Characterization of AhLea-3 and its enhancement of salt tolerance in transgenic peanut plants

BACKGROUND: Late embryogenesis abundant (LEA) proteins were reported to be related to adversity stress and drought tolerance. Lea-3 from Arachis hypogaea L. (AhLea-3) was previously found to be related to salt tolerance according to the result of transcriptome profiling and digital gene expression analysis. So, AhLea-3 was cloned and the salt tolerance was validated by transgenic peanut plants. RESULTS: AhLea-3 was isolated from M34, a salt-resistant mutant of peanut, with its cDNA as the template. AhLea-3 contains one intron and two extrons, and the full-length cDNA sequence contains 303 bp. AhLea3 was ligated to pCAMBIA1301 to obtain the overexpression vector pCAMBIA1301-AhLea-3, which was then transferred into peanut variety Huayu23. The expression level of AhLea-3, as determined by qRTPCR analysis, was >10 times higher in transgenic than in non-transgenic plants. Five days after they were irrigated with 250 mM NaCl, the transgenic plants showed less severe leaf wilting, higher activities of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase), and lower malonic dialdehyde content than non-transgenic plants. Relative to non-transgenic plants, the transgenic plants had a higher photosynthetic net rate, stomatal conductance, and transpiration rate, and a lower intercellular CO2 concentration after salt stress treatment (250 mM NaCl). CONCLUSIONS: These results indicate that overexpression of AhLea-3 increased the salt tolerance of transgenic peanut plants. AhLea-3 might become a useful gene resource for the variety breeding of salinity tolerance in peanut.

Promotion of iron nutrition and growth on peanut by Paenibacillus illinoisensis and Bacillus sp. strains in calcareous soil

ABSTRACT This study aimed to explore the effects of two siderophore-producing bacterial strains on iron absorption and plant growth of peanut in calcareous soil. Two siderophore-producing bacterial strains, namely, YZ29 and DZ13, isolated from the rhizosphere soil of peanut, were identified as Paenibacillus illinoisensis and Bacillus sp., respectively. In potted experiments, YZ29 and DZ13 enhanced root activity, chlorophyll and active iron content in leaves, total nitrogen, phosphorus and potassium accumulation of plants and increased the quality of peanut kernels and plant biomass over control. In the field trial, the inoculated treatments performed better than the controls, and the pod yields of the three treatments inoculated with YZ29, DZ13, and YZ29 + DZ13 (1:1) increased by 37.05%, 13.80% and 13.57%, respectively, compared with the control. Based on terminal restriction fragment length polymorphism analysis, YZ29 and DZ13 improved the bacterial community richness and species diversity of soil surrounding the peanut roots. Therefore, YZ29 and DZ13 can be used as candidate bacterial strains to relieve chlorosis of peanut and promote peanut growth. The present study is the first to explore the effect of siderophores produced by P. illinoisensis on iron absorption.

Plant Growth Promotion and Root Colonization by EPS Producing Enterobacter sp. RZS5 under Heavy Metal Contaminated Soil.

The heavy metal resistant bacterium isolated from field soil and identified as Enterobacter sp. RZS5 tolerates a high concentration (100-2000 mM) of various heavy metal ions such as Mn2+, Ni2+, Zn2+, Cu2+, CO2+ and Fe2+ when grown in such environment and produces exopolysaccharides (EPS). Here, we have demonstrated EPS production by Enterobacter sp. RZS5 during 60 h of growth in yeast extract mannitol broth (YEMB). The yield increased by two fold after the addition of 60 M of Ca2+; 50 M of Fe2+ and 60 M of Mg2+ ions in YEMB, and the optimization of physico-chemical parameters. EPS was extracted with 30% (v/v) of isopropanol as against the commonly used 50% (v/v) isopropanol method. EPS-rich broth promoted seed germination, shoot height, root length, number of leaves and chlorophyll content of wheat (Triticum aestivum) and peanut (Arachis hypogaea) seeds. The higher colony-forming unit of Enterobacter sp. in soil inoculated with EPS rich broth of Enterobacter sp. indicated the root colonizing potential and rhizosphere competence of the isolate. The FTIR spectra of the EPS extract confirmed the presence of the functional group characteristics of EPS known to exhibit a high binding affinity towards certain metal ions. This overall growth and vigour in plants along with the effective root colonization, reflected the potential of the isolate as an efficient bio-inoculant in bioremediation.

Identification of chilling-responsive transcripts in peanut (Arachis hypogaea L. )

To isolate differentially expressed peanut genes responsive to chilling, a suppression subtractive hybridization (SSH) cDNA library was constructed for a chilling tolerant peanut cultivar A4 with mRNAs extracted from the seeds imbibed at 2ºC and 15ºC, respectively, for 24 hrs. A total of 466 cDNA clones were sequenced, from which 193 unique transcripts (73 contigs and 120 singlets) were assembled. Of these unique transcripts, 132 (68.4 percent) were significantly similar to the sequences in GenBank non-redundant (nr) protein database, which belonged to diverse functional categories including metabolism, signal transduction, stress response, cell defense and transcriptional regulation. The remaining 61 (31.6 percent) showed no similarity to either hypothetical or known proteins. Six differentially expressed transcripts were further confirmed with real-time quantitative PCR (RT-qPCR).

