Leandro Eugenio Cardamone Diniz

The potential of high-resolution BAC-FISH in banana breeding

The genetic complexity in the genus Musa has been subject of study in many breeding programs worldwide. Parthenocarpy, female sterility, polyploidy in different cultivars and limited amount of genetic and genomic information make the production of new banana cultivars difficult and time consuming. In addition, it is known that part of the cultivars and related wild species in the genus contain numerous chromosomal rearrangements. In order to produce new cultivars more effectively breeders must better understand the genetic differences of the potential crossing parents for introgression hybridization, but extensive genetic information is lacking. As an alternative to achieve information on genetic collinearity we make use of modern chromosome map technology known as high-resolution fluorescent in situ hybridization (FISH). This article presents the technical aspects and applications of such a technology in Musa species. The technique deals with BAC clone positioning on pachytene chromosomes of Calcutta 4 (Musa acuminata ssp. burmanicoides, A genome group, section Eumusa) and M. velutina (section Rodochlamys). Pollen mother cells digestion with pectolytic enzymes and maceration with acetic acid were optimized for making cell spread preparations appropriate for FISH. As an example of this approach we chose BAC clones that contain markers to known resistance genes and hybridize them for establishing their relative positions on the two species. Technical challenges for adapting existing protocols to the banana cells are presented. We also discuss how this technique can be instrumental for validating collinearity between potential crossing parents and how the method can be helpful in future mapping initiatives, and how this method allows identification of chromosomal rearrangements between related Musa species and cultivars.

Genetic Relationships among Tall Coconut Palm ( Cocos nucifera L.) Accessions of the International Coconut Genebank for Latin America and the Caribbean (ICG-LAC), Evaluated Using Microsatellite Markers (SSRs)

The diversity and genetic relationships among two accessions of tall coconut palms collected in Brazil and seven accessions introduced from different geographic regions of the world were analyzed using 25 microsatellite primers, 19 of which were polymorphic and detected between 4 and 10 alleles per locus, with an average of 6.57. The observed and expected heterozygosity ranged from 0.25 and 0.40 in the Rennell Islands Tall (RIT) accession to 0.54 and 0.62 in the Polynesian Tall (PYT) accession. The analysis of genetic structure resulted in the formation of five distinct groups. The first group was formed by the accessions Brazilian Tall—Praia do Forte (BRTPF), Brazilian Tall—Merepe (BRTMe) and West African Tall (WAT); the second group consisted of Malaysian Tall (MLT); the third group of RIT; the fourth group of Vanuatu Tall (VTT); and the fifth group of Rotuman Tall (RTMT), Tonga Tall (TONT) and PYT. The dendrogram based on the nearest-neighbor method detected the formation of two main groups and five subgroups, indicating that the genetic relationships of the accessions are based on their geographic regions of origin. The analyses revealed genetic relationships between the accessions collected in Brazil and the accession from Africa, and among palms from South East Asia and the South Pacific, confirming the common origin of these accessions. The information obtained in this study can guide decisions on germplasm conservation activities and the efficient selection of genetically divergent parents for use in coconut breeding programs in Brazil, which are attempting to select for disease resistance, mainly to lethal yellowing, among other characteristics.

Diversidade genética de isolados de Ralstonia solanacearum e caracterização molecular quanto a filotipos e sequevares

The objective of this work was to identify Brazilian isolates of Ralstonia solanacearum according to phylotypes and sequevars, to determine their genetic diversity, to associate the pathogen genetic structure with its taxonomy and geographical origin, and to identify a specific molecular marker to diagnose banana moko disease. A group of 33 isolates of R. solanacearum, from the collection of Embrapa Tabuleiros Costeiros, collected from different plant hosts, was characterized using the repetitive extragenic palindromic sequence-based PCR (rep-PCR) and RAPD. From this group, 19 belonged to the pathogen race 2 and 14 to the race 1, and 15 isolates were associated with banana crop. Phylotypes and sequevars were characterized and determined by Multiplex PCR. It was verified that the isolates belonged to phylotypes II (82%) and III (12%). All isolates from banana plants belonged to phylotype II. The RAPD technique was efficient in grouping these isolates according to their geographical origin; however, it requires a large number of molecular markers. It was possible to establish the relationships among the isolates by rep-PCR. The enterobacterial repetitive intergenic consensus primer (ERIC) made it possible to separate the isolates according to the race, and the REP primer allowed for the discrimination among phylotypes.These were the two mostinformative analyses.

