In vitro Propagation of Banana (Musa paradisiaca L.) Plant Using Shoot Tip Explant

Banana is a fruit crop which has high demand in Ethiopia, but its production is constrained by lack of disease free planting material with conventional propagation methods. For shoot initiation, shoot tip explants were cultured on MS medium supplemented with 0.5, 1.0, 1.5 and 2.0 mg/L BAP. Similarly, MS medium supplemented with BAP at 1.0, 1.5, 2.0 mg/L in combination with IBA at 0.25 and 0.50 mg/L were used for shoot multiplication. Half- strength MS medium augmented with IBA at 1.0, 2.0, 3.0 and 4.0 mg/l were used for root induction. MS medium without PGRs were used as controls. Finally, hardening of the in vitro derived plantlets was carried out in green house both in the primary and secondary acclimatization stages. Results showed that the highest shoot initiation percent (93.40%), highest mean number of shoots per explant (4.67) and lesser day for shoot induction (11.00) were observed in explant cultured on MS + 1.0 mg/L BAP. With shoot multiplication, highest shooting percent (92.60%), maximum number of shoots (7.67) and highest shoot length (5.27 cm) were recorded on MS + 1.5 mg/L BAP + 0.5 mg/L IBA. The highest rooting percent (93.40%), maximum root number per shoot (7.67) and highest root length (11.00 cm) were found on a half strength MS medium + 2.0 mg/L IBA. The survival rate of plantlets were 96.00% in coco peat substrate in primary acclimatization and 97.92% in forest soil, sand and manure substrates mixed at 3:2:1 ratio in secondary acclimatization. Overall, the result showed that the PGRs type, concentrations and combinations used are effective for mass propagation of banana variety studied in this experiment.

Physico-chemical changes in “Xiem” banana cultivar (cultivated in Vietnam) during ripening and storage at different temperatures

There are changes in chemical and physical characteristics involved in the ripening of bananas. This study evaluated the changes in physico-chemical and nutritional characteristics of the "Xiêm" banana cultivar at the harvesting (unripe fruit) and ripe stages (ripe fruit). As the pulp to peel ratio and titrable acidity increased, the firmness decreased with an increase in ripening time. A significant increase in total polyphenol content and decrease in beta-carotene and vitamin C content was observed at climacteric peak during ripening. During ripening, the banana peel colour changed from green to yellow, the pulp softened, the flavour develops, and the moisture is lost. "Xiem" banana variety was fully mature after 7 and 22 days of storage at 28-30oC and 13-15oC, respectively. The correlation between various stages of ripeness and these properties were determined and the correlation coefficients were calculated. A very high coefficient of determination (r2 >0.937) was recorded between physical properties (pulp firmness/peel colour) and chemical properties (starch/sugar) of banana fruit with the stage of ripeness.

The vulnerability of bananas to globally emerging disease threats

Banana cultivation has increased significantly over the last century to meet the growing demand for this popular fruit. Originating in Southeast Asia, bananas are now produced in over 135 different countries in tropical and subtropical regions of the world. The vast majority of this expansion of production is based on a single banana variety ”Cavendish” which makes up almost all the export trade grown in large scale monocultures as well as a large part of the local trade and represents over 40% of all bananas grown globally. Over the last century several major diseases of the banana have emerged, and widely expanded their geographic ranges. Cultivars within the “Cavendish” variety are highly susceptible to these diseases including: Yellow Sigatoka, Black leaf streak, Eumusae leaf spot, Freckle, Fusarium wilt Tropical race 4, Banana bunchy top and the bacterial wilts Moko, Xanthomonas wilt and Banana blood disease. This review graphically illustrates the emergence and rapid intercontinental spread of these diseases and discusses several major disease epidemics in bananas. Evidently, the large-scale monoculture based on the single variety “Cavendish” has resulted in an extreme level of genetic vulnerability. The resistance to diversification in the Cavendish production chain and the lack of investment in genetics and plant breeding in the recent past means that currently limited genetic solutions are available to replace the Cavendish banana with a set of market acceptable resistant varieties utilising a range of different genetic backgrounds.

