The aim was to assess heterosis in a set of 16 summer-squash hybrids, and evaluate the combining capacity of the respective parental lines, which differed as to the degree of parthenocarpy and resistance to PRSV-W (Papaya Ringspot Virus-Watermelon strain). The hybrids were obtained using a partial diallel cross design (4 × 4). The lines of parental group I were 1 = ABX-037G-77-03-05-01-01-bulk, 2 = ABX-037G-77-03-05-03-10-bulk, 3 = ABX-037G-77-03-05-01-04-bulk and 4 = ABX-037G-77-03-05-05-01-bulk, and of group II, 1′ = ABX-037G-77-03-05-04-08-bulk, 2′ = ABX-037G-77-03-05-02-11-bulk, 3′ = Clarice and 4′ = Caserta. The 16 hybrids and eight parental lines were evaluated for PRSV-W resistance, parthenocarpic expression and yield in randomized complete-block designs, with three replications. Parthenocarpy and the resistance to PRSV-W were rated by means of a scale from 1 to 5, where 1 = non-parthenocarpic or high resistance to PRSV-W, and 5 = parthenocarpic or high susceptibility to PRSV-W. Both additive and non-additive gene effects were important in the expression of parthenocarpy and resistance to PRSV-W. Whereas estimates of heterosis in parthenocarpy usually tended towards a higher degree, resistance to PRSV-W was towards higher susceptibility. At least one F1 hybrid was identified with a satisfactory degree of parthenocarpy, resistance to PRSV-W and high fruit-yield.
The Ry adg allele is widely used by breeders to confer extreme resistance to all strains of PVY. However, the necrotic strain has increased recombination resulting in recent considerable losses in productivity. Thus far, not all necrotic recombinant strains of PVY have been tested for their reaction to the Ry gene. The objective of this study was to identify potato clones carrying the resistant allele and to assess their reaction to the following recombinant strains: NTN (PVY NTN), Wilga (PVY N-Wi), and "curly top" (PVY E). Advanced clones from the potato breeding program at Universidade Federal de Lavras were evaluated through a specific molecular marker for the Ry adg allele. The clones carrying the resistance allele were grafted on tobacco plants infected with necrotic recombinant strains of PVY. The clones carrying the allele for resistance to PVY were not infected with any of the recombinants during the grafting test. These results confirm that resistance to necrotic recombinant strains has not yet been overcome and that the Ry adg allele also confers resistance to the three recombinant strains tested.
Blister spot (Colletotrichum gloeosporioides) is now widespread in most coffee producing states of Brazil, becoming a limiting factor for production. The lack of data relating to the reproduction of typical symptoms (light green, oily patches) leaves a gap within the pathosystem, forcing the search for new methodologies for monitoring the disease. Monitoring of genetically modified organisms has proven to be an effective tool in understanding the host x pathogen interactions. Thus, the present study was carried out to evaluate the effectiveness of two systems of genetic transformation in obtaining mutants using the gfp reporter gene.Using the two transformation systems (PEG and electroporation) revealed the efficiency of both, confirmed by fluorescence microscopy and resistance to the antibiotic hygromycin-B, when incorporated into the culture medium. The fungus maintained its cultural and morphological characteristics when compared to wild strains. When inoculated on coffee seedlings, it was found that the pathogenicity of the processed isolates had not changed.
RESUMOAtu a lmente , existe a necessid a de de se desenvolv er métodos sen sí ve is, b a r a t os, r ep ro du z ív ei s e r á p id os pa ra a d e te cç ã o d e fitobactérias em sementes. O objetivo deste tra balho foi otimiza r um método de obtenção das células bacterianas e a técnica de PCR p a ra d e t ec ç ã o de C u rt o b a c t e r i u m f l a c c u m fa c i e n s p v. flaccumfaciens (Cff), em sementes de feijão. Foi utilizado o primer CffFOR2-REV4 , desenhado a partir do fra gmento amplificado via PC R b a se a do na se qü ê nci a r epet iti va (Re p-P CR) . Ava l ia r a m-se ta mbém qu a tro métodos de prepa ra çã o dos extra tos de sementes d e fe i jã o pa r a a o bt e n çã o cé l u la s de C ff : 1 ) e x tr a t o b r u t o d e se me n t e s; 2 ) e x t r a to c o nc e n t ra Essa s du a s técnica s, a lém de detecta r a ba ctéria , a presenta m a lta sensibilida de, detecta ndo a té 1 semente inocu la da artificialmente a rti ficia lm ente c om Cff em 9 9 9 seme ntes sa di a s. Ana lisa ra m -se dezessete lotes comercia is de sementes de feijã o pelo método de co nc en tra çã o de ex tra to p or ce nt rifu g a ç ã o, send o qu e e m do ze detectou-se a bactéria Cff, observado pela presença de bandas com 3 0 6 p b. Porta nto, foi possível otimiza r u m métod o de obt ençã o da s célula s bacterianas e técnica de PCR pa ra detecção de Cff em sem e n te s de fei j ã o, q u e sej a sen sí ve l , r e p ro d u zí v e l e de fá c i l execução, que poderá ser utilizado rotineira mente em labora tórios de a ná lises de sementes.Keywords: Detection of bacteria inoculation, water restriction. ABSTRACTCu rrently, there is a need to develop sensitive methods, inexpensive, reproducible and rapid detection of phytobacteria seeds. The objective of this study was to optimize a method for obtaining ba cteria l cells a nd the PCR technique to detect Cu rto b a c te riu m flaccumfaciens pv. flaccumfaciens (Cff), in bean seeds using PCR. It was used one pairs of primers CffFOR2-REV4, designed from an PCR amplified fragment of the conserved repetitive sequence (Rep-PCR). The primer pair CffFOR2-REV4 was selected in this study, because demonstrated higher reproducibility and efficacy in the detection of Cff strains in bean seeds. Four methods were also evaluated in the seed extra ct prepa ra tion for PCR: 1 ) rou gh seed extra ct; 2) millipore membrane filter (0 .2 2Mu dia meter) concentrated seed extract and subsequently ressuspended in water; 3) centrifuge concentrated seed
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