# Evaluation of cowpea varietal response to bacterial blight in Burkina Faso: Implications for breeding and integrated disease management

Nanwinyélé Euvaris Somé, Boubakar Ouattara, Benoit Joseph Batieno, Zoéyandé Oumarou Dianda, Kadidia Koita, Nicolas Wg Chen, Marie-Agnès Jacques, Issa Wonni

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Nanwinyélé Euvaris Somé, Boubakar Ouattara, Benoit Joseph Batieno, Zoéyandé Oumarou Dianda, Kadidia Koita, et al.. Evaluation of cowpea varietal response to bacterial blight in Burkina Faso: Implications for breeding and integrated disease management. African Journal of Agricultural Research, 2026, 10.5897/AJAR2025.17068. hal-05462503

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Full Length Research Paper

# Evaluation of cowpea varietal response to bacterial blight in Burkina Faso: Implications for breeding and integrated disease management

Nanwinyélé Euvaris Somé<fnref n="1" />, <fnref n="2" />*, Boubakar Ouattara<fnref n="1" />, Benoit Joseph Batieno<fnref n="3" />, Zoéyandé Oumarou Dianda<fnref n="1" />, Kadidia Koita<fnref n="2" />, Nicolas WG Chen<fnref n="4" />, Marie-Agnès Jacques<fnref n="4" /> and Issa Wonni<fnref n="1" />

Received 3 September, 2025; Accepted 18 November, 2025

Cowpea bacterial blight, caused by Xanthomonas citri pv. vignicola (Burkh.), is increasingly becoming a major constraint to cowpea productivity worldwide. The use of genotypes that are resistant and/or tolerant to the pathogen is an effective means of controlling the disease. In this study, we evaluated the response of 12 cowpea genotypes of Burkina Faso to three strains (CFBP 7111, CFBP 7112, and CFBP 7113) of X. citri pv. vignicola under greenhouse conditions. For each strain, an inoculum of 1 × 10⁸ CFU/mL⁻<fnref n="1" /> was used to inoculate two-week-old trifoliate leaves. Parameters assessed included symptom percentage, bacterial population size, yield components, and leaf chlorophyll content. The results revealed that genotype Yiisyandé was the most affected by all strains, with approximately 50% leaf symptom coverage. In contrast, genotype KVx745-11P showed no symptoms for any of the strains. Strain CFBP 7113 generally reached the highest bacterial populations (7.17 log CFU/cm<fnref n="2" /> for genotype Komcallé). KVx745-11P also exhibited the best yield, with an average per plant of 8.83 pods, 14.56 g pod weight, 90.92 seeds, and 13.37 g seed weight. These observations provide a solid basis for incorporating KVx745-11P into breeding programs aimed at developing broad-spectrum, durable resistant cowpea cultivars.

**Key words:** Cowpea, *Xanthomonas citri* pv. *vignicola*, resistance, Burkina Faso.

## INTRODUCTION

Cowpea (*Vigna unguiculata* L. Walpers) is a legume that significantly contributes to the diet of populations in sub-Saharan Africa (Durojaye et al., 2019). It is recognized as

a nutritious food that provides humans with affordable protein, thereby improving food security (Muranaka et al., 2016). Moreover, it is known for its versatile use and

<footnote n="1">¹National Center for Scientific and Technological Research (CNRST), Institute of Environment and Agricultural Research (INERA), Farako-Bâ Station, Bobo-Dioulasso 01, Burkina Faso.</footnote>

<footnote n="2">²Biosciences Laboratory, Joseph Ki-Zerbo University, 03 BP 7021, Ouagadougou 03, Burkina Faso.</footnote>

<footnote n="3">³National Center for Scientific and Technological Research (CNRST), Institute of Environment and Agricultural Research (INERA), Kamboinsin Station, Ouagadougou, Burkina Faso.</footnote>

<footnote n="4">⁴Univ Angers, Institut Agro, INRAE, IRHS, SFR Quasav, Angers, France.</footnote>

<footnote>*Corresponding author. E-mail: euvarissome@gmail.com.</footnote>
adaptability to climate fluctuations. Globally, over 12
million ha are cultivated with cowpea, producing
approximately 6.9 million tons of grain (Durojaye et al.,
2019). In Burkina Faso, cowpea is consumed by
households across all socio-economic groups, both in
rural and urban areas, making its production a key
adaptation strategy for smallholder agriculture (Dabat et
al., 2012). Grown as a sole crop but also intercropped
with cereals such as sorghum or maize, cowpea is
cultivated both for human consumption and as a source
of income for farmers (Ouedraogo et al., 2022; Raboin et
al., 2025). With groundnut, cowpea haulms, although less
productive in terms of yield, are the most available during
the cool dry season and are used as fodder for animals
(Tensaba et al., 2023). In Burkina Faso, during the 2022
to 2023 agricultural season, cowpea accounted for
10.12% of the area under food crops (Enquête
Permanente Agricole [EPA]/MARAH, 2023).

