Projects / Programmes
Investigation of resistance mechanisms of garden strawberry (Fragaria ananassa), bean (Phaseolus vulgaris) and bell pepper (Capsicum annuum) to fungi of the genus Colletotrichum - studies of the interaction plant -pathogenic fungi
| Code |
Science |
Field |
Subfield |
| 4.03.01 |
Biotechnical sciences |
Plant production |
Agricultural plants |
| Code |
Science |
Field |
| B390 |
Biomedical sciences |
Phytotechny, horticulture, crop protection, phytopathology |
| Code |
Science |
Field |
| 4.01 |
Agricultural and Veterinary Sciences |
Agriculture, Forestry and Fisheries |
Colletotrichum, antrachnose, strawberry, bean, bell pepper, phenolics, enzymatic activity, phenylpropanoid pathway
Researchers (20)
Organisations (3)
Abstract
The synthesis of phenolic compounds is often one of the defense strategies of plants to various biotic and abiotic forms of stress. Among these compounds, phenols exhibit negative impacts on infection and growth of many pathogenic organisms. Their synthesis follows the phenylpropanoid pathway with shikimic acid as its main precursor. The enzyme phenylalanine ammonia lyase (PAL) plays a key role in their synthesis. It catalyzes the conversion of phenylalanine to cinnamic acid and its derivatives are the precursors for a wide spectrum of secondary metabolites. The synthesized phenolic compounds may oxidize and cause denaturation of pathogenic proteins or they can lead to the imposition of lignin, a phenolic polymer, which represents a mechanical barrier to the advancing hyphae. Two other enzymes, namely peroxidase and polyphenol oxidase, take part in this process and therefore present an important contribution to the defense of plants against pathogenic fungi. Phenolic substances may be present in large or small quantities in advance or synthesized de novo in response to the infection - phytoalexines. The biochemical principle of the plant response via the synthesis of phenolic compounds to the infection with fungi remains unknown, despite many research studies.
Fungi of the Colletotrichum genus cause an economically significant disease, anthracnose, in many host species, including vegetables, perennials and fruit plants. Symptoms are often manifested as fruit rot, rot of the root neck, and spots on leaves, leaf stems, as well as ripe and unripe fruits. Not only is the disease control focused on fruit yield loss; the goal is to also reduce costs for the chemical and mechanical protection and with that, reduce the burden on the environment by plant protection products. It is therefore necessary to carefully investigate the defense mechanisms of alternative approaches to plant protection against this fungal disease, especially in species where the fruit ripens gradually. In these plants the use of herbicides is somewhat limited as the time of the application in regard to fruit picking and consumption has to be carefully monitored.
With this study we aim to examine the impact of infection with the Colletotrichum fungus on the activity of defense enzymes and secondary metabolites in resistant and susceptible cultivars of strawberries, beans and peppers. With the use of HPLC-MS analysis the changes in the levels of important plant defense substances, ie. individual phenolic compounds from the groups of hydroxycinnamic, hydroxybenzoic acids, and various flavonoids, will be monitored. Phenolic compounds will be examined during the growing season and thus the changes in the plant metabolism will be detected as a response to the fungal infection. The synthesis of phenolic compounds will be monitored at several metabolic levels; we will be able to detect the activity of enzymes at primary and secondary metabolic level and their connection via PAL, chalcone synthase, chalcone isomerase, glycosyl transferase as well as polyphenol oxidase and peroxidase. For this purpose plants will be artificially infected with the Colletotrichum fungus and plants response will be time-monitored.
Such an approach will enable the identification of the response mechanisms of model plants (strawberry, beans and pepper) to the infection mainly via secondary metabolism of phenolic compounds and the rate of enzymatic response, involved in the phenylpropanoid pathway. Moreover, the impact of different production technologies (organic/integrated production) from the viewpoint of diverse contents of phenolic compounds in connection to Colletotrichum fungus infection will be determined. Consequently more precise directions for environmentally friendly products, which promote enzymatic activity and accumulation of immune substances prior to infection to ensure a greater tolerance of plants to fungal infection of the Colletotrichum genus can be set.
