Genetic analysis of Karnal bunt (Neovossia indica) resistance in wheat

Embryos excised from seeds of six generations (P₁, P₂, F₁, BC₁, BC₂ and F₂) of a cross WH 283 x WH 533 were cultured on modified MS medium already inoculated with secondary sporidia ofNeovossia indica. Significant variations for callusing response (CR) (54.55–75.55%) were observed among generations but the presence or absence ofN. indicia did not affect callusing response. A clear inhibition zone (IZ) was formed around each embryo showing callusing. The diameter of IZ varied significantly among generations and was maximum in the resistant genotype, WH 283 (3.60 cm). Fresh weight and dry weight of calli, initiated from embryo cultured and inoculated withN. indica, varied significantly among generations. Coefficient of infection as well as percentage of infection reflected the overdominance of susceptibility. Generation mean analysis showed that the three parameter model was adequate for diameter of IZ only. Six-parameter model showed that additive (in presence ofN. indica), additive and additive x dominance (in absence ofN. indica) effects were also significant. Complementary type of epistasis for fresh weight of calli and dominance, and dominance x dominance effects for dry weight of calli were observed in the presence ofN. indica. Magnitude of additive effects was higher for diameter of IZ in three parameter model. Therefore, selection might assist in improving this trait and thus indirectly help in attaining the resistance towardsN. indica.     

Synergistic/potentiation interaction between nematostatic constituents from Azadirachta indica,Madhuca indica and Sapindus mukorossi

Triterpenic saponins isolated from seeds of Madhuca indica and fruit pericarp from Sapindus mukorossi exhibited inhibitory effect against two phyto-parasitic nematodes. Azadirachtin and salanin-nimbin-desacetylnimbin (SND) was extracted from seeds and oil of Azadirachta indica A. Juss, respectively. M. indica and S. mukorossi saponins were found to inhibit the movement of pre-adult (J₄) stage of Rotylenchulus reniformis with LC₅₀ of 168.8 and 181.9 µg/mL. Azadirachtin and SND affected the mobility of secondary juvenile stage (J₂) of Meloidogyne incognita by 83.3 and 80.1% respectively, at 0.5 mg m/L. M. indica saponin (LC₅₀ 220 µg/mL) exhibited a potentiation effect in the presence of azadirachtin in a 1:3 ratio (LC₅₀ 120.1 µg/mL). A binary mixture (1:1) of azadirachtin and SND was found to show significant nematicidal activity against M. incognita (LC₅₀ 70.9 µg/mL) and R. reniformis (LC₅₀ 91.2 µg/mL).     

Survival in the dark: strategies adopted by Tetraselmis indica (Chlorodendrophyceae,Chlorophyta)

The adaptive strategy of Tetraselmis indica to survive darkness was evaluated over a period of 182 days. Resting cells formation and reduction in catabolic activity facilitated dark survival and their rejuvenation. The occurrence of thick-walled cells (type 1) and thin-walled cells with the condensed chloroplast (type 2) in light-dark and dark conditions respectively indicated differential resting cell formation. The dissolved organic carbon remained nearly constant throughout the dark period signifying T. indica did not favour heterotrophy. Upon re-illumination of dark-adapted cells, the lag phase lengthened from 2 to 28 days when darkness period increased from 8 to 182 days, respectively. However, this negative influence on growth was compensated by an increase in growth rate from 0.35 to 0.95 d^?1. This resurgence capability of T. indica after six months of dark exposure and distinctive resting cell formation indicate a differential population sustenance mechanism. Further elucidation of dark adaptability and survival strategies in T. indica may have significance in ecological and evolutionary processes.     

