In vitro high frequency direct plant regeneration from whole leaves of blackberry

High frequency and direct (without callus) plant regeneration was achieved from whole leaf explants of thornless blackberry (Rubus hybrid) cv. Black Satin (EC No. 381258; PI No. 553272) in vitro. Leaf blade explants from 1-, 3- and 5-month-old mother cultures were cultured on Murashige and Skoog (MS) medium with thidiazuron (TDZ), N⁶-benzylaminopurine (BAP), indol-3-butyric acid (IBA) and α-naphthalene acetic acid (NAA), alone or in combination. Three-month explants cultured on 0.02 mg l⁻¹ TDZ produced a high regeneration frequency (91.7%) and the most shoots/leaf explant (17.3). The shoot primordia developed within 3 weeks from the point of detachment of the petiole from the leaf blade. The age of the explant source significantly affected the shoot regeneration potential of the leaf explants. Leaves excised from 3-month-old in vitro-cultured shoots performed better than those from 1- and 5-month-old shoots. Shoots rooted best on half-strength MS basal medium with 0.5 mg l⁻¹ IBA and 90% of the plantlets survived acclimatization. The regenerated plantlets were morphologically similar to the mother plants.     

Assessment of molecular genetic diversity of 384 chickpea genotypes and development of core set of 192 genotypes for chickpea improvement programs

Genetic Resources and Crop Evolution - Cicer arietinum L. (chickpea) is one of the most significant legume crops domesticated in the Fertile Crescent. This study was aimed to characterize a diverse...     

Metabolism mediated interaction of α-asarone and Acorus calamus with CYP3A4 and CYP2D6

The present study was aimed to investigate the possible interaction of the standardized extract of Acorus calamus (AC) with Cytochrome P450 enzyme, quantitative determination of the α-asarone in the AC rhizome was performed by RP-HPLC method. In vitro interaction of the plant extract was evaluated by CYP450-carbon monoxide complex (CYP450-CO) assay. Effect on individual isoforms such as CYP3A4 and CYP2D6 isozymes were analyzed through fluorescence product formation and respective IC₅₀ values were determined. CYP450-CO assay showed moderate interaction potential. Extract showed higher IC₅₀ values (46.84 ± 1.83-32.99 ± 2.21 μg/ml) comparing to the standard inhibitors and lower IC₅₀ value than α-asarone (65.16 ± 2.37-42.15 ± 2.45 μg/ml).     

Inactivation of TNF signaling by rationally designed dominant-negative TNF variants

Tumor necrosis factor (TNF) is a key regulator of inflammatory responses and has been implicated in many pathological conditions. We used structure-based design to engineer variant TNF proteins that rapidly form heterotrimers with native TNF to give complexes that neither bind to nor stimulate signaling through TNF receptors. Thus, TNF is inactivated by sequestration. Dominant-negative TNFs represent a possible approach to anti-inflammatory biotherapeutics, and experiments in animal models show that the strategy can attenuate TNF-mediated pathology. Similar rational design could be used to engineer inhibitors of additional TNF superfamily cytokines as well as other multimeric ligands.     

Endophytes from maize with plant growth promotion and biocontrol activity under drought stress

In the present study, 39 endophytic bacteria were isolated from different crops with main focus on maize roots and seeds. Endophytes were screened for drought stress tolerance, plant growth promoting (PGP) traits and antifungal activity. Out of 39 isolates, 32 could show drought tolerance up to–1.02 matric potential (MPa) and exhibited most of the plant growth promoting traits. But, only five isolates could show antagonistic activity against plant fungal pathogens. Based on the results, 10 promising isolates namely FTR, NFTR, FMZR9, FMZR2, MZ30V92, MRC12, MRC31, MRC33, MRC41 and MRR2 were selected and identified using biochemical and 16S rDNA gene sequencing as Pseudomonas aeruginosa (strains FTR and NFTR), Pseudomonas monteilii (strain FMZR2), Pseudomonas putida (strain FMZR9), Acitenobacter brumalii (strain MZ30V92), Enterobacter asburiae (strain MRC12), Sinorhizobium meliloti (strain MRC31), Pseudomonas thivervalensis (strain MRC33), Pseudomonas fulva (strain MRC41), and Pseudomonas lini (strain MRR2). Further, at–1.02 MPa all the 10 isolates showed PGP traits, and 3 isolates (FTR, NFTR and MRC12) showed antifungal activity. Thus, indicating that drought tolerant plant growth promoting antagonistic endophytic bacteria (PGPAE) helps in plant growth and disease management under drought stress.     

