Common Bacterial Blight Research Articles

Fasulye Bakteriyel Adi Yanıklık Hastalığına Karşı Farklı Bakırlı Bileşiklerin Etkililiği

Common bacterial blight (CBB) caused by Xanthomonas axonopodis pv. phaseoli is the most destructive bacterial disease affecting all bean varieties in production areas. In this study, the effectiveness of different copper preparations against CBB disease on dry beans of Alberto variety, which are widely grown in Konya and Afyonkarahisar provinces with different climatic characteristics, were investigated. In field conditions, after 5-week-old bean plants were inoculated with a bacterial suspension of 108 CFU mL-1 of high virulent Xap k133 isolate, and subsequently twice every with 5 days intervals after inoculation, copper hydroxide, copper sulphate pentahydrate, copper oxychloride + copper hydroxide and copper oxychloride were applied at the doses recommended by the manufacturers. Disease severity (%) and disease score were evaluated using the 0-9 scale, and the effectiveness of the chemicals was compared with the control plants sprayed with water and determined with the help of the Abbott formula. According to the statistical data obtained, the most effective copper compound was determined by the application of copper oxychloride with 42.59-47.25% efficiency rates, copper sulphate pentahydrate had the lowest efficiency with about 7.69-12.96%. In addition to the negative effects of excessive use of copper in agriculture on the environment and human health, copper-resistant strains develops in bacterial pathogens. In order to determine the most effective copper compounds against CBB disease in dry beans in our country, the effectiveness of used as common compounds have been investigated for the first time and an organic and environmentally friendly sustainable bean production is revealed by using less copper.

Registration of ‘White Pearl’ great northern common bean cultivar with upright plant architecture and high yield

AbstractGreat northern common bean (Phaseolus vulgaris L.) cultivar ‘White Pearl’ (Reg. no. CV‐343, PI 698189) was developed by the dry bean breeding program at the University of Nebraska and released in 2018. It was bred specifically for adaptation to western Nebraska growing conditions and for upright plant architecture, high yield, and enhanced resistance to bean rust, common bacterial blight (CBB), and Bean common mosaic virus (BCMV). Seed yield of White Pearl was comparable and slightly higher than other great northern cultivars in on‐station trials conducted in Nebraska and did not differ significantly in yield from ‘Aries’ and ‘Matterhorn’ in regional trials. Seed size (100‐seed weight) of White Pearl was larger than ‘Marquis’, ‘Orion’, ‘Gemini’, ‘Beryl‐R’, and Aries in trials grown in Nebraska. White Pearl carries the sequence characterized amplified region (SCAR) marker SAP6 linked to a major quantitative trait locus (QTL) for resistance to CBB. White Pearl had a CBB disease rating of 6.0 (intermediate) under field conditions at the Scottsbluff and Mitchell Ag Labs in 2020. White Pearl also has the Ur‐3 gene for resistance to bean rust and carries the SS68 Kompetitive Allele Specific polymerase chain reaction (KASP) and SK14 SCAR markers linked to the Ur‐3 locus. It also contains the single dominant hypersensitive I gene that confers resistance to all non‐necrotic strains of BCMV and the SW13 SCAR marker linked to the I gene. White Pearl has bright white seed, blooms 46 d after planting, and is a midseason bean, maturing 89 d after planting.

Complete and Circularized Genome Sequences of 17 Xanthomonas Strains Responsible for Common Bacterial Blight of Bean.

ABSTRACTWe report the complete and circularized genome sequences of 17 strains of Xanthomonas citri pv. fuscans and Xanthomonas phaseoli pv. phaseoli, which cause common bacterial blight of bean. These new assemblies combining PacBio and short-read sequencing methods provide high-quality material for studying the evolution of these plant pathogens.

