Given the limits of intensive agriculture (pollution, degradation of biodiversity, or soil desertification), it is necessary to develop sustainable alternatives to respond to future agricultural ...demand. Among these sustainable alternatives is the use of microbial biostimulants. Despite convincing scientific studies on them, their agricultural use remains minor. This can be explained by the lack of efficiency and reliability of their use. This review proposes to develop efficient microbial biostimulants based on the combination of two approaches, namely that of endophytic bacteria from seeds and the Back to the Future approach. Seed endophytic bacteria have a major agroindustrial potential insofar as they stand out from other microbial agents by their resistance, competitiveness, efficiency, and vertical transmission. Contrary to modern cultivars, non-domesticated plants harbor microbiomes which have not been impacted by the processes of domestication and agriculture intensification. The Back to the Future suggests therefore to use interesting microorganisms isolated from non-domesticated plants and to integrate them into modern cultivars. This could result in the rehabilitation of modern microbiomes and lead to make crop cultures more resistant and resilient. The idea consisting in the combination of both approaches aims at obtaining optimized microbiomes. Particular emphasis is placed on integrating these innovative microbiomes into variety breeding programs. Indeed, given the importance of plant-microorganism interactions, particularly from an agronomic point of view, taking the hologenome into account as a unit of selection in breeding programs is essential. This integrative and unprecedented approach to designing breeding programs is promising with a view to reconciling productivity and preservation of agroecosystems.
•Mycorrhizae stimulate plant growth and N acquisition in faba bean but not in wheat.•AM hyphal density is higher under intercropping than in sole cropping.•Mycorrhizal network enhances the transfer ...of fixed N from faba bean to wheat.•Transfer of fixed N is not correlated with proportion or total amount of fixed N.
In Morocco, the use of seed legumes is limited because significant water deficits and the low availability of soil phosphorus (P) limit nitrogen fixation. However, little is known about the ability of faba bean-rhizobium symbiosis to fix nitrogen in P-deficient soils and to transfer fixed nitrogen (N) to intercropped wheat. Arbuscular mycorrhizal fungi (AM) and their extraradical hyphae networks play an important role in the facilitation process by promoting interconnectivity and the transfer of nutrients, such as N and P, between associated plants. The aim of this study was to analyse the impact of AM inoculation on N2 fixation and the transfer of fixed N from faba bean to intercropped wheat. Germinated faba bean and wheat seeds were transferred into 1–l pots filled with a P-deficient soil that was collected from the Haouz valley near Marrakech (Morocco). Plants from the two species were grown in pots in either pure or mixed stands under greenhouse conditions, and each cropping system was subjected to three mycorrhizal inoculation treatments with a non-inoculated (AM0) and two concentrations of Rhizophagus irregularis inoculants containing 1000 (AM1) or 2000 (AM2) spores pot−1. The 15N isotope dilution method was used to determine the amount and proportion of atmospheric N fixed by faba bean (Ndfa%) and the fixed N that was transferred to wheat. Mycorrhizal inoculation had a significantly positive effect on the shoot dry weights and total shoot N in faba bean, but not in wheat. The cropping system had no significant effect on the plant growth and total shoot N in both faba bean and wheat. The Ndfa percentage was very high in all of the treatments, varying from 86 to 91%. The total N fixed by faba bean was 27% significantly higher in the AM2 treatment compared with the AM1 and AM0 treatments for both cropping systems combined. The estimated proportions of fixed N that were transferred from faba bean to wheat were far higher in AM1 (50%) and AM2 (32%) treatments than in AM0 (15%) treatment as well as for the total transferred fixed N. As corroborated by a parallel observation of root mycorrhizal colonization, these results suggest that the development of mycorrhizal networks stimulates the transfer of fixed N from faba bean to wheat, which could significantly contribute to the facilitation process under intercropping conditions.
Screening of 10 environmental samples (mainly of rhizospheric origin) for lytic activity against two bacterial phytopathogens,
Pseudomonas syringae
pv.
tomato
DC3000 (CFBP2212) and
Xanthomonas ...hortorum
pv.
vitians
(CFBP3979), revealed that four samples harboured phages that were active against one strain. Only one sample, composed of an artisanal nettle liquid manure, contained phages able to lyse both strains. Electron microscopy revealed the presence of tailed bacteriophages, with all phages isolated on the
Xanthomonas
strain displaying a contractile tail typical of members of the family
Myoviridae
, whereas phages isolated on the
Pseudomonas
strain were related to members of the family
Siphoviridae
and short-tailed members of the family
Podoviridae.