Comparison of Neural Network Methods for Classification of Banana Varieties (Musa paradiasaca)

Every region in Indonesia has a very large diversity of banana species, but no system records information about the characteristics of banana varieties. The purpose of this research is to make an encyclopedia of banana types that can be used for learning by classifying banana varieties using banana images. This banana variety classification system uses image processing techniques and artificial neural network methods as classification methods.The varieties of bananas used are pisang merah, pisang pisang mas kirana, pisang klutuk, pisang raja and pisang cavendis. The parameters used are color features (Red, Green, and Blue) and shape features (area, perimeter, diameter, and length of fruit). The intelligent system used is the Backpropagation method and the Radial Basis Function Neural Network. The results showed that both methods were able to classify banana varieties with an accuracy rate of 98% for Backpropagation and 100% for the Radial Basis Function Neural Network.

Geographic expansion of banana Blood disease in Southeast Asia

Blood disease in bananas caused by Ralstonia syzygii subsp. celebesensis is a bacterial wilt causing significant crop losses in Indonesia and Malaysia. Disease symptoms include wilting of the plant and red brown vascular staining, internal rot, and discoloration of green banana fruit. There is no known varietal resistance to this disease in the Musa genus, although variation in susceptibility has been observed, with the popular Indonesian cooking banana variety Kepok being highly susceptible. This study established the current geographic distribution of Blood disease in Indonesia and confirmed the pathogenicity of isolates by Koch's Postulates. The long-distance distribution of the disease followed an arbitrary pattern indicative of human-assisted movement of infected banana materials. In contrast, local or short distance spread radiated from a single infection source, indicative of dispersal by insects and possibly contaminated tools, water or soil. The rapid expansion of its geographical range makes Blood disease an emerging threat to banana production in Southeast Asia and beyond.

Effects of Extraction Conditions on Banana Peel Polyphenol Oxidase Activity and Insights into Inactivation Kinetics Using Thermal and Cold Plasma Treatment

The objective of this work was to characterize banana peel polyphenol oxidase (PPO) and to study the inactivation kinetics during thermal and cold atmospheric pressure plasma treatment. Since varietal differences in enzyme characteristics are a well-known phenomenon, ‘Prata’ banana peel PPO was characterized, and PPO activity and thermal stability of the peel PPO of the two dessert banana cultivars ‘Cavendish’ and ‘Prata’ were compared to identify the cultivar better suited for industrial food applications. A crude extract obtained from the peels of the Brazilian banana variety ‘Prata’ revealed highest PPO activities (46.0–55.2 nkat/mL) at 30–40 °C in a range of pH 6.0–6.5 after addition of 0.5 g/gsample polyvinylpyrrolidone and 0.5% (v/v) Triton X-100 during extraction. ‘Cavendish’ PPO activity was four times higher. Banana peel PPO exhibited the highest affinity towards dopamine (KM = 0.94 mM). Thermal inactivation of ‘Prata’ and ‘Cavendish’ PPO was achieved at 90 °C after 5 and 15 min, respectively, whereas cold plasma treatment did not decrease PPO activity below 46% of the initial enzyme activity. The inactivation behavior of PPO could successfully be described by a two-fraction model indicating at least two types of isoenzymes with different thermal stability. The overall high thermal stability was mainly attributed to membrane-bound PPO. The results may help to prevent enzymatic browning of banana peels and thereby facilitate their valorization as food ingredients.

