Seed Pathology and Plant Quarantine in India

The present situation regarding problems and achievements in seed pathology and domestic and international quarantine in India is described. Emphasis is placed upon the need for resolving present inadequacies in this country's quarantine legislation and for international alignment in seed health testing methods, in addition to a general information exchange on plant pathogens.     

Optical spectroscopic exploration of binding of Cochineal Red A with two homologous serum albumins

Cochineal Red A is a negatively charged synthetic azo food colorant and a potential carcinogen. We present here the study of binding of Cochineal Red A with two homologous serum albumins, human (HSA) and bovine (BSA), in aqueous pH 7.4 buffer by optical spectroscopic techniques. Protein intrinsic fluorescence quenching by Cochineal Red A occurs through ground-state static interaction and its binding with BSA is stronger than with HSA. The magnitudes of thermodynamic parameters suggest that dye binding occurs principally via electrostatic complexation. Site-marker competitive binding shows that Cochineal Red A binds primarily to site I of serum albumins. Circular dichroic spectra indicate that dye binding results in some conformational modification of serum albumins. Increased ionic strength of the medium results in lowering of binding. This study provides an important insight into possible means of removal of dye toxicity.     

Use of next‐generation sequencing for the identification and characterization of Maize chlorotic mottle virus and Sugarcane mosaic virus causing maize lethal necrosis in Kenya

The diagnosis of novel unidentified viral plant diseases can be problematic, as the conventional methods such as real‐time PCR or ELISA may be too specific to a particular species or even strain of a virus, whilst alternatives such as electron microscopy (EM) or sap inoculation of indicator species do not usually give species level diagnosis. Next‐generation sequencing (NGS) offers an alternative solution where sequence is generated in a non‐specific fashion and identification is based on similarity searching against GenBank. The conventional and NGS techniques were applied to a damaging and apparently new disease of maize, which was first identified in Kenya in 2011. ELISA and TEM provided negative results, whilst inoculation of other cereal species identified the presence of an unidentified sap transmissible virus. RNA was purified from material showing symptoms and sequenced using a Roche 454 GS‐FLX+. Database searching of the resulting sequence identified the presence of Maize chlorotic mottle virus and Sugarcane mosaic virus, a combination previously reported to cause maize lethal necrosis disease. Over 90% of both viral genome sequences were obtained, allowing strain characterization and the development of specific real‐time PCR assays which were used to confirm the presence of the virus in material with symptoms from six different fields in two different regions of Kenya. The availability of these assays should aid the assessment of the disease and may be used for routine diagnosis. The work shows that next‐generation sequencing is a valuable investigational technique for rapidly identifying potential disease‐causing agents such as viruses.     

A novel pathovar of Xanthomonas axonopodis causes gumming of Guggal (Commiphora wightii)

Guggal (Commiphora wightii (Arnott) Bhandari comb. nov.) is a small tree which is tapped for medicinally important oleo?Cgum?Cresin. Naturally infected plant oozes oleo?Cgum?Cresin from its trunk and primary branches. However, in either case, the plant dies slowly after oozing. A bacterium was established to be responsible for these phenomena. Four isolates of this bacterium were characterised by biochemical tests, Biolog GN2 microplate reaction, rDNA sequencing, which suggested that the pathogen belonged to the genus Xanthomonas. However, phylogenetic analysis based on chaperone protein (dnaK) gene, TonB?Cdependent receptor (fyuA) gene, DNA gyrase B (gyrB) gene and RNA polymerase sigma factor (rpoD) gene sequences placed it as a member of X. axonopodis 9.2 rep?CPCR/DNA?CDNA homology cluster close to X. perforans, X. alfalfae and X. euvesicatoria. Further elucidation of phylogenetic position of the test strains was achieved from a gyrB based tree considering sequences from 71 representative strains. Test strains were confirmed to be members of X. axonopodis. These had very narrow infectivity limited to Commiphora spp. Hence, we propose a novel pathovar, X. axonopodis pv. commiphoreae pv. nov. as the cause of gum oozing in guggal. Pathotype is DXA 01 = CFBP 7580 = LMG 26789.     

