RESUMO

Banana (Musa spp.) is the most widely consumed fruit globally. Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), is a highly threatening disease to banana production. Resistance genes to Foc exist in wild Musa genotypes such as Musa acuminata subsp. burmannicoides var. Calcutta 4. Whilst real-time PCR (RT-qPCR) is appropriate for accurate analysis of gene expression in pathways involved in host defence responses, reference genes with stable expression under specific biotic stress conditions and host tissue types are necessary for normalization of sample variation. In this context, the stability in potential host reference genes ACT1, APT, EF1α, GAPDH, αTUB, RAN, UBIQ1, UBIQ2, ßTUB1, ßTUB3, L2 and ACTA1 was evaluated in total RNA samples from root tissues in Calcutta 4 (resistant) and Musa sp. cultivar Prata-anã (susceptible) extracted during interaction with Foc subtropical race 4 (STR4). Expression stability was calculated using the algorithms geNorm, NormFinder and BestKeeper. ßTUB3 and L2 were identified as the most stable in Calcutta 4, with ACTA1 and GAPDH the most stable in Prata-anã. These reference genes for analysis of gene expression modulation in the Musa-Foc STR4 pathosystem are fundamental for advancing understanding of host defence responses to this important pathogen.

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Bananas (Musa spp.) are an essential fruit worldwide and rank as the fourth most significant food crop for addressing malnutrition due to their rich nutrients and starch content. The potential of their genetic diversity remains untapped due to limited molecular breeding tools. Our study examined a phenotypically diverse group of 124 accessions from the Colombian Musaceae Collection conserved in AGROSAVIA. We assessed 12 traits categorized into morphology, fruit quality, and yield, alongside sequence data. Our sequencing efforts provided valuable insights, with an average depth of about 7× per accession, resulting in 187,133 single-nucleotide polymorphisms (SNPs) against Musa acuminata (A genome) and 220,451 against Musa balbisiana (B genome). Population structure analysis grouped samples into four and five clusters based on the reference genome. By using different association models, we identified marker-trait associations (MTAs). The mixed linear model revealed four MTAs, while the Bayesian-information and linkage-disequilibrium iteratively nested keyway and fixed and random model for circulating probability unification models identified 82 and 70 MTAs, respectively. We identified 38 and 40 candidate genes in linkage proximity to significant MTAs for the A genome and B genome, respectively. Our findings provide insights into the genetic underpinnings of morphology, fruit quality, and yield. Once validated, the SNP markers and candidate genes can potentially drive advancements in genomic-guided breeding strategies to enhance banana crop improvement.

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WRKY transcription factors (TFs) play key roles in plant defense responses through phytohormone signaling pathways. However, their functions in tropical fruit crops, especially in banana, remain largely unknown. Several WRKY genes from the model plants rice (OsWRKY45) and Arabidopsis (AtWRKY18, AtWRKY60, AtWRKY70) have shown to be attractive TFs for engineering disease resistance. In this study, we isolated four banana cDNAs (MaWRKY18, MaWRKY45, MaWRKY60, and MaWRKY70) with homology to these rice and ArabidopsisWRKY genes. The MaWRKY cDNAs were isolated from the wild banana Musa acuminata ssp. malaccensis, which is resistant to several diseases of this crop and is a progenitor of most banana cultivars. The deduced amino acid sequences of the four MaWRKY cDNAs revealed the presence of the conserved WRKY domain of ~60 amino acids and a zinc-finger motif at the N-terminus. Based on the number of WRKY repeats and the structure of the zinc-finger motif, MaWRKY18 and MaWRKY60 belong to group II of WRKY TFs, while MaWRKY45 and MaWRKY70 are members of group III. Their corresponding proteins were located in the nuclei of onion epidermal cells and were shown to be functional TFs in yeast cells. Moreover, expression analyses revealed that the majority of these MaWRKY genes were upregulated by salicylic acid (SA) or methyl jasmonate (MeJA) phytohormones, although the expression levels were relatively higher with MeJA treatment. The fact that most of these banana WRKY genes were upregulated by SA or MeJA, which are involved in systemic acquired resistance (SAR) or induced systemic resistance (ISR), respectively, make them interesting candidates for bioengineering broad-spectrum resistance in this crop.

