Endophytic fungi facilitate the coexistence of host grasses and neighboring legumes by changing rhizobial abundance

Purpose: Grass-endophyte and legume-rhizobium symbionts coexist in grasslands. However, the effects of endophyte infection on legume-rhizobium symbionts remain poorly understood, especially in natural grasslands. Methods: In this study, Achnatherum sibiricum - Epichloë endophytes and Medicago ruthenica -rhizobia were selected as materials to investigate whether and how endophyte infection affected the growth of legume-rhizobia symbionts. It was hypothesized that endophytes can facilitate the coexistence of grass-legume systems. Results: The results demonstrated that endophyte infection affected the growth of both rhizobia and M. ruthenica -rhizobia symbionts, and the results depended on rhizobial identity. Endophyte infection inhibited the growth of Mesorhizobium ciceri , which significantly promoted the growth of M. ruthenica , and promoted Sinorhizobium meliloti , which had no significant effect on the growth of M. ruthenica . Endophyte infection also changed the interaction between A. sibiricum and M. ruthenica . When inoculated with M. ciceri , endophyte infection weakened the promoting effect of A. sibiricum on M. ruthenica , while when inoculated with S. meliloti , endophyte infection enhanced the promoting effect. Endophyte infection affected the growth of M. ruthenica -rhizobia symbionts by affecting rhizobia abundance in roots and nitrogen content in plant leaves. Conclusion: In conclusion, endophyte infection was beneficial to biomass accumulation and species coexistence in grass-legume mixed planting systems. In this study, it was proposed that endophyte infection may change the growth of legume-rhizobia symbionts by affecting the growth and nitrogen fixation of rhizobia.

​The Effects of Mesorhizobium ciceri Inoculation and Different Doses of Vermicompost Treatments on the Yield Components and Yield of Chickpea (Cicer arietinum L.) under Semi-arid Mediterranean Highland Condition of Turkey

Background: This study was conducted in 2016-2017 to determine the effects of Mesorhizobium ciceri inoculation and different doses of vermicompost applications on the yield components and yield of chickpea under semi-arid Mediterranean highland condition of Turkey. Methods: Mesorhizobium ciceri inoculant were applied to seeds (at 108 cfu bacteria per seed dose) as microbial fertilizer in the experiments. Vermicompost doses were 0, 1000, 2000 and 3000 kg ha-1. The trials were set up with three replications according to the randomized complete blocks design. Conclusion: Plant height, first pod height, pod number per plant, number of seeds per plant, 100 grain weight and grain yield were determined as 56.1-61.9 cm, 29.4-34.9 cm, 31.4-46.3 pods plant-1, 32.9-44.0 seed plant-1, 30.4-37.4 g and 1463-2072 kg ha-1, respectively. Co-application of 1000 kg ha-1 vermicompost with Mesorhizobium ciceri inoculation produced the highest values for all examined parameters for both years. Further applications of vermicompost reduced yield and related components. Control parcels and excess vermicompost applications (2000 and 3000 kg ha-1) produced lowest values. Mesorhizobium ciceri inoculation produced medium values between Co-application of 1000 kg ha-1 vermicompost with Mesorhizobium ciceri and control and excess vermicompost applied conditions. In conclusion, use of Mesorhizobium ciceri + 1000 kg ha-1 vermicompost was recommended in chickpea cultivation for maximum yield in the ecological conditions of Siirt province of Turkey or in similar ecologies.

