Physiological and biochemical mechanisms of brassinosteroid in improving anti-cadmium stress ability of Panax notoginseng / 中国中药杂志

In this study, the effect of brassinosteroid(BR) on the physiological and biochemical conditions of 2-year-old Panax notoginseng under the cadmium stress was investigated by the pot experiments. The results showed that cadmium treatment at 10 mg·kg~(-1) inhibited the root viability of P. notoginseng, significantly increased the content of H_2O_2 and MDA in the leaves and roots of P. noto-ginseng, caused oxidative damage of P. notoginseng, and reduced the activities of SOD and CAT. Cadmium stress reduced the chlorophyll content of P. notoginseng, increased leaf F_o, reduced F_m, F_v/F_m, and PIABS, and damaged the photosynthesis system of P. notoginseng. Cadmium treatment increased the soluble sugar content of P. notoginseng leaves and roots, inhibited the synthesis of soluble proteins, reduced the fresh weight and dry weight, and inhibited the growth of P. notoginseng. External spray application of 0.1 mg·L~(-1) BR reduced the H_2O_2 and MDA content in P. notoginseng leaves and roots under the cadmium stress, alleviated cadmium-induced oxidative damage to P. notoginseng, improved the antioxidant enzyme activity and root activity of P. notoginseng, increased the content of chlorophyll, reduced the F_o of P. notoginseng leaves, increased F_m, F_v/F_m, and PIABS, alleviated the cadmium-induced damage to the photosynthesis system, and improved the synthesis ability of soluble proteins. In summary, BR can enhance the anti-cadmium stress ability of P. notoginseng by regulating the antioxidant enzyme system and photosynthesis system of P. notoginseng under the cadmium stress. In the context of 0.1 mg·L~(-1) BR, P. notoginseng can better absorb and utilize light energy and synthesize more nutrients, which is more suitable for the growth and development of P. notoginseng.

Transcriptome-wide identification and expression pattern analysis for Dof gene family in Panax ginseng from Jilin / 中国中药杂志

Dof(DNA binding with one finger), a unique class of transcription factors in plants, play an important role in seed development, tissue differentiation, and metabolic regulation. To identify the number and function of Dof gene family members in Panax ginseng, this study identified the members of Dof gene family in P. ginseng and systematically analyzed their structures, evolution, functional differentiation, expression patterns, and interactions using bioinformatics methods at the transcriptome level. At the same time, the association analysis of Dof genes from P. ginseng with key enzyme genes for ginsenoside synthesis was carried out to screen the candidate PgDof genes involved in the regulation of ginsenoside biosynthesis. The results showed that there were 54 genes belonging to the Dof gene family in P. ginseng from Jilin. All PgDof genes had Zf-Dof conserved motifs, implying that they were evolutionarily conserved and could be divided into five groups. Expression pattern analysis confirmed that the expression of PgDof gene family members in different tissues, different year-old P. ginseng, and different farm varieties varied significantly. Simultaneously, as revealed by "gene-saponin content" and "gene-gene" linkage analysis, an important candidate PgDof14-1 gene involved in the regulation of ginsenoside biosynthesis was obtained. From the established genetic transformation system of this gene in the hairy roots of P. ginseng, a positive hairy root clone was determined. This study has laid a theoretical foundation for the study of Dof gene family in P. ginseng.