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Bananas (Musa ssp.) are among the world's most important crops. In terms of gross value of production, they are the fourth most important global food crop and have an important socioeconomic and ecological role. Somatic embryogenesis (SE) is a developmental process, in which somatic cells differentiate into embryos which eventually develop and regenerate into plants. SE is exploited to generate a large quantity of very high economic value, genetically identical and disease-free plantlets. In bananas, the use of shoot apexes of axillary buds to induce SE resulted an alternative for plant regeneration through embryogenic cell suspension (ECS). The protocol has been scaled up to commercial laboratories for tissue culture (biofactories) for production of planting materials. The genetic stability of regenerated plants and high yields obtained under field conditions demonstrate the feasibility of scaling up this biotechnological protocol and adapting it to commercial production of planting materials to mitigate a critical bottleneck in the value chain of this important crop.

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Banana is the most popular fruit in the world, with a relevant role in food security for more than 400 million people. However, fungal diseases cause substantial losses every year. A better understanding of the banana immune system should facilitate the development of new disease-resistant cultivars. In this study, we performed a genome-wide analysis of the leucine-rich repeat receptor-like protein (LRR-RLP) disease resistance gene family in a wild banana. We identified 78 LRR-RLP genes in the banana genome. Remarkably, seven MaLRR-RLPs formed a gene cluster in the distal part of chromosome 10, where resistance to Fusarium wilt caused by Foc race 1 has been previously mapped. Hence, we proposed these seven MaLRR-RLPs as resistance gene candidates (RGCs) for Fusarium wilt. We also identified seven other banana RGCs based on their close phylogenetic relationships with known LRR-RLP proteins. Moreover, phylogenetic analysis of the banana, rice, and Arabidopsis LRR-RLP families revealed five major phylogenetic clades shared by these plant species. Finally, transcriptomic analysis of the MaLRR-RLP gene family in plants treated with Foc race 1 or Foc TR4 showed the expression of several members of this family, and some of them were upregulated in response to these Foc races. Our study provides novel insights into the structure, distribution, evolution, and expression of the LRR-RLP gene family in bananas as well as valuable RGCs that will facilitate the identification of disease resistance genes for the genetic improvement of this crop.

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A bananeira (Musa sp.) é uma frutífera tropical, cultivada comercialmente em todo território brasileiro. Característica de regiões litorâneas, a bananicultura vem ganhando espaço no Planalto Paulista, principalmente na região Centro Oeste do estado. Diante disso, o objetivo desse trabalho foi avaliar o desempenho de genótipos de bananeiras cultivadas sob irrigação por microaspersão e sequeiro nas condições edafoclimáticas do Centro Oeste Paulista. O plantio foi realizado em dezembro de 2015, no município de Vera Cruz –SP, utilizando mudas micropropagadas e aclimatadas. O delineamento experimental adotado foi de blocos ao acaso, com 6 tratamentos, em arranjo fatorial 3x2, sendo 3 genótipos e 2 ambientes de cultivo (irrigado e sequeiro). Os genótipos avaliados foram: BRS Princesa (subgrupo Maçã), Galil 18 (subgrupo Prata) e Grande Naine (subgrupo Cavendish). Foram avaliadas variáveis vegetativas (altura de planta, circunferência do pseudocaule e número de folhas vivas no florescimento), de produção (massa dos cachos e dos engaços, produtividade, número de pencas por cacho e número de frutos por penca) e caracterização física dos frutos (diâmetro, espessura de casca e comprimento). Conclui-se que a irrigação localizada por microaspersão interfere positivamente no desempenho dos genótipos BRS Princesa (subgrupo Maçã), Galil 18 (subgrupo Prata) e Grande Naine (subgrupo Cavendish), no município de Vera Cruz, na região Centro Oeste Paulista.

