Proteome, salicylic acid, and jasmonic acid changes in cucumber plants inoculated with Trichoderma asperellum strain T34

Trichoderma spp. is one of the most commonly used biological control agents against plant pathogens. This fungus produces changes in plant metabolism, thus increasing growth and enhancing resistance to biotic and abiotic stresses. However, its modes of action remain to be defined. In the first hours of interaction between cucumber plant roots and Trichoderma asperellum strain T34, salicylic and jasmonic acid levels and typical antipathogenic peroxidase activity increase in the cotyledons to different degrees depending on the applied concentration of the fungi. The use of 2-DE protein profiling and MS analysis allowed us to identify 28 proteins whose expression was affected in cotyledons after cucumber root colonization by Trichoderma applied at high concentrations: 17 were found to be up-regulated while 11 were down-regulated. Proteins involved in ROS scavenging, stress response, isoprenoid and ethylene biosynthesis, and in photosynthesis, photorespiration, and carbohydrate metabolism were differentially regulated by Trichoderma. The proteome changes found in this study help to give an understanding of how Trichoderma-treated plants become more resistant to pathogen attacks through the changes in expression of a set of defence-oriented proteins which can directly protect the plant or switch the metabolism to a defensive, nonassimilatory state.     

Physiological effects of the induction of resistance by compost or Trichoderma asperellum strain T34 against Botrytis cinerea in tomato

Certain types of compost used as growth media can induce resistance to foliar pathogens in above-ground parts of a plant. The induction of resistance can sometimes be associated with growth impairment and yield reduction. The objective of this study was to establish whether plants grown in olive marc compost had enhanced resistance against Botrytis cinerea at the cost of growth or physiological performance.Tomato plants grown in mature olive marc compost had approximately 60% less disease severity than plants grown in perlite. As a reference, plants grown in perlite enriched with the known inducer of resistance Trichoderma asperellum strain T34 (T34) had 35% less disease severity than plants grown in perlite. The salicylic acid (SA) pathway/abscisic acid (ABA) is involved in compost induced systemic resistance. Instead, perlite enriched with T34 is not linked to SA pathway/ABA. Physiological measures of water status, root/shoot ratio, stable isotopes of C and chlorophyll fluorescence showed that the plants grown in compost were close to a stress situation. However, growth measured as biomass and plant height of plants grown in compost was higher than in plants grown in perlite suggesting that plants in compost were not grown in a stress situation, but in a eustress. Tomato plants grown in perlite enriched with T34 had better growth, measured as total leaf area, biomass, height and nutrient uptake, than plants grown in perlite. Physiological measures showed that plants grown either in perlite or perlite enriched with T34 did not show any abiotic stress situation.     

Evaluation of Soil Streptomyces spp. for the Biological Control of Fusarium Wilt Disease and Growth Promotion in Tomato and Banana

Fusarium oxysporum f. sp. lycopersici (Fol) and Fusarium oxysporum f. sp. cubense (Foc), are the causal agent of Fusarium wilt disease of tomato and banana, respectively, and cause significant yield losses worldwide. A cost-effective measure, such as biological control agents, was used as an alternative method to control these pathogens. Therefore, in this study, six isolates of the Streptomyces-like colony were isolated from soils and their antagonistic activity against phytopathogenic fungi and plant growth-promoting (PGP) activity were assessed. The results showed that these isolates could inhibit the mycelial growth of Fol and Foc. Among them, isolate STRM304 showed the highest percentage of mycelial growth reduction and broad-spectrum antagonistic activity against all tested fungi. In the pot experiment study, the culture filtrate of isolates STRM103 and STRM104 significantly decreased disease severity and symptoms in Fol inoculated plants. Similarly, the culture filtrate of the STRM304 isolate significantly reduced the severity of the disease and symptoms of the disease in Foc inoculated plants. The PGP activity test presents PGP activities, such as indole acetic acid production, phosphate solubilization, starch hydrolysis, lignin hydrolysis, and cellulase activity. Interestingly, the application of the culture filtrate from all isolates increased the percentage of tomato seed germination and stimulated the growth of tomato plants and banana seedlings, increasing the elongation of the shoot and the root and shoot and root weight compared to the control treatment. Therefore, the isolate STRM103 and STRM104, and STRM304 could be used as biocontrol and PGP agents for tomato and banana, respectively, in sustainable agriculture.     

Synthesis of Iron-Amino Acid Chelates and Evaluation of Their Efficacy as Iron Source and Growth Stimulator for Tomato in Nutrient Solution Culture

Supplying a sufficient amount of available iron (Fe) for plant growth in hydroponic nutrient solutions is a great challenge. The chelators commonly used to supply Fe in nutrient solutions have several disadvantages and may negatively affect plant growth. In this research study we have synthesized certain Fe-amino acid chelates, including Fe-arginine [Fe(Arg)₂], Fe-glycine [Fe(Gly)₂], and Fe-histidine [Fe(His)₂], and evaluated their efficacy as an Fe source for two tomato cultivars (Lycopersicon esculentum Mill. cvs. ‘Rani’ and ‘Sarika’) grown in nutrient solution. Application of Fe-amino acid chelates significantly increased root and shoot dry matter yield of both tomato cultivars compared with Fe-EDTA. Tomato plants supplied with Fe-amino acid chelates also accumulated significantly higher levels of Fe, Zn, and N in their roots and shoots compared with those supplied with Fe-EDTA. In ‘Sarika’, the effect of Fe-amino acid chelates on shoot Fe content was in the order Fe(His)₂?>?Fe(Gly)₂?>?Fe(Arg)₂. In ‘Rani’, the addition of all synthesized Fe-amino acid chelates significantly increased activity of ascorbate peroxidase (APX) in comparison with Fe-EDTA, whereas in ‘Sarika’, only Fe(His)₂ increased shoot APX activity. The results obtained indicated that using Fe-amino acid chelates in the nutrient solution could supply a sufficient amount of Fe for plant uptake and also improve root and shoot growth of tomato plants, although this increase was cultivar-dependent. According to the results, Fe-amino acid chelates can be used as an alternative for Fe-EDTA to supply Fe in nutrient solutions.