In vitro micropropagation of the macarronesian evergreen treePersea indica (L.) K. Spreng

Summary Shoot propagation ofPersea indica (L.) K. Spreng was achieved using seedling axillary buds cultured on MS (Murashige and Skoog, 1962) medium with 1 mg/l (2.8 μM) N⁶-benzyladenine (BA). Forty percent of the obtained shoots did not elongate, but showed bud proliferation, which was maximal (three axillary buds per shoot) at the end of the seventh subculture. Sixty percent of the shoots elongated, did not show bud proliferation, and formed calluses at their base. Successful rooting (84.6%) was achieved dipping the base of each elongated shoot in 3 g/l (16.11 mM) indolebutyric acid (IBA) for 1–2 s, and transferring to half strength MS medium without growth regulators. These shoots presented an acclimatization success of 100%. Results suggest that micropropagated elongated shoots ofP. indica can be adequately used in reforestation programs.     

Factors limiting the distribution ofDigitaria adscendens andEleusine indica on coastal sand dunes in Japan

Fate ofDigitaria adscendens andEleusine indica seedlings under field conditions and their responses to salt spray, drought and nutrients were experimentally investigated in order to evaluate the possible mechanisms controlling the different distributions of the two species in coastal sand dune areas. Salt spray produced no apparent positive effect on the growth or survival of both species. Seeds of each species germinated well in the field, although 80% ofE. indica seedlings died during a summer drought and surviving seedlings neither grew nor bore fruit. The mortality ofD. adscendens seedlings due to the drought was less than 10% and the survivors mostly bore fruit by the end of the growth season. No major difference in the sublethal water saturation deficit was noticed between the two species. However,D. adscendens individuals extended their roots into the deep sandy soil to a much greater extent in water-stressed conditions than in well watered conditions, whereasE. indica showed no such behavior. Additional watering in a dune environment did not help the growth ofE. indica seedlings, but additional nutrients had a markedly stimulatory effect.D. adscendens maintained its growth and fruition with much smaller amounts of nutrients thanE. indica. Soil nitrogen content at a site whereE. indica andD. adscendens were distributed sympatrically was higher than that at a site where onlyD. adscendens was present. Based on these findings, it is proposed thatE. indica seedlings are unable to become established because of their lower resistance to summer drought and the poor nutrient conditions present in a coastal rear sand dune habitat. Dedicated to Prof. emeritus Toshiro Saeki for his fruitful career in plant ecology.     

Endophytic fungus Piriformospora indica induced systemic resistance against rice sheath blight via affecting hydrogen peroxide and antioxidants

In this study, the effect of endophytic fungus Piriformospora indica on Rhizoctonia solani AG1-IA, causal agent of sheath blight disease, was investigated. In addition, plant defence responses activated in P. indica-inoculated rice plants were analysed. Two-week-old seedlings were inoculated by dipping their roots in P. indica chlamydospore suspension and transferred to pots containing sterilized soil. After two weeks, the seedlings pre-inoculated with P. indica were inoculated with R. solani. Statistical analysis of biological indicators showed that application of P. indica increased both fresh and dry weight of rice shoots and roots, compared to those of uninoculated healthy controls and the samples only inoculated with R. solani. Accumulation of hydrogen peroxide (H₂O₂) and activity of antioxidants such as superoxide dismutase (SOD) and guaiacol peroxidase (GPX) in plants inoculated with P. indica, R. solani, and P. indica-R. solani were investigated. The obtained results revealed that P. indica not only increased the plant biomass, but also delayed the infection process of R. solani and decreased sheath blight severity. Decreased severity of the disease was associated with decreased levels of H₂O₂ and increased SOD activity. Considering the necessity of reducing fungicide application, using P. indica in seedling bed before transplantation to the field could be a novel and effective method to increase rice production and decrease sheath blight progress.     

Antifungal activity of berberine iodide, a constituent ofFumaria indica

Berberine iodide, an isoquinoline alkaloid was isolated fromFumaria indica and its efficacy was tested against spore germination of some plant parasitic as well as saprophytic fungi. The alkaloid significantly curbed spore germination ofCurvularia lunata, Erysiphe cichoracearum, E. pisi, Fusarium udum andPenicillium species. Complete inhibition (100%) of spore germination was observed inE. cichoracearum andPenicillium species at 1.5 g/L.Albugo candida andAlternaria species were not affected by the chemical.     

