Browsing by Author "A. Vaishampayan"

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A cyanobacterial mutant resistant against a bleaching herbicide
(2000) A. Vaishampayan; R.P. Sinha; A.K. Gupta; D.-P. Häder
The nitrogen fixing cyanobacterium Nostoc muscorum has been found to be sensitive to the herbicide SAN 6706 [4-chloro-5 (dimethylamino)-2-(a,a,a,-trifluoro-m-tolyl)-3-(2H) pyridazinon] at 30-45 μM within 15 min. The toxicity was more severe in combined nitrogen-free N(comb)-free medium than in a combined nitrogen medium; this enhancement was reversible by supplementation of the medium with 3 mM glucose or 5 μM ATP, serving as carbon and/or energy source in this organism. A mutant of this cyanobacterium resistant to 3 mM SAN 6706 has been isolated and characterized to perform nitrogenase activity in exogenous ATP supplemented N(comb)-free medium. However, it exhibited a moderate growth in combined nitrogen media in the absence of external ATP. The resistance factor is higher than 100. Simultaneously, this strain possesses a cross-resistance to methylamine, a well-known inhibitor of photophosphorylation, irrespective of the exogenous ATP supply. The behavior of the mutant suggests a defective phosphorylation in its photosynthetic system.
A cyanobacterial recombination study, involving an efficient N2-fixing non-heterocystous partner
(2000) A. Vaishampayan; R.P. Sinha; A.K. Gupta; D.-P. Häder
Many filamentous cyanobacteria fix atmospheric nitrogen under natural conditions in specialized anaerobic compartments, heterocysts, interspersed between vegetative cells, which provide protection to the O2-sensitive nitrogenase. A few unicellular cyanobacterial strains are also known to fix nitrogen aerobically at a slower rate. Filamentous cyanobacteria lacking heterocysts are not known so far to fix nitrogen. We describe the isolation and purification of a non-heterocystous filamentous cyanobacterium from the fronds of the water-fern Azolla, fixing nitrogen at 18.7 ± 0.2 n moles ethylene μg Chl. a-1 h-1 when grown in nitrogen-free medium at a low level of oxygen between two layers of agar. This strain of Anabaena azollae has been designated as het- nif+ (non-heterocystous and nitrogen-fixing), and is found to be easily and effectively preserved in nitrogen-free medium in standard synthetic cyanobacterial nutrient medium (pH 8.5) at a continuous light intensity of 2800 lx at 25 ± 1°C. This het- nif+ strain is an effective donor of the nif+ marker to a het+ nif- strain of another cyanobacterium, Nostoc muscorum, when both are grown together in a recombination study.
Biological effects of rice-field herbicide machete on various strains of the nitrogen-fixing blue-green alga Nostoc muscorum
(1978) H.N. Singh; A. Vaishampayan
The pre-emergence rice-field herbicide machete (2-chloro-2′, 6′-diethyl-N (butoxymethyl) acetanilide), is apparently toxic and lytic to parental, het+ nif11-, and Em-R het- nif2- strains of Nostoc muscorum. The intensity of the biological effects induced by the herbicide increases with the growth-promoting efficiency of various inorganic nitrogen sources. The herbicide has no effect on heterocyst differentiation, and induced biological perturbations are not reversed by glucose. Machete appears to be strong mutagen as 5-6% of the het+ nif11- and Em-R het- are prototrophic revertants. © 1978.