Cowpea yield can be reduced due to different biotic
and abiotic constraints (Ouedraogo et al., 2022). Bacterial
pustule and bacterial blight are the main bacterial
diseases observed on cowpea worldwide (Williams,
1975). Cowpea bacterial blight, caused by *Xanthomonas
citri* pv. *vignicola* (formerly *X. campestris* pv. *vignicola*), is
considered one of the most destructive (Nandini et al.,
2014). This disease has attracted particular attention
because it has been reported in several West African
countries, including Nigeria, Benin, and Ghana, where it
can cause yield losses exceeding 70% under favorable
conditions (Williams 1975; Sikirou and Wydra 2008; Deo-
Donne et al., 2018). The rapid spread of the bacterium is
facilitated by contaminated seeds, rain splash, and
agricultural practices (Timko and Singh, 2008). Although
*X. citri* pv. *vignicola* has not yet been formally identified in
Burkina Faso, the risk of its introduction remains high,
especially given its spread in neighboring countries such
as Ghana and Benin. This risk is reinforced by the
movement of plant materials and seed trade between
Burkina Faso and these neighboring countries, as well as
agroecological similarities, which are factors that could
promote its potential emergence. Anticipating this risk
justifies preventive studies aimed at identifying resistant
genotypes before the disease potentially appears in the
country. Evaluating the resistance of local and introduced
genotypes is therefore a crucial step to guide breeding
programs and the dissemination of resistant plant
material (Roberts et al., 1997. Indeed, identifying
genotypes able to limit *X. citri* pv. *vignicola* bacterial load
(that is, resistant) or limit the deleterious effects of this
pathogen (that is, tolerant) after artificial inoculation is a
first step towards the identification and mapping of loci
controlling resistance to this bacterial disease (Agbicodo
et al., 2010). In Burkina Faso, no studies have yet
assessed the behavior of approved and adopted cowpea
genotypes against this bacterium.

To address this gap, the present study aims to evaluate
the response of twelve cowpea genotypes to bacterial

blight caused by X. citri pv. vignicola under greenhouse
conditions.

MATERIALS AND METHODS

Plant

A total of 12 commercial cowpea genotypes from the collection of the Institute of Environment and Agricultural Research of Burkina Faso were evaluated in this study (Table 1).

Bacterial strains

Strains CFBP 7111, CFBP 7112, and CFBP 7113 of X. citri pv. *vignicola* was used for the inoculations (Table 2). These strains were kindly provided by the French Collection of Plant-Associated Bacteria (CIRM-CFBP, https://cirm-cfbp.fr). The complete genome sequences of these three strains were previously obtained using single-molecule real-time sequencing technology.

Experimental design

The trial was conducted in a greenhouse using a completely
randomized block design with three replications. Within each block,
treatments corresponding to the combinations of 12 cowpea
genotypes and four inocula were randomly arranged. Seeds were
sown in a substrate consisting of sterilized soil (2/3) and homemade
compost (1/3). For each strain × genotype combination, seven
plants were established. Two weeks after sowing, thinning was
performed to retain four apparently healthy plants for inoculation
tests.

