Rot Disease Research Articles

Distribution of Pseudocercospora fruit and leaf spot, Phytophthora foot rot and scab diseases and their effect on Citrus tree decline prevalence in the humid zones of Cameroon

Introduction – Declining Citrus trees (CTD) is a major constraint causing Citrus production depletion in Cameroon. It has been established that some pests and diseases are the major sources of that phenomenon. Improving knowledge of the contributing factors to the occurrence of CTD is key to the control of this. Materials and methods – A study based on the presence of fungal diseases caused by Pseudocercospora angolensis, Elsinoe spp., and Phytophthora spp., was carried out in 39 sites of Citrus producing basins of Cameroon. The aim of the study was to determine environmental factors favouring CTD occurrence in an effort to reducing their devastating effects on three common species of Citrus. Disease symptoms were noticed by examining tree's organs (leaves, fruits, branches, trunk). A regression analysis was applied with the General Linear Model to select the main factors involved in CTD development. The prevalence of CTD was treated as dependent variable. Independent variables were Citrus species, soil texture, vegetation, rainfall, temperature, relative humidity, altitude, observation year, prevalence of PLFSD, Citrus scab and Phytophthora diseases. Results and discussion – CTD was found in all the sites, with a mean prevalence of 25%. Citrus species, soil texture, vegetation, rainfall, Pseudocercospora fruit spot disease, scab, and Phytophthora foot rot disease were the main factors associated with CTD prevalence. Conclusion – The importance of CTD was confirmed. It has been shown that PLFSD and Phytophthora diseases were much more likely to contribute to tree decline contrary to Citrus scab. However, further analysis could pave the way for the development of a risk assessment model for CTD.

Novel report on six Fusarium species associated with head blight and crown rot of wheat in Basra province, Iraq

BackgroundWheat is the main cultivated crop and the highest cereal used up by humans in Iraq. Two Fusarium species causing Fusarium head blight (FHB) disease on wheat has been detected only in the middle of Iraq, and Fusarium crown rot (FCR) disease has been detected in several provinces, but it was limited to only three species. This study was conducted to deepen and enlarge our current understanding of the causal agents of these symptoms observed in the wheat fields and to isolate, purify, and identify (molecularly) the most common soil fungi occurring in the rhizosphere of seedlings showing, root, crown, stem, and head at symptom occurrence.ResultsEighty-eight Fusarium isolates were isolated from 7 wheat cultivars planted in 14 fields in the south of Iraq, Basra province, by using polymerase chain reaction (PCR) technique. Based on molecular identification methods as well as the analysis of phylogenetic trees, the results of this study have verified that the main species belonging to the genus Fusarium causing FHB and FCR diseases on wheat in the studied areas are F. pseudograminearum, F. graminearum, F. equiseti, F. culmorum, F. solani, F. avenaceum, F. chlamydosporum, F. cerealis, and F. nygamai. The first 3 species have been identified previously in several Iraqi studies on wheat and barley. This is the first record of the last 6 Fusarium species from the wheat crop in Iraq as causative pathogens of FHB and FCR. Individual phylogenetic trees of 71 Fusarium isolates reconstructed based on the internal transcribed spacer (ITS) sequences showed that all isolates belonging to each of the 9 Fusarium species form monophyletic groups with identical isolates of the same species. Collective phylogenetic tree of the remaining 17 Fusarium isolates reconstructed based on translation elongation factor 1 alpha (TEF1-α) gene sequences showed that all isolates belonging to each of the 4 Fusarium species forms monophyletic groups with identical isolates of the same species.ConclusionIraqi wheat cropping system is seriously threatened by FHB and FCR diseases. Other Iraqi provinces should be inspected to understand the distribution of both diseases.

Deletion of the Nonribosomal Peptide Synthetase Gene nps1 in the Fungus Clonostachys rosea Attenuates Antagonism and Biocontrol of Plant Pathogenic Fusarium and Nematodes.