Photosynthesis and water-relation traits of the summer annual C4 grasses, Eleusine indica and Digitaria adscendens, with contrasting trampling tolerance

Two summer annual C₄ grasses with different trampling susceptibilities were grown as potted plants, and diurnal leaf gas exchange and leaf water potential in each grass were compared. The maximum net photosynthetic rate, leaf conductance and transpiration rate were higher in the trampling-tolerant Eleusine indica (L.) Gaertn. than in trampling sensitive Digitaria adscendens (H. B. K.) Henr. Leaf water potential was much lower in E. indica than in D. adscendens. There were no differences in soil-to-leaf hydraulic conductance and leaf osmotic potential at full turgor as obtained by pressure–volume analysis. However, the bulk modulus of elasticity in cell walls was higher in E. indica leaves than in D. adscendens leaves. This shows that the leaves of E. indica are less elastic. Therefore, the rigid cell walls of E. indica leaves reduced leaf water potential rapidly by decreasing the leaf water content, supporting a high transpiration rate with high leaf conductance. In trampled habitats, such lowering of leaf water potential in E. indica might play a role in water absorption from the compacted soil. In contrast, the ability of D. adscendens to colonize dry habitats such as coastal sand dunes appears to be due to its lower transpiration rate and its higher leaf water potential which is not strongly affected by decreasing leaf water content.     

Cadmium modulates NADPH oxidase activity and expression in sunflower leaves

The production of reactive oxygen species (ROS) and the ways by which ROS are generated are very important facts related to heavy metal toxicity in plants. In this work, superoxide anion (O₂ ^·−) generation diminished in cadmium treated sunflower (Helianthus annuus L.) leaf discs, and this reduction was time and Cd-concentration dependent. In line with these findings, we observed that NADPH-dependent oxidase activity was significantly inhibited by 0.1 and 0.5 mM Cd²⁺ treatments and the expression of the NADPH oxidase putative gene related to O₂ ^·− synthesis in sunflower leaves was 83 % inhibited by 0.1 mM CdCl₂ and almost completely depleted by 0.5 mM CdCl₂.     

Cytotaxonomic study on two putative hybrids in the genusDuchesnea (Rosaceae)

The karyotypes and chromosome associations at meiosis in two types of natural hybrids, 7x and 8x, betweenDuchesnea chrysantha (2x) andD. indica (12x) were investigated. The 7x hybrid had a haploid chromosome set from each parent plant, whereas the 8x hybrid was considered to have a full set ofD. chrysantha and half a set ofD. indica. In the two hybrids, the chromosomes ofD. chrysantha andD. indica conjugated only slightly at meiosis. It is probable that no common genome set between the diploidD. chrysantha and the dodecaploidD. indica exists. The present evidence indicates thatD. chrysantha andD. indica should be considered to be distinct species, although they have sometimes been treated as a single species.     

Feeding inhibition of Helicoverpa armigera （HiJbner） by Eucalyptus camaldulensis and Tylophora indica extracts

Crude leaf extracts of Eucalyptus camaldulensis and Tylophora indica were evaluated for their antifeedancy against Helicoverpa armigera larvae in no-choice bioassays. Cabbage leaf-disc dipped in different concentrations of leaf extracts was used for feeding fifth instars of H. armigera for 24 hours. Ethanol extracts from both the plant species exhibited significant feeding inhibition, activity. The effective concentrations of ethanol extracts that caused 50% reduction in larval feeding （EI50） were 6.9% for E. camaldulensis and 2.8% for T. indica, while these values of hexane extracts were 9.3% and 5.2%, respectively. Compared to the crude leaf extracts, crude alkaloids from T. indica and crude tannins from E. camaldulensis were more potent in reducing larval feedings.     

