ABSTRACT. Banana (Musa spp.) is one of the main fruits consumed worldwide. However, finger drop, is a physiological disorder that causes many postharvest problems, which eventually reduces market value and consumer acceptance. Therefore, the objective of the study was to evaluate the anatomical changes that occur in the pedicel rupture area (drop zone) of bananas diploids (BB França) and tetraploid (BRS Pioneira) in three ripening stages. The levels of gene expression involved in the natural ripening process and in the development of finger drop, was also investigated. The accumulation of their mRNAs and those of expansin (EXP1), pectate lyase (PEL1) and xyloglucan endotransglucosylase/hydrolase protein (XTH4) genes already isolated from bananas were measured by quantitative polymerase chain reaction in three ripening stages. BB França presented a higher resistance to finger drop due to the presence of some specific morphoanatomical characteristics, such as larger parenchymal cells and greater deposition of lignin. In contrast, there was degeneration of the pedicel parenchymal tissue of the BRS Pioneira genotype, forming large empty spaces during the ripening of the fruits, mainly in stage 6, which contributed to the finger drop. The diploid BB França is a strong candidate for use in banana breeding programs aimed at fruit drop resistance. This will certainly improve the quality of banana varieties. Moreover, PEL1 proved to be an excellent candidate gene for functional studies of finger drop in bananas.

Abstract The objective of this work was to evaluate the genetic diversity of Xanthomonas phaseoli p v. manihotis (Xpm) from eight populations from five cassava producing states in Brazil, through the rep-PCR (BOX-PCR and ERIC-PCR) and variable number of tandem repeat (VNTR) markers. Cassava leaves with symptoms of cassava bacterial blight were collected in eight municipalities, and the Xpm isolates were identified by amplification with primers specific for these isolates. The identity of the Xpm isolates was confirmed with the BOX-PCR, ERIC-PCR, and VNTR markers. The observed selection pressure, together with the mode of reproduction and the mechanisms that increase genetic variability, allows of the pathogen populations to adapt according to microclimate variation, contributing to a differentiated reproductive success. ERIC-PCR and VNTRs are the best markers for evaluating the genetic variability in the eight studied Xpm populations. However, ERIC-PCR is the marker that best separated the groups by population and presented a higher similarity between the isolates of the same population. The study of the genetic diversity of Xpm is key to improve disease monitoring and management strategies in cassava crops.

Resumo O objetivo deste trabalho foi avaliar a diversidade genética de Xa nthomona s phaseoli p v . ma nihot i s (Xpm) de oito populações de cinco estados produtores de mandioca no Brasil, por meio de marcadores rep-PCR (BOX-PCR e ERIC-PCR) e variable number of tandem repeats (VNTRs). Folhas de mandioca com sintomas de crestamento bacteriano foram coletadas em oito municípios, e os isolados Xpm foram identificados por amplificação com iniciadores específicos para esses isolados. A identidade dos isolados Xmp foi confirmada com os marcadores BOX-PCR, ERIC-PCR e VNTRs. A pressão de seleção observada, junto com o modo de reprodução e os mecanismos que aumentam a variabilidade genética, permite que as populações do patógeno se adaptem de acordo com a variação dos microclimas, o que contribui para o sucesso reprodutivo diferenciado. ERIC-PCR e VNTRs são os melhores marcadores para avaliar a variabilidade genética das oito populações Xpm estudadas. No entanto, ERIC-PCR é o marcador que melhor separou os grupos por população e apresentou maior similaridade entre os isolados de uma mesma população. O estudo da diversidade genética de Xpm é fundamental para delinear estratégias de manejo e monitoramento de doenças na cultura da mandioca.

