Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 28

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  nodulation
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
The effect of different rates and methods of fertilizer nitrogen application and potassium nutrition on the root nodule formation of faba bean plants var. Nadwiślański and on their nitrogenase activity was studied. It was found that fertilizer N depressed the nodule formation and nitrogenase activity, but inhibitory effect of N was smaller when it was supplied to the leaves instead to the soil. Plants growing at higher K level were in a position allowing on better development of nodules and consequently higher N₂₋ fixation.
Compatibility between rhizobial inoculants and fungicides used for seeds treatment remains controversial. The aim of this study was to investigate the effect of the fungicide Funaben T (thiram – 45%, carbendazim – 20%) on the nodulation of soybean (Glycine max cv. Nawiko) inoculated with two Bradyrhizobium japonicum strains (USDA 110 and USDA 123). Reduced nodulation of soybean was observed in the treatments with fungicide applied and fertilized with nitrogen (80 kg ha–1). The strongest depression of nodulation was observed when both treatments were used simultaneously.
Mutants of Mesorhizobium ciceri BICC 651 were generated by N-methyl-N'-nitro-Af-nitrosoguanidine mutagenesis. Siderophore overproducing mutants were identified on Chrome azurol S agar plates. One of them determined as N15 was examined for symbiotic efficiency and compared to its wild type parent i.e. BICC 651 strain under sterile conditions using Leonard jars in growth chamber and also in pots containing nonsterile alluvial field soil. It was observed that the strain N15 produced about 30% higher number of nodules per plant, fixed 25% more nitrogen per gram of nodule and caused more than 30% increased dry weight of plant shoots.
Astragalus nitidiflorus is an endangered legume endemic to the southeast of the Iberian Peninsula. This species develops symbiotic relationships with N-fixing bacteria. However, the problem of isolating its rhizobia has not been solved. Because poor N fixation in plants can be corrected by fertilization, the effect of N-P-K fertilizers on growth, leaf chlorophyll and mineral ions was studied. Plants of A. nitidiflorus were grown in 100%-substrate with different N-P-K fertilizer rates (mg l–1): 1-1-8 (S0), 69-29-35 (SL), 144-43-131 (SM) and 245-58-235 (SH). A treatment with substrate plus soil from the natural habitat and no fertilizers (T0) was included. The reference foliar contents of N, P and K were 42.5, 3.5 and 36.5 mg g–1, respectively. Although the species did not form root nodules when grown in substrate, T0 plants produced active nodules that allowed the plants to grow properly without fertilization. In the absence of nodules, both N fertilization (~144 mg l–1) and Fe fertilization (>12 mg l–1) are vital, as is, to a lesser extent, K fertilization (~75 mg l–1 K2O). The S0 and SL reduced leaf chlorophyll, while SM prevented its degradation.
The authors investigated the impact of the Sinorhizobium inoculum density on the plant development of alfalfa, nodulation and nitrogenase activity. It was found that plants inoculated with a 10% inoculant (4.9 x 10⁶ CFU) were characterized by the best growth, more profuse fresh material and a very well developed root system and, additionally, they revealed higher nitrogenase activity.
Effects of pre-sowing soybean seed inoculation with Bradyrhizobium japonicum alone or with mixed inoculants containing soybean rhizobia and Azotobacter chroococcum were compared. In the pot experiment all the tested strains of soybean rhizobia in pure cultures or in mixtures with A. chroococcum significantly improved nodulation of soybean plants and seed yields of this crop. In micro-plot experiments pre-sowing soybean seeds treatment with the inoculant containing the most effective strain 94P of B. japonicum alone or with the mixed inoculant of strain 94P and A. chroococcum were equally effective in improving nodulation intensity and seed yields of soybean in comparison to the uninoculated soybean.