Secondary metabolites produced by biological control agents may influence the outcome of their interactions with plant pathogenic microorganisms and plants. In the present study, we investigated the role of the nonribosomal peptide synthetase gene nps1 expressed by the biocontrol fungus Clonostachys rosea. A gene expression analysis showed that nps1 was induced during confrontations with the plant pathogenic fungus Botrytis cinerea. Gene deletion strains of nps1 displayed increased growth rates and conidiation. However, the nematicidal activity of culture filtrates from C. rosea Δnps1 strains was significantly weaker than that from wild-type filtrates (P ≤ 0.001); after 24 h of incubation with culture filtrates from nps1 deletion strains, only 13 to 33% of a mixed community of nematodes were dead compared with 42% of nematodes incubated with wild-type culture filtrates. The Δnps1 strains also showed reduced biocontrol efficacy during pot experiments, thus failing to protect wheat seedlings from foot rot disease caused by the plant pathogenic fungus Fusarium graminearum. Furthermore, C. rosea Δnps1 strains were not able to reduce populations of plant-parasitic nematodes in soil or in roots of wheat as efficiently as the wild-type strain. Both C. rosea wild-type and Δnps1 strains increased the dry shoot weight and shoot length of wheat by 20 and 13%, respectively. We showed that NPS1, a putative nonribosomal peptide synthetase encoded by nps1, is a biocontrol factor, presumably by producing a hitherto unknown nonribosomal peptide compound with antifungal and nematicidal properties that contributes to the biocontrol properties of C. rosea.

Pseudomonas grimontii, causal agent of turnip bacterial rot disease in Japan

From April to May 2012, a rot disease on turnips grown in greenhouses in southern Hokkaido, Japan caused severe leaf blight, brown discoloration of crown surface, and browning and rot of the interior of main roots. From diseased tissues, bacteria that formed pale beige- to cream-colored colonies were isolated and demonstrated to be pathogenic on turnip after inoculation and reisolation of the isolates. They were gram-negative, aerobic rods with one to three polar flagella, and identified as Pseudomonas grimontii based on biochemical and physiological characterizations, multilocus sequence analysis using concatenated sequences of 16S rRNA, rpoD, gyrB, and rpoB genes, and MALDI-TOF MS analysis using the Bruker MALDI Biotyper system. To the best of our knowledge, P. grimontii has not been isolated previously in Japan, so this study might be the first report of the species in Japan. Although the significance of P. grimontii as a plant pathogenic bacterium has not yet been fully evaluated, we proved in this study that the bacterium is the causal agent of the disease and that its virulence is strong. These findings indicate that it is necessary to record P. grimontii as a novel pathogen posing a threat to plants and requiring vigilance.

EFISIENSI PENGGUNAAN FAKTOR-FAKTOR PRODUKSI DALAM PRODUKSI JAHE GAJAH

ABSTRACT
 The maximum production can be achieved if using optimum inputs. Production efficiency is influenced by the use of production inputs. The purpose of this research was to examin;: (1) the effect of production factors of jahe gajah; (2) inefficiency and efficiency factor of jahe gajah; (3) farmer's income in jahe gajah farming; and (4) constraints faced in Jahe Gajah production. The research method uses quantitative descriptive methods. The number of samples in this is researc were 66 people determined by the Simple Random Sampling technique. Production efficiency was analyzed using the Stochastic Frontier production function with the Frontier 4.1c program and farmer’s income was analyzed using R/C ratio. The results of the research indicate that; (1) land area variables affect production; (2) education, experience, counseling dummy variables influence production, while jahe gajah farm is stated to be technically efficient with an average value of 0.910, but not yet allocatively efficient with an average value of 0.668 and not economically efficient with average values of 0.599; (3) the jahe gajah farm has profit R/C ratio 1,7; (4) constraints faced by jahe gajah farmers there is no standards price, difficulty in obtaining market access, and rhizome rotten disease.