Phytochrome inhibits the effectiveness of gibberellins to induce cell elongation in rice

Red light controls cell elongation in seedlings of rice (Oryza sativa L.) in a far-red-reversible manner (Nick and Furuya, 1993, Plant Growth Regul. 12, 195–206). The role of gibberellins and microtubules in the transduction of this response was investigated in the rice cultivars Nihon Masari (japonica type) and Kasarath (indica type). The dose dependence of mesocotyl elongation on applied gibberellic acid (GA₃) was shifted by red light, and this shift was reversed by far-red light. In contrast, coleoptile elongation was found to be independent of exogenous GA₃. Nevertheless, it was inhibited by red light, and this inhibition was reversed by far-red light. The content of the active gibberellin species GA₁ and GA₄ was estimated by radio-immunoassay. In the mesocotyl, the gibberellin content per cell was found to increase after irradiation with red light, and this increase was far-red reversible. Conversely, the cellular gibberellin content in japonica-type coleoptiles did not exhibit any significant light response. Microtubules reoriented from transverse to longitudinal arrays in response to red light and this reorientation could be reversed by subsequent far-red light in both the coleoptile and the mesocotyl. This movement was accompanied by changes in cell-wall birefringence, indicating parallel reorientations of cellulose deposition. The data indicate that phytochrome regulates the sensitivity of the tissue towards gibberellins, that gibberellin synthesis is controlled in a negative-feedback loop dependent on gibberellin effectiveness, and that at least two hormone-triggered signal chains are linked to the cytoskeleton in rice.Abbreviations D darkness - FR far-red light - GA₃ gibberellic acid - GC-SIM gas chromatography-selected ion monitoring - R red light This work was supported by a grant of the Human Frontier Science Organization to P.N. Advice and organizational support by Prof. M. Furuya (Hitachi Advanced Research Laboratory, Hatoyama, Japan) and Prof. N. Murofushi (Department of Agricultural Chemistry, University of Tokyo, Japan) is gratefully acknowledged. Seeds of both rice cultivars were kindly provided by Dr. O. Yatou (Institute for Radiation Breeding, Hitachi-Ohmiya, Japan), and the antiGA₁ Me-antiserum for the radio-immunoassays by Dr. I. Yamaguchi (Department of Agricultural Chemistry, University of Tokyo, Japan).     

Uptake of sulphate,taurine, cysteine and methionine by symbiotic and free-living dinoflagellates

Sulphate uptake by Amphidinium carterae, Amphidinium klebsii and Gymnodinium microadriaticum grown on artificial seawater medium with sulphate, cysteine, methionine or taurine as sulphur source occurred via an active transport system which conformed to Michaelis-Menten type saturation kinetics. Values for K _m ranged from 0.18–2.13 mM and V _max ranged from 0.2–24.2 nmol · 10⁵ cells^–1 · h^–1. K _m for symbiotic G. microadriaticum was 0.48 mM and V _max was 0.2 nmol · 10⁵ cells^–1 · h^–1. Sulphate uptake was slightly inhibited by chromate and selenate, but not by tungstate, molybdate, sulphite or thiosulphate. Cysteine and methionine (0.1 mM), but not taurine, inhibited sulphate uptake by symbiotic G. microadriaticum, but not by the two species of Amphidinium. Uptake was inhibited 45–97% under both light and dark conditions by carbonylcyanide 3-chlorophenylhydrazone (CCCP); under dark conditions sulphate uptake was 40–60% of that observed under light conditions and was little affected by 3-(3,4-dichlorophenyl) 1,1-dimethylurea (DCMU).The uptake of taurine, cysteine and methionine by A. carterae, A. klebsii, cultured and symbiotic G. microadriaticum conformed to Michaelis-Menten type saturation kinetics. K _m values of taurine uptake ranged from 1.9–10 mM; for cysteine uptake from 0.6–3.2 mM and methionine from 0.001–0.021 mM. Cysteine induced a taurine uptake system with a K _m of 0.3–0.7 mM. Cysteine and methionine uptake by all organisms was largely unaffected by darkness or by DCMU in light or darkness. CCCP significantly inhibited uptake of these amino acids. Thus energy for cysteine and methionine uptake was supplied mainly by respiration. Taurine uptake by A. carterae was independent of light but was inhibited by CCCP, whereas uptake by A. klebsii and symbiotic G. microadriaticum was partially dependent on photosynthetic energy. Taurine uptake by cultured G. microadriaticum was more dependent on photosynthetic energy and was more sensitive to CCCP. Cysteine inhibited uptake of methionine and taurine by cultured and symbiotic G. microadriaticum to a greater extent than in the Amphidinium species. Methionine did not greatly affect taurine uptake, but did inhibit cysteine uptake. Taurine did not affect the uptake of cysteine or methionine.     

