Salinity tolerance of mung bean (Vigna radiata L.): Seed production

Plant growth and seed yield of mung bean were studied in sand culture at different levels of NaCl [0, 50, 100, 150, 200, 250 mM] in the root medium. Results showed that both dry matter yield and seed yield of plants grown for 14 weeks at 50 mM NaCl and 100 mM NaCl were around 60 % and 25 %, respectively of those for plants grown in control solution. Higher concentrations caused wilting and necrosis of leaves. Very effective exclusion of Na and Cl from salt grown mung bean seed was observed with concommitant high accumulation of Na and Cl in the stem. It is speculated that mung bean plant stem may act as a ‘sink’ for NaCl during the reproductive stage of the plant growth cycle.     

Characterization of new microsatellite markers in mung bean,Vigna radiata (L.)

The present work reports the isolation and characterization of new polymorphic microsatellites in mung bean (Vigna radiata L.). Of 93 designed primer pairs, seven were found to amplify polymorphic microsatellite loci, which were then characterized using 34 mung bean accessions. The number of alleles ranged from two to five alleles per locus with an average of three alleles. Observed and expected heterozygosity values ranged from 0 to 0.088 and from 0.275 to 0.683, respectively. All seven loci showed significant deviations from Hardy–Weinberg equilibrium, whereas only one pairwise combination (GBssr‐MB77 and GBssr‐MB91) exhibited significant departure from linkage disequilibrium. These newly developed markers are currently being utilized for diversity assessment within the mung bean germplasm collection of the Korean Gene Bank.     

Connections between dictyosomes,ER and GERL in cotyledons of mung bean (Vigna radiata L.)

Summary The connections and structural inter-relations of dictyosomes and endoplasmic reticulum (ER) in cotyledons of germinating mung beans were studied using thick (0.3 m) sections of aldehyde fixed, zinc iodide-osmium tetroxide (ZIO) impregnated tissue. The sections were examined by conventional (100 kV), rather than high voltage, transmission electron microscopy.Continuity of cisternal ER with tubular ER was confirmed and a direct connection of tubular ER totrans dictyosome cisternae was observed as were GERL networks associated withtrans dictyosome cisternae.Dictyosomes also gave rise to an extensive system of very fine tubules (10–20 nm diam) which have not been described previously in plant tissue. These tubules, which originated at thetrans dictyosome face, extended throughout the cytoplasm and were found connected to cisternal ER and tubular ER.The implications of these observations are discussed with regard to present ideas concerning endomembrane flow and protein sorting by the Golgi apparatus.     

Variation in elemental composition as influenced by chlorpyrifos application in mung bean (Vigna radiata L.)

Chlorpyrifos (O,O-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate), is an organophosphate insecticide effective against a broad spectrum of insect pests of economically important crops. The present study investigated the effects of chlorpyrifos application on sulfate assimilation and macro elemental composition in different plant parts at different phenological stages. Field experiments were conducted in the month of April 2008–2009. The individual plot size was 6 m² (4 m × 1.5 m) having 4 rows with a row-to-row distance of 15 inches and plant to plant distance of 10 inches. The number of plants per m² was 15. Seedlings were collected at 5 (preflowering), 10 (flowering) and 20 (postflowering) DAT (day after treatment) to analyze the effect of chlorpyrifos on APR activity and elemental composition. At harvest stage, seed from individual treatments were analyzed for sulfur containing amino acids like methionine and cysteine content. Twenty-day-old seedlings of Vigna radiata L. were subjected to chlorpyrifos at different concentrations ranging from 0 to 1.5 mM through foliar spray in the field condition. A significant increase (50% in cysteine content and 50–92% in methionine content) in sulfur containing amino acids at a higher dose rate of 1.5 mM was recorded in seeds, however the increased activity of adenosine 5-phosphosulfate reductase (APR), the key enzyme in sulfate assimilation was recorded in all the three parts of the plant (leaf, stem, root.). Transiently lower nitrogen, sulfur and carbon content in 0.6 and 1.5 mM chlorpyrifos application in V. radiata L. supports the inhibition of metabolic processes. However, reverse trend was exhibited at 0.3 mM for same parameters. These results suggest the stimulatory effects on sulfate assimilation in V. radiata L. while as inhibitory effects were prevalent on elemental composition.     

