Induction of systemic resistance against fusarial wilt in pigeon pea through interaction of plant growth promoting rhizobacteria and rhizobia

A Bacillus cereus strain BS 03 and a Pseudomonas aeruginosa strain RRLJ 04 were studied for their effect on induction of systemic resistance against Fusarium udum wilt in pigeon pea, both individually and in combination with a rhizobial strain RH 2. Split root experiments confirmed that plants with combination treatment of PGPR and Rhizobium can survive longer than individual treatments and control. An increased level of defense-related enzymes, viz., l-phenylalanine ammonia lyase (PAL), peroxidase (POX) and polyphenol oxidase (PPO), were also recorded in co-inoculated plants. Production of β-1,3-glucanase and polymethyl galacturonase by the pathogen in culture medium was also sharply reduced in presence of both the PGPR strains. An increased level of phenol content with a decreased level of nitrogen content was recorded in the leaves of bacterized plants grown in pathogen infested soil. Presence of BS 03 in the culture medium stimulated the production of chlamydospore-like structures in the fungal mycelium. Such structures were not observed in case of RRLJ 04 treatment but the dry weight of mycelium was reduced significantly. Fusaric acid production by the pathogen was also drastically reduced in the presence of the PGPR strains. The results promise the combined use of PGPR and rhizobia for induction of systemic resistance against fusarial wilt in pigeon pea.     

Impact of boron fertilization on boron fractions at different crop growth stages in cauliflower_cowpea_okra sequence in an inceptisols of North East India

Abstract

A field experiment was conducted at Horticultural Experimental Farm, Assam Agricultural University, Jorhat during the year 2015–17 to assess the impact of boron fertilization on dynamics of boron fractions in soil and crop yields in cauliflower–cowpea–okra cropping sequence. Five levels of boron (0, 0.5, 1.0, 1.5 and 2.0?kg ha^?1) along with the recommended dose of NPK fertilizer were applied in soil in cauliflower once in each 2 years (2015–17) of experimentation to assess the direct effect of boron fertilization, while cowpea and okra were grown as a suceeding test crop to study the residual effects of boron fertilization in the cropping sequence. Among the different levels of boron, the highest content of all the boron fractions in soil was recorded at rate of 2?kg B ha^?1 at different crop growth stages for all the three crops. Progressive decrease in content of all the boron fractions with crop ageing was noticed. The content of different boron fractions in soil follows the order readily soluble boron (RSB)<oxide bound boron (OXB)<organic bound boron (ORBB)<specifically adsorbed boron (SAB) <residual boron, respectively. The boron level of 2?kg B ha^?1 was found to prominent in increasing the yield in all the crops. In respect of contributions of different boron fractions to yield of crops, oxide bound boron(2.10) was found to be the highest contributor of cauliflower yield, while the residual boron (1.10), contributed the highest to cowpea yield and organic bound boron fraction (1.24) was found to be most prominent contributor of boron in leveraging okra yield.     

Litter decomposition and nutrient release in relation to atmospheric deposition of S and N in a dry tropical region

Temporal and spatial variations in litterfall, leaf litter decomposition and nutrient release were quantified along an air pollution gradient around an industrial area in a dry tropical region of India. Significant differences were found in litterfall between the sites. Litter decomposition rates also significantly varied among the study sites. Litter decomposition was faster at sites away from the industrial region with coal-fired power plants. The concentrations of N and P increased, whereas that of Ca and SO₄-S decreased in decomposing litter over time. The nutrient release pattern was also modified by atmospheric deposition. Concentrations of SO₂ and NO₂ were negatively correlated with relative mass loss. Turnover time of nutrients, except SO₄-S in decomposing litter was maximal at the site receiving highest atmospheric depositions. The study documents that industrial emissions significantly modified nutrient cycling in adjacent terrestrial ecosystems.     

Suberin Biopolymer in Rice Root Exodermis Reinforces Preformed Barrier Against Meloidogyne graminicola Infection

Exploration of novel genetic resources against root-knot nematode (RKN) is necessary to strengthen the resistance breeding program in cultivated rice, and investigations on the role of genotype-specific root anatomy in conferring a structural barrier against nematode invasion are largely underexplored. Here, we reported a highly-resistant rice germplasm Phule Radha that conferred remarkably lower RKN parasitic fitness in terms of reduced penetration and delayed development and reproduction when compared with susceptible cultivar PB1121. Using histological and biochemical analyses, we demonstrated that an enhanced suberin deposition in the exodermal root tip tissue of Phule Radha compared to PB1121 can effectively form a penetrative barrier against RKN infection, and this preformed barrier in the control tissue did not necessarily alter to a greater extent when challenged with RKN stress. Using qRT-PCR analysis, we showed that a number of suberin biosynthesis genes were greatly expressed in the exodermis of Phule Radha compared to PB1121. In sum, the present study established the role of rice exodermal barrier system in defense against an important soil-borne pathogen.     