Identification of Owen-Type Male Sterility Maintainers Carrying Resistance Against Rhizoctonia Crown and Root Rot (Rcrr) Disease in Sugar Beet Germplasm

Propagation and maintaining cytoplasmic male-sterile (CMS) lines are prerequisite of hybrid production programs in sugar beet. The identification of Owen-type (O-type) source materials is important to maintain CMS plants that accelerate crosses between single plants. The objectives of the present study were to assess a base beet germplasm (SB19) to identify O-type plants for use in hybrid production programs and test for resistance against rhizoctonia crown and root rot (Rcrr) disease. A family was developed from each two identified candidate monogerm O-types. A number of 100 plants of each family were crossed with FC708 (male sterile) in insulated cages, and the progenies of hybrids were tested for the frequency of male sterility. Progenies of candidate O-types crossed with FC708 revealed various levels of male sterility. Type I and Type II male sterility had lowest frequency, while completely sterile type was the most frequent. The results demonstrated that 6 plants in each family were fully male sterile and their parallels S1 were selected as O-type and male sterility maintainer. The mean for male sterility frequency was 10.5%. The mean disease index (DI) in the selected O-types was 2.22 that was lower than DI in SB19 as a resistant check. Mean comparison for Rcrr demonstrated that all O-types and SB19 plants were discriminated form Jolgeh as Rcrr-susceptible check. In conclusion, the identified O-types can be tested for combining ability for the development of Rcrr-resistant sugar beet hybrids with respect to root and sugar yield traits.

Occurrence of Leaf Tip Mutation in Black Pepper ( Piper nigrum L.)

Black pepper ( Piper nigrum L., family: Piperaceae) is one of the oldest and most widely used culinary spices. Convention-ally leaves of black pepper plant have a single acuminate or mucronate tip 1 , but we found multiple tips in some black pepper plants. Panniyur-5 is a variety bred at the Pepper Research Station Panniyur by Kerala Agricultural Univer-sity, Thrissur, India. It is a selection from open pollinated seedling progeny of Pe-rumkodi with moderate susceptibility to foot rot disease at nursery 2 . Horticulture Section of ICAR-Central Coastal Agri-cultural Research Institute is engaged in research of black pepper as suitable inter/ mixed crop in perennial crop-based cropping systems.

Athelia rolfsii (= Sclerotium rolfsii) infects banana in the Philippines

We surveyed eight banana farms planted with cultivar “Lakatan” in Central Visayas, Philippines, for fungal diseases in 2014. A rotting disease on the corm and leaf sheaths, splitting of the pseudostem and yellowing of the leaves were observed only in Toledo City, Cebu province. These symptoms were associated with sclerotial bodies and mycelial growth. The causal organism was identified by morphology and ITS sequence as Athelia rolfsii (= Sclerotium rolfsii) which is the first report of this fungal pathogen on banana from the Philippines.

Livelihood Pattern of Betel Leaf Cultivators: A Case Study at Fakirhat Upazila in Bagerhat District of Bangladesh

Betel leaf is a traditional cash crop in Bangladesh. Betel leaf cultivation is such like traditional agro-based occupation. This cash crop is locally known as pan and it’s scientific name is Piper betel that is the leaf of a vine belonging to the Piperaceae family. This study makes a modest attempt to know the livelihood pattern of betel leaf cultivators of south-west region of Bangladesh. The data were collected from Maskata Village in Betaga Union and Piljanga Village in Piljanga Union under Fakirhat Upazila in Bagerhat District, Bangladesh. This study was descriptive in nature. The paper is based upon qualitative approach which includes analysis of existing secondary sources of data. It also deals with primary data collected through Case Studies, Focus Group Discussions (FGDs), Key Informants Interview (KII) methods. The data were analyzed into five categories including: natural capital, financial capital, social capital, physical capital and human capital. Betel leaf cultivation is an ancestral occupation of the respondents. Most of the family structure is nuclear and have strong bonding within community. Poor socio-economic conditions include lack of sanitation, unavailability of pure drinking water and lack of health care center creates pressure on their health status. On the contrary, low education, poor savings and poor credit facilities with high rates of bank interest makes them more vulnerable. Water logging and rot diseases are other challenges of this cultivation. The children who are involved in tertiary education, they mostly not come back their ancestral occupation. From the study it is revealed that, integrated as well as comprehensive intervention program with social awareness and safety net program should be run by the Government and NGOs for the betterment of this vulnerable occupation. Moreover, health worker should provide medicine and other health incentives for physically vulnerable groups. This paper would contribute to the policy making and taking necessary initiatives especially for this occupational groups.
 South Asian J. Agric., 7(1&2): 34-37

