Antioxidant potential of chili seedlings against anthracnose

Indian Phytopathology, 2014

Acta Physiologiae Plantarum

Chili plants are affected by the hemibiotrophic ascomycota fungus Colletotrichum capsici causing Anthracnose. Infection results in yield and marketability loss due to a decrease in the quality of fruits. The study of morphological symptom development in two cultivars, Bullet, and Beldanga, showed very different disease expression pattern. To understand the reasons behind such differential response, we investigated, in a time-dependent manner, biochemical activities of important defense enzymes, PR proteins, like peroxidase, polyphenol-oxidase, phenylalanine ammonia lyase, β-glucanase, chitinase, catalase, as well as phenols, flavonoids, chlorophyll and the key signaling molecule nitric oxide in their leaves. We further performed real-time nitric oxide (NO) detection studies. The results showed striking differences in the activity profile of these defense molecules through the course of the study. We monitored the gene expression levels of 12 important defense-related genes under in vivo condition. The transcription levels were mostly increased in the tolerant cultivar till 7 days post-infection (DPI), while downregulation of some of the genes were observed in the susceptible one. These data indicated that disease manifestation is a simulated response of these defense molecules which can nullify the effect of the pathogen and its products, when resistance occurs. Alternatively, the pathogen suppresses the host defense when the disease develops.

Anthracnose disease caused by Colletotrichum truncatum is a major economic constraint to chilli production in the tropical and subtropical regions of the world including India. To understand the molecular mechanisms of defense against anthracnose, we used a differential chilli-C. truncatum system consisting of two cultivars of chilli (Susceptible; Teja Jhal, TJ and resistant; Bhut Jolokia, BJ) and a highly virulent C. truncatum isolate to evaluate the temporal expression of seventeen defense-related genes associated with multiple defense signaling pathways. Quantitative real time PCR demonstrated rapid induction and significant accumulation of jasmonic acid (JA) and ethylene (ET) responsive genes such as plant defensin 1.2, Lypoxygenase 3, Allene oxide synthase and ACC synthase 2 in the resistant cultivar post treatment with C. truncatum. Significant induction of these genes was also realized upon exogenous treatment with JA and ET. The salicylic acid (SA) responsive phenylalanine ammonia-lyase 2 gene was upregulated only under incompatible interaction. Further, the transcript levels of pathogenesis related proteins PR2 and PR5 was significantly higher in the resistant genotype whereas PR1 and PR3 were moderately responsive. In addition, the expression of defense responsive transcription factors increased gradually in the resistant cultivar and remained significantly higher at 9 dpi as opposed to the susceptible one. Combined result analyses revealed that chilli adopts multiple defense strategies in mediating defence responses against the C. truncatum infection. Overall, this work represents a valuable resource for future functional ge-nomics experiments to unravel the molecular mechanisms of host resistance and pathogen virulence in the agriculturally important chilli-C. truncatum pathosystem.

Plant …, 2010

Anthracnose of chilli (Capsicum annuum L.) caused by Colletotrichum capsici is a major fungal disease in Bangladesh. In this study, the causal pathogen was identified based on symptoms, morphological characteristics including fruiting bodies, conidia as well as pathogenicity test. Among the eleven chilli cultivars tested in this study all the cultivars except V 8 /comilla-2 were found to be susceptible by C. capsici. However, the incidence of anthracnose was varied from 2.06-17.17% depending on the cultivar while the highest incidence were found in V 9 /kustia followed by V 4 /Jamalpur and V 1 /BARI Marich-1. Moreover, the fruit infection at the matured stage was recorded as 2.53 to 11.57% while highest was in V 6 /chandpur and the lowest was in V 8 /comilla-2. Due to anthracnose infection plant height and canopy diameter reduction were recorded as 0 to 36.39% and 0 to 35.74%, respectively while lowest was in V 8 /comilla-2 and highest was in V 1 /BARI Marich-1. Marketable yield lose were observed as 2.53 to 11.57% after C. capsici infection where highest was recorded in V 6 /chandpur and lowest was in V 8 /comilla-Based on the result of field performance it seemed that field resistance was found in V 8 /commilla-2 variety against anthracnose.