The banana tree is a tropical fruit plant, grown commercially throughout Brazil. It’s commonly found of coastal regions, the banana production has been gaining space in the Paulista Plateau, mainly in the Midwest region of the state. The objective of this work was to evaluate the performance of banana genotypes cultivated under microaspersion irrigation and rainfed in the edaphoclimatic conditions of Vera Cruz municipality in São Paulo state. The planting was carried out in December 2015, with micropropagated and acclimated seedlings. The statistical design adopted was randomized blocks, with 6 treatments, in a 3 x 2 factorial arrangement with 3 genotypes and 2 cultivation environments (irrigated and non-irrigated). The genotypes evaluated were: BRS Princesa (Maçã subgroup), Galil 18 (Prata subgroup) and Grande Naine (Cavendish subgroup). Vegetative variables (plant height, pseudostem circumference and the number of live leaves in flowering); production variables (clusters and weight mass, productivity, number of hands per bunches and number of fruit for hand) and fruit quality (diameter, shell thickness and length), were evaluated. It is concluded that the localized irrigation by microaspersion positively interfered in the plant performance, improving the vegetative and productive characteristics of the BRS Princesa (Maçã subgroup), Galil 18 (Prata subgroup) and Grande Naine (Cavendish subgroup) genotypes, in Vera Cruz, Midwest region of São Paulo state.

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RESUMO

A bananeira (Musa sp.) é uma frutífera tropical, cultivada comercialmente em todo território brasileiro. Característica de regiões litorâneas, a bananicultura vem ganhando espaço no Planalto Paulista, principalmente na região Centro Oeste do estado. Diante disso, o objetivo desse trabalho foi avaliar o desempenho de genótipos de bananeiras cultivadas sob irrigação por microaspersão e sequeiro nas condições edafoclimáticas do Centro Oeste Paulista. O plantio foi realizado em dezembro de 2015, no município de Vera Cruz –SP, utilizando mudas micropropagadas e aclimatadas. O delineamento experimental adotado foi de blocos ao acaso, com 6 tratamentos, em arranjo fatorial 3x2, sendo 3 genótipos e 2 ambientes de cultivo (irrigado e sequeiro). Os genótipos avaliados foram: BRS Princesa (subgrupo Maçã), Galil 18 (subgrupo Prata) e Grande Naine (subgrupo Cavendish). Foram avaliadas variáveis vegetativas (altura de planta, circunferência do pseudocaule e número de folhas vivas no florescimento), de produção (massa dos cachos e dos engaços, produtividade, número de pencas por cacho e número de frutos por penca) e caracterização física dos frutos (diâmetro, espessura de casca e comprimento). Conclui-se que a irrigação localizada por microaspersão interfere positivamente no desempenho dos genótipos BRS Princesa (subgrupo Maçã), Galil 18 (subgrupo Prata) e Grande Naine (subgrupo Cavendish), no município de Vera Cruz, na região Centro Oeste Paulista.(AU)

The banana tree is a tropical fruit plant, grown commercially throughout Brazil. Its commonly found of coastal regions, the banana production has been gaining space in the Paulista Plateau, mainly in the Midwest region of the state. The objective of this work was to evaluate the performance of banana genotypes cultivated under microaspersion irrigation and rainfed in the edaphoclimatic conditions of Vera Cruz municipality in São Paulo state. The planting was carried out in December 2015, with micropropagated and acclimated seedlings. The statistical design adopted was randomized blocks, with 6 treatments, in a 3 x 2 factorial arrangement with 3 genotypes and 2 cultivation environments (irrigated and non-irrigated). The genotypes evaluated were: BRS Princesa (Maçã subgroup), Galil 18 (Prata subgroup) and Grande Naine (Cavendish subgroup). Vegetative variables (plant height, pseudostem circumference and the number of live leaves in flowering); production variables (clusters and weight mass, productivity, number of hands per bunches and number of fruit for hand) and fruit quality (diameter, shell thickness and length), were evaluated. It is concluded that the localized irrigation by microaspersion positively interfered in the plant performance, improving the vegetative and productive characteristics of the BRS Princesa (Maçã subgroup), Galil 18 (Prata subgroup) and Grande Naine (Cavendish subgroup) genotypes, in Vera Cruz, Midwest region of São Paulo state.(AU)