Probing the responses of barley cultivars (Hordeum vulgare L.) by chlorophyll a fluorescence OLKJIP under drought stress and re-watering

The main objective of this study was to evaluate the effects of drought and re-watering on 10 varieties of barley (Hordeum vulgare L.) originating from Morocco. Five varieties obtained from the National Institute of Agricultural Research (INRA) of Morocco and five landraces (local varieties defined by high stress tolerance, high yield stability, an intermediate yield and low-input demand) collected at five localities in the south of Morocco were used in the present study. After 2 weeks of growth, drought stress was initiated by withholding water for 2 weeks followed by 1 week of re-watering. The polyphasic OJIP fluorescence transient was used to evaluate photosystem II (PSII) criteria at the end of the first week of drought stress (moderate drought), at the end of the second week (severe drought) and the end of the recovery phase. Drought and re-watering had little effect on the maximum quantum yield of primary photochemistry φ_Po(=F_V/F_M). The photosynthetic performance index (PI) is the product of an antenna, reaction center and electron transport dependent parameter. It revealed differences between varieties as a function of drought and re-watering. For the screening for drought stress tolerance, changes in the PI during a 2-week drought stress treatment were analysed and a new parameter was defined: the drought factor index (DFI) = log(PI_week 1/PI_control) + 2 log(PI_week 2/PI_control). The DFI of the tested varieties correlated with their drought tolerance. Another parameter that was analysed was the relative water content. It decreased during the drought stress treatment varying between 61% and 78.2% at the end of the drought period. During the subsequent recovery period, it increased in a species-dependent manner (65.1–94.1%). A third parameter studied were changes in the initial fluorescence rise. The fluorescence rise during the first 300 μs (L-band) can give information on the energetic connectivity between PSII units whereas changes in the rise during the first 2 ms (K-band) offer information on developing limitations on the donor side of PSII. Changes in respectively the L and K-bands of the fluorescence transients OJIP were shown to have predictive value with respect to the vitality of leaves and the tolerance of the varieties to drought stress.     

Copper oxide nanoparticle toxicity in mung bean (Vigna radiata L.) seedlings: physiological and molecular level responses of in vitro grown plants

In this study, the toxic effect of copper oxide nanoparticles (CuONPs) at the physiological and molecular level was investigated in mung bean (Vigna radiata L.) plants. The seedlings were grown in half strength Murashige and Skoog medium supplemented with different concentrations of CuONPs (0, 20, 50, 100, 200 and 500 mg l^?1) for 21 days under controlled growth conditions. Exposure to 200 and 500 mg l^?1 of CuONPs significantly reduced shoot length and biomass. Significant reduction in root length and biomass was observed upon exposure to all concentrations of CuONPs. Retardation of primary and lateral root growth was observed upon exposure to different concentrations of CuONPs. At 100, 200 and 500 mg l^?1 of CuONPs exposure, the total chlorophyll contents reduced significantly. Exposure to different concentrations of CuONPs has not resulted in any significant change in carotenoid contents. The proline content significantly increased upon exposure to 100, 200 and 500 mg l^?1 of CuONPs. Significant increase in hydrogen peroxide content and lipid peroxidation was observed in roots upon exposure to 20, 50, 100, 200 and 500 mg l^?1 of CuONPs. Histochemical staining with nitroblue tetrazolium and treatment with 3′-(p-hydroxyphenyl) fluorescein indicated a concentration-dependent increase in reactive oxygen species generation in roots. Exposure to CuONPs has resulted in excess lignification of roots cells as revealed by phloroglucionol-HCl staining. Gene expression analysis using real-time polymerase chain reaction showed modulations in the expression of CuZn superoxide dismutase, catalase and ascorbate peroxidase genes in roots of CuONPs exposed plants.     