Significance for science
Synthesis of phenolic compounds is a part of the defense mechanism of plants against the attack by pests and diseases, which includes the pathogenic fungi. Despite many research studies in this field, biochemical processes in plants triggered by such an infection are not fully known. Our study were based on the interaction of environment and important agricultural crops (strawberries, peppers, beans) and fungi of the Colletotrichum genus, which infect and cause serious economic damage on these plants. The results of the study showed some interesting scientific results, we have successfully published in various scientific journals. In the case of strawberries, we found that infection by fungus affects the content of primary and secondary metabolites. The differences were shown between the varieties, where the content of epicatechin stood tolerant variety 'Honeoye'. After infection with fungi of the genus Colletotrichum the content of phenolic compounds increased significantly and with the further development of the disease the concentration of these substances again reduced. The increase in the synthesis of phenolic substances at the start of infection suggests that they form in response to the plants to infection by pathogens. Reduced phenols synthesis of the further development of the disease and the increased infection may be due to tissue destruction. In the case of beans, we found that all of the selected varieties contain the same primary and analyzed secondary metabolites, but vary in quantity. It has been shown that the amount influenced on the variety, production method, as well as infection with the fungus Colletotrichum lindemuthianum. The content of all groups of the phenols after infection increased in the bounary region between the spot and the healthy tissue, while in the healthy tissue it was lowest. The increase in the synthesis of phenolic substances in the boundary tissues indicating that the plant with the formation of these substances prevent the spread of fungi in the area of healthy tissue and represents the chemical defense plants to pathogen attack. Infection of sweet pepper with C. coccodes encourage the accumulation of chlorogenic acid, crysoeriol glucoside, glycosides of luteolin and quercetin in the boundary tissues between the spot and the healthy tissue compared with healthy tissue and spot. Given that the total derivatives of apigenin unlike other phenols do not show a statistical increase in the boundary part of spots, this suggests a minor role of apigenin glycosides in the protection of peppers from infection with fungi of the genus Colletotrichum. The resulting scientific knowledge on the interaction between plant and pathogen, understanding of synthesis pathways and the results have influenced the science development, as we successful published results in top scientific journals of our field, as well as on the development of the profession, because we transferred in new production technology through conferences, professional meetings ...
Significance for the country
Slovenian agriculture in recent years has gained in importance mainly due to self-sufficiency, short production chains and low-carbon society (short products transport). The Slovenian parliament in 2011 adopted a resolution on the strategic orientations of the development of Slovenian agriculture and food industry till 2020 - "Ensure.ourself food for tomorrow." Horticultural products have in this resolution a special role. In the case of vegetables we produce only 30% of the necessary quantities, so it is in these strategic guidelines provided for expansion of production of horticultural crops. In Slovenia we have never had intensive horticultural production in large areas, farm structure is relatively small and environment is very natural. That is why we can produce high quality food, particularly through new and improved production technologies, such as integrated and organic production. The knowledge that we have gained in the project "Study of the mechanisms of resistance in the strawberry (Fragaria ananassa), beans (Phaseolus vulgaris) and peppers (Capsicum annuum) on fungi of the genus Colletotrichum - studies the interaction between the plant and the pathogenic fungus" we have successfully scientific evaluated and all the results obtained successfully transferred to the improvement of existing technologies in practice. The use of natural plant defense mechanisms is rarely applied in current technologies, since it takes a lot more knowledge and respect for the biotic and abiotic factors. However, this approach is much more sustainable, allows lower power consumption and, consequently, more healthy food and is in accordance with the guidelines of low-carbon society.
Most important scientific results
Annual report
2011,
2012,
2013,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2011,
2012,
2013,
final report,
complete report on dLib.si