Sequence analysis of the two
Podoviridae
-like bacteriophages isolated on
Pseudomonas syringae
pv.
tomato
, Pst_GM1 isolated from nettle manure and Pst_GIL1 isolated from infected lettuce leaves, revealed (i) strong homology between the two isolated phages, (ii) a high degree of sequence similarity to various phages isolated from various environments and from different geographical locations, and (iii) similarity of these phages to members of the family
Autographiviridae
, and more precisely, the genus
Ghunavirus
. Further investigation of the potential of nettle manure to host phages that could be active against a wider range of strains revealed that it contained phages active against 10 phytopathogens (out of 16 tested). Thus, nettle manure (and likely other plant manures) could represent a valuable source of phages, especially those targeting bacterial phytopathogens, in the same way that anthropized environments such as sewage are widely used as sources of phages active against opportunistic or acute pathogens of humans.
Arbuscular mycorrhizal fungi are major components of soil microbiota and mainly interact with other microorganisms in the rhizosphere. Mycorrhiza establishment impacts the plant physiology and some ...nutritional and physical properties of the rhizospheric soil. These effects alter the development of the root or mycorrhizas resulting from the activity of soil microorganisms. The rhizosphere of mycorrhizal plants (mycorrhizosphere), is inhabited by large microbial activities responsible for several key ecosystem processes. This review is focused on the microbial interactions between mycorrhizal fungi and components of rhizosphere microbiota and highlight the agronomic potentialities of the Mycorrhiza Helper Bacteria on mycorrhiza formation. The main conclusion is that this MHB effect in the rhizosphere of mycorrhizal plants, enhance plant fitness and soil quality and are of great interest to ensure sustainable agricultural development and ecosystem functioning.
The carob tree (Ceratonia siliqua L.) is an important component in semi-arid Mediterranean ecosystems, particularly in Morocco where it plays a considerable socio-economic role. This species is ...widely used in the reforestation programmes and in the rehabilitation of degraded soils serving both environmental and socio-economic objectives. In spite of these assets, this species is suffering the particular climatic conditions, rare and irregular rains, long hot and dry summers, generally, leading to desertification processes. To withstand these contrasting conditions, selected arbuscular mycorrhizal fungi (AMF) were tested for their contribution to the growth, nutrient uptake and photosynthesis improvement of the carob tree C. siliqua under nursery conditions.
The objective of this study was, to evaluate the effects of some arbuscular mycorrhizal fungi complexes isolated in different Mediterranean ecosystems compared to single-species isolates selected using morphological tools on the growth, mineral nutrition, and chlorophyll content of C. siliqua seedlings.
The results indicate that all the used AMF inocula stimulated significantly the height of C. siliqua seedlings after eight months under nursery conditions. An increase in plant height between 33% and 70% compared to a control without inoculation was recorded. Similarly, the aerial dry weight recorded an increase of 62% to 124% comparing inoculated and non-inoculated seedlings. The root dry weight has shown an increase rate of 24% to 86% compared to the control. The analysis of mineral contents in plant tissues, showed a highly significant increase in P. N. K. Ca and Mg levels of the aerial parts compared to the control. A significant increase in chlorophyll contents was noticed when inoculated seedlings were compared to non-inoculated ones. This study had confirmed the importance of AMF improving the growth of C. siliqua seedlings; the AMF complexes remain to have the important growth and mineral nutrition responses. However some single- species have shown similar magnitude to the complexes for all analysed parameters. A large biofertilizer potential of the single-species isolates in the inoculation of C. siliqua is demonstrated for the first time.
•Characterization of eighty coffee bacterial endophytes.•Twelve bacterial genera described for the first time as coffee endophytes.•Wide range of plant growth promoting and biocontrol ...activities.•Antifungal activity on Fusarium oxysporum.•Nematicidal activity on Radopholus duriophilus and Pratylenchus coffeae.
The endophytic bacteria were isolated from coffee roots and seeds in Vietnam and identified with 16S rDNA sequencing as belonging to the Actinobacteria, Firmicutes and Proteobacteria phyla with the Nocardia, Bacillus and Burkholderia as dominant genera, respectively. Out of the thirty genera recovered from Coffea canephora and Coffea liberica, twelve were reported for the first time in endophytic association with coffee including members of the genera Brachybacterium, Caballeronia, Kitasatospora, Lechevalieria, Leifsonia, Luteibacter, Lysinibacillus, Mycolicibacterium, Nakamurella, Paracoccus, Sinomonas and Sphingobium. A total of eighty bacterial endophytes were characterized in vitro for several plant growth promoting and biocontrol traits including: the phosphate solubilization, the indolic compounds, siderophores, HCN, esterase, lipase, gelatinase and chitinase production. A subset of fifty selected bacteria were tested for their potential as biocontrol agents with in vitro confrontations with the fungal pathogen Fusarium oxysporum as well as the coffee parasitic nematodes Radopholus duriophilus and Pratylenchus coffeae. The three most efficient isolates on F. oxysporum belonging to the Bacillus, Burkholderia, and Streptomyces genera displayed a growth inhibition rate higher than 40%. Finally, five isolates from the Bacillus genus were able to lead to 100% of mortality in 24 h on both R. duriophilus and P. coffeae.