Association of common bacterial blight (Xanthomonas axonopodis pv. phaseoli) epidemics with agro ecological factors in Southwestern Ethiopia

Common bacterial blight, caused by Xanthomonas axonopodis pv. phaseoli, is an economically important disease of common bean and causes significant yield losses in Ethiopia. A field survey was conducted to understand the spatial distribution, relative importance and association of common bacterial blight epidemics with agro-ecological factors in low and mid-land areas of Southwestern, Ethiopia, during the 2018-19 cropping season. A total 85 bean fields were assessed in four common bean growing districts. High diseases incidence and severity was recorded at Debub Ari (77.6 and 52.7%, respectively) while the lowest was from Male (38.5 and 28.0%, respectively). The associations between disease parameters and agro-ecological factors were analyzed using multiple logistic regression models. Agronomic practices including NPS fertilization, preceding crop, weed management and plant population had highly significant (P<0.0001) association with both disease incidence and severity. Also, altitude, seed source and cropping system significantly (P<0.05) influenced disease severity while cropping pattern showed significant (P<0.05) association with disease incidence in the reduced model. Higher mean disease severity (≥40%) had high probability of association with district, absence of NPS fertilization, poor weed management practice, and preceding crops, than their counter parts. Adequate NPS fertilization increases growth performance of the crop in turn decreases disease intensity, weed serve as alternate host for incoming inoculum and previous crops were source for inocula as well as crop rotation used as reduce inoculum load. Therefore, the present study showed that the disease is a major production constraint of common bean, and suggested proper nutrient and weed management practices, and crop rotation to reduce common bacterial blight in the study areas.
 Int. J. Agril. Res. Innov. Tech. 11(1): 74-83, June 2021

The Induction of the Isoflavone Biosynthesis Pathway Is Associated with Resistance to Common Bacterial Blight in Phaseolus vulgaris L.

Xanthomonas axonopodis infects common bean (Phaseolus vulgaris L.) causing the disease common bacterial blight (CBB). The aim of this study was to investigate the molecular and metabolic mechanisms underlying CBB resistance in P. vulgaris. Trifoliate leaves of plants of a CBB-resistant P. vulgaris recombinant inbred line (RIL) and a CBB-susceptible RIL were inoculated with X. axonopodis or water (mock treatment). Leaves sampled at defined intervals over a 48-h post-inoculation (PI) period were monitored for alterations in global transcript profiles. A total of 800 genes were differentially expressed between pathogen and mock treatments across both RILs; approximately half were differentially expressed in the CBB-resistant RIL at 48 h PI. Notably, there was a 4- to 32-fold increased transcript abundance for isoflavone biosynthesis genes, including several isoflavone synthases, isoflavone 2′-hydroxylases and isoflavone reductases. Ultra-high performance liquid chromatography-tandem mass spectrometry assessed leaf metabolite levels as a function of the PI period. The concentrations of the isoflavones daidzein and genistein and related metabolites coumestrol and phaseollinisoflavan were increased in CBB-resistant RIL plant leaves after exposure to the pathogen. Isoflavone pathway transcripts and metabolite profiles were unaffected in the CBB-susceptible RIL. Thus, induction of the isoflavone pathway is associated with CBB-resistance in P. vulgaris.

Genome‐wide association study (GWAS) of Phaseolus vulgaris resistance to Xanthomonas citri pv. fuscans

AbstractCommon bean is one of the main legumes used for food worldwide. Among the main limitations for its production is common bacterial blight (CBB) caused by Xanthomonas citri pv. fuscans (Xcf). The most desirable method to control the disease is the use of plant genetic resistance, but resistance against Xcf has not been sufficiently investigated. Genetic studies have shown that resistance to CBB is of quantitative type, but no gene associated with resistance has been identified. Here, we aimed to determine the resistance to CBB of 103 Mesoamerican common bean cultivars by evaluating disease severity and the area under the disease progress curve (AUDPC) after inoculation with a Xcf strain. In addition, 80 of the evaluated cultivars were used to investigate the association of single nucleotide polymorphisms (SNPs) with the resistance phenotype in a genome‐wide association study (GWAS). Twenty‐nine cultivars were classified as highly resistant, 15 of which are shown to be resistant to CBB for the first time in this work. A positive correlation between AUDPC and disease severity was observed. The 10 SNPs with the highest −log10(p) values in the GWAS are located on bean chromosomes Pv01, Pv03, Pv06, Pv07, Pv08, Pv09, Pv10, and Pv11 within or near genes predicted to code for biochemical functions such as serine/threonine‐protein kinase, glutamine synthase, lectin domain protein, MADS‐domain transcription factor, and pentatricopeptide repeat protein, previously associated with immunity. This work identifies common bean germplasm resistant to Xcf, molecular markers for germplasm selection, and genes potentially involved in the resistance response.