Diterpenoid alkaloids from roots of Aconitum kongboense / 中国中药杂志

The chemical constituents from the roots of Aconitum kongboense were studied. Twenty-five diterpenoid alkaloids were isolated from the 95% methanol extract of the roots of A. kongboense by silica gel, reverse-phase silica gel and basic alumina column chromatography. They included a new aconitine-type diterpenoid alkaloid, named as kongboensenine(1), and twenty-four known ones(2-25), i.e., acotarine F(2), acotarine G(3), 14-acetyltalatisamine(4), talatisamine(5), indaconitine(6), yunaconitine(7), chasmanine(8), 6-epi-foresticine(9), homochasmanine(10), 8-deacetyl-yunaconitine(11), chasmaconitine(12), ajaconine(13), franchetine(14), ezochasmanine(15), crassicautine(16), 14-O-deacylcrassicausine(17), genicunine A(18), falconeridine(19), sachaconitine(20), liljestrandisine(21), 8-methyl-14-acetyltalatisamine(22), kongboendine(23), 14-benzoylchasmanine(24) and pseudaconine(25). Their structures were elucidated by common spectroscopic methods including high-resolution electrospray ionization mass spectrometry(HR-ESI-MS) and nuclear magnetic resonance(NMR) techniques. Compounds 2-4, 10, 13, 15-19 and 21-22 were isolated from this plant for the first time. Experimental results showed that all compounds did not have a significant inhibitory activity against acetylcholinesterase(AChE).

Stress and defense responses in plant secondary metabolites production

In the growth condition(s) of plants, numerous secondary metabolites (SMs) are produced by them to serve variety of cellular functions essential for physiological processes, and recent increasing evidences have implicated stress and defense response signaling in their production. The type and concentration(s) of secondary molecule(s) produced by a plant are determined by the species, genotype, physiology, developmental stage and environmental factors during growth. This suggests the physiological adaptive responses employed by various plant taxonomic groups in coping with the stress and defensive stimuli. The past recent decades had witnessed renewed interest to study abiotic factors that influence secondary metabolism during in vitro and in vivo growth of plants. Application of molecular biology tools and techniques are facilitating understanding the signaling processes and pathways involved in the SMs production at subcellular, cellular, organ and whole plant systems during in vivo and in vitro growth, with application in metabolic engineering of biosynthetic pathways intermediates.

Changes induced by co-inoculation in nitrogen-carbon metabolism in cowpea under salinity stress

ABSTRACT To mitigate the deleterious effects of abiotic stress, the use of plant growth-promoting bacteria along with diazotrophic bacteria has been increasing. The objectives of this study were to investigate the key enzymes related to nitrogen and carbon metabolism in the biological nitrogen fixation process and to elucidate the activities of these enzymes by the synergistic interaction between Bradyrhizobium and plant growth-promoting bacteria in the absence and presence of salt stress. Cowpea plants were cultivated under axenic conditions, inoculated with Bradyrhizobium and co-inoculated with Bradyrhizobium sp. and Actinomadura sp., Bradyrhizobium sp. and Bacillus sp., Bradyrhizobium sp. and Paenibacillus graminis, and Bradyrhizobium sp. and Streptomycessp.; the plants were also maintained in the absence (control) and presence of salt stress (50 mmolL-1 NaCl). Salinity reduced the amino acids, free ammonia, ureides, proteins and total nitrogen content in nodules and increased the levels of sucrose and soluble sugars. The co-inoculations responded differently to the activity of glutamine synthetase enzymes under salt stress, as well as glutamate synthase, glutamate dehydrogenase aminating, and acid invertase in the control and salt stress. Considering the development conditions of this experiment, co-inoculation with Bradyrhizobium sp. and Bacillus sp. in cowpea provided better symbiotic performance, mitigating the deleterious effects of salt stress.

Cadmium tolerance of Typha domingensis Pers. (Typhaceae) as related to growth and leaf morphophysiology / A tolerância ao cádmio por Typha domingensis Pers. (Typhaceae) correlacionada com o crescimento e a morfofisiologia foliar

