Figure - available from: Frontiers in Plant Science
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(A–C) Root rot symptoms in alfalfa grown in field. (A), healthy root. (B), brown lesions on the root and stem node of diseased alfalfa. (C), Black streaking of the vascular system, showing necrotic symptoms. Bars = 1 cm.
Source publication
Root rot is a major disease that causes decline of alfalfa production, and Fusarium is a major pathogen associated with root rot. In this study, 13 Fusarium isolates were obtained from alfalfa with root rot in Gansu Province, the major alfalfa production region in China. The isolates were characterized by molecular genotyping (ITS, TEF 1-α and RPB2...
Citations
... [63] and (iv) Corynascus verrucosus which has the capacity of decomposing crop residue such as cellulose, lipid and lignin in the composting process [64]. Alfalfa showed the following crop-specific fungal species: Aspergillus niveus, a xylanase producer [65]; Bipolaris sorokiniana, identified as a plant pathogen causing spot blotch [66]; and Fusarium oxysporum, a plant pathogen causing vascular wilt [67]. Maize also shared with alfalfa a few fusarium species: Fusarium proliferatum, the main source of fumonisins, a health risk mycotoxin, contaminating agro-products [68], and Fusarium equiseti which causes stalk rot in maize [69,70]. ...
Agricultural practices affect the physical, chemical, and biological properties of soil in agroecosystems. This study evaluated the impact of food production strategies on the rhizosphere microbial communities in the Yaqui Valley, Mexico, on key crops (Medicago sativa, Brassica oleracea, Asparagus officinalis, Phaseolus vulgaris, Citrus sinensis, Zea mays, Solanum tuberosum, Triticum durum, and an undisturbed native ecosystem). Soil samples were collected from 30 cm depths across one-hectare fields and analyzed for bulk density, pH, organic matter content, and electrical conductivity. Standardized methods were used for these analyses, along with microbial isolation through culturing, PCR amplification, and DNA sequencing for microbial identification. The use of synthetic fertilizers in the region was linked to increased salinity and soil compaction. Organic matter content was notably low at ≤1.4%, which negatively impacted microbial diversity. A total of 317 microbial strains were isolated, with bacteria comprising 73% and fungi 27%. Bacillus was the most dominant bacterial genus (41% of isolates), while Aspergillus was the most abundant fungal genus (31% of isolates). Crop-specific microbial strains were identified. This study provides the first detailed insight into how agricultural practices shape microbial communities in the Yaqui Valley's major crops, highlighting the link between soil properties and microbial diversity.
... Leptosphaeria spp. cause phoma leaf spot and stem cancer in many plant species [46,47]. This means that old alfalfa plants created favorable conditions for rhizosphere colonization by harmful microbes, rather than beneficial microbes. ...
The growth and biological decline of alfalfa may be linked to the rhizosphere microbiome. However, plant–microbe interactions in the rhizosphere of alfalfa and associated microbial community variations with stand age remain elusive. This study explored the successional pattern of rhizosphere microbial communities across different aged alfalfa stands and its relationship with alfalfa decline. Rhizosphere soils were collected from 2- and 6-year-old alfalfa stands. Control soils were collected from interspaces between alfalfa plants in the same stands. Soil bacterial and fungal communities were characterized by 16S and ITS rRNA gene sequencing, respectively. Specific microbial taxa colonized the rhizosphere soils, but not the control soils. The rhizosphere-specific taxa mainly included potentially beneficial genera (e.g., Dechloromonas, Verrucomicrobium) in the young stand and harmful genera (e.g., Peziza, Campylocarpon) in the old stand. Alfalfa roots regulated soil microbial communities by selective promotion or inhibition of distinct taxa. The majority of time-enriched taxa were reported as harmful fungi, whose relative abundances were negatively correlated with plant traits. Time-depleted taxa were mostly known as beneficial bacteria, which had relative abundances positively correlated with plant traits. The relative abundances of functional bacterial genes associated with vancomycin biosynthesis, zeatin biosynthesis, and amino acid metabolism trended lower in rhizosphere soils from the old stand. An upward trend was observed for fungal pathogens and wood saprotrophs with increasing stand age. The results suggest that root activity drives the negative succession of rhizosphere microbial communities during alfalfa decline in old stands.
O controle biológico de patógenos em sementes vem conquistando destaque por ser uma alternativa promissora no manejo integrado de doenças e ação benéfica sobre o crescimento das plantas. Assim, o objetivo deste estudo foi avaliar o potencial de produtos à base de Trichoderma spp. e Bacillus amyloliquefaciens no controle de fungos associados a sementes de Cajanus cajan (L.) Millsp e no crescimento inicial das plântulas. Foram utilizandos quatro produtos biológicos comerciais Ecotrich® (Trichoderma harzianum) (60g/100kg contato); Quality® (Trichoderma asperellum) (200g/100kg imersão); Pardelha® (Trichoderma harzianum, Trichoderma asperallum, Bacillus amyloliquefaciens) (60g/100kg imersão) Shocker® (T. harzianum, B. amyloliquefaciens) (300g/100kg imersão). Também foi realizado o tratamento das sementes com fungicida Captana (240g / 100 kg de sementes) e imersão em água destilada esterilizada 100 ml. O controle biológico de sementes é eficaz na redução da incidência de fungos e apresentam atividade antimicrobiana semelhante ao fungicida. O controle biológico reduziu a incidência dos fungos bem como, não afetou a qualidade fisiológica das sementes.