Co-Inoculation of Mesorhizobium ciceri with Either Bacillus sp. or Enterobacter aerogenes on Chickpea Improves Growth and Productivity in Phosphate-Deficient Soils in Dry Areas of a Mediterranean Region

Biological nitrogen fixation requires a large amount of phosphorus (P). However, most of the soils are P-deficient and the extensive use of P- chemical fertilizers constitute a serious threat to the environment. In this context, two field experiments were carried out to investigate the effect of co-inoculation of Mesorhizobium ciceri with phosphate solubilizing bacteria (PSB), Bacillus sp., and Enterobacter aerogenes, on chickpea as an alternative to chemical nitrogen (N) and phosphorous fertilizers in P-deficient soils in dry areas of Morocco. The results revealed that combined inoculation of chickpea with rhizobia and PSB showed a significant enhancement of chickpea nodulation, biomass production, yields and N, P, and protein content in grains as compared to single inoculation or single application of N or P. A significantly higher increase was obtained by inoculating chickpea with Mesorhizobium sp. MA72 combined with E. aerogenes P1S6. This combination allowed an enhancement of more than 270% in nodulation, 192% in shoot dry weight and 242% in grain yield. The effect of this combination was equivalent to the effect of combined application of N and P fertilizers. Formulation of biofertilizers based on tasted strains could be used for chickpea co-inoculation in P-deficient soils for an eco-friendly sustainable production of chickpea.

Evolution of diverse effective N2-fixing microsymbionts of Cicer arietinum following horizontal transfer of the Mesorhizobium ciceri CC1192 symbiosis integrative and conjugative element

Rhizobia are soil bacteria capable of forming N2-fixing symbioses with legumes, with highly effective strains often selected in agriculture as inoculants to maximize symbiotic N2 fixation. When rhizobia in the genus Mesorhizobium have been introduced with exotic legumes into farming systems, horizontal transfer of symbiosis Integrative and Conjugative Elements (ICEs) from the inoculant strain to soil bacteria has resulted in the evolution of ineffective N2-fixing rhizobia that are competitive for nodulation with the target legume. In Australia, Cicer arietinum (chickpea) has been inoculated since the 1970’s with Mesorhizobium ciceri sv. ciceri CC1192, a highly effective strain from Israel. Although the full genome sequence of this organism is available, little is known about the mobility of its symbiosis genes and the diversity of cultivated C. arietinum-nodulating organisms. Here, we show the CC1192 genome harbors a 419-kb symbiosis ICE (ICEMcSym1192) and a 648-kb repABC-type plasmid pMC1192 carrying putative fix genes. We sequenced the genomes of 11 C. arietinum nodule isolates from a field site exclusively inoculated with CC1192 and showed they were diverse unrelated Mesorhizobium carrying ICEMcSym1192, indicating they had acquired the ICE by environmental transfer. No exconjugants harboured pMc1192 and the plasmid was not essential for N2 fixation in CC1192. Laboratory conjugation experiments confirmed ICEMcSym1192 is mobile, integrating site-specifically within the 3’ end of one of the four ser-tRNA genes in the R7ANS recipient genome. Strikingly, all ICEMcSym1192 exconjugants were as efficient at fixing N2 with C. arietinum as CC1192, demonstrating ICE transfer does not necessarily yield ineffective microsymbionts as previously observed.Importance Symbiotic N2 fixation is a key component of sustainable agriculture and in many parts of the world legumes are inoculated with highly efficient strains of rhizobia to maximise fixed N2 inputs into farming systems. Symbiosis genes for Mesorhizobium spp. are often encoded chromosomally within mobile gene clusters called Integrative and Conjugative Elements or ICEs. In Australia, where all agricultural legumes and their rhizobia are exotic, horizontal transfer of ICEs from inoculant Mesorhizobium strains to native rhizobia has led to the evolution of inefficient strains that outcompete the original inoculant, with the potential to render it ineffective. However, the commercial inoculant strain for Cicer arietinum (chickpea), M. ciceri CC1192, has a mobile symbiosis ICE (ICEMcSym1192) which can support high rates of N2 fixation following either environmental or laboratory transfer into diverse Mesorhizobium backgrounds, demonstrating ICE transfer does not necessarily yield ineffective microsymbionts as previously observed.