Inoculum preparation and inoculation

Bacterial strains were grown at 28°C for 72 h on Trypticase Soy Agar (TSA) medium (17.0 g L⁻¹ pancreatic digest of casein, 3.0 g L⁻¹ enzymatic digest of soya bean, 5.0 g L⁻¹ NaCl, 2.5 g L⁻¹ K₂HPO₄, 2.5 g L⁻¹ glucose, 15 g L⁻¹ agar, pH 7.3 at 25°C, in distilled water), then transferred for 24 h at the same temperature on a 1/10 dilution of TSA (that is, TSA 10%), except for agar kept at 15 g·L⁻¹. To prevent fungal contamination, the media were supplemented with kasugamycin (40 mg·mL⁻¹). Fresh 24 h old cultures were used to prepare bacterial suspensions in 11 mL sterile distilled water, adjusted to an optical density of 0.1 at **□** = 600 nm, corresponding to a concentration of 1 × 10⁸ CFU·mL⁻¹. Inoculations were performed on the first trifoliate leaves of two-week-old plants by gently rubbing the adaxial leaf surface with a 70 mL applicator pad (Vaessen creative, ref: SKU:7005-009) to avoid tearing the leaf tissue. Sterile distilled water was used as a negative control. After inoculation, all plants were covered with a plastic bag for 24 h to promote bacterial infection and incubated until complete pod maturation (duration may differ between genotypes under greenhouse conditions at an average temperature of 29.56°C and a relative humidity of 69.21%).

Phenotyping and bacterial population assessment

Symptoms were evaluated 21 days post-inoculation, by taking
photographs of detached inoculated leaflets. Pixels corresponding
to the background, healthy leaf tissues or symptoms were classified
using a machine learning-based image analysis tool called Ilastik
<table><caption>**Table 1.** General characteristics of the tested cowpea genotypes.</caption><thead><tr><th>Genotypes ID</th><th>Commercial Name</th><th>Potential yield (t/ha)</th><th>Farmer Field Yield (t/ha)</th><th>Cycle (days)</th></tr></thead><tbody><tr><td>KVx780-6</td><td>Nerwaya</td><td>2</td><td>1</td><td>60</td></tr><tr><td>KVx780-1</td><td>Yipoussi</td><td>1.8</td><td>1</td><td>60</td></tr><tr><td>KVx780-3</td><td>Issa sosso</td><td>2</td><td>1</td><td>60</td></tr><tr><td>KVx780-4</td><td>Makoyin</td><td>3</td><td>1</td><td>64</td></tr><tr><td>TZ1</td><td>Gourgou</td><td>4</td><td>2</td><td>75</td></tr><tr><td>BC3F12P34-3</td><td>Teek-songo</td><td>4 - 5</td><td>0.8</td><td>70</td></tr><tr><td>KVx442-3-25SH</td><td>Komcallé</td><td>1.5 - 2</td><td>0.75</td><td>60</td></tr><tr><td>KVx61-1</td><td>Bengsiido</td><td>1.5</td><td>0.85</td><td>70</td></tr><tr><td>KVx771-10G</td><td>Nafi</td><td>1.5</td><td>0.8</td><td>70</td></tr><tr><td>KVx775-33-2G</td><td>Tilligré</td><td>1.5 - 2.5</td><td>0.85</td><td>70</td></tr><tr><td>KVx745-11P</td><td>-</td><td>0.8</td><td>0.6 - 0.7</td><td>70</td></tr><tr><td>IT99K-573-2-1</td><td>Yiisyandé</td><td>2.170</td><td>0.8</td><td>60</td></tr></tbody></table>

Source: Ministère de la Recherche Scientifique et de l'Innovation (MRSI, 2014).

<table><caption>**Table 2.** Genomic characteristics of the strains used for inoculation.</caption><thead><tr><th>Strains</th><th>Number of chromosomes</th><th>Number of plasmids</th><th>Size (bp)</th><th>G+C content</th></tr></thead><tbody><tr><td>CFBP 7111</td><td>1</td><td>3</td><td>5,710,499</td><td>64.5</td></tr><tr><td>CFBP 7112</td><td>1</td><td>2</td><td>5,155,996</td><td>64.7</td></tr><tr><td>CFBP 7113</td><td>1</td><td>0</td><td>5,105,205</td><td>64.7</td></tr></tbody></table>

Source: Ruh et al. (2017)

v.1.3.3 (Berg et al., 2019; Foucher et al., 2020). The proportion of symptomatic leaf pixels relative to healthy leaf pixels was calculated using FiJi (Schindelin et al., 2012). For each strain x genotype combination, 12 leaf discs (0.6 cm) were collected from inoculated trifoliates, ground in 2 mL sterile distilled water, and serial decimal dilutions ($10^{-1}$ to $10^{-6}$) were prepared. Fifty microliters of each dilution were plated on TSA 10%, then incubated at 28°C for 72 h and bacterial colonies phenotypically identical to X. citri pv. vignicola were counted.

