Phenotypic diversity and biochemical characteristics of selected rhizobia nodulating the common bean (Phaseolus vulgaris L.)

Increasing interest in using rhizobia as biofertilizers in smallholder agricultural farming systems has prompted scientists to investigate rhizobia diversity, resulting in the identification of many strains. Fifty-five Rhizobium strains nodulating in the common bean (Phaseolus vulgaris L.) were isolated from soil samples from different areas of Tunisia and phenotypically characterized to determine their symbiotic nitrogen fixation capabilities. Their tolerance to pH, salinity, temperature and alkalinity, as well as their cultural and biochemical characteristics indicated wide physiological diversity. These phenotypic characteristics significantly affected rhizobia growth, and strains of interest were identified and used in inoculation trials. They were efficient and able to tolerate pH from 4 to 9, NaCl concentrations of 25 to 100 mM, temperature variation from 10 to 40 °C, and lime (CaCO3) from 0.05 to 0.20 mM. Selected Rhizobium strains were identified as candidates for biofertilizer production for a variety of Tunisian soil types.

USE OF RHIZOBIUMBACTERIA TO INCREASE THE PRODUCTION OF FIVE TROPICAL LEGUMES WITH FORAGE POTENTIAL

The objective of the work was to evaluate the effect of the application of Rhizobium bacteria in the biomass production of forage legumes. Rhizobiumstrains were isolated and selected from the rhizosphere of five forage species. Characterization and subsequent cultivation were carried out to inoculate plants in a greenhouse. Subsequently, the biofertilizer was prepared to apply it to five forage legumes: C. ternatea, L. leucocephala, C. macrocarpum, M. pruriens and C. cajan. Plants were germinated in petri dishes and on substrate, after 10 days of germination, they were transplanted into Leonards Jugs and watered with distilled water. The plants were placed in a completely randomized design with three replicates. The evaluations were carried out every week measuring plant heightand at the end of the experiment root weigh, dry matter of aerial part and radicular volume. The best values obtained were in M. pruriens which showed from 49 to 50 cm of plant height. For cross inoculation in weight variable was observed that the strains from C. ternatea and L. leucocephala showed the best results with 0.22 and 0.25 g/plant respectively. Although the best data of dry matter of aerial part was observed in L. leucocephalawith 0.40 g, better response of Radicular volume and plant height was observed in strains that came from C. ternatea with 2 mL and 7 cm respectively. In this study it can be conclude that the use of biofertilizers can be an alternative for low-cost forage production, as long as it contains Rhizobium strains capable of associating with legumes and fixing atmospheric nitrogen.

Development of wheat plants coinoculated with rhizobium strains

ABSTRACT This study aimed to evaluate the efficiency of diaztrophic bacteria coinoculation in wheat cultivars grown in Cerrado Oxisol. A randomized block design was used, with a 13 x 3 factorial scheme and four replicates. The treatments consisted of inoculation with Azospirillum brasilense (strains AbV5 and AbV6 strains combined) and coinoculation with Bradyrhizobium japonicum (strains SEMIA 5079 and SEMIA 5080 combined, and strain BR3267), as well as Rhizobium tropici (strains MT08 and MT15) and R. leguminosarum (strain MT16) combined or in isolation, tested in wheat cultivars BRS 394, BRS 264 and BRS 254. The variables analyzed were grain nitrogen concentration and accumulation and crude protein content, 100-grain weight and total grain mass. The treatment containing the commercial cowpea inoculant showed a higher total grain mass (5.8766 g). Interaction was observed for grain nitrogen concentration, particularly for A. brasilense + MT 15 (R. tropici) and MT 15 in wheat cultivar BRS 264. Coinoculation with diazotrophic bacteria isolated from leguminous plants shows potential for use in wheat cultivars.