Journal of Plant Interactions, 2013

Enhancing the host resistance by using naturally occurring elicitors derived from pathogenic organisms is emerging as an ecofriendly approach in plant disease management. Cerebrosides, categorized as glycosphingolipids, were isolated and partially purified from the wilt causing fungus (Fusarium oxysporum f. sp. lycopersici). Cerebroside treatment significantly reduced the anthracnose disease incidence under greenhouse conditions. Cerebroside elicitors were found to stimulate the early H 2 O 2 accumulation followed by the production of plant defense-related enzymes such as Phenylalanine ammonia lyase (PAL), Peroxidase (POX), Polyphenol oxidase (PPO), and Lipoxygenase (LOX) when applied to chilli (Capsicum annuum L.) plants by spray treatment and also induced the accumulation of capsidiol. Defense-related enzyme activities were increased by the elicitor treatment and an high level in activity was maintained during the experimental period. Under greenhouse conditions, the cerebroside elicitors effectively protected chilli plants against infection by anthracnose causing organism, Colletotrichum capsici.

International Journal of Current Microbiology and Applied Sciences, 2019

The activity of defense enzymes viz., peroxidase, polyphenol oxidase, catalase and superoxide dismutase up on treatment with azoxystrobin and chaetoglobosin was studied in this experiment. The chilli plants inoculated with C.capsici showed various levels of peroxidase activity with respect to the treatments. The combined application of azoxystrobin with chaetoglobosin at 0.2 per cent concentration showed the highest level of peroxidase activity (1.130). The next highest level (0.872) was observed in azoxystrobin with tebuconazole combination. In the case of chilli plants inoculated with L. taurica, the maximum peroxidase activity was recorded in the same combination (0.817). The highest polyphenol oxidase activity in chilli plants inoculated with C.capsici recorded in azoxystrobin and chaetoglobosin combination (0.883). The next best increase (0.721) of PPO was noted in combined application of azoxystrobin with tebuconazole at 0.2 per cent concentration. The same trend was noticed when chilli plant inoculated with L. taurica. In the case of catalase and superoxide dismutase, azoxystrobin and chaetoglobosin combination, followed by azoxystrobin (Willowood) and tebuconazole combination showed the highest level of activity in chilli plants inoculated with C. capsici and L.taurica.

Australasian Plant Pathology, 2013

Pre-and post-harvest anthracnose fruit rot is a main disease of chilli (Capsicum spp.). Among Colletotrichum species causing anthracnose, C. capsici is the most common in India. A total of 41 Capsicum genotypes were screened for anthracnose resistance under field conditions. Bhut Jolokia, PBC-380 and IC-383072 were found symptomless and some marginally cultivated lines and other crosses were observed to be resistant. In vitro inoculation of the selected set of genotypes with C. capsici revealed that 9 days after inoculation was appropriate to record observations on disease resistance. Screening the 41 genotypes for resistance to anthracnose under in vitro conditions revealed four symptomless and 11 highly resistant lines. Comparing field and in vitro evaluations, nine lines (BS-35, BS-20, BS-28, Punjab Lal, Bhut Jolokia, Taiwan-2, IC-383072, Pant C-1 and Lankamura Collection) showed consistent resistance in field as well as in vitro to the disease. The study on differential reactions on fruits of 16 genotypes inoculated by the two C. capsici isolates (Ccf-Varanasi and Ccc2-Raichur) clearly showed that these isolates are two different pathotypes. A detailed analysis on prevalent strains in the target region would be needed to initiate resistance breeding. Nevertheless, newly identified resistant sources offer better choices for the ongoing anthracnose resistance breeding program.