## Physiological and agronomic parameter evaluation

Leaf chlorophyll content was measured using a Signal Passed at Danger (SPAD) meter on each leaflet of the inoculated trifoliate. Readings were taken before inoculation, and at four and 12-days post-inoculation, by simply placing the leaf between the electrodes and pressing the measurement head. The mean of the readings for the three leaflets of each trifoliate was used. For each strain x genotype combination, pods were harvested, counted and dried at the end of genotypes cycle. After drying, pods were weighed using a precision balance RADWAG manufacturer, model PS 6000.R1 (Max 6000g, d = 0.01), then shelled to count and weigh the seeds.

## RESULTS

### Disease severity and bacterial population size by genotype

Analysis of the percentage of leaf area showing bacterial blight symptoms revealed significant variability (p < 0.05)

among the twelve cowpea genotypes tested with the three X. citri pv. vignicola strains used (Figure 1). The low values observed in the distilled water control corresponded to background noise inherent to the image analysis process.

Most genotypes exhibited similar levels of symptoms regardless of the strain. Among them, genotype Yiisyandé was the most severely affected by all strains, with an average of about 50% symptomatic leaf area, followed by genotypes Yipoussi, Gourgou, and Nafi, which showed mean values ranging between 15 and 30%. In contrast, genotype Bengsiido showed relatively low mean symptom percentages (below 10%), while genotype KVx745-11P exhibited no symptoms at all. For genotype Teek-songo, few plants presented middle to high symptom percentages, but the results were overall not statistically different than the control.

Interestingly, genotypes Nerwaya, Issa sosso, Makoyin, Komcallé, and Tilligré showed contrasting phenotypes depending on the strain used. Strain CFBP 7111 induced moderate symptom levels on genotypes Nerwaya, Issa sosso, and Komcallé (13.79, 10.37, and 22.44%, respectively), but was much less aggressive on genotypes Makoyin and Tilligré (less than 5%). Conversely, strain CFBP 7112 displayed a consistent moderate aggressiveness across all these genotypes, with symptom percentages ranging from 10.05% for genotype Nerwaya to 25.09% for genotype Komcallé.
<figure><img src="image_3.png" /><figcaption>**Figure 1.** Symptom levels observed for each cowpea genotype after inoculation of *X. citri* pv. *vignicola*.</figcaption></figure>

Finally, strain CFBP 7113 was particularly aggressive on genotype Komcallé (71.75%), but caused very few symptoms (less than 8%) on genotypes Nerwaya, Issa sosso, Makoyin, and Tilligré.

Symptoms were evaluated 21 days after inoculation with strains CFBP 7111, CFBP 7112 or CFBP 7113. SDW: sterile distilled water was used as negative control. The boxes represent the distribution of individual symptom percentage values (n = 12 for each genotype); the line inside each box indicates the median, and the points show individual data values. Different lowercase letters above bars indicate significant differences among inoculum according to the Kruskal–Wallis test followed by Dunn's test with Bonferroni correction (p < 0.05).

The mean bacterial population size varied significantly (p < 0.05) depending on the inoculum for all genotypes studied (Figure 2). For each genotype, strain CFBP 7111 exhibited the lowest bacterial populations (5.11 log CFU/cm² for genotype Nerwaya), whereas strain CFBP 7113 generally reached the highest populations (7.17 log CFU/cm² for genotype Komcallé). Strain CFBP 7112 showed intermediate values. A few genotypes (Teek- songo, Tilligré, KVx745-11P) displayed less pronounced differences between strains CFBP 7112 and 7113, with these two inocula belonging to the same statistical group. Furthermore a significant but weak positive correlation

was found between symptom severity and bacterial population levels (Pearson's correlation, r = 0.16, t(430) = 3.43, p < 0.001) (Figure 3). The 95% confidence interval of the correlation coefficient ranged from 0.07 to 0.25.

Sampling was done 21 days after inoculation with strains CFBP 7111, CFBP 7112 or CFBP 7113. Population levels are expressed in colony forming units (CFU) per square centimeter of leaf tissue. The boxes represent the distribution of individual values (n = 12 for each genotype), and the points show the individual measurements. Significant differences between inoculums were assessed using a Kruskal–Wallis test followed by Dunn's post hoc test (p < 0.05). The line represents the linear regression, and the shaded area indicates the 95% confidence interval.