Activin receptor type IIB in rohu (Labeo rohita): molecular characterization,tissue distribution and immunohistochemical localization during different stages of gonadal maturation

Fish Physiology and Biochemistry - Activin receptor type IIB (ActRIIB) is a transmembrane serine/threonine kinase receptor which plays a pivotal role in regulating the reproduction in vertebrates...     

A STUDY OF THE DUPLEX YIELD CHARACTER OF DUAL PHASE STEEL

In this paper, the duplex yield character (DYC) of dualphase steel has been discussed. The results of the tests show that the DYC is due to the martensite deformation from the elastic state to the plastic state and the microvoid formed from the interphase boundaries. The DYC is directly affected by the phase ratio and the shape of structure. According to the different deformation character of the duplex phase, the uniform deformation of dual phase steel divide into three stages.     

Genetic divergence among a non-restorer collection of sorghum (Sorghum bicolor (L.) Moench) and its relationship with heterosis

Summary A genetic diversity analysis in a collection of 171 non-restorer lines of sorghum (Sorghum bicolor (L.) Moench) using D² technique and canonical variate analysis indicated that considerable variation in grain yield has been added to the collection by the addition of lines derived from random mating populations. The efficiency of D² and canonical variate techniques in distinguishing extremely diverse genotypes was confirmed. However, the two techniques showed weak correspondence in their clusters. The F₁ hybrids of 15 diverse lines exhibited no relationship between heterosis or per se performance of crosses and diversity in their parents. Therefore, traditional plant breeding methods are being advocated.Approved by ICRISAT as Journal Article no. 435.     

Pseudocercospora griseola,the causal agent of common bean angular leaf spot: Strain characterization and sensitivity to fungicides

Angular leaf spot (ALS), an important disease of common bean (Phaseolus vulgaris), is caused by the fungus Pseudocercospora griseola. This pathogen has a wide genetic variability and, therefore, poses a challenge to integrated disease management. The use of resistant cultivars is difficult; hence, the application of fungicides has been a common practice in common bean cultivation. P. griseola strains were morphophysiologically characterized and their sensitivity to common fungicides used to control ALS was studied. The strains were evaluated for sporulation capacity and a representative sample of 34 strains was bioassayed to determine their sensitivity to commercial concentrations of five fungicides, namely pyraclostrobin, mancozeb, pyraclostrobin + metconazole, chlorothalonil and tebuconazole. Another sample of 29 strains was studied for conidial germination and dimensions. Sporulation capacity ranged from 0.88 to 27.67 × 10⁴ conidia/ml and germination percentage ranged from 39% to 72%. The large differences among strains suggest a wide genetic variability among the strains. A wide variability in aggressiveness of P. griseola was observed, which has consequences for breeding programmes aimed at resistance. The behaviour of pathogen strains differed in every fungicide evaluated, even in a population that has not been under selection pressure in the field. These results confirm the need for further studies and may guide future research with this pathogen.     

Activin A as a novel biomarker of equine inflammatory abdominal disease: preliminary findings

This study evaluated the inflammatory mediator activin A in horses with acute abdominal disease and compared this putative novel biomarker with serum amyloid A (SAA). Thirty-three adult horses referred for evaluation of acute abdominal disease were grouped into three lesion categories, non-strangulating, strangulating or inflammatory. Eleven healthy adult horses served as controls. Serum activin-A was significantly increased in animals with inflammatory or strangulating lesions compared with controls. Horses with non-strangulating, strangulating or inflammatory lesions had significantly elevated SAA concentrations. Activin A, along with other biomarkers, may be useful in monitoring inflammation in cases of acute abdominal disease in horses. Further validation is warranted to determine the utility of this biomarker in evaluating the effectiveness of novel anti-inflammatory treatments for equine colic and endotoxaemia.     

Genetic control of surface curvature

Although curvature of biological surfaces has been considered from mathematical and biophysical perspectives, its molecular and developmental basis is unclear. We have studied the cin mutant of Antirrhinum, which has crinkly rather than flat leaves. Leaves of cin display excess growth in marginal regions, resulting in a gradual introduction of negative curvature during development. This reflects a change in the shape and the progression of a cell-cycle arrest front moving from the leaf tip toward the base. CIN encodes a TCP protein and is expressed downstream of the arrest front. We propose that CIN promotes zero curvature (flatness) by making cells more sensitive to an arrest signal, particularly in marginal regions.