Abstract Typha domingensis (cattail) is a native macrophyte known by its capacity to tolerate several heavy metals effects and the potential use for phytoremediation. However, in despite that cadmium (Cd) is one of the most toxic pollutants; its effects in T. domingensis biology remain uninvestigated. Thus, the objective of this study was to study the tolerance of T. domingensis to cadmium contamination by evaluating its growth, Cd uptake, leaf anatomy and gas exchange. The experiment was designed using three cadmium concentrations (0, 10 and 50 µM) and ten replicates for 90 days. The cadmium uptake, growth, gas exchange, chlorophyll content and leaf anatomy were evaluated. Data was submitted to ANOVA and Scott-Knott test for P<0.05. Typha domingensis accumulates Cd proportionally to its concentration on the solution and the content of this metal was higher in roots as compared to shoots. Plants showed no significant modifications on growth parameters such as the biomass production, number of leaves, number of clones and the biomass allocation to organs. The photosynthesis, transpiration and chlorophyll content were not modified by Cd. Most anatomical traits evaluated were not modified by the metal but the stomatal density and the proportion of vascular tissues were reduced under 50 µM of Cd. In despite, the leaf anatomy showed no toxicity evidences for any Cd level. The absence of growth reduction and the stability of anatomical and physiological traits give insight about the Cd tolerance of this species. Therefore, T. domingensis is able to overcome Cd toxicity and shows potential for phytoremediation.

Resumo A espécie Typha domingensis (taboa) é uma macrófita nativa conhecida por sua tolerância a vários metais pesados e potencial uso na fitorremediação. Contudo, apesar de que o Cd é um dos poluentes mais tóxicos; Seus efeitos em T. domingensis ainda não foram investigados. Assim, o objetivo desse estudo foi avaliar a tolerância de T. domingensis ao cádmio, avaliando o crescimento, absorção de Cd, anatomia foliar e trocas gasosas. O experimento foi conduzido utilizando três concentrações de Cd (0, 10 e 50 µM) e dez repetições por 90 dias.. O crescimento, trocas gasosas e o teor de clorofila e anatomia foliar foram avaliados. Os dados foram submetidos à ANOVA e ao teste de Scott-Knott para P<0,05. A absorção de cádmio, crescimento, trocas gasosas, teor de clorofila e anatomia foliar foram analisados. As plantas de T. domingensis podem acumular Cd proporcionalmente à sua concentração na solução e o teor deste metal foi maior nas raízes em comparação com a parte aérea. As plantas não apresentam modificações significativas nos parâmetros de crescimento como produção de biomassa, número de folhas, número de clones produzidos e alocação de biomassa nos órgãos. A fotossíntese, transpiração e conteúdo de clorofila não foram afetados de forma significativa pelo Cd. A maioria das características anatômicas avaliadas não apresentou diferenças, mas houve redução na densidade estomática e na proporção de tecidos vasculares na concentração de 50 µM de Cd. A anatomia foliar não mostrou evidências de toxicidade em nenhum dos níveis de Cd. A ausência de redução de crescimento e estabilidade das características anatômicas e fisiológicas caracteriza alta tolerância da espécie ao Cd. Portanto, T. domingensis é capaz de superar a toxicidade do Cd e demostra potencial para fitorremediação.

Contribution of dark septate fungi to the nutrient uptake and growth of rice plants

ABSTRACT The use of dark septate fungi (DSE) to promote plant growth can be beneficial to agriculture, and these organisms are important allies in the search for sustainable agriculture practices. This study investigates the contribution of dark septate fungi to the absorption of nutrients by rice plants and their ensuing growth. Four dark septate fungi isolates that were identified by Internal transcribed spacer phylogeny were inoculated in rice seeds (Cv. Piauí). The resulting root colonization was estimated and the kinetic parameters Vmax and Km were calculated from the nitrate contents of the nutrient solution. The macronutrient levels in the shoots, and the NO3--N, NH4+-N, free amino-N and soluble sugars in the roots, sheathes and leaves were measured. The rice roots were significantly colonized by all of the fungi, but in particular, isolate A103 increased the fresh and dry biomass of the shoots and the number of tillers per plant, amino-N, and soluble sugars as well as the N, P, K, Mg and S contents in comparison with the control treatment. When inoculated with isolates A103 and A101, the plants presented lower Km values, indicating affinity increases for NO3--N absorption. Therefore, the A103 Pleosporales fungus presented the highest potential for the promotion of rice plant growth, increasing the tillering and nutrients uptake, especially N (due to an enhanced affinity for N uptake) and P.