Genetic diversity analysis of Varronia curassavica Jacq. accessions using ISSR markers

Varronia curassavica Jacq. is a medicinal and aromatic plant from Brazil with significant economic importance. Studies on genetic diversity in active germplasm banks (AGB) are essential for conservation and breeding programs. The aim of this study was to analyze the genetic diversity of V. curassavica accessions of the AGB of Medicinal and Aromatic Plants of the Federal University of Sergipe (UFS), using inter-simple sequence repeat molecular markers. Twenty-four primers were tested, and 14 were polymorphic and informative, resulting in 149 bands with 97.98% polymorphism. The UPGMA dendrogram divided the accessions into Clusters I and II. Jaccard similarity coefficients for pair-wise comparisons of accessions ranged between 0.24 and 0.78. The pairs of accessions VCUR-001/VCUR-503, VCUR-001/VCUR-504, and VCUR-104/VCUR-501 showed relatively low similarity (0.24), and the pair of accessions VCUR-402/VCUR- 403 showed medium similarity (0.78). Twenty-eight accessions were divided into three distinct clusters, according to the STRUCTURE analysis. The genetic diversity of V. curassavica in the AGB of UFS is low to medium, and it requires expansion. Accession VCUR-802 is the most suitable for selection in breeding program of this species, since it clearly represents all of the diversity present in the AGB.

Antimicrobial potential of Actinomycetes by NRPS and PKS-I pathways

BackgroundActinomycetes may account for 10 to 30% of the totalsoil rhizosphere microorganisms. The attention given tothe actinomycetes in biotechnological applications is aresult of their metabolic versatility that is accompaniedby the production of primary and secondary metabolitesof economic importance, which are a promising source ofproducts (e.g., antibiotics, enzyme inhibitors, antiparasiticand anticancer agents) [1,2]. Included in this range ofcompounds are secondary metabolites synthesized bypolyketide synthase (PKS) and non-ribosomal peptidesynthetase (NRPS) pathways. An effective method forassessing the presence of these biosynthetic pathways isthe detection of PKS and NRPS genes by PCR [3,4].Thus, this study was based on targeted analyses of 31 soilisolate actinomycetes aiming to evaluate their antimicro-bial potential through the NRPS and PKS-I pathways.MethodsThe antimicrobial activity was evaluated by the antagon-ism test against two economically important phyto-pathogens, the bacterium Xanthomonas campestris andthe fungus Thielaviopsis paradoxa,usingthetechniqueof double layer. TheX. campestris and T. paradoxawere propagated at 28°C in YM (yeast malt) pH 6.0 andPDB (potato dextrose broth) respectively. The resultswere statistically analyzed using the Bonferroni test.The presence of genes PKS and NRPS was evaluatedby PCR, using degenerate primers for highly conservedregions encoding enzymes associated with biosynthesisof polyketides and peptides.Results and conclusionsAccording to the experimental results, 52% of the iso-lates showed antimicrobial activity against at least oneof the target bacterial pathogens tested. Among theseactive isolates, some belong to rare families. Thus, thisfinding can be a source of novel biomolecules with anti-microbial activity. From those isolates that presentedone of the NRPS and PKS-I genes, 75% of them showedantagonistic activity against one of the phytopathogensevaluated. Preliminary data on this screening demon-strate the importance of the biotechnological potentialof these actinomycetes due to the antagonistic activityagainst plant pathogens of economic interest and thepossibility of be used as biocontrol, besides offering astrong area for metabolic research [2,5].