International Journal of Current Microbiology and Applied Sciences

Chilli (Capsicum annuum) is an important spice as well as vegetable crop that are grown throughout the world especially in tropical and subtropical regions. India is a major producer, exporter and consumer of chilli. Chilli is grown in almost all states. Anthracnose disease can occur on leaves, stems, and both pre and post-harvest fruits. It is one of the major and devastating diseases of chilli causes severe losses (10-60%) both in yield and quality of the chilli depending upon the varieties. Diseases are the major problem for successful cultivation of chilli in India. For successful cultivation of chilli, it is important to identify resistant and tolerant varieties against anthracnose diseases. Therefore, experiment was conducted in the Department of Plant Pathology, college of Agriculture Gwalior and the field experiment were carried out in the Krishi Vigyan Kendra Research farm, RVSKVV Gwalior (M.P.) using CRD with 3 replication during kharif 2015-16. For Screening of 25 varieties & genotypes of chilli received from ICAR/National institutes were evaluated against anthracnose (Colletotricum capsici) under laboratory condition using three artificial inoculation treatment viz distilled water inoculation, without injury inoculation, injury + inoculation. Under laboratory/controlled condition, Semiripe full mature chilli fruits (25 days old) were chosen for this study. Fruits were carefully detached from plants and washed with sterile distilled water (SDW). Therefore suspension of conidia (5 x 10 5 conidia ml-1 water) of pathogen isolate was prepared and drops of conidial suspension were placed at proximal and distal ends on each fruit after puncturing the fruit (0. 6 mm diameter × 1. 2 mm depth). Three sets of fruits were prepared for experiment. In 1 st set, two drops (10µl. each) of conidial suspension were placed on two sites of fruits surface (Proximal and Distal ends). Similarly in another set of fruits were slightly puncher with sharp blade was inoculated with two drops conidial suspension (10µl. Each) on two sites (Proximal and Distal ends) of fruits observed anthracnose lesion development on fruit surface. In 3 rd sets of fruits, sterilized distilled water was used instead of conidial suspension, which acts as control. After inoculation, the chilli fruits were placed in a plastic container/ box (30 × 20 × 7 cm 3) lined with four layers of paper towel moistened with sterile distilled water to produce a well humid environment and later sealed with a plastic tape. Symptoms on the chilli fruit were examined and evaluated after 5, 7, and 10 days after inoculation by measuring the area of the lesion for disease development or % disease intensity. The PDI was observed on infected fruits. The percent disease severity on fruits was recorded by using 0-5 scale. The disease reaction of each genotype was categorised on the basis of following rating scale viz., 0%-immune, 0 to 5%-resistant, 5 to 25%-moderately resistant, 25 to 50%-susceptible, above 50%highly susceptible. The genotypes were rated as resistant and susceptible based on the range of lesion area (mm) or of the disease incidence (%). Among the artificial inoculation, two drops of conidial suspension after injury the fruit was found to be best treatment of inoculation and no infection noticed in other remaining both treatments. It was observed that injury to the fruits favoured the C. capsici development on detached fruit surface. Varieties Arka Harita, Classica-152 and Madhurima-148 were showing resistance reaction under two drops of conidial suspension after injury the fruits while EC-341075, Pusa Jwala, Pant C-1, Arka Meghna, LAC-434 and Sonakshi-44 were show moderately resistance reaction as compared to rest of varieties after five, seven and ten days of inoculation.

South African Journal of Botany, 2023

Plants, being sessile in nature, are inept to escape biotic stress that adversely impact their growth, development, and productivity. Rather, plants employ a variety of processes at the molecular, morphological, physiological as well as biochemical levels to mitigate the negative impacts of such stressors. Plants have a complex defense system against pathogens, pests and diseases, which includes collaborative actions regulated by array of genes and transcription factors. Immunity against pathogenic attack is determined by the plant's ability to avoid early infection and limit the growth of harmful pathogens, whereas resistance to microbial toxins is determined by the capacity of plant tissues to reduce toxin accumulation and its detoxification. This ability can be achieved through modulations in multiple processes. Among these processes, regulation of the antioxidant defense system, generation of reactive oxygen species and production of secondary metabolites is reckoned as an essential component of defense mechanism. Antioxidants such as superoxide dismutase (SOD), peroxidase (POD) and secondary metabolites, specifically phenolics, terpenes, and nitrogen-containing compounds have been widely proven to defend plants against range of biotic stresses. It is essentially needed to improve existing management practices to control pathogens and breed immunity in crops for sustainable agriculture and food security. Particularly to improve resistance to pathogenesis, the breeding of long-term resilience in cereals genotypes is one of the most promising strategies. A better grasp of the molecular processes underlying plant resilience to microbial assault will cast light on plant-pathogen interactions and provide useful information for breeding programs. This review emphasizes the ongoing investigation and significant operation of key molecular, physiological, and biochemical factors for tolerance and resistance in Oryza sativa against microbial infections. Additionally, we have focused on secondary metabolites and antioxidant defense system playing a crucial role in deciding how plants react to pathogen attacks.