Endophytic Bacillus strains enhance pearl millet growth and nutrient uptake under low-P

Abstract Bacterial endophytes are considered to have a beneficial effect on host plants, improving their growth by different mechanisms. The objective of this study was to investigate the capacity of four endophytic Bacillus strains to solubilize iron phosphate (Fe-P), produce siderophores and indole-acetic acid (IAA) in vitro, and to evaluate their plant growth promotion ability in greenhouse conditions by inoculation into pearl millet cultivated in a P-deficient soils without P fertilization, with Araxá rock phosphate or soluble triple superphosphate. All strains solubilized Fe-P and three of them produced carboxylate-type siderophores and high levels of IAA in the presence of tryptophan. Positive effect of inoculation of some of these strains on shoot and root dry weight and the N P K content of plants cultivated in soil with no P fertilization might result from the synergistic combination of multiple plant growth promoting (PGP) traits. Specifically, while B1923 enhanced shoot and root dry weight and root N P content of plants cultivated with no P added, B2084 and B2088 strains showed positive performance on biomass production and accumulation of N P K in the shoot, indicating that they have higher potential to be microbial biofertilizer candidates for commercial applications in the absence of fertilization.

Endophytic fungus Purpureocillium sp. A5 protect mangrove plant Kandelia candel under copper stress

Abstract Mangrove is an important ecosystem in the world. Mangrove ecosystems have a large capacity in retaining heavy metals, and now they are usually considered as sinks for heavy metals. However, the mechanism of why the soil of mangrove ecosystems can retain heavy metal is not certain. In this research, endophytic fungus Purpureocillium sp. A5 was isolated and identified from the roots of Kandelia candel. When this fungus was added, it protected the growth of K. candel under Cu stress. This can be illustrated by analyzing chlorophyll A and B, RWC and WSD to leaves of K. candel. Purpureocillium sp. A5 reduces uptake of Cu in K. candel and changes the pH characterization of soil. Furthermore, A5 increase the concentration of Cu complexes in soil, and it enhanced the concentration of carbonate-bound Cu, Mn-Fe complexes Cu and organic-bound Cu in soil. Nevertheless, a significant reduction of the Cu ion was noted among A5-treated plants. This study is significant and illustrates a promising potential use for environmental remediation of endophytes, and also may partially explain the large capacity of mangrove ecosystems in retaining heavy metals.

Microbial transformation of ginsenosides extracted from Panax ginseng adventitious roots in an airlift bioreactor

Background: Ginsenoside is the most important secondary metabolite in ginseng. Natural sources of wild ginseng have been overexploited. Although root culture can reduce the length of the growth cycle of ginseng, the number of species of ginsenosides is reduced and their contents are lower in the adventitious roots of ginseng than in the roots of ginseng cultivated in the field. Results: In this study, 147 strains of ß-glucosidase-producing microorganisms were isolated from soil. Of these, strain K35 showed excellent activity for converting major ginsenosides into rare ginsenosides, and a NCBI BLAST of its 16S rDNA gene sequence showed that it was most closely related to Penicillium sp. (HQ608083.1). Strain K35 was used to ferment the adventitious root extract, and the fermentation products were analyzed by high-performance liquid chromatography. The results showed that the content of the rare ginsenoside CK was 0.253 mg mL-1 under the optimal converting conditions of 9 d of fermentation at pH 7.0 in LL medium, which was significantly higher than that in the adventitious roots of ginseng. Conclusion: These findings may not only solve the problem of low productivity of metabolite in ginseng root culture but may also result in the development of a new valuable method of manufacturing ginsenoside CK.