Damage pattern and status of the leaf miner Aphanisticus aeneus Kerremans (Coleoptera: Buprestidae) in Saccharum spp.

Biology, damage pattern, incidence levels and status of the leaf miner Aphanisticus aeneus Kerremans (Coleoptera: Buprestidae) were studied in accessions of Saccharum spp. Egg, grub and pupal periods of the miner lasted 6.0 ± 0.8, 18.5 ± 1.9 and 7.0 ± 1.3 days, respectively; adults lived for 8–10 days. The grub tunneled the leaf on the lower surface just above the epidermis forming a linear channel; infested tissues showed brownish discoloration. The extent of leaf miner attack among the 331 accessions of Saccharum spp. ranged 4.00%–76.47% on cane basis and 7.14%–100.00% on leaf basis; the mined leaf area ranged 3.22–11.00 cm². When the accessions were grouped on the basis of an infestation index developed with the above three parameters, 267 occupied very low category, 51 were in low category, 11 were in moderate category and 2 were placed in high incidence category. All accessions showed miner attack in at least one study year. Within each of the four Saccharum spp., accessions differed significantly among the three study years for all infestation parameters. Among the four species, while S. robustum accessions recorded significantly highest infestation index, the other three species remained on par.     

Purification of an antifungal endochitinase from a potential biocontrol Agent Streptomyces griseus

Streptomyces griseus (MTCC 9723) is a chitinolytic bacterium isolated from prawn cultivated pond soil of Peddapuram Village; East Godavari District was studied in detailed. Chitinase (EC 3.2.1.14) was extracted from the culture filtrate of Streptomyces griseus and purified by ammonium sulfate precipitation, DEAE-cellulose ionexchange chromatography, Sephadex G-100 and Sephadex G-200 gel filtration chromatography. The molecular mass of the purified chitinase was estimated to be 34, 32 kDa by SDS gel electrophoresis and confirmed by activity staining with Calcofluor White M2R. Chitinase was optimally active at pH of 6.0 and at 40 degrees C. The enzyme was stable from pH 5-9 and up to 20-50 degrees C. The chitinase exhibited Km and Vmax values of 400 mg and 180 IU mL(-1) for colloidal chitin. Among the metals and inhibitors that were tested, the Hg+, Hg2+ and P-chloromercuribenzoic acid completely inhibited the chitinase activity at 1 mM concentration. The purified chitinase showed high activity on colloidal chitin, chitobiose, and chitooligosaccharide. An in vitro assay proved that the crude chitinase, actively growing cells of S. griseus having antifungal activity against all studied fungal pathogen. This result implies that characteristics of S. griseus producing endochitinase made them suitable for biotechnological purpose such as for degradation of chitin containing waste and it might be a promising biocontrol agent for plant pathogens.     

International Symposium on the Evaluation of Biological Activity,Wageningen, April, 1975

Abstract

A method was devised for estimating large populations of cowpea aphid Aphis craccivora Koch (Hemiptera: Aphididae) on cowpea. The densities of the aphid on stem, leaves and pod were first estimated in the laboratory for use in the field later. The densities were estimated in three arbitrary classes of infestation, viz. heavy, medium and low, determined visually based on the intensity of colonization. The densities of the aphid per cm² on stems were 108.50, 49.77 and 2503, while on pods they were 80.68, 44.46 and 23.20, in the three classes of infestation respectively. The aphid did not show any preference for the thickness of stems whereas young pods were preferred to old pods for colonization. The mean aphid densities on leaflets of topmost leaves were 62.10, 36–35 and 18–50, while on leaflets of top 2nd and 3rd leaves they were 124–60, 69–35 and 38.20, in the three infestation classes respectively. Comparisons made between the aphid densities on different parts of cowpea plant showed that the aphid colonized them in descending order of preference as stem > pod > top most leaf > top 2nd and 3rd leaves.