Sources of Resistance to Common Bacterial Blight and Charcoal Rot Disease for the Production of Mesoamerican Common Beans in the Southern United States.

The gene pool of Mesoamerican common beans (Phaseolus vulgaris L.) includes genotypes in the small-to-medium-size seeded dry beans, as well as some snap beans from hotter environments adapted to the Southeastern United States. However, the warm and humid climate of the Southeastern United States is conducive to diseases such as Common Bacterial Blight (CBB) and Charcoal Rot (CR). The pathogens for these two diseases can survive long periods in infested soil or on seeds and are difficult to control through pesticides. Hence, field-level resistance would be the best management strategy for these diseases. The goals of this study were (1) to evaluate field-level resistance from the various commercial classes and subgroups represented in the Mesoamerican gene pool as sources for breeding beans for the region and (2) to evaluate genome-wide marker × trait associations (GWAS) using genetic markers for the genotypes. A total of 300 genotypes from the Mesoamerican Diversity Panel (MDP) were evaluated for CBB and CR in field experiments for three years. CBB resistance was also tested with a field isolate in controlled greenhouse conditions. The analysis of variance revealed the presence of variability in the MDP for the evaluated traits. We also identified adapted common bean genotypes that could be used directly in Southeastern production or that could be good parents in breeding programs for CBB and CR resistance. The GWAS detected 14 significant Single-Nucleotide Polymorphism (SNP) markers associated with CBB resistance distributed on five chromosomes, namely Pv02, Pv04, Pv08, Pv10, and Pv11, but no loci for resistance to CR. A total of 89 candidate genes were identified in close vicinity (±100 kb) to the significant CBB markers, some of which could be directly or indirectly involved in plant defense to diseases. These results provide a basis to further understand the complex inheritance of CBB resistance in Mesoamerican common beans and show that this biotic stress is unrelated to CR resistance, which was evident during a drought period. Genotypes with good yield potential for the Southeastern U.S. growing conditions were found with resistant to infection by the two diseases, as well as adaptation to the hot and humid conditions punctuated by droughts found in this region.

Editorial on Occurrence of Common Bacterial Blight in Plants

Editorial on Occurrence of Common Bacterial Blight in Plants

Common bacterial blight of bean: a model of seed transmission and pathological convergence.

