Pircinque: new strawberry cultivar for Brazilian producers

ABSTRACT The strawberry cultivar ‘Pircinque’ was developed by the breeding program of Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria - Centro di Olivicoltura, Frutticoltura e Agrumicoltura (CREA-OFA-FRF), an Italian research entity, and introduced in Brazil in 2013 by the Centro de Ciências Agroveterinárias da Universidade do Estado de Santa Catarina (CAV-UDESC). In the breeding program in which it originated, ‘Pircinque’ was selected for plant rusticity and resistance to soil pathogens. It can be cultivated where soil sterilization techniques are not used. In Brazil, the cultivation of ‘Pircinque’ has shown to be promising in the major strawberry producing regions. The main characteristics that allowed the development of this cultivar among the growers were plant vigor, productivity, rusticity, flavor, pulp firmness, crispness, sweetness and fruit color. When grown with excessive nitrogen fertilization fruit sensitivity to Botrytis cinerea fungal attack has been found, and a high vegetative plant growth. Due to fruits peculiarity, many growers make differentiated sales, adding value to quality product. Also, due to the high post-harvest period, many growers allocate part of the production to more distant locations. These characteristics are determinant for the cultivar Pircinque be distinguishable from other strawberry cultivars already marketed in Brazil. The cultivar was registered at the Ministério da Agricultura, Pecuária e Abastecimento (MAPA) in 2016, and the commercialization of plants started in 2017 with five nurseries accredited to produce and market ‘Pircinque’ plants throughout Brazil.

Factors underlying the prevalence of Pythium infection of corn seeds following seed treatment application of tebuconazole

Microbial communities are essential for soil health, but fungicide application may have significant effects on their structure. It is difficult to predict whether non-target pathogens of applied fungicides in the soil will cause crop damage. Tebuconazole is a triazole fungicide that can be used as a seed treatment and thereby introduced to the soil. However, seed-applied tebuconazole has a potential risk of causing poor emergence of corn (Zea mays) seedlings. Using soil with a history of poor corn seedling emergence, we demonstrate through TA-cloning and isolation that the poor emergence of corn seedlings from tebuconazole-coated corn seeds was primarily due to infection by surviving soil pathogens, specifically Pythium species that are not targeted by tebuconazole, rather than the phytotoxic effects of tebuconazole. Bioassay tests on tebuconazole amended media showed that tebuconazole can suppress soil fungi while allowing Pythium to grow. Pythium species primarily contributing to the corn seed rot were more pathogenic at cooler temperatures. Furthermore, the non-target biocontrol agent of Trichoderma spp. was strongly inhibited by tebuconazole. Taken together, the non-target effects of tebuconazole are likely not significant under favorable plant growing conditions, but are considerable due to low-temperature stress.

Development of fungal-mediated soil suppressiveness against Fusarium wilt disease via plant residue manipulation

Background The development of suppressive soils is a promising strategy to protect plants against soil-borne diseases in a sustainable and viable manner. The use of crop rotation and the incorporation of plant residues into the soil are known to alleviate the stress imposed by soil pathogens through dynamics changes in soil biological and physicochemical properties. However, relatively little is known about the extent to which specific soil amendments of plant residues trigger the development of plant-protective microbiomes. Here, we investigated how the incorporation of pineapple residues in soils highly infested with the banana Fusarium wilt disease alleviates the pathogen pressure via changes in soil microbiomes. Results The addition of above- and below-ground pineapple residues in highly infested soils significantly reduced the number of pathogens in the soil, thus resulting in a lower disease incidence. The development of suppressive soils was mostly related to trackable changes in specific fungal taxa affiliated with Aspergillus fumigatus and Fusarium solani, both of which displayed inhibitory effects against the pathogen. These antagonistic effects were further validated using an in vitro assay in which the pathogen control was related to growth inhibition via directly secreted antimicrobial substances and indirect interspecific competition for nutrients. The disease suppressive potential of these fungal strains was later validated using microbial inoculation in a well-controlled pot experiment. Conclusions These results mechanistically demonstrated how the incorporation of specific plant residues into the soil induces trackable changes in the soil microbiome with direct implications for disease suppression. The incorporation of pineapple residues in the soil alleviated the pathogen pressure by increasing the relative abundance of antagonistic fungal taxa causing a negative effect on pathogen growth and disease incidence. Taken together, this study provides a successful example of how specific agricultural management strategies can be used to manipulate the soil microbiome towards the development of suppressive soils against economically important soil-borne diseases.