## Yield and chlorophyll content of the genotypes

Variations in yield components were observed among the twelve cowpea genotypes under the different inoculation treatments (p < 0.001) (Figure 4). In the control treatment (EDS, sterile distilled water), all genotypes produced higher yields than the infected plants. The highest mean values were recorded for genotype KVx745-11P, with an average per plant of 8.83 pods, 14.56 g pod weight, 90.92
<figure><img src="image_4.png" /><figcaption>**Figure 2.** Levels of *X. citri* pv. *vignicola* populations for each cowpea genotype.</figcaption></figure>

<figure><img src="image_5.png" /><figcaption>**Figure 3.** Relationship between symptom severity (%) and bacterial population size (log UFC/cm²) across cowpea genotypes.</figcaption></figure>

seeds, and 13.37 g seed weight, while the lowest yields were observed in Nerwaya and Makoyin. The mean

number of seeds per plant ranged from 29.17 (genotype Yipoussi) to 69.73 (genotype KVx745-11P).
<figure><img src="image_6.png" /><figcaption>**Figure 4.** Distribution of yield-related traits number of pods, pod weight, number of seeds, and seed weight per plant across 12 cowpea genotypes under different inoculation treatments (CFBP 7111, CFBP 7112, CFBP 7113, and SDW).</figcaption></figure>

The mean seed weight per plant varied from 4.57 g (genotype Yipoussi) to 9.44 g (genotype KVx745-11P).

For strain CFBP 7111, the mean number of pods per plant ranged from 3.5 (genotype Yiisyandé) to 6.75 (genotype Bengsiido). Genotypes KVx745-11P (6.58 pods) and Bengsiido (6.75 pods) showed the highest mean values per plant, while Yiisyandé (3.5) and Gourgou (3.67) had the lowest. The mean pod weight per plant varied from 3.37 g (Yiisyandé) to 9.74 g (KVx745-11P). Similarly, the mean number of seeds ranged from 17.67 (Komcallé) to 67.25 (KVx745-11P). The mean seed weight followed the same pattern, with KVx745-11P showing the highest value (8.63 g) compared to only 2.43 g for Yiisyandé.

After inoculation with strain CFBP 7112, genotype Issa sosso produced the highest mean number of pods per plant (5.5), while Nafi showed the lowest (3.08). The mean pod weight per plant ranged from 3.34 g (Yipoussi) to 8.51 g (KVx745-11P). Genotypes KVx745-11P and Issa sosso also exhibited higher mean numbers of seeds (51.83 and 28.92, respectively) and greater mean seed weights per plant (6.65 g and 4.52 g). For inoculum CFBP 7113, the mean number of pods per plant ranged from 3.5 (Yipoussi, Makoyin) to 6.67 (KVx745-11P), once again demonstrating the superiority of genotype KVx745-11P. The mean pod weight per plant was lowest in Yiisyandé (3.23 g) and highest in KVx745-11P (10.28 g).

The mean number of seeds per plant ranged from 16.33 (KVx442-3-25SH) to 68.92 (KVx745-11P), while the mean seed weight varied between 2.32 g (Yiisyandé) and 9.12 g (KVx745-11P). Negative correlations were observed between symptom severity, expressed as symptom percentage, and all yield-related traits measured (Figure 5). Specifically, the number of pods per plant was negatively correlated with symptom percentage (r = -0.11, p = 0.011). Similarly, pod weight was negatively correlated (r = -0.22, p < 0.001), as were the number of seeds per plant (r = -0.17, p < 0.001) and seed weight (r = -0.22, p < 0.001).

The boxes represent the distribution of individual values (n = 12 for each genotypes), and dots correspond to individual plant measurements. Different letters above the boxes indicate statistically significant differences between inoculum treatments for each genotype according to the Kruskal-Wallis test followed by Dunn's post hoc test (p < 0.05). Each panel shows the linear regression line (red) with 95% confidence intervals (pink area). Pearson's correlation coefficient (r) and corresponding p-value are indicated for each trait.

Furthermore, the analysis of variance of chlorophyll content in inoculated leaves indicated that this trait was influenced by not only the genotype, the inoculum and the time after infection, but also by the complex interactions between these factors (p < 0.001). Effect
<figure><img src="image_7.png" /><figcaption>**Figure 5.** Relationship between symptom percentage (%) and yield-related traits (number of pods, pod weight, number of seeds, and seed weight) in cowpea plants</figcaption></figure>

size analysis (Table 3) showed that chlorophyll content was mainly explained by the genotype ($\eta^2_p$ = 0.30; $f$ = 0.65; large effect) and the time after inoculation ($\eta^2_p$ = 0.35; $f$ = 0.73; large effect). The inoculum had a moderate effect ($\eta^2_p$ = 0.08; $f$ = 0.30; medium effect).

