Banana and plantain production systems in Benin: ethnobotanical investigation, varietal diversity, pests, and implications for better production

Phytoparasitic Nematodes of Musa spp. with Emphasis on Sources of Genetic Resistance: A Systematic Review

Bananas are a staple food that considerably contributes to both food security and income generation, especially in countries of Africa, Asia, and Central and South America. The banana plant (Musa spp.) is affected by various pathogens, of main concern being the plant-parasitic nematodes associated with the rhizosphere, the most important of which are Radopholus similis (burrowing nematode), Helicotylenchus sp. (spiral nematode), Pratylenchus sp. (root lesion nematode), and Meloidogyne sp. (gall nematode). Infected plants reduce their ability to absorb water and nutrients, which can lead to delayed flowering, fewer bunches, and lower fruit mass. Obtaining nematode-resistant banana cultivars through genetic improvement is an effective and sustainable option compared with chemical control with nematicides. Here, we provide the first systematic review of existing banana sources of resistance to nematodes to aid the management and control of nematodes in banana and plantain crops. Articles selected from different databases were evaluated, and searches were conducted using pre-established inclusion and exclusion criteria. We found 69 studies dealing with genetic improvement for nematode resistance in banana cultivation. Our findings revealed that sources of resistance are currently under investigation to combat the diseases caused by different nematode species in banana plants.

Toward tailored interventions in plantain (Musa paradisiaca L.) industry: Insights from heterogeneity and constraints to plantain-based cropping systems in South-Benin

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Narrow genetic diversity in germplasm from the Guinean and Sudano-Guinean zones in Benin indicates the need to broaden the genetic base of sweet fig banana (Musa acuminata cv Sotoumon)

Sweet fig (M. acuminata cv. Sotoumon) is an economically important dessert banana in Benin, with high nutritional, medicinal, and cultural values. Nevertheless, its productivity and yield are threatened by biotic and abiotic stresses. Relevant knowledge of the genetic diversity of this economically important crop is essential for germplasm conservation and the development of breeding programs. However, very little is known about the genetic makeup of this cultivar in Benin. To advance the understanding of genetic diversity in sweet fig banana germplasm, a Genotype-By-Sequencing (GBS) was performed on a panel of 273 accessions collected in different phytogeographical zones of Benin. GBS generated 8,457 quality SNPs, of which 1992 were used for analysis after filtering. The results revealed a low diversity in the studied germplasm (He = 0.0162). Genetic differentiation was overall very low in the collection as suggested by the negative differentiation index (Fstg = -0.003). The Analysis of Molecular Variance (AMOVA) indicated that the variation between accessions within populations accounted for 83.8% of the total variation observed (P < 0.001). The analysis of population structure and neighbor-joining tree partitioned the germplasm into three clusters out of which a predominant major one contained 98.1% of all accessions. These findings demonstrate that current sweet fig banana genotypes shared a common genetic background, which made them vulnerable to biotic and abiotic stress. Therefore, broadening the genetic base of the crop while maintaining its quality attributes and improving yield performance is of paramount importance. Moreover, the large genetic group constitutes an asset for future genomic selection studies in the crop and can guide the profiling of its conservation strategies.

Analysis of genetic diversity and agronomic variation in banana sub-populations for genomic selection under drought stress in southern Benin

In the perspective of investigating genomic selection (GS) among Musa genotypes in West and Central Africa, banana accessions were phenotyped under natural drought stress in Benin and genotyped using genotyping by sequencing. Sixty-one (61) accessions grouped into three major genomic groups AAA, AAB and ABB and those without genomic affiliation information were used. Variation within the population was determined by phenotypic variables while population structure and clustering analysis were carried out to understand the genetic diversity at the molecular level. Among the genomic groups evaluated, the group AAB showed the best performance for fruit weight at maturity, (3.41 ± 1.99 kg) and for plant height (198.46 ± 12.66 cm). At the accession level, HD 117 S1 and NIA 27 showed the best plant height (263.16 ± 20.98 cm) and the best fruit weight at maturity (9.43 ± 0.0 kg) respectively. Phenotypic data did not reveal clear genetic diversity among accessions; however, the genetic diversity was conspicuous at the molecular level using 5000 markers. The affiliations of local accessions in genomic groups were determined for the first time based on the phenotypic and molecular data obtained in this study. The knowledge generated allows the possibility to apply GS in banana.

Nutritional and functional characterisation of flour from six plantain (Musa spp.) cultivars grown in Benin

Plantain flour is a promising functional ingredient of various domains in the food industry. The present work investigated the functional attributes and proximate composition of flours derived from six plantain cultivars from Benin, and evaluated their nutritional composition. Among the cultivars, proximate composition of the flours varied with moisture, ash, protein, and fibre ranging from 4.59 - 6.85, 2.01 - 2.56, 2.54 - 3.47, and 0.95 - 1.37% (dry basis), respectively. Significantly higher β-carotene contents (± 9 µg) were found in flours from Orishele and Pelipita cultivars, whereas flours from Aloga 2M and Kpahissi cultivars yielded the highest content of vitamin C (9.64 µg). Flour from Kpahissi cultivar exhibited higher water and oil absorption capacity (161.29 and 81.29%, respectively) than the other flours. In addition, higher viscosity, emulsion, and foaming capacities were recorded in flour from Kpahissi cultivar. Flours from different plantain cultivars differed in their physicochemical and functional properties, and could therefore be used in various food domains. In that respect, Kpahissi, Orishele, and Aloga 2M flours could be more suitable in the formulation of particular composite flour for specific uses having the functional parameters such as water and oil absorption, viscosity, emulsion, and foaming capacities.