Evaluation of tolerance to Phytophthora capsici-the causal agent of foot rot disease in black pepper

Vietnam is the leading black pepper export country in the world. However, the production of pepper may be affected by natural disasters, pests such as Phytophthora capsici. The Phytophthora capsica disease has caused a significant decline in pepper yields. The disease is characterized with a high mortality rate (up to 100%) and rapid outbreak and thus is very challenging to control. In the present study, eight strains of P. capsici were isolated from 100 samples of leaf, stem, root and soil that were collected from pepper-growing areas of Dong Nai, Binh Duong and Ba Ria - Vung Tau provinces. These isolates' straits had capacity to cause foot rot on pepper leaf after two days of inoculation. Among them, the isolates with the highest pathogenicity are BR-L1, DN-D1 and DN-D2. In order to determine the resistance level to P. capsici of commonly grown pepper varieties (Vinh Linh, Se, Xanh, Trau and Kuching), the pepper leaves were in vitro infected with P. capsici BR-L1 spores in laboratory and greenhouse conditions. Trau variety showed the highest resistance level to P. capsici with the as indicated by (P < 0.01) disease ratio (74.1%) and disease index (73.7%) after 6 days in laboratory condition and the corresponding numbers of 17.3% and 15.8% after 12 days in greenhouse condition.

Karakteristik morfologi dan sebaran tipe kawin Phytophthora capsici asal lada di Pulau Jawa

Morphology characters and mating types distribution of Phytophthora capsici from black pepper in Java IslandPepper (Piper nigrum) is one of the most important spice crops in Indonesia. Recently its production declining due to infection of foot rot disease caused by Phytophthora capsici. This pathogen has two different mating types, namely A1 and A2, in which the presence of opposite two mating types is important for sexual reproduction and formation of oospores. The movement of pepper seedling from one area to another is highly facilitated alteration of mating type distribution map of P. capsici. The objectives of this research were to determine the morphological characteristics and the spread of mating types of P. capsici in Java. Morphology characters of P. capsici isolates were indicated by variation in sporangial size and shape, as well as types of colony appearance. The length (l) and width (w) of sporangium were in the range of 15.1–76.2 µm and 9.8–44.8 µm, respectively; while the l/w ratio was 1.12–2.27. Mating type assay showed that A2 type was more dominantly found than A1 type. This study found two different mating types present in the same area, i.e. Regency of Pacitan (East Java) and Regency of Sleman (Special Region of Yogyakarta). The findings of this research suggested that it is required more strict control strategy on the mobilization of black pepper seedling particularly in the area where the certain mating type is not found yet so that the emergence of new more virulent genotype of pathogen can be prevented.

Integration Analysis of Small RNA and Degradome Sequencing Reveals MicroRNAs Responsive to Dickeya zeae in Resistant Rice.

Rice foot rot disease caused by the pathogen Dickeya zeae (formerly known as Erwinia chrysanthemi pv. zeae), is a newly emerging damaging bacterial disease in China and the southeast of Asia, resulting in the loss of yield and grain quality. However, the genetic resistance mechanisms mediated by miRNAs to D. zeae are unclear in rice. In the present study, 652 miRNAs including osa-miR396f predicted to be involved in multiple defense responses to D. zeae were identified with RNA sequencing. A total of 79 differentially expressed miRNAs were detected under the criterion of normalized reads ≥10, including 51 known and 28 novel miRNAs. Degradome sequencing identified 799 targets predicted to be cleaved by 168 identified miRNAs. Among them, 29 differentially expressed miRNA and target pairs including miRNA396f-OsGRFs were identified by co-expression analysis. Overexpression of the osa-miR396f precursor in a susceptible rice variety showed enhanced resistance to D. zeae, coupled with significant accumulation of transcripts of osa-miR396f and reduction of its target the Growth-Regulating Factors (OsGRFs). Taken together, these findings suggest that miRNA and targets including miR396f-OsGRFs have a role in resisting the infections by bacteria D. zeae.