DISCUSSION

In this study, 12 cowpea genotypes cultivated in Burkina Faso display a diversity of responses to X were demonstrated. *citri* pv. *vignicola*, which reflects the genetic variability existing among these genotypes. These results are consistent with the previous observation that African genotypes possess partial or quantitative resistance genes to cowpea bacterial blight, often with moderate heritability (Agbicodo et al., 2010). Observed differences could also be linked to single-nucleotide polymorphisms (SNPs) and insertions/deletions (Indels) within resistance genes (Kwon et al., 2024). Genotype KVx745-11P maintained the highest performance across all tested strains, making it a valuable source of genes for breeding programs. The differences in symptom severity and bacterial populations observed among the three strains of X. *citri* pv. *vignicola* confirmed that aggressiveness varies depending on the strain. Similar studies conducted in Nigeria have also shown that symptom severity and yield loss vary greatly depending on the X. *citri* pv. *vignicola* strain used, with some strains capable of reducing seed production by more than 70% (Alabi, 2024). Strain CFBP 7113 caused the most severe effects and the largest yield reductions, suggesting the presence of particularly active virulence

factors such as type III secretion system effectors responsible for suppressing plant defenses (Boch and Bonas, 2010; Büttner, 2016). Indeed, the three strains used presented high differences in terms of content and localization of genes encoding type III effectors of the transcription activator-like (TAL) family (Ruh et al., 2017). These variations highlight the need to evaluate genotype resistance under multiple pathogen pressures to identify durable and stable resistance (Mundt, 2014). Inoculation led to significant reductions in pod number, pod weight, seed number, and seed weight compared to the control, with a significant negative correlation between symptom severity and yield-related traits. These results corroborate the negative correlation between bacterial blight severity and seed yield in different cowpea genotypes (Masmola, 2024). Genotypes Yiisyandé, Gourgou, Nerwaya, and Makoyin showed the greatest losses, whereas KVx745-11P maintained high yield, suggesting tolerance or partial resistance. Yield reduction likely resulted from disruptions in photosynthesis, assimilate translocation, pollination, and seed filling, exacerbated by vascular obstruction caused by biofilm formation (Wydra et al., 2001; de Lima-Primo et al., 2015). Chlorophyll content in inoculated leaves was strongly influenced by genotype, inoculum, and time after infection. This result is consistent with previous observations indicating that bacterial blight of cowpea directly affects photosynthesis and assimilate translocation, thereby reducing pod formation and filling (Mahesha et al., 2022; Olatunde et al., 2024). KVx745-11P maintained higher chlorophyll levels, while susceptible genotypes showed a substantial decline, indicating that maintaining photosynthetic function is a
<table><caption>**Table 3.** Effect size (partial η² and Cohen's f) of the main factors and interactions on chlorophyll content in the genotypes.</caption><thead><tr><td>Parameter</td><td>Eta2_partial</td><td>cohen_f</td><td>Effect_size</td></tr></thead><tbody><tr><td>Genotypes</td><td>0.3</td><td>0.6480654</td><td>Large</td></tr><tr><td>Inoculum</td><td>0.08</td><td>0.2979543</td><td>Medium</td></tr><tr><td>DPI</td><td>0.35</td><td>0.7314259</td><td>Large</td></tr><tr><td>Genotypes:Inoculum</td><td>0.17</td><td>0.4557491</td><td>Large</td></tr><tr><td>Genotypes:DPI</td><td>0.29</td><td>0.6467266</td><td>Large</td></tr><tr><td>Inoculum:DPI</td><td>0.09</td><td>0.3222547</td><td>Medium</td></tr><tr><td>Genotypes:Inoculum:DPI</td><td>0.18</td><td>0.4630649</td><td>Large</td></tr></tbody></table>

key mechanism of resistance or tolerance (Faye et al., 2024). Overall, we showed that resistance or tolerance to bacterial blight in cowpea depends on both the pathogen strain and the genotype. KVx745-11P stood out as the best-performing genotype, capable of maintaining yield and photosynthesis despite infection, making it an ideal candidate for breeding programs (Faye et al., 2024).