Spatial parameters associated with the risk of banana bunchy top disease in smallholder systems

The Banana Bunchy Top Disease (BBTD), caused by the Banana Bunchy Top Virus (BBTV) is the most important and devastating in many tropical countries. BBTD epidemiology has been little studied, mixed landscape smallholder systems. The relative risks associated with this disease vary between geographical areas and landscapes. This work analyzed the management and vegetation conditions in smallholder gardens to assess the factors linked to landscape-level BBTV transmission and management. Mapping was done in this study area which is in a BBTD-endemic region, involving farmers actively managing the disease, but with household-level decision making. A spatial scanning statistic was used to detect and identify spatial groups at the 5% significance threshold, and a Poisson regression model was used to explore propagation vectors and the effect of surrounding vegetation and crop diversity. Spatial groups with high relative risk were identified in three communities, Dangbo, Houéyogbé, and Adjarra. Significant associations emerged between the BBTD prevalence and some crop diversity, seed systems, and BBTD management linked factors. The identified factors form important candidate management options for the detailed assessment of landscape-scale BBTD management in smallholder communities.

RNAi technology for management of banana bunchy top disease

Banana bunchy top disease (BBTD) is one of the world's most destructive viral diseases of banana and plantain, causing up to 100% yield loss in severe cases. The disease is vectored by banana aphids (Pentalonia nigronervosa) and carried long distances through the movement of infected plant materials. The banana aphids harboring banana bunchy top virus (BBTV) present in banana producing regions are the sole vector and the most efficient method of transmitting the virus to the healthy plants. Controlling the spread of BBTD has been very challenging since no known banana germplasm is immune to BBTV. The disease can be managed with the use of virus-free planting material and roguing. However, once BBTD is established in the field, it is very difficult to eradicate or manage it. Therefore, a more sustainable way of controlling the disease is developing host plant resistance against the virus and the vector. Biotechnological strategies via RNA interference (RNAi) could be used to target the banana aphid as well as BBTV to reduce virus-associated yield losses of banana and plantain, which feed over 500 million people around the world. This review discusses the status of BBTD and perspectives on effective RNAi technologies for controlling BBTV and the vector, banana aphid, transmitting the virus as sustainable management of the disease.

Evaluation of the sensitivity and synergistic effect of Trichoderma reesei and mancozeb to inhibit under in vitro conditions the growth of Fusarium oxysporum

Trichoderma

is a saprophytic, soil-borne fungus with a worldwide distribution that has been extensively studied due to their capacity to synthesize secondary metabolites with antimicrobial activity, parasitize other fungi and directly interact with plant roots, inducing resistance to disease and tolerance to abiotic stresses. Fusarium wilt caused by the soil-inhabiting fungus Fusarium oxysporum is considered one of the most important diseases that affect banana cultivars. Currently, more environmentally friendly alternatives to control this disease are being proposed, these strategies include the application of low doses of synthetic fungicides and the use of biocontrol agents such as Trichoderma or Xylaria. Thus, this study aimed to evaluate under in vitro conditions the synergistic effect of the biological control agent T. reesei C2A combined with low doses of mancozeb to inhibit the mycelial growth of F. oxysporum F1. To perform the synergistic essays, 0.1 mg/mL of mancozeb was suspended in PDA plates, then plugs of T. ressei C2A were placed at the center of the Petri dishes, the plates were incubated for 7 days at 28°C. Results showed that the mycoparasitic capacity of the biocontrol strain to inhibit the mycelial growth of F. oxysporum F1 was enhanced approximately 36% compared to the control plates. Although these results are promising, future studies under greenhouse and field conditions are necessary to corroborate the effectiveness of this approach.

Role of phospholipase C in banana in response to anthracnose infection

Phospholipase C (PLC) plays an important role in plant immunity, and anthracnose caused by the Colletotrichum species is a common postharvest disease of the banana fruit. This study aims to evaluate the role of PLC in anthrax resistance in banana. The experimental group of banana samples was treated with a banana anthracnose conidia suspension, and the control group was treated with distilled water. After inoculation, the groups were sprayed with ethephon, and indicators, such as hardness and conductivity changes; PLC activity, 1,2-diacylglycerol (DAG) and phosphatidic acid (PA)content; and MaPLC-1and MaPLC-2 expression levels, were assessed at 0, 3, 6, 9, 12, and 15 days. Moreover, the expression levels of MaPLC-1 and MaPLC-2 were detected in various tissues. The hardness of banana fruits in the experimental group decreased faster than that in the control group. Furthermore, the conductivity was higher in the experimental group than in the control group. Regarding PLC activity, DAG, and PA content, bananas in the experimental group showed higher activities than those in the control group. Moreover, relatively higher expression of PLC mRNA was detected in anthracnose-inoculated tissues. The evaluation of MaPLC-1 and MaPLC-2 expression levels showed that the mature peel had the highest MaPLC-1 expression level. However, the MaPLC-2 gene was expressed at relatively low levels in the fruit and at relatively high levels in the flower organs. PLC might play a role in fruit ripening in response to anthracnose resistance.