The properties of rhizobacteria from tomato rhizosphere as biocontrol and biofertilizer

Low soil fertility and the presence of pathogen are the limiting factors in horticultural crops cultivation in Ambon City. This study aimed to isolate plant growth promoting rhizobacteria from tomato rhizosphere as a potential biocontrol, biostimulant and biofertilizer. The research consisted of two stages, namely (1) isolation of bacteria from tomato rhizosphere and purification of the isolates, and (2) characterization of colony morphology, gram reaction, hypersensitivity test and antagonist test to soil pathogens, phosphate dissolution, and phytohormones indole acetic acid (IAA) production. Forty-two isolates were found from tomato rhizosfer, 36 isolates suppressed growth of Rhizoctonia solani while 6 isolates increased the growth of those pathogen. The growth of Phytophthora sp. pathogen was decreased by 35 bacterial isolates and increased by 7 bacterial isolates. All isolates produce IAA but only 13 isolates are enabled to dissolve inorganic phosphate. Based on bacterial properties, the isolates of TT-22, TT-21, TT-12, TT-11, WT-11 and WT-332 are the promising isolates for developing the biological agent as pathogen control and biofertilizer.

The use of Pseudomonas spp. as bacterial biocontrol agents to control plant disease

Most Pseudomonas biocontrol strains are associated with the rhizosphere of plants, where they control soil pathogens by antibiosis or competition, and leaf pathogens via induced systemic resistance. Genome mining and the division of the vastly heterogeneous genus Pseudomonas in phylogenomic (sub)groups has clarified the relation between biocontrol characteristics and phylogeny. Based on their activity, Pseudomonas biocontrol strains come in three types. A first type, represented by P. chlororaphis, P. protegens, P. corrugata and P. aeruginosa (sub)group strains, produces an arsenal of secondary metabolites with broad antimicrobial activity. The second type is found in the P. putida, P. fluorescens, P. koreensis, P. mandelii, and P. gessardii (sub)group. The spectrum of biocontrol properties of these strains is less diverse and involves siderophores and cyclic lipopeptides. The third type colonizes above-ground plant parts. Strains from this type mainly belong to the P. syringae group and are used to control postharvest pathogens. This chapter starts with recent advances in Pseudomonas taxonomy and a summary of its most important biocontrol traits. It then provides an overview of the most important Pseudomonas groups and subgroups harboring biocontrol strains. Examples of well-characterized and representative biocontrol strains show the links between phylogeny, ecology and biocontrol traits. The chapter concludes by reviewing commercially-available biocontrol strains.

Effects of Interspecific Grafting Between Capsicum Species on Scion Fruit Quality Characteristics

Production of Capsicum annuum peppers is often limited, especially in tropical environments, by susceptibility to soil pathogens including Ralstonia solanacearum. Grafting desirable cultivars onto selected rootstocks can increase adaptation to abiotic stress and is an alternative to pesticides for managing soilborne pathogens. Cultivars of two other pepper species, Capsicum baccatum and Capsicum chinense, are tolerant or resistant to an array of soilborne pathogens and have potential as rootstocks; however, knowledge of how interspecific grafting may affect scion fruit quality is lacking. Flowering time, yield, and fruit quality characteristics were evaluated in 2017 and 2020 for C. annuum cultivars Dulcitico, Nathalie (2017), Gypsy (2020), and California Wonder used as scions grafted onto Aji Rico (C. baccatum) and Primero Red (C. chinense) rootstocks, including self-grafted and nongrafted scion checks. In 2020, the rootstocks per se were evaluated. The two rootstocks (‘Aji Rico’ and ‘Primero Red’), three scions, and self- and nongrafted scions were evaluated using a factorial, replicated, completely randomized design in fields at the West Madison and Eagle Heights Agricultural Research Stations located in Madison, WI, in 2017 and 2020, respectively. Differences among the main effects for scion fruit quality characteristics were consistent with cultivar descriptions. No scion × rootstock interactions were observed. Rootstocks did not result in changes in total fruit number, yield, fruit shape (length-to-width ratio), or soluble solids of scion fruit compared with self- and nongrafted checks. The rootstock ‘Primero Red’ increased fruit weight and decreased time to flowering regardless of scion compared with self- and nongrafted checks. All scions were sweet (nonpungent) cultivars and both rootstocks were pungent cultivars. No capsaicinoids were detected in the fruit of sweet pepper scions grafted onto pungent pepper rootstocks. The results indicate that interspecific grafts involving ‘Aji Rico’ and ‘Primero Red’ will not have deleterious effects on fruit quality characteristics of sweet pepper scions.

Effect of Seed Dressing and Soil Chemical Properties on Communities of Microorganisms Associated with Pre-Emergence Damping-Off of Broad Bean Seedlings