## Conclusion

This study confirms that bacterial blight caused by *X. citri* pv. *vignicola* exerts a considerable depressive effect on cowpea productivity. The genotype KVx745-11P emerged as the most stable and high-performing under different bacterial pressures, suggesting a more robust resistance. In contrast, genotypes Yiisyandé, Makoyin, and Komcallé exhibited high susceptibility, reflected by a drastic yield reduction. These findings are crucial for guiding breeding programs and varietal dissemination strategies to prevent a potential introduction of the pathogen in Burkina Faso. However, *X. citri* pv. *vignicola* was able to cause significant yield reduction after being inoculated on only one leaf, indicating that this bacterium can impact the whole plant even in the absence of dissemination factors such as wind, splashing rain, or cultural practices.

## CONFLICT OF INTERESTS

The authors have not declared any conflict of interests.

## REFERENCES

Agbicodo EM, Fatokun CA, Bandyopadhyay R, Wydra K, Diop NN, Muchero W, Ehlers JD, Roberts PA, Close TJ, Visser RGF, van der Linden CG (2010). Identification of markers associated with bacterial blight resistance loci in cowpea [Vigna unguiculata (L.) Walp.]. *Euphytica* 175(2):215-226. https://doi.org/10.1007/s10681-010-0164-5.

Alabi TT (2024). Variation in Response of Cowpea (Vigna unguiculata L. Walp.) genotypes to inoculant and phosphorus applications for seed yield improvement. Master's Thesis, Kwara State University (Nigeria)

Berg S, Kutra D, Kroeger T, Straehle CN, Kausler BX, Haubold C,

Schiegg M, Ales J, Beier T, Rudy M, Eren K (2019). Ilastik: interactive machine learning for (bio) image analysis. Nature Methods 16(12):1226-1232.

Boch J, Bonas U (2010). *Xanthomonas* AvrBs3 Family-Type III Effectors: Discovery and Function. Annual review of phytopathology 48(1):419-436. https://doi.org/10.1146/annurev-phyto-080508-081936

Büttner D (2016). Behind the lines—actions of bacterial type III effector proteins in plant cells. FEMS Microbiology Reviews 40(6):894-937. https://doi.org/10.1093/femsre/fuw026

Dabat MH, Lahmar R, Guissou R (2012). Growing Cowpeas in Burkina Faso: A Pathway for Small-Scale Contextual Farming Adaptation?. Autrepart 62(3):95-114.

Deo-Donne PL, Annan ST, Adarkwah F, Pady F, Anyamesem-Poku A (2018). Reaction of Cowpea genotypes to bacterial blight (*Xanthomonas campestris* pv. *vignicola*) disease in Ghana. World Journal of Agricultural Research 6:105-112.

Durojaye HA, Moukoumbi YD, Dania VO, Boukar O, Bandyopadhyay R, Ortega-Beltran A (2019). Evaluation of cowpea (*Vigna unguiculata* (L.) Walp.) landraces to bacterial blight caused by *Xanthomonas axonopodis* pv. *vignicola*. Crop protection 116:77-81. https://doi.org/10.1016/j.cropro.2018.10.013

Enquête Permanente Agricole (EPA)/MARAH (2023). Enquête permanente agricole. DGESS, Burkina Faso. https://www.spcpsa.bf/donnees-denquetes/

Faye A, Obour AK, Akplo TM, Stewart ZP, Min D, Prasad PVV, Assefa Y (2024). Dual-purpose cowpea grain and fodder yield response to variety, nitrogen-phosphorus-potassium fertilizer, and environment. Agrosystems Geosciences and Environment 7(1): e20459. https://doi.org/10.1002/agg2.20459

Foucher J, Ruh M, Préveaux A, Carrère S, Pelletier S, Briand M, Serre RF, Jacques MA, Chen NWG (2020). Common bean resistance to *Xanthomonas* is associated with upregulation of the salicylic acid pathway and downregulation of photosynthesis. BMC Genomics 21(1):566. https://doi.org/10.1186/s12864-020-06972-6

Kwon JS, Lee J, Shilpha J, Jang H, Kang WH (2024). The landscape of sequence variations between resistant and susceptible hot peppers to predict functional candidate genes against bacterial wilt disease. BMC Plant Biology 24(1):1036.

de Lima-Primo HE, de Nechet KL, de Halfeld-Vieira BA, de Oliveira JR, Mizubuti ES, de Souza GR (2015). Epidemiological aspects of cowpea bacterial blight. Tropical Plant Pathology 40(1):46-55. https://doi.org/10.1007/s40858-015-0007-y

Mahesha HS, Keerthi MC, Shivakumar KV, Bhargavi HA, Saini RP, Manjunatha L, Hickok D, Blair MW (2022). Development of Biotic Stress Resistant Cowpea. In: Kole C (ed) Genomic Designing for Biotic Stress Resistant Pulse Crops. Springer International Publishing, Cham, pp 213-251.