Cyanobacterial biofertilizers in rice agriculture
(2001) A. Vaishampayan; R.P. Sinha; D.-P. Häder; T. Dey; A.K. Gupta; U. Bhan; A.L. Rao
Floodwater and the surface of soil provide the sites for aerobic phototrophic nitrogen (N) fixation by free-living cyanobacteria and the Azolla-Anabaena symbiotic N2-fixing complex. Free-living cyanobacteria, the majority of which are heterocystous and nitrogen fixing, contribute an average of 20-30 kg N ha-1, whereas the value is up to 600 kg ha-1 for the Azolla-Anabaena system (the most beneficial cyanobacterial symbiosis from an agronomic point of view). Synthesis and excretion of organic/growth-promoting substances by the cyanobacteria are also on record. During the last two or three decades a large number of studies have been published on the various important fundamental and applied aspects of both kinds of cyanobacterial biofertilizers (the free-living cyanobacteria and the cyanobacterium Anabaena azollae in symbiotic association with the water fern Azolla), which include strain identification, isolation, purification, and culture; laboratory analyses of their N2-fixing activity and related physiology, biochemistry, and energetics; and identification of the structure and regulation of nitrogen-fixing (nif) genes and nitrogenase enzyme. The symbiotic biology of the Azolla-Anabaena mutualistic N2-fixing complex has been clarified. In free-living cyanobacterial strains, improvement through mutagenesis with respect to constitutive N2 fixation and resistance to the noncongenial agronomic factors has been achieved. By preliminary meristem mutagenesis in Azolla, reduced phosphate dependence was achieved, as were temperature tolerance and significant sporulation/spore germination under controlled conditions. Mass-production biofertilizer technology of free-living and symbiotic (Azolla-Anabaena) cyanobacteria was studied, as were the interacting and agronomic effects of both kinds of cyanobacterial biofertilizer with rice, improving the economics of rice cultivation with the cyanobacterial biofertilizers. Recent results indicate a strong potential for cyanobacterial biofertilizer technology in rice-growing countries, which opens up a vast area of more concerted basic, applied, and extension work in the future to make these self-renewable natural nitrogen resources even more promising at the field level in order to help reduce the requirement for inorganic N to the bare minimum, if not to zero.
Evidence for the involvement of a genetic determinant controlling functional specificity of group VI B elements in the metabolism of N2 and NO3- in the blue-green alga Nostoc muscorum
(1978) H.N. Singh; A. Vaishampayan; R.K. Singh
The parent N. muscorum is Mo-requiring for growth on N2 or NO3- as nitrogen source. W and Cr both are observed to competitively inhibit the function of Mo in growth on N2 and NO3- media in parent strain. Spontaneous mutants growing in the presence of W or Cr were isolated and when examined, found to be W- or Cr-requiring for growth with both N2 and NO3- as nitrogen source. The results of the characterization of the three strains with respect to mutation frequency, interaction among Mo, W and Cr in growth on N2 as nitrogen source, and requirement of W or Cr for NO3- inhibition of heterocyst formation in W- or Cr-requiring strain growing in NO3- medium, all suggest the operation of a single genetic determinant in specifying whether Mo, W or Cr (group VI B elements) is required for growth with both N2 and NO3- as nitrogen sources. They also further suggest that this single genetic determinant is common to nitrogenase and nitrate reductase. © 1978.
Genetics of heat stress tolerance traits in tomato (Solanum lycopersicum L.)
(Society for Plant Research, 2017) Kartikeya Srivastava; Sunil Kumar; H.R. Bhandari; A. Vaishampayan
High temperature during crop growth severely restricts the yield and quality of tomato. Pollen viability, pollen germination, corolla tip burning, stigma exertion, membrane thermo-stability and fruit set are affected severely under high temperature and in turn affect total yield. An improvement in these traits may result in increased tolerance towards high temperature. This necessitates knowledge of gene action governing these traits under target environment. Hence, present investigation was carried out to unravel the gene action governing these traits using six generations of ten interacting crosses of tomato under high temperature regime. Pooled data over two years were used for statistical analysis. The results revealed complementary gene action for corolla tip burning in all the crosses. In contrast, stigma exertion was controlled by duplicate gene action in all the cross-combinations. For rest of the traits duplicate gene action was noted in majority of the crosses. Significant and high values of epistatic variances are suggestive of efficacy of selection between families and lines following hybridization. © 2017, SPR, All Rights Reserved.