The establishment of the nitrogen-fixing symbiosis between rhizobia and legumes re quires an ex change of sig nals be tween the two part ners. In re sponse to flavonoids ex creted by the host plant, rhizobia syn the size Nod fac tors (NFs) which elicit, at very low con cen tra tions and in a spe cific man ner, var i ous sym bi otic re sponses on the roots of the le gume hosts. NFs from sev eral rhizobial spe cies have been char ac ter ized. They all are lipo-chitooligosaccharides, con sist ing of a back bone of gen er ally four or five glucosamine residues N-acylated at the non-reducing end, and carrying various O-substituents. The N-acyl chain and the other substituents are important determi nants of the rhizobial host spec i fic ity. A num ber of nodulation genes which spec ify the syn the sis of NFs have been iden ti fied. All rhizobia, in spite of their di ver sity, pos sess conserved nodABC genes responsible for the synthesis of the N-acylated oligo­saccharide core of NFs, which sug gests that these genes are of a monophyletic or i gin. Other genes, the host spe cificnod genes, spec ify the sub sti tu tions of NFs. The cen tral role of NFs and nod genes in the Rhizo bium-legume sym bi o sis sug gests that these fac­tors could be used as mo lec u lar mark ers to study the evo lu tion of this sym bi o sis. We have stud ied a num ber of NFs which are N-acylated by α,β-unsaturated fatty ac­ids. We found that the abil ity to syn the size such NFs does not cor re late with tax o- nomic po si tion of the rhizobia. How ever, all rhizobia that pro duce NFs such nodulate plants be long ing to re lated tribes of le gumes, the Trifolieae, Vicieae, and Galegeae, all of them be ing mem bers of the so-called galegoid group. This sug gests that the abil ity to recognize the NFs with α,β-unsaturated fatty acids is limited to this group of le­gumes, and thus might have ap peared only once in the course of le gume evo lu tion, in the galegoid phy lum.
The fucosyltransferase NodZ is involved in the biosynthesis of the nodulation factor in nitrogen-fixing symbiotic bacteria. It catalyzes α1,6 transfer of l-fucose from GDP-fucose to the reducing residue of the synthesized Nod oligosaccharide. We present the structure of the NodZ protein from Bradyrhizobium expressed in Escherichia coli and crystallized in the presence of phosphate ions in two crystal forms. The enzyme is arranged into two domains of nearly equal size. Although NodZ falls in one broad class (GT-B) with other two-domain glycosyltransferases, the topology of its domains deviates from the canonical Rossmann fold, with particularly high distortions in the N-terminal domain. Mutational data combined with structural and sequence alignments indicate residues of potential importance in GDP-fucose binding or in the catalytic mechanism. They are all clustered in three conserved sequence motifs located in the C-terminal domain.
The ontogeny and (ultra)structure of vascular tissue in Lupinus luteus L. root nodules were studied by light and transmission electron microscopy in juvenile nodule primordia up to the 11th day after inoculation. Vascular meristem originated from centripetally dedifferentiated root cortical parenchyma, endodermis and pericycle. The vascular trace was formed between bacteroid tissue initials and the root stele. In the trace's proximal part, cambial strands connecting the vascular trace and root cambium were formed. In the distal part, non-anastomosing vascular bundles started differentiating from the trace at the end of the juvenile stage. In lupine, the formative stage of the indeterminate root nodule vascular system was shown to be unique within the legumes.
The present study reports a high frequency in vitro propagation protocol through apical bud sprouting and basal organogenic nodule formation in shoot tip explants of Decalepis hamiltonii, an endemic and endangered medicinal liana. Among different combinations of plant growth regulators (PGRs) and growth additives, maximum of 8.20 shoots per explant with mean shoot length of 6.54 cm were induced on Murashige and Skoog’s medium (MS) supplemented with 5.0 µM 6-benzyladenine (BA) + 0.5 µM indole-3-acetic acid (IAA) + 30.0 µM adenine sulphate (ADS) through apical bud sprouting. On single cytokinin treatment explants did not exhibit good multiplication but showed nodulation (N₁) from the basal cut end similar to cytokinin–auxin combination (N₂). Between two types of nodular tissues, N₂ was proved to be better for maximum shoot regeneration (15.40 shoots per explant) and shoot length (4.56 cm) when cultured on MS medium supplemented with 5.0 µM BA, 0.5 µM IAA, 30.0 µM ADS and 1.0 µM gibberellic acid (GA₃). Microshoots were efficiently rooted on half-strength MS medium supplemented with 2.5 µM α-naphthalene acetic acid (NAA). After successful acclimatization in Soilrite, 95.10 % plantlets were survived in field conditions. Histological investigation proved useful in ascertaining the callogenic nature of the regenerating nodular tissue formed at the basal cut end of shoot tip explant. Acclimatized plantlets were studied for the estimation of chlorophyll and carotenoid content as well as the net photosynthetic rate (PN) during subsequent days of transfer to ex vitro condition. Moreover, acclimatization had a significant effect on biomass production and the synthesis of 2-hydroxy-4-methoxy benzaldehyde (2HMB). Maximum fresh weight (3.78 gm/plant), dry weight (0.39 gm/plant) of roots and 2HMB content (15.94 µg/ml of extract) were noticed after 8 weeks of acclimatization.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.