Efficacy of bio agents and fungicides against collar rot and early leaf spot of groundnut

Collar rot caused by (Aspergillus niger Van Teighem) and early leaf spot caused by (Cercospora arachidicola Hori) are the two major diseases, affecting the groundnut cultivation across the India and worldwide. The main aim of this study was to find out the effective management module to control the collar rot and early leaf spot diseases of groundnut. Efficacy of bio agents and fungicides either alone or with combination were assessed under field conditions. The treatment module consisting of seed treatment with Tebuconazole 2 DS @ 1.5 g kg−1 + furrow application of T. viride @ 4.0 kg enriched with 50 kg FYM ha−1 + broadcasting of T. viride @ 4.0 kg enriched with 50 kg FYM ha−1 at 40 DAS + two foliar sprays of Tebuconazole 25.9% EC @ 1.0 ml l−1 starting from initiation of diseases and second spray at 15 days intervals was found most effective and economically beneficial treatment module in controlling of collar rot and early leaf spot diseases of groundnut.

Soil fungal biodiversity and pathogen identification of rotten disease in Aconitum carmichaelii (Fuzi) roots.

Aconitum carmichaelii, commonly known as Fuzi, is a typical traditional Chinese medicine (TCM) herb that has been grown for more than one thousand years in China. Although root rot disease has been seriously threatening this crop in recent years, few studies have investigated root rot disease in Fuzi, and no pathogens have been identified. In this study, fungal libraries from rhizosphere soils were constructed by internal transcribed spacer (ITS) sequencing using the HiSeq 2500 high-throughput platform. A total of 948,843 tags were obtained from 17 soil samples, and these corresponded to 195,583,495 nt. At 97% identity, the libraries yielded 12,266 operational taxonomic units (OTUs), of which 97.5% could be annotated. In sick soils, Athelia, Mucor and Mortierella were the dominant fungi, comprising 10.3%, 10.1% and 7.7% of the fungal community, respectively. These fungi showed 2.6-, 1.53- to 6.31- and 1.38- to 2.65-fold higher enrichment in sick soils compared with healthy soils, and their high densities reduced the fungal richness in the areas surrounding the rotted Fuzi roots. An abundance analysis suggested that A. rolfsii and Mucor racemosus, as the dominant pathogens, might play important roles in the invading Fuzi tissue, and Phoma adonidicola could be another pathogenic fungus of root rot. In contrast, Mortierella chlamydospora, Penicillium simplicissimum, Epicoccum nigrum, Cyberlindnera saturnus and Rhodotorula ingeniosa might antagonize root rot pathogens in sick soils. In addition, A. rolfsii was further verified as a main pathogen of Fuzi root rot disease through hypha purification, morphological observation, molecular identification and an infection test. These results provide theoretical guidance for the prevention and treatment of Fuzi root rot disease.

Antifungal Activity and Action Mechanism of Ginger Oleoresin Against Pestalotiopsis microspora Isolated From Chinese Olive Fruits