Combating soil pathogens that disable plant emergence is among the most difficult challenges of global agriculture. Legumes, preferred in sustainable cultivation systems, are particularly sensitive to pre-emergence damping-off of seedlings. Seed dressing is therefore a very important element in the cultivation technology. The aim of this study was to compare the impact of biological (Pythium oligandrum) and chemical (carboxin + thiuram) seed dressing on the quantitative and qualitative composition of microorganisms participating in the epidemiology of this disease, under specific hydrothermal conditions and chemical properties of the soil (pH, humus, macro-, and micronutrient). Microorganism identification was done using the MALDI-TOF MS (Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry) technique. Species were assigned to frequency groups, and populations of pathogens, saprophytes, and antagonists were identified. The biodiversity of these communities was expressed with Simpson’s Reciprocal, Shannon–Wiener, and Evenness (Shannon) indices. In individual variants of seed pre-treatment, the correlations between individual edaphic factors and the suppression of pre-emergence damping-off, the number of isolates obtained from infected seedlings, and the share of individual trophic groups of fungi were assessed. The main causes of pre-emergence damping-off of broad bean seedlings are Ilyonectria destructans, Globisporangium irregulare, Fusarium equiseti, Rhizoctonia solani, and Fusarium solani. Eliminating seed treatment results in a seedling mortality rate of 33.5%–42.5%. The effectiveness of the chemical protection product is 44.2% and 25.9%. Carboxin and thiuram reduce the diversity of microorganisms involved in the pathogenesis of pre-emergence damping-off and limit the presence of antagonistic fungi. Under the influence of P. oligandrum, there was a five-fold increase in the population of antagonists. An increase in humus in the soil reduces the percentage of diseased broad bean seedlings.

Bacterial Community Analysis and Potential Functions of Core Taxa in Different Parts of the Fungus Cantharellus cibarius

Cantharellus cibarius is a widely distributed, popular, edible fungus with high nutritional and economic value. However, significant challenges persist in the microbial ecology and artificial cultivation of C. cibarius. Based on the 16S rRNA sequencing data, this study analyzed bacterial community structures and diversity of fruit bodies and rhizomorph parts of C. cibarius and mycosphere samples (collected in the Wudang District, Guiyang, Guizhou Province, China). It explored the composition and function of the core bacterial taxa. The analyzed results showed that the rhizomorph bacterial community structure was similar to mycosphere, but differed from the fruit bodies. Members of the Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium complex had the highest abundance in the fruit bodies. However, they were either absent or low in abundance in the rhizomorphs and mycosphere. At the same time, members of the Burkholderia-Caballeronia-Paraburkholderia complex were abundant in the fruit bodies and rhizomorphs parts of C. cibarius, as well as mycosphere. Through functional annotation of core bacterial taxa, we found that there was an apparent trend of potential functional differentiation of related bacterial communities in the fruit body and rhizomorph: potential functional groups of core bacterial taxa in the fruit bodies centered on nitrogen fixation, nitrogen metabolism, and degradation of aromatic compounds, while those in rhizomorphs focused on aerobic chemoheterotrophy, chemoheterotrophy, defense against soil pathogens, decomposition of complex organic compounds, and uptake of insoluble inorganic compounds. The analysis of functional groups of bacteria with different structures is of great significance to understand that bacteria promote the growth and development of C. cibarius.

Role of soil in the regulation of human and plant pathogens: soils' contributions to people

Soil and soil biodiversity play critical roles in Nature's Contributions to People (NCP) # 10, defined as Nature's ability to regulate direct detrimental effects on humans, and on human-important plants and animals, through the control or regulation of particular organisms considered to be harmful. We provide an overview of pathogens in soil, focusing on human and crop pathogens, and discuss general strategies, and examples, of how soils' extraordinarily diverse microbial communities regulate soil-borne pathogens. We review the ecological principles underpinning the regulation of soil pathogens, as well as relationships between pathogen suppression and soil health. Mechanisms and specific examples are presented of how soil and soil biota are involved in regulating pathogens of humans and plants. We evaluate how specific agricultural management practices can either promote or interfere with soil's ability to regulate pathogens. Finally, we conclude with how integrating soil, plant, animal and human health through a ‘One Health’ framework could lead to more integrated, efficient and multifunctional strategies for regulating detrimental organisms and processes. This article is part of the theme issue ‘The role of soils in delivering Nature's Contributions to People’.

ISOLATION OF ANTIBIOTIC PRODUCING BACTERIA FROM SOIL

Antibiotics are a major secondary metabolite produced by a wide range of bacteria. The microbes developed various antibiotics that could be used to treat various infectious diseases. Are useful In vitro isolation, the culture and care of bacteria are quite simple, and we can easily improve their stress. The main soil pathogens of the Bacillus species are caused by important antibiotics such as bactericidal Endospores produced by the Bacillus species are very resistant. They are always found to inhibit the growth of other microbes. In the present research study, soil bacteria with antimicrobial activity have been screened and isolated. Subsequently, various pathogenic bacterial lawns were prepared to check the antimicrobial activity against various pathogens. Different zones are observed against different pathogenic bacteria. Comparison of antimicrobial activity of soil isolation with different antibiotic discs as well as various pathogenic bacteria. A clear zone of soil isolates of 5 mm, 15 mm, 21 mm, 12 mm, 30 mm, 32 mm and 40 mm against germs or pathogenic bacteria. The zones produced by antibiotic discs against pathogenic bacteria were zones of 5 mm, 10 mm, 12 mm, 15 mm, 20 mm, and 21 mm observed.