Characterization of shiga toxin producing (STEC) and enteropathogenic Escherichia coli (EPEC) in raw yak (Poephagus grunniens) milk and milk products

Thirty-one shiga toxin-producing (STEC) and 6 enteropathogenic Escherichia coli (EPEC) were isolated from 87 raw yak milk and 63 'churpi' samples. Of 18 stx(1) positive isolates (48.6%), 14 carried stx(1c) (77.7%). Subtyping of 28 stx(2) positive isolates (75.7%) revealed the presence of stx(2c) (9, 32.1%), stx(2d) (3, 10.7%), stx(2e) (1, 3.57%) and stx(2f) (3, 10.7%) variants. Furthermore, intimin (eaeA), enterohaemolysin (ehxA), autoagglutinating adhesin (saa), iha (adherence conferring protein), efa1 (EHEC factor for adherence), bundle forming pilli (bfpA) and toxB (type III secreted protein encoded on LEE Island, similar to toxin B of Clostridium difficile) genes were detected in 14, 16, 12, 4, 3, 2 and 2 isolates, respectively. Univariate and multivariate analysis depicted that both stx(1) and stx(2) or their variants were more likely to occur in isolates from Arunachal Pradesh (p<0.04) rather than Sikkim. Dendogram constructed on the basis of RAPD and ERIC PCR profile distributed the STEC and EPEC isolates in separate clusters irrespective of their sources and serotypes. The STEC and EPEC isolates exhibited resistance against erythromycin, amikacin, azithromycin, amoxicillin, ampicillin+cloxacillin, cephalothin, furazolidone, gentamicin, kanamycin, streptomycin and tetracycline. This is the first ever report on occurrence and characterization of STEC and EPEC isolated from yak milk and milk products.     

Prevalence and molecular characterization of porcine Picobirnavirus in piglets of North East Region of India

Tropical Animal Health and Production - Picobirnaviruses (PBVs) have been recognized as one of the important causal viral agents of gastroenteritis in several animal species especially in young...     

Variability in Mucuna pruriens L. germplasm for L-Dopa, an anti parkinsonian agent

Mucuna pruriens L. (Fabaceae) is a popular Indian medicinal plant, which has long been used in traditional Ayurvedic system of Indian medicine for diseases including parkinsonism. The seeds of M. pruriens contain 3,4-dihydroxyphenyl-L-alanine (L-dopa) as a major constituent, an intermediate precursor of the neurotransmitter dopamine. L-dopa extracted from seeds of Mucuna is more effective as drug than the synthetic counterpart. The plant is widely distributed throughout the India and in other parts of the tropics including Central and South America. The present study was aimed to screen thirty-eight accessions of Mucuna germplasm collected from different geographical regions of India for L-dopa content, an effective drug used for Parkinson’s disease. The L-dopa content in seeds of M. pruriens was quantitatively analyzed by high performance thin-layer chromatography (HPTLC) at 280?nm wavelength. Results indicated wide variability among thirty-eight accessions of M. pruriens for seed characters like seed colour, size and shape. The L-dopa content in seeds of M. pruriens ranged between 3.29 and 5.44?% (on dry weight basis) among different germplasm collections augmented from various parts of India. Promising accessions identified having high L-dopa content were IC551549 (5.44?%), IC551514 (5.41?%), IC331536 (5.40?%), IC552857 (5.36?%), IC385844 (5.32?%) and IC439197 (5.32?%). Due to the economic importance of the drug, these promising M. pruriens accessions can be exploited for large scale cultivation for their pharmacological important constituents mainly L-dopa content.     

Exploitation of wild annual Cicer species for widening the gene pool of chickpea cultivars

Introgression of unadapted genes from the wild Cicer species could contribute to the widening of genetic base of important traits such as yield, yield attributes and resistance to major biotic and abiotic stresses. An attempt was made successfully to intercross two wild annual Cicer species with three cultivated chickpea cultivars. Four interspecific cross‐combinations were made, and their true hybridity was ascertained through morphological and molecular markers. These cross‐combinations were also studied for some important quantitative traits under real field conditions. The range, mean and coefficient of variation of agro‐morphological traits were assessed in the parental lines, their F₁ and F₂ generations to determine the extent of variability generated in cultivated chickpea varieties. A high level of heterosis was recorded for number of pods/plant and seed yield/plant in F₁ generation. Three cross‐combinations of ‘Pusa 1103’ × ILWC 46, ‘Pusa 256’ × ILWC 46 and ‘Pusa 256’ × ILWC 239 exhibited substantially higher variability for important yield‐related traits. The present research findings indicate that these wild annual Cicer species can be easily exploited to broaden the genetic base of cultivated gene pool for improving seed yield as well as adaptation.     

In vitro interference between equine herpesvirus types 1 and 2

Interference between equine herpesvirus types 1 (EHV-1) and 2 (EHV-2) was studied in equine dermis (ED) monolayer cell cultures and equine lymphocyte cultures. Cell cultures were infected with EHV-2, and after a short incubation period, the cultures were superinfected with EHV-1. At various intervals, different measurements of EHV-1 expression in dually infected cultures, compared with those in cultures infected with EHV-1 alone, were studied. In dually infected ED cell cultures, the EHV-1 cytopathic effect, EHV-1 titer, and EHV-1 enzyme-linked immunosorbent assay antigen titer were maximally reduced to values of 40%, 58.5%, and 54.9%, respectively, at postsuperinfection hour (PSIH) 36. Values of these EHV-1 expressions were subsequently increased at PSIH 48. However, thymidine kinase activity was reduced to a maximum of 67.3% reduction at PSIH 48. In dually infected lymphocyte cultures, the EHV-1 titer, EHV-1 infective centers, EHV-1 enzyme-linked immunosorbent assay antigen titer, and thymidine kinase activity were maximally reduced to values of 77.4%, 78.7%, 98.3%, and 72.9%, respectively, at PSIH 24. These reductions of EHV-1 expressions were completely abrogated at PSIH 48 to 72. In both cell culture systems, a marked interference of EHV-1 by EHV-2 was observed; this was transient in the lymphocyte cultures, but was more prolonged in ED cell cultures. This interference appeared not to be interferon mediated. The multiplication of EHV-2 in the dually infected ED cell cultures appeared unaffected.