Resumo A Sigatoka-negra, causada pelo fungo Mycosphaerella fijiensis Morelat, é uma doença que afeta as folhas da bananeira, reduzindo a fotossíntese e ocasionando queda na produtividade. O controle baseia-se no uso de fungicidas; no entanto, essa prática eleva o custo de produção e pode causar impactos ambientais e na saúde. O plantio de cultivares resistentes mostra-se mais viável economicamente. O objetivo deste estudo foi realizar a fenotipagem de diploides, visando à identificação de genótipos resistentes. Foram fenotipados 31 acessos (30 com genoma AA e um com genoma AB), a partir da expressão dos sintomas da doença, por meio de escala de notas. Estimaramse a área abaixo da curva do progresso da doença (AACPD), o índice de severidade da doença (ID) e o índice de aumento da severidade da doença (AID). A variável AID mostrou-se eficiente na identificação de acessos de bananeira com resistência à Sigatoka-negra. O índice de seleção para o ranqueamento de acessos, com moderada resistência à Sigatoka-negra, permitiu identificar os genótipos com maior resistência quantitativa. Cinco acessos diploides foram resistentes (Krasan Saichon, Zebrina, Birmanie, Nº 118 e Tuu Gia), e oito moderadamente resistentes (PA Rayong, Pisang Cici, Malaccensis 1, 028003-01, Microcarpa, Pisang Lidi, Lilin e Malbut).

Abstract Black Sigatoka (black leaf streak disease) is caused by the fungus Mycosphaerella fijiensisMorelet. This phytopathogen colonizes banana leaves, resulting in reduced photosynthesis and decreased productivity. Fungicide applications are useful to control black Sigatoka; however, they increase production costs and can have adverse environmental and health impacts. The cultivation of resistant cultivars is regarded as a more economically viable option. The objective of this study was to perform diploid phenotyping in a set of wild banana accessions to identify resistant genotypes. A total of 31 accessions (30 with AA genome and one with AB genome) were phenotyped based on the presence of disease symptoms using a scoring scale. The area under the disease progress curve (AUDPC), the disease severity index (DI), and the disease severity increase index (DII) were estimated. The DII variable proved to be efficient in identifying banana accessions with black Sigatoka resistance. Likewise, the selection index for ranking accessions with moderate black Sigatoka resistance allowed us to identify those genotypes with the highest quantitative resistance. Five diploid accessions (Krasan Saichon, Zebrina, Birmanie, Nº 118, and Tuu Gia) were found to be resistant to this fungal disease; eight accessions (PA Rayong, Pisang Cici, Malaccensis 1, 028003- 01, Microcarpa, Pisang Lidi, Lilin, and Malbut) were moderately resistant.

ABSTRACT ‘Persian’ lime (PL) [Citrus latifolia (Yu. Tanaka) Tanaka] is an important species both for domestic fresh fruit consumption in Brazil as well as the export market, since the country is one of the largest producers in the world despite the fact that, in commercial plantations, it is still not uncommon to find trees with low productivity and high plant vigor of unknown origin. Selections of Persian lime ‘CNPMF–2000’, ‘CNPMF–2001’, ‘CNPMF–01’, ‘CNPMF–02’, ‘IAC–5’, ‘IAC–5.1’, ‘Bearss’, ‘Persian–58’, and ‘5059’, were therefore grafted onto Swingle citrumelo [C. paradisi Macfad. cv. Duncan × Poncirus trifoliata (L.) Raf.] rootstocks and evaluated in Cruz das Almas, Bahia, Brazil in a field experiment conducted in a completely randomized block design with five replications and two trees per plot. The biometric attributes (canopy height, diameter and volume), yield parameters (yield during the off-season harvest period, yield per plant, production efficiency), and fruit quality traits, were evaluated. The ‘CNPMF–2001’, ‘CNPMF–01’, ‘CNPMF–02’, ‘IAC–5’, and ‘Bearss’ selections had 5-11 % shorter trees than the other cultivars. ‘CNPMF–01’, ‘CNPMF–02’, ‘Persian–58’, and ‘5059’ presented higher yield efficiency values, between 3.1-3.4 kg m−3, and higher yield levels during the off-season harvest periods. The ‘Bearss’, ‘Persian–58’, ‘CNPMF–2000’, ‘IAC–5.1’ and ‘5059’ selections had more acid fruits and the latter three, smaller fruits. Based on their horticultural performance up to eight years of age, ‘CNPMF–01’, ‘CNPMF–02’, ‘Persian–58’ and ‘5059’ selections were the most promising varieties of Persian lime.