Pestalotiopsis microspora (P. microspora) is one of dominant pathogenic fungi causing rotten disease in harvested Chinese olive (Canarium album Lour.) fruits. The purposes of this study were to evaluate the antifungal activities of ginger oleoresin (GO) against P. microspora and to illuminate the underlying action mechanisms. The in vitro assays indicate that GO exhibited strong antifungal activity against mycelial growth of P. microspore, and with 50%-inhibition concentration (EC50) and 90%-inhibition concentration (EC90) at 2.04 μL GO and 8.87 μL GO per mL propylene glycol, respectively, while the minimal inhibitory concentration (MIC) and minimal fungicidal concentration were at 10 μL GO and 30 μL GO per mL propylene glycol, respectively. Spore germination of P. microspora was inhibited by GO in a dose-dependent manner, and with 100% inhibition rate at the concentration of 8 μL GO per mL propylene glycol. Compared to the control, the cellular membrane permeability of P. microspora increased due to severe leakage of intercellular electrolytes, soluble proteins, and total sugars with the treatments (EC50, EC90) by GO during incubation. In addition, analysis of fatty acid contents and compositions in cellular membrane by GC-MS indicated that GO could significantly promote the degradation or peroxidation of unsaturated fatty acids in P. microspore, resulting in the enhancement of membrane fluidity. Moreover, observations of microstructure further showed the damage to plasma membrane and morphology of P. microspora caused by GO, which resulted in distortion, sunken and shriveled spores and mycelia of the pathogen. Furthermore, in vivo assay confirmed that over 3 MIC GO treatments remarkably suppressed disease development in P. microspore inoculated-Chinese olive fruit. These results demonstrate that owing to its strong antifungal activity, GO can be used as a promising antifungal agent to inhibit the growth of pathogenic fungi in Chinese olives.

Understanding Bakanae: a major threat and an emerging disease of Basmati rice

Rice foot rot (bakanae) disease caused by Fusarium moniliforme (syn. F. verticilloides), teleomorph: Gibberella fujikuroi (syn. Gibberella moniformis) has become a serious bottleneck in the successful cultivation of rice particularly basmati rice in all the rice growing regions of the world. It is becoming a threat for sustainable rice production as developing resistant rice varieties is difficult due to the high genetic variation of Fusarium spp. In recent years, conflicting results suggested the involvement of different other Fusarium species in the section Liseola in causing the disease. Investigations on the pathogenic, bio-chemical, molecular and genetic diversity of foot rot pathogen is becoming very important to tackle the yield losses. Identification of the species and understanding host–pathogen interaction, variability of pathogen, its survival and identification of resistant sources have been a difficult task. Understanding this disease and the pathogen will effectively help in promulgation of effective strategies for management of foot rot.

In vitro and in vivo fungicidal effects of γ-irradiation synthesized silver nanoparticles against Phytophthora capsici causing the foot rot disease on pepper plant

γ-rays irradiation, is a powerful method for the preparation of colloidal silver nanoparticles (AgNPs). Three different AgNPs with average particle size of 5, 10 and 15 nm were synthesized and stabilized by chitosan (1%), and demonstrated a significant in vitro activities against Phytophthora capsici with 62.5, 84.3 and 100%, inhibition efficacy, respectively. An improved antifungal activity of 10 nm size AgNP was noticed by increasing the initial silver concentration with maximum inhibition efficiency of 92.9% at 100 ppm. The in vivo study performed for fungicidal effect of AgNPs in pepper plants showed that pretreatment of 1–10 ppm AgNPs effectively reduced P. capsici infection leading to enhanced rate of non-disease-outbreak of 53.3 and 95.0%, respectively. On the other hand plants treated with AgNPs after fungus infection displayed 60.0 and 91.7% non-disease-outbreak after the treatment at 10 and 50 ppm concentration, respectively. The results specify the potential role of γ-irradiation synthesized AgNPs for controlling the pathogen P. capsici on black peppers. Moreover, the environmental friendly production of AgNPs and its high effectiveness against fungi prove it a safe and alternative against the conventional antifungal agents.