Cell elongation and cell division in elongating lettuce hypocotyl sections

The roles of cell division and cell elongation in the growth of sections excised from hypocotyls of lettuce (Lactuca sativa L. cv. Arctic) were investigated. Elongation of sections incubated in the light is inhibited compared to dark-grown sections and this inhibition is reversed by gibberellic acid (GA₃). The elongation of both dark-grown and GA₃-treated, light-grown sections can be enhanced by 10mM KCl. Under all conditions of incubation, elongation growth is greatest in the uppermost quarter of the hypocotyl section while the basal quarter does not elongate. In darkness the two apical segments of sections marked into four equal parts grow at the same rate, while in light, growth of the apical segment exceeds that of the second segment. Cell division in cortical or epidermal cells, as measured by mitotic index or cell number, is not affected by illumination conditions nor by GA₃ or KCl treatments. Although -irradiation and FUDR pretreatment eliminate or cause a marked reduction in cell division in the excised hypocotyl, sections from seeds irradiated with -rays or incubated in 5-fluorodeoxyuridine elongate in response to GA₃ and KCl treatment as do sections from non-pretreated controls. Therefore, since neither GA₃ nor darkness affect celldivision activity and since treatments which eliminate or significantly reduce cell division do not affect growth, we conclude that the effect of GA₃ and darkness in this material is to increase cell elongation.Abbreviations FUDR 5-fluorodeoxyuridine - GA(s) gibberellin(s) - GA₃ gibberellic acid     

Protective antifungal effect of neem (Azadirachta indica) extracts on mango (Mangifera indica) and rain tree (Albizia saman) wood

Neem (Azadirachta indica) extract (NE) and NE combined with copper sulfate and boric acid (NECB) were examined for their protective effect against fungal deterioration of mango (Mangifera indica) and rain tree (Albizia saman) wood. Growth of the white-rot fungus Schizophyllum commune was completely inhibited on solid medium containing 1.8% (w/w) NE or 5% (w/w) NECB. The average weight losses of NE and NECB treated wood blocks inoculated with S. commune were respectively 4.7% and 3.3% for M. indica and 4.1% and 3.0% for A. saman. These numbers were significantly lower compared to those obtained in the untreated condition. Similar observations were also noticed in the case of field tests. An average increase of life span of M. indica and A. saman due to NE treatment compared to untreated samples was about 6–7 times higher. Therefore, both NE and NECB treatments are promising preservation options for enhancing the durability of both M. indica and A. saman woods.     

Using Heading date 1 preponderant alleles from indica cultivars to breed high‐yield,high‐quality japonica rice varieties for cultivation in south China