O objetivo do trabalho foi verificar a divergência genética entre 25 genótipos de mangaba da região de Iramaia-Chapada Diamantina-Bahia, utilizando os marcadores morfológicos e os marcadores RAPD. As seguintes aferições foram realizadas nos frutos maduros: diâmetro longitudinal (DL) e transversal (DT), massas do fruto (MF), da semente (MS) e da polpa (MP), rendimento de polpa (%P) e a contagem do número de sementes (NS). Os caracteres químicos avaliados no fruto maduro foram: pH, acidez (Ac), sólidos solúveis totais (SST), ácido ascórbico (AA), açúcar total (ACT) açúcar redutor (ACR), açúcar não redutor (ACNR) e relação sólidos solúveis totais: acidez (SST/Ac). Para a amplificação, foram testados 51 random primers. Os resultados médios das aferições foram: DL (37,03 mm), DT (34,34 mm), MF (24,45 g), MS (2,42 g), MP (22,03 g), e NS (11,14). Para as avaliações químicas, foram verificados os resultados médios: %P (88,44%), AA (80,23 mg 100 g-1), Ac (0,96%), pH (3,67), SST (14,15 ºBrix), ACT (9,26 mg 100 g-1), ACR (5,13 mg 100 g-1), ACNR (4,13 mg 100g-1) e SST/Ac (14,56 mg 100g-1). Oito random primers foram selecionados por apresentarem bandas mais intensas, e seis (OPA 08, OPB 12, OPB 19, OPH 15, OPH 18 e OPH 19) geraram 28 regiões de bandas polimórficas. Dentre os marcadores morfológicos, MF e MP foram os que mais efetivamente contribuíram para a divergência genética. A formação de seis e sete grupos para os marcadores moleculares e morfológicos, respectivamente, indicou a presença de variabilidade genética na população avaliada.

The objective was to assess the genetic diversity among 25 Mangaba genotypes in the Iramaia-Chapada Diamantina region, Bahia, using morphological markers and RAPD markers. The following measurements were performed in mature fruits: longitudinal (LD) and transverse (TD) diameter, fruit (FM), seed (SM) and the pulp (PM) mass, pulp yield (% P) and the count seed number (SN). The chemical characters were evaluated in mature fruit: pH, acidity (Ac), total soluble solids (TSS), ascorbic acid (AA), total sugar (TS) reducing sugar (RS), non-reducing sugar (NRS) and total soluble solids /acidity (TSS/Ac). For amplification were tested 51 random primers. The average results of the measurements were LD (37.03 mm), TD (34.34 mm), FM (24.45 g), SM (2.42 g), PM (22.03 g), and SN (11.14). For chemical evaluations were checked the average results: % P (88.44%), AA (80.23 mg100g-1), Ac (0.96%), pH (3.67), TSS (14.15 ºBrix) TS (9.26 mg100g-1), RS (5.13 mg100g-1), NRS (4.13 mg100g-1) and TSS/Ac (14.56 mg100g-1). Eight random primers were selected for having more intense bands and six (OPA 08, OPB 12, OPB 19, OPH 15, OPH 18, OPH 19) were sufficient to generate 28 polymorphic bands. Among the morphological markers, FM and PM were the most effectively contributed to divergence. The formation of six and seven groups for molecular markers and morphological, respectively, indicated the presence of genetic variability in the population. .

O objetivo deste trabalho foi estimar a diversidade genética entre diploides melhorados de bananeira por meio de dados quantitativos e de marcadores de sequências simples repetidas (SSR), simultaneamente. O experimento foi conduzido com 33 diploides, em blocos aumentados com 30 tratamentos regulares e três comuns. Dezoito características agronômicas e 20 iniciadores SSR foram usados. Os dados agronômicos e de SSR foram analisados, simultaneamente, via os procedimentos Ward-MLM, de agrupamento e IML. O método de agrupamento de Ward considerou matriz híbrida obtida pelo algoritmo de Gower. O procedimento Ward-MLM identificou três grupos (G1, G2 e G3) baseados nas estatísticas de pseudo-F and pseudo-t². O dendrograma mostrou similaridade relativa entre os genótipos do G1, justificada pela genealogia. No G2, 'Calcutta 4' aparece em 62% das genealogias. Comportamento similar foi observado no grupo G3, em que o diploide 028003-01 é o parental masculino dos genótipos 086079-10 e 042079-06. O método com uso de variáveis canônicas teve maior poder discriminatório que o Ward-MLM. Embora reduzida, a variabilidade genética disponível é suficiente para ser usada no desenvolvimento de novos híbridos.