Effect of phosphorus on arsenic uptake and metabolism in rice cultivars differing in phosphorus use efficiency and response

ABSTRACT A hydroponic experiment was carried out to investigate the effect of phosphorus (P) nutrition on arsenic (As) uptake and translocation within the seedlings of rice cultivars. The experiment occurred in three stages: I 5 days of acclimatization (nutritive solution); II 10 days under P (0.0 and 0.09 mM) and As (0.0 and 100 mM) treatments; III 5 days under recovery. The As exposure had significant effect reducing dry weights of shoots or roots, resulted in elevated concentrations of As in shoot tissues. BR-IRGA 409 showed the highest susceptibility to As in biomass production and root system parameters regardless the P level. This cultivar showed contrasting responses of As translocation to shoot tissue dependent on P levels, with the highest As concentration under low P and lowest under normal P levels. P nutrition was most striking on plants recovery for all cultivars under As exposure. Clearer separation of cultivars for phosphorus use efficiency (PUE) occurred at lower shoot P contents, that was, at higher levels of P deficiency stress. IRGA 424 showed higher PUE as compared to the others cultivars. Our results go some way to understanding the role of P nutrition in controlling the effects of As in rice shoots.

Effect of arbuscular mycorrhizal fungi on young vines in copper-contaminated soil

Abstract High copper (Cu) levels in uprooted old vineyard soils may cause toxicity in transplanted young vines, although such toxicity may be reduced by inoculating plants with arbuscular mycorrhizal fungi (AMF). The objective of this study was to evaluate the effects of AMF on the plant growth, chlorophyll contents, mycorrhizal colonization, and Cu and phosphorus (P) absorption in young vines cultivated in a vineyard soil contaminated by Cu. Commercial vineyard soil with high Cu levels was placed in plastic tubes and transplanted with young vines, which were inoculated with six AMF species (Dentiscutata heterogama, Gigaspora gigantea, Acaulospora morrowiae, A. colombiana, Rhizophagus clarus, R. irregularis) and a control treatment on randomized blocks with 12 replicates. After 130 days, the mycorrhizal colonization, root and shoot dry matter (DM), height increment, P and Cu absorption, and chlorophyll contents were evaluated. The height increment, shoot DM and chlorophyll contents were not promoted by AMF, although the root DM was increased by R. clarus and R. irregularis, which had the greatest mycorrhizal colonization and P uptake. AMF increased Cu absorption but decreased its transport to shoots. Thus, AMF species, particularly R. clarus and R. irregularis, contribute to the establishment of young vines exposed to high Cu levels.

Screening and characterization of endophytic Bacillus and Paenibacillus strains from medicinal plant Lonicera japonica for use as potential plant growth promoters

Abstract A total of 48 endophytic bacteria were isolated from surface-sterilized tissues of the medicinal plant Lonicera japonica, which is grown in eastern China; six strains were selected for further study based on their potential ability to promote plant growth in vitro (siderophore and indoleacetic acid production). The bacteria were characterized by phylogenetically analyzing their 16S rRNA gene similarity, by examining their effect on the mycelial development of pathogenic fungi, by testing their potential plant growth-promoting characteristics, and by measuring wheat growth parameters after inoculation. Results showed that the number of endophytic bacteria in L. japonica varied among different tissues, but it remained relatively stable in the same tissues from four different plantation locations. Among the three endophytic strains, strains 122 and 124 both had high siderophore production, with the latter showing the highest phosphate solubilization activity (45.6 mg/L) and aminocyclopropane-1-carboxylic acid deaminase activity (47.3 nmol/mg/h). Strain 170 had the highest indoleacetic acid (IAA) production (49.2 mg/L) and cellulase and pectinase activities. After inoculation, most of the six selected isolates showed a strong capacity to promote wheat growth. Compared with the controls, the increase in the shoot length, root length, fresh weight, dry weight, and chlorophyll content was most remarkable in wheat seedlings inoculated with strain 130. The positive correlation between enzyme (cellulose and pectinase) activity and inhibition rate on Fusarium oxysporum, the IAA production, and the root length of wheat seedlings inoculated with each tested endophytic strain was significant in regression analysis. Deformity of pathogenic fungal mycelia was observed under a microscope after the interaction with the endophytic isolates. Such deformity may be directly related to the production of hydrolytic bacterial enzymes (cellulose and pectinase). The six endophytic bacterial strains were identified to be Paenibacillus and Bacillus strains based on the results of 16S rRNA gene sequencing analysis and their physiological and biochemical characteristics. Results indicate the promising application of endophytic bacteria to the biological control of pathogenic fungi and the improvement of wheat crop growth.