Heading date 1 (Hd1) is an important gene for the regulation of flowering in rice, but its variation in major cultivated rice varieties, and the effect of this variation on yield and quality, remains unknown. In this study, we selected 123 major rice varieties cultivated in China from 1936 to 2009 to analyse the relationship between the Hd1 alleles and yield‐related traits. Among these varieties, 19 haplotypes were detected in Hd1, including two major haplotypes (H8 and H13) in the japonica group and three major haplotypes (H14, H15 and H16) in the indica group. Analysis of allele frequencies showed that the secondary branch number was the major aimed for Chinese indica breeding. In the five major haplotypes, SNP₃₁₆(C‐T) was the only difference between the two major japonica haplotypes, and SNP₄₉₅(C‐G) and SNP₆₁₄(G‐A) are the major SNPs in the three indica haplotypes. Association analysis showed that H16 is the most preponderant allele in modern cultivated Chinese indica varieties. Backcrossing this allele into the japonica variety Chunjiang06 improved yield without decreasing grain quality. Therefore, our analysis offers a new strategy for utilizing these preponderant alleles to improve yield and quality of japonica varieties for cultivation in the southern areas of China.     

Metabolic regulation of glycolate synthesis, photorespiration, and net photosynthesis in tobacco by L-glutamate

Experiments were undertaken to identify and characterize control mechanisms in tobacco leaf tissue which decrease the relative contribution of photorespiratory CO₂ release and thereby increase net photosynthetic CO₂ fixation. A number of metabolites were supplied to illuminated leaf discs and their effect on the inhibition of glycolate synthesis was measured. Glycolate accumulation, in the presence of α-hydroxy-2-pyridinemethanesulfonic acid, was inhibited in leaf discs previously floated on 30 mM solutions of either L-glutamate, L-aspartate, phospho-enolpyruvate, or glyoxylate. The effect of glutamate on glycolate synthesis, which was investigated in detail, was concentration- and time-dependent. Glycolate synthesis was inhibited about 40% by treating leaf discs with 30 mM glutamate, and the inhibition continued for more than 4 hours after the glutamate solution was removed.     

Improved Al tolerance of saffron (Crocus sativus L.) by exogenous polyamines

The aluminum (Al) tolerance of saffron (Crocus sativus L.) in hydroponics and the method of improving Al tolerance were investigated. Compared with the Al-free control, saffron root elongation was decreased by 59.3 and 75% at 0.05 and 0.2 mM Al stress, respectively. At 0.5 mM Al stress, the root elongation was inhibited completely. Addition of 1 mM polyamines improved saffron root growth markedly at 0.2 mM Al stress. Putrescine (Put) showed better amelioration effect than spermidine (Spd) and spermine (Spm). The root elongation in Put treatment was only 15% lower than that of Al-free control. The alleviation of Al rhizotoxicity by polyamines might be attributed to lower Al content in the root tips, and subsequent less lipid peroxidation and oxidative stress. Higher activities of amine oxidases and Hydrogen peroxide (H₂O₂) content might decrease the effects of Spd and Spm on alleviating oxidative damage compared with that of Put.     

Effect of activated charcoal and 6-benzyladenine on in vitro nitrogen uptake by Lagerstroemia indica

A sterile hydroponic culture system suitable for studying nitrogen (N) uptake ofLagerstroemia indica L.in vitro was developed. Four different treatments were assayed: with and without activated charcoal (AC and NAC, respectively), with and without 50 μM of 6-benzyladenine (+BA and −BA, respectively). Medium pH, electrical conductivity (EC), NO₃ ⁻ and NH₄ ⁺ concentrations were measured weekly. At the end of the culture, propagules were sampled and SPAD indices, and shoot and root fresh weights were determined. Explants grown in media with activated charcoal were able to take up both NO₃ ⁻ and NH₄ ⁺, although NH₄ ⁺ uptake was lower. Subsequently the pH of the media was maintained between 5.5–6.0. In treatments with no addition of activated charcoal, NH₄ ⁺ uptake was preferential and the pH dropped to 3.1. Explants in these conditions were unable to raise the pH by taking up NO₃ ⁻, especially when root morphogenesis was inhibited by addition of BA. Supply of this PGR produced root growth inhibition, which was almost complete in the treatment without activated charcoal. This component significantly reduced the inhibitory effect of 50 μM BA on root growth. This revised version was published online in June 2006 with corrections to the Cover Date.