Mesorhizobium Ciceri as a Biological Tool for Improving Physiological, Biochemical and Antioxidant State of Cicer Aritienum L. by Lowering the Fungicide Induced Oxidative Stress

The present study demonstrates the interactions of fungicide-tolerant symbiotic bacteria Mesorhizobium ciceri with Cicer arietinum-kitazin (KITZ) in greenhouse conditions. Under both in vitro and soil systems, KITZ imparted deleterious impacts on plants as a function of dose. The three-time KITZ dose detrimentally and maximally reduced germination efficiency, vigor index, dry matter production, symbiosis, leaf pigments and seed attributes of C. arietinum. KITZ- induced morphological alterations in root tips, oxidative damage and cell death in root cells of C. arietinum were shown by SEM. M. ciceri tolerated up to 2400 µgmL− 1 of KITZ, synthesized considerable amounts of bioactive molecules including indole-3-acetic-acid (IAA), 1-aminocyclopropane 1-carboxylate (ACC) deaminase, siderophores, exopolysaccharides (EPS), HCN and ammonia, and solubilised inorganic phosphate even in fungicide-stressed media. Following application to soil, M. ciceri improved performance of C. arietinum and enhanced dry biomass production, yield, symbiosis and leaf pigments even in a fungicide-polluted environment. At 92 µgKITZkg− 1 soil, M. ciceri maximally and significantly (p ≤ 0.05) augmented whole plant length by 41%, total dry biomass by 18%, carotenoid content by 9%, LHb content by 21%, root N by 9%, shoot P by 11% and pod yield by 15%. Additionally, M. ciceri was associated with decreased levels of stressor molecules (proline and MDA) and antioxidant defence enzymes (APX, GPX, CAT and POD) of C. arietinum plants when inoculated in soil. The symbiotic strain effectively colonized the plant rhizosphere/rhizoplane. In pesticide- contaminated soils, inoculation of M. ciceri may serve as an excellent strategy for augmenting C. arietinum productivity.

Siirt Ekolojik Koşullarında Mikrobiyolojik ve İnorganik Gübrelemenin Nohut (Cicer arietinum l.)’un Kalite Özellikleri Üzerine Etkileri

Siirt ekolojik koşullarında mikrobiyolojik ve inorganik gübrelemenin nohut (Cicer arietinum L.)’ un verim, verim öğeleri ve nodülasyonu üzerine etkilerini belirlemek amacıyla yapılan bu çalışma tesadüf bloklarında faktöriyel deneme deseninde 3 tekerrürlü olarak 2016-2017 ve 2017-2018 yılları arasında yürütülmüştür. Çalışmada simbiyotik bakteri olarak Mesorhizobium ciceri, asimbiyotik bakteri olarak azot bağlayıcı Basillus atrophaeus, fosfat çözücü olarak Basillus GC-group ve inorganik gübre olarak DAP gübresi kullanılmıştır. Araştırmada; tane protein oranı, protein verimi, tane fosfor içeriği, tane potasyum içeriği, tane nem oranı ve tanede toplam kuru madde oranı özellikleri incelenmiştir. Çalışmadan elde edilen bulgulara göre, tane protein oranı %22.3-25.6, protein verimi 21.2-40.4 kg/da, tane fosfor içeriği %0.43-0.71, tane potasyum içeriği %0.96-1.58, tane nem oranı %4.02-6.01 ve tanede toplam kuru madde oranı %93.98-95.97 arasında değişim göstermiştir. Çalışmada en yüksek protein içeriği, Mesorhizobium ciceri + %50 DAP ve Bacillus atrophaeus (N) + %50 DAP uygulamaları ile elde edilmiştir. Sonuç olarak, mikrobiyolojik gübre kullanımının inorganik gübrelere tamamen bir alternatif olmamasına rağmen kullanım miktarının azalmasına olanak sağladığı tespit edilmiştir.