Masemola BM (2024). Heritability and expression of grain yield and nutritional characteristics of cowpea. PhD Thesis, University of the Free State.

Ministère de la Recherche Scientifique et de l'Innovation (MRSI) (2014). National Catalogue of Agricultural Species and Varieties of Burkina Faso. https://innovateurs-inventeurs.com/wp-content/uploads/2019/10/catalogue-national-des-especes-et-varietesagricoles-du-burkina-faso_2014.pdf
Mundt CC (2014). Durable resistance: A key to sustainable management of pathogens and pests. Infection, Genetics and Evolution 27:446-455. https://doi.org/10.1016/j.meegid.2014.01.011

Muranaka S, Shono M, Myoda T, Takeuchi J, Franco J, Nakazawa Y, Boukar O, Takagi H (2016). Genetic diversity of physical, nutritional and functional properties of cowpea grain and relationships among the traits. Plant Genetic Resources 14(1):67-76.

Nandini R, Sripad K, Veerendra AC, Pavithra AH (2014). Severity of bacterial blight (Xanthomonas axonopodis pv. vignicola) of Cowpea in northern regions of Karnataka. International Journal of Advances in Pharmacy, Biology and Chemistry 3:128-135.

Olatunde BI, Afolabi OB, Oguntade O, Onasanya AA, Okiki PA (2024). Analyses of virulence and genetic diversity among Xanthomonas axonopodis pv. vignicola isolates from different cowpea varieties. Vegetos 37(2):476-485. https://doi.org/10.1007/s42535-023-00806-y

Ouedraogo A, Kabore F, Kabore O (2022). Perception of soil fertility and adaptation strategies of farmers in Samandéni (Burkina Faso). International Journal of Biological and Chemical Sciences 16:1536-1553.

Raboin LM, Lairez J, Kabore M, Dusserre J, Kaboré R (2025). An overview of the role and agronomic performance of cowpea in farms of the Centre-North region of Burkina Faso pp. 1-30. https://agritrop.cirad.fr/613076/3/613076

Roberts PA, Ehlers JD, Hall AE, Matthews WC (1997). Characterization of new resistance to root-knot nematodes in cowpea. Diseases and Parasitic Weeds 207-214.

Ruh M, Briand M, Bonneau S, Jacques MA, Chen NWG (2017). First Complete Genome Sequences of Xanthomonas citri pv. vignicola strains CFBP7111, CFBP7112, and CFBP7113 obtained using long-read technology. Genome Announcements 5(36):10-128.

Schindelin J, Arganda-Carreras I, Frise E, Kaynig V, Longair M, Pietzsch T, Preibisch S, Rueden C, Saalfeld S, Schmid B (2012). Fiji: an open-source platform for biological-image analysis. Nature Methods 9:676–682. https://pubmed.ncbi.nlm.nih.gov/22743772/

Sikirou R, Wydra K (2008). Effect of intercropping cowpea with maize or cassava on cowpea bacterial blight and yield. Journal of Plant Diseases and Protection 115(4):145-151. https://doi.org/10.1007/BF03356262

Tensaba RS, Kiema A, Zongo M, Gnanda BI, Tiema AK (2023). Ressources alimentaires et stratégies d'alimentation des petits ruminants en Région Centre-Nord du Burkina Faso. Journal of Applied Biosciences 182:19007-19017.

Timko MP, Singh BB (2008). Cowpea, a Multifunctional Legume. In: Moore PH, Ming R (eds) Genomics of Tropical Crop Plants. Springer, New York, NY pp 227-258.

Williams RJ (1975). Diseases of Cowpea (Vigna unguiculata (L.) Walp.) in Nigeria. PANS Pest Articles and News Summaries 21(3):253-267. https://doi.org/10.1080/09670877509411407

Wydra K, Fanou A, Sikirou R, Zandjanakou M, Zinsou V, Rudolph K (2001). Integrated Control of Bacterial Diseases of Cassava and Cowpea in West Africa. In: de Boer SH (ed) Plant Pathogenic Bacteria. Springer Netherlands, Dordrecht, pp 280–287.