Phosphorus amendment competitively prevents chromium uptake and mitigates its toxicity in Spinacea oleracea L.

In this study, we assessed the role of phosphorus in preventing chromium uptake by plants. Two-factor complete randomized pot experiment (5x5 pattern) was conducted hydroponically with Spinacea oleracea L. (spinach), for 28 days in green house. Five concentrations of Cr (2.0, 3.5, 5.0, 6.5 and 8.0 mM), each amended with five concentrations of phosphorus (25, 50, 75, 100 and 125 mM) were supplied. With the phosphorus amendment in the growth medium, accumulation of chromium decreased up to 55% in root and 50% in shoot tissues. A 1.8-fold enhancement in total chlorophyll and 2-fold increase in the biomass of root and shoot were observed due to phosphorus amendment. Levels of superoxide dismutase, catalase, peroxidase and malondialdehyde were reduced by 27, 11.7, 38.1 and 45.5% in root tissues; and 27, 17.4, 32.3 and 35.1%, in shoot tissues, respectively. In conclusion, the phosphorus amendment has been shown not only to moderate the Cr-toxicity in S. oleracea but also enrich chlorophyll content as well as the biomass.

Avaliação dos estudantes de enfermagem sobre a aprendizagem com a simulação clínica / Evaluación de los estudiantes de enfermería sobre el aprendizaje con la simulación clínica / Evaluation of nursing students about learning with clinical simulation

RESUMO Objetivo: descrever as contribuições da simulação clínica para aprendizagem de atributos cognitivos e procedimentais, por meio do debriefing, na perspectiva dos estudantes de enfermagem. Método: estudo descritivo exploratório. Participaram 20 estudantes de Graduação em Enfermagem de uma universidade do interior paulista. Na coleta de dados, realizada na etapa do debriefing, foi registrada a percepção do aluno sobre a simulação, aspectos positivos e o que poderia ser feito de forma diferente. Os relatos foram agrupados em categorias temáticas centrais, segundo referencial de análise de conteúdo de Bardin (2011), analisadas por meio de estatística descritiva. Resultados: identificada valorização da aprendizagem ativa, crítica e reflexiva (47,5%) em decorrência da aproximação à realidade assistencial (20,3%), manifestação dos sentimentos vivenciados durante a simulação (16,9%) e composição do cenário (15,3%). Conclusão: a simulação clínica seguida do debriefing favorece a compreensão da relação entre ação e resultados alcançados na aprendizagem. .

RESUMEN Objetivo: describir las contribuciones de simulación clínica para aprender atributos cognitivos y de procedimiento, a través de debriefing, desde la perspectiva de los estudiantes de enfermería. Método: estudio exploratorio descriptivo. 20 estudiantes participaron en el Pregrado en Enfermería de una universidad de São Paulo. Durante la recolección de datos, que se aplicó durante el debriefing, fue grabado en la percepción de los estudiantes de la simulación, los aspectos positivos y lo que podría hacerse de otra manera. Los informes de los estudiantes se agrupan de acuerdo a los temas centrales, según el referencial de análisis de contenido de Bardin (2011) y analizados mediante estadística descriptiva. Resultados: identificado la mejora de aprendizaje activo, crítico y reflexivo (47,5%) debido a la aproximación a la realidad en la atención de enfermería (20,3%), un resultado de la composición del escenario (16,9%), lo que favorece el desarrollo de sentimientos experimentados durante la simulación (15,3%). Conclusión: la simulación clínica seguida de debriefing favorece la comprensión de la relación entre la acción y los resultados obtenidos en el aprendizaje. .

