are minute and non-endospermic. The mature embryo has two well-developed cotyledons but lacks a piumule and distinct radicle. Anatomy of the rhizome shows a broad cortex and a few undifferentiated vascular elements.

A survey of bryophytes for presence of cholinesterase activity

The neurotransmitter acetylcholine (ACh) is present in plants including bryophytes. The first biochemical evidence for ACh hydrolysis by enzyme cholinesterase (ChE) in bryophytes is presented. Thirty-nine species belonging to 16 families of bryophytes were surveyed for ChE activity. Thirty species belonging to 13 families showed ChE activity. Of the bryophytes tested, Anoectangium bicolor showed the highest ChE activity. Widespread distribution of ChE in bryophytes indicates their suitability as a system to study the role of ACh in plants.

Karyomorphological studies in some members of Podostemaceae

Karyotype analysis was performed using thallus tips in three taxa of the family Podostemaceae. The chromosome numbers for Polypleurum stylosum (Wight) J.B. Hall (2n=34) and Hydrobryopsis sessilis (Willis) Engler (2n=26) have been investigated for the first time. The chromosome number (2n=30) in Dalzellia zeylanica (Gardner) Wight differs from the previous count (2n=20) reported by Magnus. Critical notes have been made on the karyotype characteristics and their interrelationships among species.

Genetic Homogeneity Revealed Using SCoT, ISSR and RAPD Markers in Micropropagated Pittosporum eriocarpum Royle- An Endemic and Endangered Medicinal Plant

Pittosporum eriocarpum Royle, a medicinally important taxon, is endemic to Uttarakhand region of Himalaya. It has become endangered due to over-collection and the loss of habitats. As raising plants through seeds in this plant is problematic, a reliable protocol for micropropagation using nodal explants has been developed. High shoot regeneration (95%) occurred in MS medium augmented with BA 0.4mg/l in combination IBA 0.6mg/l. In vitro regenerated shoots were rooted in MS medium supplemented with three auxins, of which 0.6 mg/l indole butyric acid proved to be the best for rooting (90%) with maximum number of roots per shoot. Thereafter, rooted plants were hardened and nearly 73% of rooted shoots were successfully acclimatized and established in the field. Start codon targeted (SCoT), inter simple sequence repeats (ISSR) and random amplified polymorphic DNA (RAPD) markers were used to validate the genetic homogeneity amongst nine in vitro raised plantlets with mother plant. DNA fingerprints of in vitro regenerated plantlets displayed monomorphic bands similar to mother plant, indicating homogeneity among the micropropagated plants with donor mother plant. The similarity values were calculated based on SCoT, ISSR and RAPD profiles which ranged from 0.89 to 1.00, 0.91 to 1.00 and 0.95 to 1.00 respectively. The dendrograms generated through Unweighted Pair Group Method with arithmetic mean (UPGMA) analysis revealed 97% similarity amongst micropropagated plants with donor mother plant, thus confirming genetic homogeneity of micropropagated clones. This is the first report on micropropagation and genetic homogeneity assessment of P. eriocarpum. The protocol would be useful for the conservation and large scale production of P. eriocarpum to meet the demand for medicinal formulations and also for the re-introduction of in vitro grown plants in the suitable natural habitats to restore the populations.

Differential responses of hydrogen peroxide, lipid peroxidation and antioxidant enzymes in Azolla microphylla exposed to paraquat and nitric oxide

The present investigation was carried out to decipher the interplay between paraquat (PQ) and exogenously applied nitric oxide (NO) in Azolla microphylla. The addition of PQ (8 μM) increased the activities of superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) by 1.7, 2.7, 3.9 and 1.9 folds respectively than that control in the fronds of Azolla. The amount of H2O2 was also enhanced by 2.7 times in the PQ treated plants than that of control. The supplementation of sodium nitroprusside (SNP) from 8–100 μM along with PQ, suppressed the activities of antioxidative enzymes and the amount of H2O2 compared to PQ alone. The drop in the activity of antioxidative enzymes — SOD, GPX, CAT and APX was highest (39.9%, 48.4%, 41.6% and 41.3% respectively) on the supplementation of 100 μM SNP with PQ treated fronds compared to PQ alone. The addition of NO scavengers along with NO donor in PQ treated fronds neutralized the effect of exogenously supplied NO. This indicates that NO can effectively protect Azolla against PQ toxicity by quenching reactive oxygen species. However, 200 μM of SNP reversed the protective effect of lower concentration of NO donor against herbicide toxicity. Our study clearly suggests that (i) SNP released NO can work both as cytoprotective and cytotoxic in concentration dependent manner and (ii) involvement of NO in protecting Azolla against PQ toxicity.

Moss Flora of Kedarnath Wildlife Sanctuary (KWLS), Garhwal Himalaya, India

Mosses are one of the dominant plant communities at higher elevations in the Himalaya and play an important role in the ecosystem dynamics. The authors assessed the diversity of mosses in the Kedarnath Wildlife Sanctuary (KWLS) of Garhwal Himalaya, India. A total of 113 species of mosses belonging to 65 genera are recorded along with their habitat preference, life strategies, growth forms and pattern of distribution at an altitudinal gradient in KWLS. Seven species of mosses viz., Dicranum orthophylloides Dix., Prionidium setschwanicum (Broth.) Hilp., Funaria microstoma Bruch ex Schimp., Plagiomnium drummondii (Bruch & Schimp.) T. Kop., Aerobryopsis wallichii (Brid.) Fleisch., Barbella turgida Nog. and Thuidium talongense Besch. are recorded for the first time from India. Twelve species of mosses are found new to western Himalaya, which were earlier reported to be endemic to eastern Himalayan region. Fifty two species are new records for Garhwal Himalayan region. Bryaceae (22 spp.) and Bryum (9 spp.) are found to be widely distributed taxa followed by Meteoriaceae (8 genera), Pottiaceae (8 genera) and Dicranaceae (6 genera).