Farklı Sıra Arası Mesafeleri, Tavuk Gübresi Dozları Ve Tohum Ön Uygulamalarının Nohut (Cicer arietinum L.)’Un Verim Ve Verim Özellikleri Üzerine Etkileri

Farklı sıra arası mesafeleri, tavuk gübresi dozları ve tohum ön uygulamalarının nohut (Cicer arietinum L.)’un verim ve verim özellikleri üzerine etkilerini belirlemek amacıyla yapılan bu çalışma, 2016 ve 2017 yetiştirme sezonunda Siirt koşullarında yürütülmüştür. Denemeler bölünen bölünmüş parseller deneme deseninde 3 tekerrürlü olarak kurulmuştur. Araştırmada 20, 30 ve 40 cm olmak üzere 3 farklı sıra arası mesafe ana parsellere; tohum ön uygulaması ve Mesorhizobium ciceri aşılama alt parsellere; tavuk gübresi dozları 0, 40, 120 ve 200 kg/da hesabına göre altın altı parsellere uygulanmıştır. Bu çalışmanın sonuçlarına göre; bitki boyu 54.4-66.0 cm, ilk bakla yüksekliği 29.5-36.7 cm, bitkide bakla sayısı 29.3-43.9 adet/bitki, bitkide tane sayısı 29.4-44.9 adet/bitki, 100-tane ağırlığı 30.1-36.2 g ve tane verimi 83.4-253.7 kg/da değerleri arasında değişim göstermiştir. Sıra arası mesafelerin, ön uygulamaların ve tavuk gübresi dozlarının tane verimine etkileri önemli bulunmuştur. Sıra arası mesafe azaldıkça ve tavuk gübresi dozu arttıkça tane verimi artış göstermiştir. En yüksek tane verimi 190.3 kg/da ile 20 cm sıra arası mesafeden elde edilirken, ön uygulamalardan Mesorhizobium ciceri aşılaması 157.8 kg/da ile en yüksek tane verimini vermiştir. Tavuk gübresi uygulamasında ise 157.7 kg/da ile 200 kg/da dozundan elde edilmiştir. Sonuç olarak, Siirt ili ekolojik koşullarında yürütülen bu çalışmada en yüksek tane verimi 253.7 kg/da ile 20 cm sıra arası mesafe + Mesorhizobium ciceri + 40 kg/da tavuk gübresi uygulamasından elde edilmiştir.

Desert Soil Microbes as a Mineral Nutrient Acquisition Tool for Chickpea (Cicer arietinum L.) Productivity at Different Moisture Regimes

Drought is a major constraint in drylands for crop production. Plant associated microbes can help plants in acquisition of soil nutrients to enhance productivity in stressful conditions. The current study was designed to illuminate the effectiveness of desert rhizobacterial strains on growth and net-return of chickpeas grown in pots by using sandy loam soil of Thal Pakistan desert. A total of 125 rhizobacterial strains were isolated, out of which 72 strains were inoculated with chickpeas in the growth chamber for 75 days to screen most efficient isolates. Amongst all, six bacterial strains (two rhizobia and four plant growth promoting rhizobacterial strains) significantly enhanced nodulation and shoot-root length as compared to other treatments. These promising strains were morphologically and biochemically characterized and identified through 16sRNA sequencing. Then, eight consortia of the identified isolates were formulated to evaluate the growth and development of chickpea at three moisture levels (55%, 75% and 95% of field capacity) in a glass house experiment. The trend for best performing consortia in terms of growth and development of chickpea remained T2 at moisture level 1 > T7 at moisture level 2 > T4 at moisture level 3. The present study indicates the vital role of co-inoculated bacterial strains in growth enhancement of chickpea under low moisture availability. It is concluded from the results that the consortium T2 (Mesorhizobium ciceri RZ-11 + Bacillus subtilis RP-01 + Bacillus mojavensis RS-14) can perform best in drought conditions (55% field capacity) and T4 (Mesorhizobium ciceri RZ-11 + Enterobacter Cloacae RP-08 + Providencia vermicola RS-15) can be adopted in irrigated areas (95% field capacity) for maximum productivity of chickpea.