Background Xanthomonas citri pv. fuscans (Xcf) and Xanthomonas phaseoli pv. phaseoli (Xpp) are the causal agents of common bacterial blight of bean (CBB), an important disease worldwide that remains difficult to control. These pathogens belong to distinct species within the Xanthomonas genus and have undergone a dynamic evolutionary history including the horizontal transfer of genes encoding factors probably involved in adaptation to and pathogenicity on common bean. Seed transmission is a key point of the CBB disease cycle, favouring both vertical transmission of the pathogen and worldwide distribution of the disease through global seed trade.TaxonomyKingdom: Bacteria; phylum: Proteobacteria; class: Gammaproteobacteria; order: Lysobacterales (also known as Xanthomonadales); family: Lysobacteraceae (also known as Xanthomonadaceae); genus: Xanthomonas; species: X. citri pv. fuscans and X. phaseoli pv. phaseoli (Xcf‐Xpp).Host rangeThe main host of Xcf‐Xpp is the common bean (Phaseolus vulgaris). Lima bean (Phaseolus lunatus) and members of the Vigna genus (Vigna aconitifolia, Vigna angularis, Vigna mungo, Vigna radiata, and Vigna umbellata) are also natural hosts of Xcf‐Xpp. Natural occurrence of Xcf‐Xpp has been reported for a handful of other legumes such as Calopogonium sp., Pueraria sp., pea (Pisum sativum), Lablab purpureus, Macroptilium lathyroides, and Strophostyles helvola. There are conflicting reports concerning the natural occurrence of CBB agents on tepary bean (Phaseolus acutifolius) and cowpea (Vigna unguiculata subsp. unguiculata).SymptomsCBB symptoms occur on all aerial parts of beans, that is, seedlings, leaves, stems, pods, and seeds. Symptoms initially appear as water‐soaked spots evolving into necrosis on leaves, pustules on pods, and cankers on twigs. In severe infections, defoliation and wilting may occur.DistributionCBB is distributed worldwide, meaning that it is frequently encountered in most places where bean is cultivated in the Americas, Asia, Africa, and Oceania, except for arid tropical areas. Xcf‐Xpp are regulated nonquarantine pathogens in Europe and are listed in the A2 list by the European and Mediterranean Plant Protection Organization (EPPO).GenomeThe genome consists of a single circular chromosome plus one to four extrachromosomal plasmids of various sizes, for a total mean size of 5.27 Mb with 64.7% GC content and an average predicted number of 4,181 coding sequences.Disease controlManagement of CBB is based on integrated approaches that comprise measures aimed at avoiding Xcf‐Xpp introduction through infected seeds, cultural practices to limit Xcf‐Xpp survival between host crops, whenever possible the use of tolerant or resistant bean genotypes, and chemical treatments, mainly restricted to copper compounds. The use of pathogen‐free seeds is essential in an effective management strategy and requires appropriate sampling, detection, and identification methods.Useful websites https://gd.eppo.int/taxon/XANTPH, https://gd.eppo.int/taxon/XANTFF, and http://www.cost.eu/COST_Actions/ca/CA16107.

Effects of Solid and Liquid Vermicompost Application on Bean Growth and Common Bacterial Blight Disease in Different Growth Medium

In this study, the effect of solid and liquid forms of vermicompost on plant growth and bacterial common blight disease in different growth media were investigated. Vermicompost was applied at the rate of 1/100, 1/150, 1/200 in liquid form and vermicompost in solid form at the rate of 10%, 20%, 40% to peat and soil growing medium. The pathogen, Xanthomonas axonopodis pv. phaseoli (Xap), was applied to the leaves by spraying at a concentration of 107 CFU mL-1. The effects of applications on plant growth parameters, total chlorophyll content, and disease severity were evaluated. It was determined that the effects of the applications varied according to vermicompost form and growth medium. Liquid vermicompost applications displayed more positive effects on root growth in the soil growing medium. However, the application of liquid vermicompost did not affect disease severity. It was observed that the 40% dose of vermicompost in solid form inhibited plant growth and caused chlorosis in both growth media. However, 10 and 20% of doses had no adverse effects on plant growth. Also, the application of 10% solid vermicompost to peat growing medium reduced the disease development by 48%. In soil growth medium, application doses of 10% and 20% prevented disease development by 62% and 54%.

Using Breeding Populations With a Dual Purpose: Cultivar Development and Gene Mapping-A Case Study Using Resistance to Common Bacterial Blight in Dry Bean (Phaseolus vulgaris L.).

Dry bean (Phaseolus vulgaris L.) is an important worldwide legume crop with low to moderate levels of resistance to common bacterial blight (CBB) caused by Xanthomonas axonopodis pv. phaseoli. A total of 852 genotypes (cultivars, preliminary and advanced breeding lines) from the North Dakota State University dry bean breeding program were tested for their effectiveness as populations for genome-wide association studies (GWAS) to identify genomic regions associated with resistance to CBB, to exploit the associated markers for marker-assisted breeding (MAB), and to identify candidate genes. The genotypes were evaluated in a growth chamber for disease resistance at both the unifoliate and trifoliate stages. At the unifoliate stage, 35% of genotypes were resistant, while 25% of genotypes were resistant at the trifoliate stage. Libraries generated from each genotype were sequenced using the Illumina platform. After filtering for sequence quality, read depth, and minor allele frequency, 41,998 single-nucleotide polymorphisms (SNPs) and 30,285 SNPs were used in GWAS for the Middle American and Andean gene pools, respectively. One region near the distal end of Pv10 near the SAP6 molecular marker from the Andean gene pool explained 26.7–36.4% of the resistance variation. Three to seven regions from the Middle American gene pool contributed to 25.8–27.7% of the resistance, with the most significant peak also near the SAP6 marker. Six of the eight total regions associated with CBB resistance are likely the physical locations of quantitative trait loci identified from previous genetic studies. The two new locations associated with CBB resistance are located at Pv10:22.91–23.36 and Pv11:52.4. A lipoxgenase-1 ortholog on Pv10 emerged as a candidate gene for CBB resistance. The state of one SNP on Pv07 was associated with susceptibility. Its subsequent use in MAB would reduce the current number of lines in preliminary and advanced field yield trial by up to 14% and eliminate only susceptible genotypes. These results provide a foundational SNP data set, improve our understanding of CBB resistance in dry bean, and impact resource allocation within breeding programs as breeding populations may be used for dual purposes: cultivar development as well as genetic studies.