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Leaf pathogens are limiting factors in banana (Musa spp.) production, with Pseudocercospora spp. responsible for the important Sigatoka disease complex. In order to investigate cellular processes and genes involved in host defence responses, quantitative real-time PCR (RT-qPCR) is an analytical technique for gene expression quantification. Reliable RT-qPCR data, however, requires that reference genes for normalization of mRNA levels in samples are validated under the conditions employed for expression analysis of target genes. We evaluated the stability of potential reference genes ACT1, α-TUB, UBQ1, UBQ2, GAPDH, EF1α, APT and RAN. Total RNA was extracted from leaf tissues of Musa acuminata genotypes Calcutta 4 (resistant) and Cavendish Grande Naine (susceptible), both subjected to P. musae infection. Expression stability was determined with NormFinder, BestKeeper, geNorm and RefFinder algorithms. UBQ2 and RAN were the most stable across all M. acuminata samples, whereas when considering inoculated and non-inoculated leaf samples, APT and UBQ2 were appropriate for normalization in Calcutta 4, with RAN and α-TUB most stable in Cavendish Grande Naine. This first study of reference genes for relative quantification of target gene expression in the M. acuminata-P. musae interaction will enable reliable analysis of gene expression in this pathosystem, benefiting elucidation of disease resistance mechanisms.

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Bioactive amines are found in food and can be relevant for the assessment of fruits shelf life and nutritional quality. The pulp and peel of 20 banana and plantain were analyzed and the bioactive amine content varied according to the genotype, ripening stage, fruit tissue and thermal processing. In most of the analyzed genotypes, tyramine, histamine, dopamine, serotonin, spermidine, and spermine were decreased during the ripening process in the pulps. By contrast, there was an increase in putrescine level. In many genotypes of plantains, the serotonin and dopamine contents in pulp decreased until stage 5 and increased at stage 7. Peels contain higher levels of serotonin, dopamine, histamine and tyramine than pulps. Additionally, thermal processing affects the content of amines present in fruit. Boiling with the peel should be preferred in domestic preparations, regardless of the genotype used.

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RESUMO

BACKGROUND: Banana is one of the most important crops in tropical and sub-tropical regions. To meet the demands of international markets, banana plantations require high amounts of chemical fertilizers which translate into high farming costs and are hazardous to the environment when used excessively. Beneficial free-living soil bacteria that colonize the rhizosphere are known as plant growth-promoting rhizobacteria (PGPR). PGPR affect plant growth in direct or indirect ways and hold great promise for sustainable agriculture. RESULTS: PGPR of the genera Bacillus and Pseudomonas in banana cv. Williams were evaluated. These plants were produced through in vitro culture and inoculated individually with two rhizobacteria, Bacillus amyloliquefaciens strain Bs006 and Pseudomonas fluorescens strain Ps006. Control plants without microbial inoculum were also evaluated. These plants were kept in a controlled climate growth room with conditions required to favor plant-microorganism interactions. These interactions were evaluated at 1-, 48- and 96-h using transcriptome sequencing after inoculation to establish differentially expressed genes (DEGs) in plants elicited by the interaction with the two rhizobacteria. Additionally, droplet digital PCR was performed at 1, 48, 96 h, and also at 15 and 30 days to validate the expression patterns of selected DEGs. The banana cv. Williams transcriptome reported differential expression in a large number of genes of which 22 were experimentally validated. Genes validated experimentally correspond to growth promotion and regulation of specific functions (flowering, photosynthesis, glucose catabolism and root growth) as well as plant defense genes. This study focused on the analysis of 18 genes involved in growth promotion, defense and response to biotic or abiotic stress. CONCLUSIONS: Differences in banana gene expression profiles in response to the rhizobacteria evaluated here (Bacillus amyloliquefaciens Bs006 and Pseudomonas fluorescens Ps006) are influenced by separate bacterial colonization processes and levels that stimulate distinct groups of genes at various points in time.

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