Inheritance studies on Cercospora leaf spot (CLS) resistance in mung and urdbean
(Society for Plant Research, 2017) D.K. Singh; A. Vaishampayan; M.N. Singh; S.K. Singh; Prudhvi Raj Vennela; Varsha Gayatonde; Deepak Kumar Jaiswal; Vaibhav Singh
Knowledge of inheritance pattern is prerequisite for breeding of any disease resistance. In the present experiment the inheritance pattern for Cercospora Leaf Spot (CLS) resistance in Mung bean was studied. Ten genotypes of mungbean were crossed with five genotypes of urd bean to obtain 50 crosses out of which only 15 crosses could be harvested successfully. Six CLS susceptible varieties were crossed with three CLS resistant genotypes of mungbean i.e. HUM-1, ML-1194 and ML-1229 to obtain 18 crosses, however 12 were successful. Out of these, 12 each of F1s, F2s and F3s of intra-specific crosses along with their parents and three each of F1s, F2s and F3s of inter-specific crosses along with their parents were grown in the field in compact family block design with three replications during kharif 2009. Highly susceptible variety HUM-8 was used as infector row for CLS after every two rows of the test entries. The F1 generation of all the intra and inter-spesific crosses showed resistant reaction to CLS. This indicates that resistance was dominant over susceptibility. The segregation ratios in F2 population of all the crosses except HUM-1 x Shekhar-2, was observed to be 3 (Resistant): 1 (Susceptible) and the segregation pattern within the F3 segregating population was also in agreement with the results of F2 observation further confirming the control of single dominant gene for inheritance of resistance to CLS. © 2017, SPR, All Rights Reserved.
Mutation from molybdenum-dependent growth to tungsten-dependent growth and further evidence for a genetic determinant common to nitrogenase and nitrate reductase in the blue-green alga nostoc muscorum
(1978) H.N. Singh; A. Vaishampayan; K.C. Sonie
[No abstract available]
Physiological significance of vanadium uptake during N2 and NC3- metabolism in various strains of a N2-fixing cyanobacterium nostoc muscorum
(1984) A. Vaishampayan; A. Hemantaranjan
The nitrogenase and nitrate reductase activities of the molybdenum (Mo)-requiring parent Nostoc muscorum and its tungsten (W)- and chromium (Cr)-requiring mutant strains, growing with Mo, W and Cr, respectively, were significantly enhanced by the addition of 0.063 μM vanadium (V). Such interactions were not observed with NO2- as a nitrogen source. © 1984 The Japanese Society of Plant Physiologists.
Plant-cyanobacterial symbiotic somaclones as a potential bionitrogen-fertilizer for paddy agriculture: Biotechnological approaches
(Elsevier GmbH, 1999) R.P. Sinha; A. Vaishampayan; D.-P. Häder
The role of N2-fixing cyanobacteria in improving the fertility of rice paddy fields is well known. Among all symbiotic associations, involving cyanobacteria, the Azolla-Anabaena complex is very efficient in water-logged rice paddy fields, contributing significant levels of nitrogen and organic matter thereby improving the physico-chemical properties of soils. This review focuses on some of the recent advances made in the areas of developing genetically improved somaclones of Azolla-Anabaena associative complex, and artificial plant-cyanobacterial symbiotic associations.
Reduced phosphorus requirement of a mutant Azolla-Anabaena symbiotic N2-fixing complex
(1992) A. Vaishampayan; Y.R. Reddy; B.D. Singh; R.M. Singh
The use of the photo-autotrophic nitrogen-fixing water fern Azolla as an effective source of organic nitrogen in tropical paddy fields has been limited by a high phosphorus requirement. Azolla species with a minimum of 1.5 to 2.0 mM phosphate (P) requirement, under controlled conditions, are known.A local Azolla species requiring at least 1.5 mM sodium phosphate for a normal rate of multiplication and N2 fixation was exposed to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). The resulting mutant population had a significantly lower P requirement, but was auxotrophic for glutamine with an extremely reduced glutamine synthetase (GS) activity. An L-methionine-DL-sulphoximine (MSX)-resistant (MSXr) Azolla population, having an approximately 1.5 times higher GS activity than that of the wild type (WT) parent organism, was cultured and subjected to MNNG-induced mutation for low P requirement while putting MSX as a control in the mutant selection medium. The resulting population of mutant Azolla was a normal prototroph with a P requirement as low as 0.75 mM for its 'WT parent-like' usual growth and N2 fixation. © 1992 Oxford University Press.