Prevalence of banana Xanthomonas wilt in Nithi, Tharaka-Nithi County in Kenya

Banana (Musa spp.) is a nutrient rich crop grown in small and large scale across the globe. It is rich in carbohydrates, vitamins and minerals thus, it may serve as the source of nutrition in low resourced regions such as Tharaka Nithi County, Kenya. However, banana production in many areas is faced with biotic constraints such as banana Xanthomonas wilt (BXW) disease caused by Xanthomonas campestris pv. musacearum. The pathogen attacks photosynthetic leaves and young fruits, reducing palatability and marketability. There is currently scanty information on prevalence of BXW in Nithi region of Tharaka Nithi County. Additionally, it remains unclear whether farmers in the region are knowledgeable on occurrence of BXW disease, symptoms and management practices. The prevalence of BXW was assessed through survey method in five villages (Kiang’ondu, Marima, Mitheru, Kibumbu and Giampampo) in Nithi. Percentage BXW prevalence in the studied villages was not significantly different (p>0.05). However, slightly higher BXW prevalence value of 21.14% was recorded at Giampampo village and was lower at Mitheru 11.24%. There was significant relationship (X2 (8, N = 46) = 19.93, p= 0.0034) between banana variety grown and occurrence of banana diseases. There was significant relationship (X2 (8, N = 46) = 31.165, p = 0.0053) between banana variety grown and susceptibility to diseases. The relationship between years of growing banana in the same farm and occurrence of banana diseases was significant (X2(6,N= 46) = 8.761,p= <0.0001. The relationship between occurrence of banana diseases and season of the year was significant (X2(8,N= 46) = 32.4591, p= <0.0001). The relationship between occurrence of banana diseases and management option in Nithi was significant (X2(4,N= 46) = 6.9758,p= 0.0025). Majority of the farmers (92%) were unaware of existence of BXW in the region. Farmers expressed lack of knowledge on managing BXW diseases in their banana farms with the majority not being able to identify common diseases of banana. Based on these observations, there is need to educate farmers on best banana farming practices, disease identification and management.

Comparative transcriptome analysis revealed resistance differences of Cavendish bananas to Fusarium oxysporum f.sp. cubense race1 and race4

Background Banana Fusarium wilt is a devastating disease of bananas caused by Fusarium oxysporum f. sp. cubense (Foc) and is a serious threat to the global banana industry. Knowledge of the pathogenic molecular mechanism and interaction between the host and Foc is limited. Results In this study, we confirmed the changes of gene expression and pathways in the Cavendish banana variety ‘Brazilian’ during early infection with Foc1 and Foc4 by comparative transcriptomics analysis. 1862 and 226 differentially expressed genes (DEGs) were identified in ‘Brazilian’ roots at 48 h after inoculation with Foc1 and Foc4, respectively. After Foc1 infection, lignin and flavonoid synthesis pathways were enriched. Glucosinolates, alkaloid-like compounds and terpenoids were accumulated. Numerous hormonal- and receptor-like kinase (RLK) related genes were differentially expressed. However, after Foc4 infection, the changes in these pathways and gene expression were almost unaffected or weakly affected. Furthermore, the DEGs involved in biological stress-related pathways also significantly differed after infection within two Foc races. The DEGs participating in phenylpropanoid metabolism and cell wall modification were also differentially expressed. By measuring the expression patterns of genes associated with disease defense, we found that five genes that can cause hypersensitive cell death were up-regulated after Foc1 infection. Therefore, the immune responses of the plant may occur at this stage of infection. Conclusion Results of this study contribute to the elucidation of the interaction between banana plants and Foc and to the development of measures to prevent banana Fusarium wilt.

Comparison transcriptome analysis revealed resistance differences of Cavendish bananas to Fusarium oxysporum f.sp. cubense race1 and race4

Background: Banana Fusarium wilt is a devastating disease of bananas caused by Fusarium oxysporum f. sp. cubense (Foc) and is a serious threat to the global banana industry. Knowledge of the pathogenic molecular mechanism and interaction between the host and Foc is limited. Results: In this study, we confirmed the changes of gene expression and pathways in the Cavendish banana variety ‘Brazilian’ during early infection with Foc1 and Foc4 by comparative transcriptomics analysis. 1862 and 226 differentially expressed genes (DEGs) were identified in ‘Brazilian’ roots at 48 h after inoculation with Foc1 and Foc4, respectively. After Foc1 infection, lignin and flavonoid synthesis pathways were enriched. Glucosinolates, alkaloid-like compounds and terpenoids were accumulated. Numerous hormonal- and receptor-like kinase (RLK) related genes were differentially expressed. However, after Foc4 infection, the changes in these pathways and gene expression were almost unaffected or weakly affected. Furthermore, the DEGs involved in biological stress-related pathways also significantly differed after infection within two Foc races. The DEGs participating in phenylpropanoid metabolism and cell wall modification were also differentially expressed. By measuring the expression patterns of genes associated with disease defense, we found that five genes that can cause hypersensitive cell death were up-regulated after Foc1 infection. Therefore, the immune responses of the plant may occur at this stage of infection. Conclusion: Results of this study contribute to the elucidation of the interaction between banana plants and Foc and to the development of measures to prevent banana Fusarium wilt.