Intervarietal Differences of Winter Wheat in Conditions of the Southeastern Volga-Vyatka Region

The article makes an effort to assess ten varieties of winter wheat and select the ones most adapted to the conditions of the study region, which would combine a significant yield potential with high quality grains and possess a complex of important economic traits. It has been determined that yield performance of the studied varieties ranges from of 4.78 t/ha in variety Pamyati Fedina to 6.02 t/ha in variety Nemchinovskaya 57. Varieties Nemchinovskaya 17 and Nemchinovskaya 57 have been found to produce a significantly higher yield than standard variety Moskovskaya 39, that is, by 1.03 and 1.16 t/ha or 21.2 and 23.9%, respectively. Protein content varies within the range from 15.2 in variety Pamyati Fedina to 19.1% in variety Moskovskaya 40. This indicator is 17.5% in the standard variety. Moskovskaya 40 is also significantly distinguished by gluten content of 35.9%. In addition, the above-noted varieties reveal a significant winter survival and resistance to leaf and rot diseases. Thus, it can be concluded that Nemchinovskaya 57, Nemchinovskaya 17, and Moskovskaya 40 are the most remarkable among the varieties in the context of important economic traits, that is, yield performance, protein and gluten content, components of yield structure, and resistance to diseases.

Hydrothermal treatment in the management of anthracnose in ‘Prata-Anã’ banana produced in the semiarid region of Minas Gerais, Brazil

Abstract Anthracnose stands out among rot diseases that can occur in the post-harvest phase of banana. The aim of this study was to evaluate the thermotherapy in the control of anthracnose in ‘Prata Anã’ banana produced in northern state of Minas Gerais. Bananas ‘Prata Anã’ variety were divided into groups of three fruits and inoculated with Colletotrichum musae. Groups were submitted to thermotherapy using five temperatures (40°C, 44°C, 48°C, 52°C and 56°C) and four immersion times (4, 8, 12 and 16 minutes) and control. Treatments were repeated five times in a completely randomized design. Area under the incidence progress curve (AUIPC) and area under the severity progress curve (AUSPC) were calculated. To evaluate the thermotherapy efficiency compared to chemical control, fruits were submitted to the following treatments: thermotherapy with and without fungicide application and fruits treated with fungicide only, the control fruits without thermotherapy and without fungicide application. After fifteen days of storage, fruits were evaluated for anthracnose severity. The results of experiments were submitted to analysis of variance and regression and means were compared by the Scott-Knott test (p<0.05). Control was compared to treatments by the Dunnett test (p<0,05). The lowest anthracnose AUIPC values were observed when using temperature of 48°C for eight and 12 minutes. Thermotherapy at 52°C from eight minutes of immersion, in addition to reducing the anthracnose AUSPC in fruits up to 81.6%, delayed maturation of fruits. Fruits submitted to thermotherapy at 56°C presented higher severity of the disease and resulted in the maturation of fruits. Thermotherapy reduces anthracnose severity in fruits in a manner similar to fungicide use, but the association of both results in better control of the disease in ‘Prata Anã’ banana. Thermotherapy is an efficient technique to reduce the severity of the disease in ‘Prata Anã’ banana produced in northern state of Minas Gerais.

Fis is a global regulator critical for modulation of virulence factor production and pathogenicity of Dickeya zeae

Dickeya zeae is the causal agent of rice foot rot disease, which has recently become a great threat to rice planting countries and regions. The pathogen produces a family of phytotoxins named zeamines that is critical for bacterial virulence, but little is known about the signaling pathways and regulatory mechanisms that govern zeamine production. In this study, we showed that a conserved transcriptional regulator Fis is involved in the regulation of zeamine production in D. zeae strain EC1. Deletion mutants were markedly attenuated in the virulence against rice seed germination. Transcriptome and phenotype analyses showed that Fis is a potent global transcriptional regulator modulating various virulence traits, including production of extracellular enzymes and exopolysaccharides, swimming and swarming motility, biofilm formation and cell aggregation. DNA gel retardation analysis showed that Fis directly regulates the transcription of key virulence genes and the genes encoding Vfm quorum sensing system through DNA/protein interaction. Our findings unveil a key regulator associated with the virulence of D. zeae EC1, and present useful clues for further elucidation of the regulatory complex and signaling pathways which govern the virulence of this important pathogen.