Random amplified polymorphic DNA (RAPD) analysis in Indian mung bean (Vigna radiata (L.) Wilczek) cultivars

Greengram [Vigna radiata (L.) Wilczek], also known as mung bean, widely cultivated in a large number of countries, is an important pulse crop of Asia and is considered one of the ancestral species of the genus Vigna. Since yields of greengram have remained low across subtropical and tropical Asia, it is important to estimate genetic diversity in existing cultivars in order to see if the lack of genetic variability might be a constraining factor. In this study, 32 Indian cultivars of greengram were subjected to random amplified polymorphic DNA (RAPD) analysis using 21 decamer primers. A total of 267 amplification products were formed at an average of 12.71 per primer with an overall polymorphism of 64%. The extent of polymorphism was moderate to low. Jaccard similarity coefficient values ranged from 0.65 to 0.92. The cluster analysis resulted in mainly three clusters revealing greater homology between cultivars released from the same source. The results of principal components analysis also substantiated this conclusion. The close genetic similarity between the cultivars could be explained due to the high degree of commonness in their pedigrees. The narrow genetic base of the greengram cultivars revealed in the present analysis emphasises the need to exploit the large germplasm collections having diverse morphoagronomic traits in cultivar improvement programs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Histological study of callus formation and root regeneration from mung bean (Vigna radiata W.)

We have established a reproducible culture system for callus formation and root development from juvenile stem segments of mung bean(Vigna radiata). In particular, we have studied the influence of plant growth regulators. Induction of calli from young stem explants was very effective on MS inorganic salts supplemented with 0.5 mg/L 2,4-D and 1.0 mg/L kinetin. In regenerating adventitious roots from callus tissues, we found that a combination of 0.75 mg/L NAA, 1.5 mg/L kinetin, and MS salts resulted in 20% efficiency. Histological examination showed that callus tissues originated from out-growths of the cambium rings through de-novo meristematic activity. Those rings were localized outside the vascular cambium. Adventitious roots that developed from root primordia originated from the center of the Callus masses. These primordia produced tracheid-like cells, which then became meristemoid cells for the cambium. Newly formed adventitious roots had the typical tetrarche actinostele type.     

Effect of plant growth promoting rhizobacteria containing ACC-deaminase on maize (Zea mays L.) growth under axenic conditions and on nodulation in mung bean (Vigna radiata L.)

AIMS: This study was conducted to test the hypothesis that the bacterial strains possessing 1-aminocyclopropane-1-carboxylic acid (ACC)-deaminase activity may also promote growth of inoculated plants and could increase nodulation in legumes upon co-inoculation with rhizobia. METHODS AND RESULTS: Several rhizobacteria were isolated from maize rhizosphere through enrichment on ACC as a sole N source. Purified isolates were screened for growth promotion in maize under axenic conditions and for in vitro ACC-deaminase activity. A significant positive correlation was observed between in vitro ACC-deaminase activity of bacterial cells and root elongation. None of the isolates produced auxins. Bradyrhizobium japonicum produced less amount of auxins but did not carry ACC-deaminase activity. Results of pot experiment revealed that co-inoculation with Bradyrhizobium and plant growth promoting rhizobacteria (PGPR) isolates enhanced the nodulation in mung bean compared with inoculation with Bradyrhizobium alone. CONCLUSIONS: It is highly expected that inoculation with rhizobacteria containing ACC-deaminase hydrolysed endogenous ACC into ammonia and alpha-ketobutyrate instead of ethylene. Consequently, root and shoot growth as well as nodulation were promoted. SIGNIFICANCE AND IMPACT OF THE STUDY: The ACC-deaminase trait could be employed as an efficient tool to screen effective PGPR, which could be successfully used as biofertilizers to increase the growth of inoculated plants as well as nodulation in legumes.     

A quantitative description of fluorescence excitation spectra in intact bean leaves greened under intermittent light

We present a simple approach for the calculation of in vivo fluorescence excitation spectra from measured absorbance spectra of the isolated pigments involved. Taking into account shading of the pigments by each other, energy transfer from carotene to chlorophyll a, and light scattering by the leaf tissue, we arrive at a model function with 6 free parameters. Fitting them to the measured fluorescence excitation spectrum yields good correspondence between theory and experiment, and parameter estimates which agree with independent measurements. The results are discussed with respect to the origin and the interpretation of in vivo excitation spectra in general.     