The objective of this work was to estimate the genetic diversity of improved banana diploids using data from quantitative analysis and from simple sequence repeats (SSR) marker, simultaneously. The experiment was carried out with 33 diploids, in an augmented block design with 30 regular treatments and three common ones. Eighteen agronomic characteristics and 20 SSR primers were used. The agronomic characteristics and the SSR were analyzed simultaneously by the Ward-MLM, cluster, and IML procedures. The Ward clustering method considered the combined matrix obtained by the Gower algorithm. The Ward-MLM procedure identified three ideal groups (G1, G2, and G3) based on pseudo-F and pseudo-t² statistics. The dendrogram showed relative similarity between the G1 genotypes, justified by genealogy. In G2, 'Calcutta 4' appears in 62% of the genealogies. Similar behavior was observed in G3, in which the 028003-01 diploid is the male parent of the 086079-10 and 042079-06 genotypes. The method with canonical variables had greater discriminatory power than Ward-MLM. Although reduced, the genetic variability available is sufficient to be used in the development of new hybrids.

O fungo Phaeoisariopsis griseola é o agente causador da mancha-angular do feijoeiro (Phaseolus vulgaris L.), doença que se vem destacando no Estado de Minas Gerais. Com o intuito de identificar marcadores ligados ao gene de resistência à mancha-angular (raça 63.39 de P. griseola), executou-se, previamente, o estudo da herança da resistência. Avaliaram-se, quanto à segregação, as populações derivadas dos cruzamentos entre Rudá (progenitor suscetível - origem mesoamericana) e MAR-2 (progenitor resistente - origem mesoamericana). Foi obtida a segregação de 3:1 (plantas resistentes:suscetíveis) na geração F2; 1:1, no retrocruzamento com Rudá, e 1:0, no retrocruzamento com MAR-2. Os resultados sugeriram a existência de um alelo dominante governando a resistência. Posteriormente, foram construídos bulks (grupos) de DNA, de indivíduos F2 resistentes e suscetíveis à raça 63.39 (origem mesoamericana) do patógeno. Esses grupos foram amplificados com 400 iniciadores. Tal amplificação com o iniciador OPE-04 gerou um fragmento de, aproximadamente, 500 pb, o qual co-segregou com o gene de resistência. Na análise de co-segregação, verificou-se que esse marcador está ligado ao gene de resistência à raça 63.39 de P. griseola, a uma distância de 5,8 cM.

Phaeoisariopsis griseola is the causal agent of common bean (Phaseolus vulgaris L.) angular leaf spot, considered one of the most important bean diseases in the State of Minas Gerais, Brazil. Aiming at identifying RAPD markers closely linked to the angular leaf spot resistance genes (race 63.39 - mesoamerican origin), a previous study of their inheritance was carried out. Populations derived from the cross Rudá (susceptible) x MAR-2 (resistant) both mesoamerican genetic materials, were evaluated as to disease behaviour. F2 generation presented segregation of 3:1 (resistant: susceptible); 1:1 for the backcross to the susceptible parent (Rudá) and 1:0, for the backcross to the resistant one (MAR-2). These results strongly suggested that one dominant gene is in charge of the patogen resistance. Resistant and susceptible DNA bulks, extracted from the F2 population, were set up and amplified with 400 primers. Bulks amplified with primer OPE-04 gave rise to a 500 bp fragment, which co-segregated with the resistance gene. Co-segregation analysis revealed that this marker is linked to the pathogen resistance gene, at a distance of 5.8 cM.