Common bacterial blight (Xanthomonas axonopodis pv. phaseoli) resistance reaction in common bean genotypes and their agronomic performances in Southern Ethiopia

Common bacterial blight (CBB) is an economically important disease of common beans and causes significant yield losses worldwide, including Ethiopia. Therefore, development and use of resistant cultivars are important options to manage the disease. Thus, field reactions of common bean genotypes to CBB and their agronomic performances were conducted at two locations in Southern Ethiopia, during 2018/2019. The experiment was arranged in a randomized complete block design with three replications. Analysis of variance revealed significant (P < 0.01) genotypic variation for disease and yield parameters at both locations. The results showed wide ranges of variation in incidence (26.05–82.75%), severity (23.75–70.70%), AUDPC (773.9–2544%-days) and disease progress rate (0.024–0.142 unit day−1) on average for both locations. And also, remarkable genotypic variation for quantitative growth and yield characters such as plant height, days to 50% flowering, days to 90% maturity, number of pods, number of seeds, seed weight and grain yield were observed. Based on mean severity and R8_severity score, genotypes were grouped as 20% resistant, 55% moderately resistant and 25% susceptible at JARC, and 15% resistant, 80% moderately resistant and only 5% susceptible at Debub Ari. Variable relationships were found among and between parameters studied. The overall results indicated that SER119 and MALB135 showed consistent resistance reaction to CBB, and SER119 also gave high yield across fields. It is recommended to use SER119 with proper management practices for bean production and MALB135 as parent for CBB resistance development in plant breeding programs of the country.

Biological effectiveness of Bacillus subtilis on common bean bacterial blight

Chemical compounds, which are used on beans to manage common bacterial blight (CBB) disease, cause serious damage to natural ecosystems and often fail to control CBB. A greenhouse experiment was conducted to assess the effectiveness of foliar sprays of Bacillus subtilis str. QST 713 against CBB in a susceptible bean cultivar in comparison with copper hydroxide (CH) and its mixes. A concentration of 108 CFU mL− 1 for Xanthomonas axonopodis pv. phaseoli (Xap) was used to inoculate 21-day-old plants after 3 days of first-time treatment applications. The 2nd and 3rd time treatment applications were applied every 7 days after bacterial inoculation. The disease severity, disease infection rate, AUDPC and disease incidence were significantly reduced over the control treatment. The lowest disease severity, incidence and AUDPC were observed from the mix applications with str. QST713 and CH followed by str. QST 713 and CH alone compared to control treatments. The plants treated with mixes and str. QST 713 showed a reduction of the infection rate by 51.21 and 40.36%, and the disease incidence by 53 and 52.25%, respectively. In addition, the lowest bacterial population per gram of fresh weight of leaves was recorded in plants that had been treated with the mix treatments followed by str. QST713 and CH. Results suggest that integrated management with biocontrol agents is the best strategy for effective control of CBB in sustainable and organic agriculture.