Changes in oxidative stress defense system in wheat (Triticum aestivum L.) and mung bean (Vigna radiata L.) cultivars grown with and without mineral nutrients and irradiated by supplemental ultraviolet-B

Field study was conducted to evaluate the inter- and intra-specific variations in sensitivity of two cultivars each of wheat (Triticum aestivum L. cv. HD 2329 and HUW 234) and mung bean (Vigna radiata L. cv. Malviya Jyoti and Malviya Janpriya) to supplemental levels of UV-B irradiation (sUV-B, 280–315 nm) with and without recommended levels of mineral nutrients. Results showed decrease in photosynthetic pigments and biomass of all the four cultivars due to sUV-B radiation. Antioxidative defense system was activated in all the cultivars after irradiation with sUV-B. SOD, peroxidase and total thiol contents increased, while catalase activity and ascorbic acid contents decreased under sUV-B irradiation. On the basis of biomass, UV-B sensitivity can be arranged in decreasing order as: Malviya Janpriya < Malviya Jyoti < HD 2329 < HUW 234. Application of mineral nutrients (N, P and K) showed significant positive response in all cultivars by ameliorating the negative impact of sUV-B.     

In vitro induction of multiple shoots and plant regeneration from shoot tips of mung bean (Vigna radiata (L.) Wilczek)

Conditions for plant regeneration from excised shoot tips of Vigna radiata were studied. Complete plants were regenerated directly without an intervening callus phase from shoot tips on basal medium (MS salts+B₅vitamins). Regeneration frequency varied with genotype, explant size and growth regulator combinations in the medium. Addition of cytokinins induced a variable amount of callus at the base of the shoot tip, followed by multiple shoot formation. Benzyladenine (BA), kinetin and zeatin at 5×10^-6 M each induced multiple shoots in 100% of the explants but the highest number of regenerants per explant (9) was produced with BA. The efficacy of BA for shoot multiplication was not improved when it was supplemented with naphthaleneacetic acid (NAA) or indoleacetic acid (IAA). NAA or adenine sulphate, when applied alone, induced complete plantlets. The growth regulator requirement of explants for the induction of multiple shoots varied with explant size. The shoot tip explants maintained proliferation ability on subculture. None of the treatments was effective in inducing shoot bud differentiation from callus. Regenerated shoots were rooted on MS basal medium and MS supplemented with either IAA or indolebutyric acid. The rooted plants were transferred to the field; 60% subsequently survived and grew.Abbreviations BM basal medium [MS (Murashige & Skoog 1962) salts+B₅ (Gamborg et al. 1968) vitamins] - BA 6-benzyladenine - AdS adenine sulphate - IAA indole-3-acetic acid - NAA-1 naphthaleneacetic acid - IBA indolebutyric acid     

Chlorophyll a fluorescence during flag leaf senescence of field-grown winter wheat plants under drought conditions

Improving wheat grain yield plays a significant role in ensuring global food security. Wheat production could be increased by the genetic improvement of wheat genotypes where delayed senescence with enhanced post-anthesis capacity and staygreen traits could have an important role. In this study, chlorophyll a fluorescence (ChlF) rise kinetics from the early until late senescence of flag leaves, grain yield and other agro-morphological characteristics were compared for three winter wheat advanced lines (Osk.4.312/10-18, Osk.4.330/6-18 and Osk.4.354/12-18) under natural drought conditions. The differences between lines were observed when considering the heading date which was 1 and 4 days earlier for the line Osk.4.354/12-18, than lines Osk.4.312/10-18 and Osk.4.330/6-18, respectively. Furthermore, line Osk.4.354/12-18 had the highest test weight (kg hl⁻¹), while line Osk.4.330/6-18 showed a tendency of decreased grain yield, compared to the other two lines. Analysis of ChlF transients and several JIP-test parameters indicated that all three lines had a generally similar course of changes in the photosynthetic performance of flag leaves during senescence under drought conditions. However, at the point when a decrease in photosynthetic performance was initiated, it was slightly less intensive in line Osk.4.354/12-18 accompanied by longer preservation of functionality and connectivity of PSII units, than in the other two lines, which contributed to its better agronomical performance. These results indicated that even delicate variations in the functioning of the photosynthetic apparatus of the flag leaf during grain filling were agronomically important, especially when plants were exposed to drought stress, and could be used to differentiate otherwise similar wheat genotypes. Even small genotype-specific differences in the photosynthetic performance of senescing flag leaves, along with earlier heading dates, could assist in the selection of genotypes with a better ability to cope with unfavourable environmental conditions.     