The improvement of plant growth and yield becomes crucial to feed the rising world population, especially in harsh conditions, drought, salt stress, lack of nutrition, and many other challenges. To ...cope with these stresses, plants developed an adaptation strategy (mycorrhiza), which is an efficient way to reinforce their growth and resistance. For this purpose, we studied the influence of mycorrhizal fungi isolated from a natural rock phosphate mine in the vicinity of some native plants and agricultural soil to assess their capacity in increasing the growth, nutritional profile improvement, and biochemical parameters in the inoculated wheat plants. Results showed a high diversity of isolated arbuscular mycorrhizal fungi (AMF) spores in the agricultural soil, and less diversity in the natural phosphate samples, where three main genera were identified: glomus, gigaspora, and acaulospora. The chlorophyll content increased by 116% in the native inoculum (NM) flowed by Glomus sp2 from agricultural soil (98%) compared to non-mycorrhized plants, which significantly impact the growth and plant biomass (an increase of 90 and 73%, respectively). The same rate of change was shown on total phenolic compounds with an increase of 64% in the plants inoculated with Glomus sp2 in the presence of TSP, compared to the non-mycorrhized plants. In conclusion, the inoculation of wheat plants with AMF spores improved plants' growth
the increase in the density of the root system, which implies better assimilation of nutrients, especially in mycorrhizal plants with phosphorus fertilization regime, triple superphosphate (TSP) or natural rock phosphate (RP). This improvement of the physiological and biochemical parameters (chlorophyll contents and phenolic compound) of the treated plants reflected the positive impact of AMF, especially those originating from RP. AMF in phosphate mine could be an important source of inoculum to improve plant nutrient efficiency with the direct use of RP as fertilizer.
By dint of the development of agroecological practices and organic farming, stakeholders are becoming more and more aware of the importance of soil life and banning a growing number of pesticide ...molecules, promoting the use of plant bio-stimulants. To justify and promote the use of microbes in agroecological practices and sustainable agriculture, a number of functions or services often are invoked: (i) soil health, (ii) plant growth promotion, (iii) biocontrol, (iv) nutrient acquiring, (v) soil carbon storage, etc. In this paper, a review and a hierarchical classification of plant fungal partners according to their ecosystemic potential with regard to the available technologies aiming at field uses will be discussed with a particular focus on interactive microbial associations and functions such as Mycorrhiza Helper Bacteria (MHB) and nurse plants.
Soil fungi associated with plant roots, notably ectomycorrhizal (EcM) fungi, are central in above- and below-ground interactions in Mediterranean forests. They are a key component in soil nutrient ...cycling and plant productivity. Yet, major disturbances of Mediterranean forests, particularly in the Southern Mediterranean basin, are observed due to the greater human pressures and climate changes. These disturbances highly impact forest cover, soil properties and consequently the root-associated fungal communities. The implementation of efficient conservation strategies of Mediterranean forests is thus closely tied to our understanding of root-associated fungal biodiversity and environmental rules driving its diversity and structure. In our study, the root-associated fungal community of Q. suber was analyzed using high-throughput sequencing across three major Moroccan cork oak habitats. Significant differences in root-associated fungal community structures of Q. suber were observed among Moroccan cork oak habitats (Maâmora, Benslimane, Chefchaoun) subjected to different human disturbance levels (high to low disturbances, respectively). The fungal community structure changes correlated with a wide range of soil properties, notably with pH, C:N ratio (P = 0.0002), and available phosphorus levels (P = 0.0001). More than 90 below-ground fungal indicators (P < 0.01)-either of a type of habitat and/or a soil property-were revealed. The results shed light on the ecological significance of ubiquitous ectomycorrhiza (Tomentella, Russula, Cenococcum), and putative sclerotia-associated/ericoid mycorrhizal fungal taxa (Cladophialophora, Oidiodendron) in the Moroccan cork oak forest, and their intraspecific variability regarding their response to land use and soil characteristics.
The Sahelian Great Green Wall (SGGW) is an influential project to combat desertification and promote sustainable land management on a large scale, involving 11 countries in the Sahel region of ...Africa. The UNCCD’s 2020 progress report showed a mixed picture concerning the meeting of the initial targets. At the One Planet Summit in 2021, announcements were made to consolidate the implementation of the SGGW, most notably with the creation of the Great Green Wall Accelerator. In this context, our paper sets out to review the scientific work conducted with regard to the SGGW. We have thus carried out a bibliometric analysis of the literature on SGGW. Although the initiative involves 11 countries and covers a large spectrum of scientific disciplines, our results show the predominance of ecological studies in the SGGW literature and a concentration of studies in certain geographies of interest, such as northern Senegal. Moreover, based on a secondary analysis of publications on land restoration and sustainable ecosystem management in Sahelian countries, we show that the literature relevant to SGGW topics is richer and fills in the information gaps we have identified at thematic and geographical levels. By showing that SGGW studies are overly focused on certain topics and geographical areas, our paper argues for a better interdisciplinary mobilization of researchers working on GGW-related topics. The scientific and operational success of the project depends on stronger networking between the different research teams and themes, both in Africa and internationally.
PDF