Management of Common Bacterial Blight (Xanthomonas campestris pv. phaseoli (Smith) Dye.) of Common Bean (Phaseolus vulgaris L.) Using Resistant Varieties and Bactericidal Chemicals in Southern Ethiopia

Common bacterial blight (CBB) caused by the bacterium Xanthomonas campestris pv. phaseoli is a major disease of common bean affecting its production in southern Ethiopia. This study was conducted to determine the effect of variety, seed treatment and foliar spraying frequencies of bactericide on disease severity, yield and yield components of common bean. Field research was conducted at Hawassa agricultural research center during 2017/18 main cropping season using Hawassa dumme and Mexican-142 varieties. Streptomycin seed treatment was integrated with Kocide-101 foliar spraying frequency at the rate of 2.31 kg ha-1 at two, three and four week’s intervals. The design was randomized complete block design arranged in factorial with three replications. Due to the effect of variety, severity was reduced by 17.2% and the mean seed yield was increased by 18% over Mexican 142. Seed treatment reduced disease severity by 10.7% and increased yield by 24.2% as compared with other untreated control. Two week interval spraying reduced severity upto 31.8% and increased yield upto 42.3% over untreated control. Integration of variety and seed treatment with two week interval foliar sprays gave higher marginal benefit and higher marginal rate of return.

IAC 2051: common bean cultivar of carioca type with slow seed coat darkening

Abstract: IAC 2051 is a common bean (Phaseolus vulgaris L.) cultivar with carioca-type seed coat, mean 1000 seed weight of 300g, indeterminate semi-upright type II growth habit, slow post-harvest seed coat darkening, resistance to Fusarium wilt, common bacterial blight, and three races of anthracnose, and mean yield of 2729 kg ha-1.

Ekonomski najznačajnije bakterioze pasulja

Beans are an important plant species that is grown in our agroecological conditions. One of the significant factors in the reduction and quality of yield are phytopathogenic bacteria that appear on leaves, stems, pods and seeds. Also, one of the reasons for the frequent incidence of the disease is the use of seeds that are not declared, and very often infected. In our conditions, depending on the environmental conditions, two species from the genus Xanthomonas and Pseudomonas predominantly appear. Species Xanthomonas axonopodis pv. phaseoli, the causal agent of common bacterial blight is affected by warmer and wet conditions, while the species Pseudomonas savastanoi pv. phaseolicola is affected by colder weather and humid conditions. Other bacteria that appear are of minor economic importance.

A new black bean with resistance to bean rust: Registration of ‘ND Twilight’

Abstract‘ND Twilight’ (Reg. no. CV‐332, PI 693268; PVP‐202000258) is a new black bean (Phaseolus vulgaris L.) cultivar developed by the Dry Edible Bean Breeding Program at North Dakota State University and released by the North Dakota Agricultural Experiment Station. ND Twilight was developed using a modified pedigree method (F1–F5), followed by pure line selection based on agronomic, disease, and quality traits, along with specific DNA markers. With ∼24% of the total dry bean production in the United States, black bean is the second most important market class after pinto. Accounting for ∼35% of the total production, North Dakota is the largest producer of dry bean in the United States. However, both biotic and abiotic stresses are the main factors responsible for seed yield reductions. Between 2014 and 2019, ND Twilight was tested across more than 21 environments in North Dakota, where seed yield was significantly different from ‘Zorro’ and similar to ‘Eclipse’ and ‘Loreto’. ND Twilight is resistant to the most common race (20‐3) of the bean rust pathogen and Bean common mosaic virus. It also has intermediate resistance to common bacterial blight and to soybean cyst nematode (HG Type 0). ND Twilight has desirable upright architecture (Type IIa). Under North Dakota conditions, ND Twilight shows an average plant height of 49 cm, has a 100‐seed weight of 19.7 g, and matures in ∼99 d. Canning quality was rated as acceptable. Other traits of agronomic and economic importance are within acceptable commercial ranges.