Sodium azide mutagenesis resulted in a peanut plant with elevated oleate content

Screening of peanut seeds resulting from 0.39 percent sodium azide treatment with NIRS calibration equation for bulk seed samples identified a plant with more than 60 percent oleate. Oleate content in individual seeds of the plant, as predicted by NIRS calibration equation for intact single peanut seeds, ranged from 50.05 percent ~ 68.69 percent. Three seeds with >60 percent oleate thus identified were further confirmed by gas chromatography. Multiple sequence alignments of the FAD2B gene from Huayu 22 (wild type) and peanut seeds with elevated oleate (mutant type) revealed a C281T transition in the coding region causing an I94T substitution in the oleoyl-PC desaturase, which may be responsible for reduction in the enzyme activity.

Calidad nutricional en variedades de maní tegua y granoleico: estabilidad y aceptabilidad de sus aceites: efecto de su ingesta sobre niveles de lípidos plasmáticos en ratones / Nutritional quality tegua peanut varieties and granola: stability and acceptability of their oils: effect of intake on plasma lipid levels in mice

El maní es una de las principales oleaginosas del mundo y Argentina es uno de sus principales productores y exportadores. En la provincia de Córdoba se concentra el 94,63% del cultivo. Las variedades del tipo Runner: cultivar Tegua y Granoleico, presentan perfiles muy diferentes de ácidos grasos. El alto contenido en ácido graso nonoinsaturado en los productos derivados de maní lo hace muy estable ante los procesos de oxidación y altamente beneficioso para la prevención de enfermedades cardiovasculares. El objetivo de este estudio fue valorar la calidad nutricional de los maníes de las variedades Tegua (T) y Granoleico (GO) mediante el análisis de la estabilidad y aceptabilidad de sus aceites y en especial la evaluación de sus efectos sobre los lípidos plasmáticos en ratones Albino swiss. Materiales y métodos: Se utilizaron granos de maní de las variedades citadas, se determinaron macronutrientes, humedad, minerales y tocoferoles. Se obtuvo aceite de maní por método de prensado en frío. Se evaluó la composición de ácidos grasos y se la comparó con las de otros aceites vegetales (girasol, maíz, soja, canola y oliva). Estabilidad. Se analizaron índice de peróxido(IP), índice de p‐anisidina (IA) y dienos conjugados (DC) en aceites puros (T‐GO 100‐0 y T‐GO 0‐ 100) y en mezclas de las variedades: al 25% (T‐GO 75‐25), al 50% (T‐GO 50‐50) y al 75% (T‐GO 25‐ 75) almacenados en estufa a 60 ºC. Lípidos plasmáticos. Se realizó un modelo experimental conratones Albino swiss (n=81), se utilizaron dietas semisintéticas con la adición de aceites refinados de girasol, oliva, maní GO y dieta comercial. Se controló el peso semanalmente. A los 77 y 126 días de tratamiento se los sacrificó y midieron los lípidos plasmáticos: triglicéridos, colesterol total, cHDL y cLDL. Análisis sensorial. Se comparó la aceptabilidad de los aceites de maní, girasol y oliva extravirgen. Estadística. Varianza, test de LSD Fisher (α=0,05) y regresión.

Avaliação da interferência da tolerância oral na rejeição do transplante de coração alogênico avascular na orelha de camundongo / Evaluation of the interference of oral tolerance in the rejection of avascular allogeneic heart grafts to mouse ears

OBJETIVO: Apesar da evolução das técnicas cirúrgicas que permitiram a padronização do transplante cardíaco e da descoberta dos imunossupressores, ainda hoje, a rejeição, os efeitos colaterais dos medicamentos e o processo de vasculopatia crônica são os principais problemas nos pós-transplantados. A procura por alternativas para superar estes impedimentos é o objetivo principal deste trabalho. Assim, foram realizados experimentos para determinar se a tolerância oral pode interferir no transplante cardíaco. MÉTODO: Camundongos C57BI/6J e C3H/HEJ, machos adultos foram divididos em dois grupos. O grupo denominado tolerante recebeu amendoim ad libitum na dieta por sete dias, enquanto o grupo imune foi mantido com uma dieta convencional para murinos. Ambos foram imunizados com 100 mg de extrato protéico derivado do amendoim por via sc. O transplante de coração de BAL/C recém-nato, de 24h, foi depositado no tecido subcutâneo das orelhas dos animais de ambos os grupos, com ou sem imunização concomitante do antígeno alimentar. RESULTADOS: Confirmamos que a administração de proteínas por via oral é capaz de induzir tolerância sistêmica, uma vez que os grupos tolerantes apresentam títulos de anticorpos específicos ao amendoim mais baixos que os grupos imunes. O coração transplantado apresentou-se mais preservado no grupo de animais C3H/HEJ tolerantes que foram desafiados concomitantemente com o antígeno da dieta do que os demais grupos. CONCLUSAO: Foi determinado que os mecanismos de tolerância oral interferem no processo de rejeição de transplantes cardíacos alogênicos avasculares para a orelha de camundongos adultos, no entanto, de maneira não homogênea. Como os mecanismos de tolerância oral que alteram o sistema imunológico de modo a reduzir a rejeição ainda não foram esclarecidos, são precisos mais trabalhos nesta linha de pesquisa.

Peanut agglutinin binding by gastric mucosal epithelial cells in Helicobacter pylori associated gastritis.

Gastric biopsies (42) from patients with peptic ulcer disease were classified into Helicobacter pylori positive (32) and negative (10) groups, based on the results of tissue urease test and microscopic demonstration of spiral bacteria. A statistically significant difference in peanut agglutinin (PNA) binding between the two groups was observed, attributable to exposure of sialic acid residues on gastric epithelium in the H. pylori positive group. That the negative binding was due to sialic acid, was further confirmed by application of sialidase digestion technique. These results support the existing biochemical evidence for exposure of sialic acid residues on H. pylori colonized epithelium.