New varieties of forage crops and technologies for Russian agriculture

Рассмотрено значение селекции специализированных сортов и использования новых видов кормовых культур в решении проблем кормопроизводства, улучшении экологической обстановки. В Федеральном научном центре проводятся комплексные исследования со многими видами кормовых культур: клевером луговым, клевером ползучим, райграсом пастбищным, фестулолиумом, тимофеевкой луговой и ещё с 44 кормовыми и масличными культурами различного назначения. Сорта последнего поколения предназначены для выращивания во всех регионах России. За последние 3 года сотрудниками ФНЦ «ВИК им. В. Р. Вильямса» передано в государственное сортоиспытание и зарегистрировано 38 новых сортов: три сорта люцерны, три сорта люпина белого, два сорта лядвенца рогатого, два сорта фестулолиума, три сорта клевера лугового и т.д. Учёные ФНЦ «ВИК им. В. Р. Вильямса» ежегодно получают от 12 до 16 патентов на новые селекционные достижения по более чем 44 кормовым и масличным культурам различного назначения. За последние годы получены новые сортомикробные системы современных сортов клевера лугового и люцерны, отработаны технологии и получены патенты на способы фитомелиорации, на конструкции агрегатов для заготовки высококачественных кормов; работает лаборатория молекулярно-генетических исследований кормовых культур, в практику внедряются адаптированные ДНК-технологии, повышающие эффективность селекционного процесса. Показана важность ускоренного введения новых сортов в производство путём заключения неисключительных лицензионных договоров. Основная деятельность ФНЦ «ВИК им. В. Р. Вильямса» направлена на комплексные исследования в области селекции кормовых культур, а также на создание системы их семеноводства, которая обеспечит страну не только оригинальными, но и элитными и репродукционными семенами. This article reports on breeding and cultivation of new varieties of forage crops as means to improve forage production and ecology. The Federal Williams Research Center conducts investigations involving various crop species: red clover, white clover, perennial ryegrass, festulolium, common timothy and 44 other forage and oil crops. The latest varieties are to be grown all over Russia. For the last 3 years the Center submitted for the State variety trial and registered 38 new varieties: three varieties of alfalfa, red clover and white lupine, two varieties of birdʼs-foot trefoil and festulolium, etc. Scientists of the Center annually get 12–16 selection patents for over 44 forage and oil crops. Recent achievements are new systems of Rhizobium strains with red clover and alfalfa; improved technologies and patents for phytomelioration and designing fodder equipment; the laboratory of Molecular Biology and Genetics and application of DNA technologies in breeding. Nonexclusive license was shown to accelerate introduction of new varieties into the production process. The Center focuses on forage crop breeding and optimization of seed production.

Identification of Sigma Factor 54-Regulated Small Non-Coding RNAs by Employing Genome-Wide and Transcriptome-Based Methods in Rhizobium Strains

Rhizobium-legume symbiosis is considered as the major contributor of biological nitrogen fixation. In the present study, we have identified sigma factor 54-regulated sRNAs from the genome of five Rhizobium strains and integrated with the free-living and symbiotic specific transcriptome data to identify the novel putative sRNAs that are over expressed during the regulation of nitrogen fixation. A total of 1059 sRNAs were predicted from each genome of the select set of Rhizobium strains and 1,375 sRNAs were predicted from the transcriptome data of Bradyrhizobium japonicum. Target mRNA analysis revealed the functional role of putative novel sRNAs from different free-living and symbiotic strains. Those novel sRNAs were inferred to target several nodulation and nitrogen fixation genes including nodC, nodJ, nodY, nodJ, nodM, nodW, nodZ, nifD, nifN, nifQ, fixK, fixL, Fdx, nolB, and several cytochrome proteins. Further, sRNAs of Bradyrhizobium japonicum which targeted the regulatory genes of nitrogen fixation were experimentally confirmed with semi-quantitative reverse transcription polymerase chain reaction. Predicted target mRNAs were functionally classified based on the COG analysis and GO annotations. Studies on this sigma factor 54-regulated sRNA identification could be a better method to relate the role of sRNAs in nitrogen metabolism during free-living and symbiotic association with legumes.

Legume-rhizobium specificity effect on nodulation, biomass production and partitioning of faba bean (Vicia faba L.)

Greenhouse and multi-location experiments were conducted for two consecutive years to investigate the effects of rhizobium on nodulation, biomass production and partitioning of faba bean. Split-plot in randomized complete block design was used for field experiments. Treatments consisted of six rhizobium strains and three faba bean varieties. Peat carrier-based inoculant of each strain was applied at the rate of 10 g kg−1 seed. Non-inoculated plants without N fertilizer and with N fertilizer served as –N and + N controls, respectively. Data on nodulation, shoot dry weight and root dry weight were collected and analyzed. Inoculation of rhizobium significantly increased nodulation of faba bean under greenhouse and field conditions. Location x strain x variety interaction had significant effects on nodulation, dry matter production and partitioning. Rhizobium inoculation increased nodulation, shoot and root dry weights of faba bean across locations. For example, inoculation with rhizobium strains NSFBR-15 and NSFBR-12 to variety Moti resulted in 206.9 and 99.3% shoot dry weight increase at Abala Gase and Hankomolicha, respectively and 133.3 and 70.7% root dry weight increase on the same variety at the same sites, respectively. Nodulation and biomass production depend on the compatibility between faba bean genotype and rhizobium strain and its interaction with soil bio-physical conditions.