Screening of tomato genotypes for reproductive characters under high temperature stress conditions
(2012) Kartikeya Srivastava; Sunil Kumar; Surender Kumar; Pravin Prakash; A. Vaishampayan
A drastic decrease in tomato (Lycopersicon esculentum MIL L.) yield is recorded during the summer season in India, due to high temperature. Fruit-set at high temperature is strictly dependent on proper gametogenesis (pollen and ovule development) and fertilization of this plant. In this investigation, thirty four tomato genotypes were screened for tolerance to high temperature stress under spring-summer season (February to May) at the day and night temperature range of 32-44 °C and 19.6-26.7 °C, respectively. At an average day/night temperatures of 38 0C/22.2 0C, a significant increase in flower drop (22.55-42.56%), stigma exertion (7.82-50.35%) and significantly decrease in pollen viability (18.8-86.49%), pollen germination (15.29-67.59%) and fruit set truss-1 (21.7-56.15%); along with the relative cell injury ranging between 18 and 52%, were noted among the genotypes, as compared to that recorded in autumn-winter season under optimal temperature condition. On the basis of initial screening with respect to fruit set at high temperature stress, three lines i.e. FLA-7171, Pusa Sadabahar and NDTVR-60 emerged as heat tolerant genotypes. These lines, along with two highly heat susceptible varieties i.e. Floradade and H-86, were critically observed for the stress tolerance traits. The results demonstrated that: (1) the high temperature condition adversely affects the vegetative and reproductive parts of the plant; (2) membrane thermo-stability, pollen viability, pollen germination, stigma exertion, percentage of flower drop, and percentage of fruit set ability could be used as a selection criterion for heat tolerant genotypes with better fruit set, and (3) the three tomato genotypes Pusa Sadabahar, FLA-7171 and NDTVR-60 could affirmatively be useful as a source of heat tolerance genes for further breeding programs.
Toxic and mutagenic action of the herbicide alachlor (lasso) on various strains of the nitrogen-fixing blue-green alga Nostoc muscorum and characterization of the herbicide-induced mutants resistant to methylamine and l-methionine-dl-sulfoximine
(1979) H.N. Singh; H.R. Singh; A. Vaishampayan
Alachlor (lasso), like butachlor (machete) shows mutagenic properties when tested in Nostoc muscorum systems. The mutagenicity of the two herbicides seems considerably higher than that of MNNG (N-methyl-N′-nitro-N-nhitrosoguanidine). A dose of alachlor considerably higher than that of butachlor is needed to obtain a comparable level of growth inhibition and mutagenesis, thus suggesting that butachlor is the more efficient mutagen. Methylamine-resistant (MA-R) and l-methionine-dl-sulfoximine-resistant (MSO-R) mutants have been obtained spontaneously or following mutagenic treatment with either herbicide. MA-R strains appear to metabolize methylamine as a nitrogen source. MSO-R strains do not form heterocysts in NO3- or NH4+ medium containing or lacking MSO; the parent N. muscorum does not form heterocysts in NO3- or NH4+ medium lacking MSO but does form them in either nitrogen medium containing MSO. © 1979.
Use of genetically improved nitrogen-fixing cyanobacteria in rice paddy fields: Prospects as a source material for engineering herbicide sensitivity and resistance in plants
(Georg Thieme Verlag, 1998) A. Vaishampayan; R.P. Sinha; D.-P. Häder
Cyanobacteria are the largest and most widely distributed group of photosynthetic prokaryotes on Earth, forming a prominent component of microbial populations in wetland soils, especially in rice paddy fields, and significantly contributing to fertility as a natural biofertilizer. Modern agricultural fields are generally treated with high doses of synthetic nitrogenous fertilizers and pesticides having adverse effects on the soil microflora of naturally occurring N2-fixing cyanobacteria. This review deals with some of the advances made during the last few decades in the areas of developing ammonia derepressible pesticide-resistant cyanobacterial mutants for algalization of the wet agricultural fields as a viable and efficient N-photobiofertilizer.