ABSTRACT Objective: to describe the contributions of clinical simulation for learning cognitive and procedural attributes through debriefi ng, from the perspective of nursing students. Method: descriptive exploratory study. Twenty nursing undergraduate students from a university in the interior of the state of São Paulo participated in this study. Data collection was performed at the debriefi ng stage. Student’s perceptions about the simulation, positive aspects and what they could have done differently were registered. The students’ statements were grouped according to the central themes and the framework of Bardin’s content analysis (2011) and were analyzed using descriptive statistics. Results: enhancement of active, critical and refl ective learning (47.5%) was identifi ed due to the closeness to reality in nursing care (20.3%), manifestation of feelings experienced during the simulation (15.3%) and composition of the scenario (15.3%). Conclusion: the clinical simulation followed by debriefi ng promotes the understanding of the link between action and achievements in learning. .

In vitro response of date palm (Phoenix dactylifera L) to K/Na ratio under saline conditions

BACKGROUND: Salinity is a serious factor limiting the productivity of agricultural plants. One of the potential problems for plants growing under saline conditions is the inability to up take enough K+. The addition of K+ may considerably improve the salt tolerance of plants grown under salinity. It is assumed that increasing the K+ supply at the root zone can ameliorate the reduction in growth imposed by high salinity. The present study aims to determine whether an increase in the K/Na ratio in the external media would enhance the growth of date palm seedlings under in vitro saline conditions. METHODS: Date palm plants were grown at four concentrations of Na + K/Cl (mol/m³) with three different K/Na ratios. The 12 salt treatments were added to modified MS medium. The modified MS medium was further supplemented with sucrose at 30 g/l. RESULTS: Growth decreased substantially with increasing salinity. Growth expressed as shoot and root weight, enhanced significantly with certain K/Na ratios, and higher weight was maintained in the presence of equal K and Na. It is the leaf length, leaf thickness and root thickness that had significant contribution on total dry weight. Na+ contents in leaf and root increased significantly increased with increasing salinity but substantial decreases in Na+ contents were observed in the leaf and root with certain K/Na ratios. This could be attributed to the presence of a high K+ concentration in the media. The internal Na+ concentration was higher in the roots in all treatments, which might indicate a mechanism excluding Na+ from the leaves and its retention in the roots. K/Na ratios up to one significantly increased the leaf and root K+ concentration, and it was most pronounced in leaves. The K+ contents in leaf and root was not proportional to the K+ increase in the media, showing a high affinity for K+ uptake at lower external K+ concentrations, but this mechanism continues to operate even with high external Na+ concentrations. CONCLUSION: Increasing K/Na ratios in the growing media of date plam significantly reduced the absorption of Na+ less than 200 mM and also balance ions compartmentalization.

Chromium accumulation potential of Zea mays grown under four different fertilizers.

Chromium (Cr) contamination in soil is a growing concern in sustainable agriculture production and food safety. We performed pot experiment with chromium (30 mg/ soil) to assess the accumulation potential of Zea mays and study the influence of four fertilizers, viz. Farm Yard Manure (FYM), NPK, Panchakavya (PK) and Vermicompost (VC) with respect to Cr accumulation. The oxidative stress and pigment (chlorophyll) levels were also examined. The results showed increased accumulation of chromium in both shoots and roots of Zea mays under FYM and NPK supply, and reduced with PK and VC. While the protein and pigment contents decreased in Cr treated plants, the fertilizers substantiated the loss to overcome the stress. Similarly, accumulation of Cr increased the levels of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) indicating the enhanced damage control activity. However, these levels were relatively low in plants supplemented with fertilizers. Our results confirm that the maize can play an effective role in bioremediation of soils polluted with chromium, particularly in supplementation with fertilizers such as farm yard manure and NPK.

In vitro callus induction and estimation of plumbagin content from Plumbago auriculata Lam.