SCREENING OF COMMON BEAN GENOTYPES FOR RESISTANCE AGAINST Xanthomonas campestris pv. phaseoli IN KAKAMEGA COUNTY, KENYA

Purpose: To screen nine available bean genotypes for resistance to common bacterial blight disease under green house and field conditions.Methodology: Experiments were conducted in randomized complete block design with three replications in a 9×2×2 factorial factor of 9 bean genotypes, grown in sterile or non-sterile soil and inoculated or non-inoculated (control) during the greenhouse and a 9×2 field screening of 9 bean genotypes, and inoculated or non-inoculated. During growth, data on plant height number of pods per plant, length of pods and size and number ofCBB spots was taken. Yield parameters were also assessed.Findings: The findings from the experiment revealed a significant variation (P&lt;0.05) on the entire traits studied among the nine bean genotypes. Data from the field and greenhouse experiments were in conformity. None of the evaluated genotype was immune to CBB. In the green house, it was observed that disease symptoms were severe in beans planted in non-sterile soil and inoculated with Xap compared to those planted in sterile soil and non-inoculated respectively.Contribution to practice and policy: There was a strong positive correlation between size and number of CBB spots and growth and yield parameters. CAL77 and Cal 156A genotypes exhibited high levels of resistance to CBB which could improve the bean yields resulting to sufficient food supply, improved nutrition, health and improvement of the source of income to the local communities

Genotype-by-environment interaction and stability of resistance in mungbean landraces against common bacterial blight across semi-arid environments

Common bacterial blight (CBB) of mungbean (Vigna radiata [L.] Wilczek var. radiata) is a major limitation to mungbean production in semi-arid areas of the world where mungbean is a major crop. Deployment of resistant varieties is a significant sustainable strategy for controlling CBB in marginal production systems. The objective of this study was to identify sources of resistance and the stability of mungbean landraces to CBB attack across drought-endemic environments. A total of 240 mungbean genotypes were evaluated for CBB resistance and performance of agronomic traits in an alpha lattice design at four locations for 2 years (2019, 2020). Data were subjected to residual maximum likelihood (REML) analysis to partition variance components attributed to main effects and interactions, respectively. REML analysis revealed significant main effects for genotype, environment (combination of cropping season and location) and genotype-by-environment interaction (p < 0.01), demonstrating the influence of environment on genotypic expression. A genotype main effect plus genotype-by-environment biplot was used to analyse the multi-location trial data based on CBB score to determine genotypic stability. The GGE analysis demonstrated that the Kambi Ya Mawe location in 2019 was the most suitable environment for the assessment of CBB resistance. Accessions GBK 004852, GBK 004789, GBK 026986, GBK 004970, GBK 004961, GBK 004882 and GBK 043573 were selected as having high and stable resistance across all environments. The identification of high and stable resistance sources is a first step towards deploying resistance in mungbean breeding programmes against CBB and the future deployment of resistant cultivars.

Management of the Common Bacterial Blight of the Bean by Rhodotorula glutinis and Sporidiobolus johnsonii

Bean common bacterial blight reduces crop productivity and is difficult to control. However, biological control by yeast can be an efficient complementary measure in management. The objective was to evaluate the ability of Rhodotorula glutinis and Sporidiobolus johnsonii to reduce the severity of bean common bacterial blight. The cultivar used was IAPAR Tuiui&amp;uacute;. The first experiment was sown in March and repeated in October, in a 4 &amp;times; 3 factorial scheme (zero, one, two and three applications and three treatments R. glutinis, S. johnsonii and Acibenzolar-S-Methyl (ASM)). For this purpose were evaluated the area under the disease progress curve (AACPD), number of pods per plant (NVP), number of grains per pod (NGV), thousand grain mass (MMG) and productivity. For the results of the March cultivation, due to the low temperature, the maximum severity of bean common bacterial blight was 8% and the applications of yeasts were not significant for AACPD. The isolate R. glutinis showed the highest average of productivity with two applications, being 1006.44 kg ha-1. For October cultivation, R. glutinis and S. johnsonii isolates reduced AACPD by 66.84 and 58.42%, respectively with three applications. For productivity, R. glutinis and S. johnsonii showed no difference between the number of applications. The ASM showed a productivity of 4418.56 kg ha-1 with three applications. The results indicate that the yeasts R. glutinis and S. johnsonii reduce the severity of bean common bacterial blight and the most appropriate number of applications are two for both isolates.