Morphogenetic responses from in vitro cultured seedling explants of mung bean (Vigna radiata L. Wilczek)

The morphogenetic responses of seedling explants of mung bean (Vigna radiata L. Wilczek cv ML-5) were studied in vitro. Direct induction of shoots/plants was possible from shoot tip, cotyledon and cotyledonary node explants. Dedifferentiation of the explants viz; Shoot tip, cotyledons, cotyledonary node, primordial leaves and roots was obtained on basal medium supplemented with auxin and cytokinin. Shoot regeneration was limited to primary calli while rhizogenesis was of common occurrence in established calli. In addition to differences in hormonal requirements, the various explants showed preferential growth in different basal media.     

Chlorophyll a fluorescence and CO2 exchange of Umbilicaria aprina under extreme light stress in the cold

A lichen growing in a continental Antarctic region with low temperatures and strong irradiance in summer was investigated for evidence of photoinhibition. Field experiments with Umbilicaria aprina from a sheltered site with heavy snowpack showed no effects of photoinhibition when the lichen was exposed to strong sun irradiance for nearly 11 h a day. This was evident from CO₂ exchange and simultaneous chlorophyll a fluorescence measurements. CO₂ exchange was also not affected if quartz glass allowing greater UV penetration, was used as a lid for the cuvette. The dependency of net photosynthesis on photosynthetic photon flux density suggests that the lichen is photophilous. Received: 2 April 1997 / Accepted: 11 August 1997     

Yield, growth and physiological responses of mung bean [Vigna radiata (L.) Wilczek] genotypes to waterlogging at vegetative stage

A study was conducted to examine the physiological response of contrasting mung bean (Vigna radiata) genotypes viz., T 44 & MH–96–1 (tolerant) and Pusa Baisakhi & MH–1K–24 (sensitive) under waterlogging conditions. Plants were waterlogged at vegetative stage (30 days after sowing) for 3, 6 and 9 days. Waterlogging resulted in decreased leaf area, crop growth rate, root growth and nodules number, membrane stability index, photosynthesis rate, chlorophyll and carotenoid contents, flowering rate, pod setting, yield and altered dry matter partitioning. Sensitive genotypes showed large reductions in aforementioned physiological traits and slow recovery in photosynthesis rate. On the other hand, tolerant genotypes maintained higher photosynthetic rate, chlorophylls and carotenoids, growth rate, membrane stability and fast photosynthetic recovery under waterlogging. After 9 days of exposure to waterlogging, photosynthetic rate and yield losses in most sensitive genotype (MH-1K-24) were 83 and 85 %, respectively. On an average, photosynthetic loss at 3, 6 and 9 days of waterlogging was 43, 51, and 63 %, respectively, while grain yield loss was 20, 34 and 52 % respectively.     

Transmembrane topography of plasma membrane constituents in mung bean (Vigna radiata L.) hypocotyl cells. I. Transmembrane distribution of phospholipids.

The transmembrane distribution of phospholipids (PLs) in the plasma membrane (PM) of mung bean (Vigna radiata L.) hypocotyl cells was investigated using annexin V-fluorescein isothiocyanate, porcine pancreas phospholipase A(2), and (31)P-nuclear magnetic resonance (NMR) spectroscopy. Phosphatidylserine was not located on the cell surface of mung bean protoplasts. However, phosphatidylcholine, phosphatidylethanolamine and phosphatidic acid were found to be almost symmetrically distributed across right-side-out PM vesicles obtained by aqueous two-phase partitioning by porcine pancreas phospholipase A(2) assay. (31)P-NMR assay showed that the amount of PLs is about equal in the outer and the inner leaflets of the right-side-out PM vesicles. These results suggest that the topography of PM PLs might not contribute to well-known asymmetrical properties of the outer and inner surfaces of higher plant PMs. It is also indicated that inside-out PM vesicles created by Brij 58-treatment do not retain the native PL topography on dithionate reduction of 7-nitro-2,1,3-benzoxadiazol-4-yl-labeled PLs incorporated in the PM vesicles.     

The wild ancestors of urid and mung beans (Vigna mungo (L.) Hepper and V. radiata (L.) Wilczek)

The crop plants Vigna mungo (urid, urd or black gram) and V. radiata (mung bean or green gram: and related taxa have been studied by seed protein electrophoresis, leaf phenolics chromatography, vegetative morphology, and seed testa patterns. The results disprove the theory that these species are very closely related and have evolved from a single wild taxon. The present evidence shows that V. mungo var. mungo and I. radiata var. radiata have independent lineages and were domesticated from two very distinct taxa. namely V. mungo var. silvestris and V. radoata var. sublobata respectively.