The medicinal plant Plumbago contains a very potent secondary metabolite, plumbagin having many therapeutic properties. Callus culture was induced using explants, leaf, stem and shoot apex, from P. auriculata. Murashige and Skoog media fortified with various growth hormones like NAA, IAA, IBA and 2, 4-D individually and in various combinations were checked for callus induction. Among the growth hormones used, 1 mg/L 2, 4-D showed best callusing. The hormonal combinations of 1 mg/L IAA and 1.5 mg/L NAA in the media exhibited best callus induction using stem internode as an explant. Plumbagin content from root, stem, leaf and callus was analyzed by using thin layer chromatographic technique. The callus derived from stem showed comparable plumbagin content to the in vivo plant parts. Quantitative spectrophotometric analysis of plumbagin from plant samples and callus indicated that plumbagin content was maximum in roots which was followed by callus, stem and leaf samples respectively. Generation of in vitro sources for plumbagin, for therapeutic applications will serve as a continuous supply and will contribute to preserve the natural plant recourses.

Manganese influx and its utilization efficiency in wheat.

Manganese deficiency in wheat has become an important nutritional disorder particularly in alkaline calcareous soils where rice-wheat rotation is followed. This experiment was aimed to study the mechanism of Mn efficiency during various developmental stages in six wheat cultivars grown at two Mn levels viz. 0 and 50 mg Mn kg-1soil (Mnapplied as MnSO4.H20) in pots. The Mn vegetative efficiency calculated on the basis of shoot dry weight at anthesis indicated HD 2967 and PBW 550 (bread wheat) as Mn efficient and durums as Mn inefficient. The efficient cultivars recorded highest values for influx, uptake, shoot dry weight, leaf area/plant, SPAD index, Fv/Fmratio and root length that explained their higher efficiencies whereas inefficiency of durum cultivars was attributed to their smaller roots and lower influx. Under Mn deficiency, PDW 314 and PDW 291 retained 68% and 64%, respectively, of total Mn uptake in vegetative parts (stem and leaves) and lowest in grains 7% and 5%, respectively, whereas PBW 550, BW 9178 and HD 2967 retained 29, 37 and 34% in vegetative parts, and 21, 17 and 15 % in grains, respectively at maturity. Higher utilization efficiency of efficient genotypes also indicated that increased Mn uptake with Mn supply produced more efficiently grains in efficient genotypes but vegetative parts in inefficient genotypes. Hence Mn efficiency of a cultivar could be explained by longer roots, higher uptake, influx and efficiency index during vegetative phase and higher grain yield and utilization efficiency during generative phase.

Phenylpropanoid enzymes, phenolic polymers and metabolites as chemical defenses to infection of Pratylenchus coffeae in roots of resistant and susceptible bananas (Musa spp.).

Activity differences of the first (phenylalanine ammonia lyase, PAL) and the last (cinnamyl alcohol dehydrogenase, CAD) enzymes of phenylpropanoid pathway in the roots of resistant (Yangambi Km5 and Anaikomban) and susceptible (Nendran and Robusta) banana cultivars caused by root lesion nematode, Pratylenchus coffeae, were investigated. Also, the accumulation of phenolics and deposition of lignin polymers in cell walls in relation to resistance of the banana cultivars to the nematode were analyzed. Compared to the susceptible cultivars, the resistant cultivars had constitutively significantly higher PAL activity and total soluble and cell wall-bound phenolics than in susceptible cultivars. The resistant cultivars responded strongly to the infection of the nematode by induction of several-time higher PAL and CAD enzymes activities, soluble and wall-bound phenolics and enrichment of lignin polymers in cell wall and these biochemical parameters reached maximum at 7th day postinoculation. In addition, profiles of phenolic acid metabolites in roots of Yangambi Km5 and Nendran were analyzed by HPLC to ascertain the underlying biochemical mechanism of bananas resistance to the nematode. Identification and quantification of soluble and cell wall-bound phenolic acids showed six metabolites and only quantitative, no qualitative, differences occurred between the resistant and susceptible cvs. and between constitutive and induced contents. A very prominent increase of p-coumaric, ferulic and sinapic acids, which are precursors of monolignols of lignin, in resistant cv. was found. These constitutive and induced biochemical alterations are definitely the chemical defenses of resistant cvs. to the nematode infection.