Viability of Metarhizium anisopliae conidia (metsch.) Sorok preserved in packages containing silica gel

Background The entomopathogenic fungi are important microbial agents for their efficient performance as microbial biopesticides in pest control. The development of commercial products formulated with entomopathogenic fungi is in a promising market for biopesticides. However, the fungi can lose their viability when exposed to unfavorable conditions of temperature, humidity and ultraviolet radiation, affecting the life of conidia. Among these constraints, there is the relative humidity through the presence of free water in formulated as one of the main factors that affect the viability of the organism in the form and function of storage time. The use of desiccant agents, such as silica gel, may be a viable alternative to favor the retention of moisture in the air, reducing the adsorption of water molecules by the system. Thus, the aim of this study was to determine the efficiency of silica gel in maintaining the viability of dry conidia of Metarhizium anisopliae.

A new species of Oecleus Stål (Hemiptera: Fulgoroidea: Cixiidae) from coconut in Brazil

A new species of cixiid planthopper (Hemiptera: Fulgoroidea) in the genus Oecleus Stål, Oecleus sergipensis n. sp., is described from Sergipe State, Brazil. This new taxon is associated with coconut (Cocos nucifera L.) and date palm (Phoenix L). The species was detected in Auchenorrhyncha surveys to find potential vectors of lethal yellowing type syndrome. This is the first report of the genus Oecleus in Brazil. Sequence data from the mitochondrial cytochrome c oxidase subunit I (COI) barcoding region was obtained and accessioned into GenBank.

Rainfall and Coconut Accession Explain the Composition and Abundance of the Community of Potential Auchenorrhyncha Phytoplasma Vectors in Brazil

Abstract Coconut plantations are attacked by the lethal yellowing (LY), which is spreading rapidly with extremely destructive effects in several countries. The disease is caused by phytoplasmas that occur in the plant phloem and are transmitted by Haplaxius crudus (Van Duzee) (Auchenorrhyncha: Cixiidae). Owing to their phloem-sap feeding habit, other planthopper species possibly act as vectors. Here, we aimed at assessing the seasonal variation in the Auchenorrhyncha community in six dwarf coconut accessions. Also, we assessed the relative contribution of biotic (coconut accession) and abiotic (rainfall, temperature) in explaining Auchenorrhyncha composition and abundance. The Auchenorrhyncha community was monthly evaluated for 1 yr using yellow sticky traps. Among the most abundant species, Oecleus sp., Balclutha sp., Deltocephalinae sp.2, Deltocephalinae sp.3, Cenchreini sp., Omolicna nigripennis Caldwell (Derbidae), and Cedusa sp. are potential phytoplasma vectors. The composition of the Auchenorrhyncha community differed between dwarf coconut accessions and periods, namely, in March and April (transition from dry to rainy season) and August (transition from rainy to dry season). In these months, Oecleus sp. was predominantly found in the accessions Cameroon Red Dwarf, Malayan Red Dwarf, and Brazilian Red Dwarf Gramame, while Cenchreini sp. and Bolbonota sp. were dominant in the accessions Brazilian Yellow Dwarf Gramame, Malayan Yellow Dwarf, and Brazilian Green Dwarf Jequi. We conclude that dwarf coconut host several Auchenorrhyncha species potential phytoplasma vectors. Furthermore, coconut accessions could be exploited in breeding programs aiming at prevention of LY. However, rainfall followed by accessions mostly explained the composition and abundance of the Auchenorrhyncha community.

Gene expression of Ceriporiopsissubvermispora during lignocellulosic substrate degradation

Background Lignin is a complex aromatic polymer whose microbial degradation is essential for carbon recycling [1]. The fungus Ceriporiopsis subvermispora has attracted attention for its valuable biotechnological applications, especially for pretreatment of lignocellulosic material studies in order to expose the cellulose for hydrolysis and industrial fermentation. Thus, ligninolytic enzymes of white-rot fungi remain the subject of intensive investigations for their potential applications in a wide range of industrial bioprocesses and applications such as the paper industry, textile industry, decolorization of industrial wastewater treatment, and the degradation of organopollutants [2]. The goal of the present work was to grow C. subvermispora in coconut fibers as substrate in order to analyze its degradation potential and evaluate the lignin peroxidase expression (Lip1 and Lip2).