Browsing by Author "Pereira, G."
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- Identification of DNA markers linked to an induced mutated gene conferring resistance to powdery mildew in pea (Pisum sativum L.)Publication . Pereira, G.; Marques, C.; Ribeiro, R.; Formiga, S.; Damaso, M.; Sousa, M. T.; Farinho, M.; Leitão, J. M.We have recently induced two powdery mildew (Erysiphe pisi Syd) resistant mutants in Pisum sativum L. via ethylnitrosourea (ENU) mutagenesis. Both mutations (er1mut1 and er1mut2) affected the same locus er1 that determines most of the identified natural sources of powdery mildew resistance (PMR) in this crop. The mutated gene er1mut2 was mapped to a linkage group of 16 DNA markers combining three main strategies: near isogenic lines (NILs) analysis, bulked segregant analysis and genetic mapping of randomly identified polymorphic markers, together with three DNA-markers techniques: ISSR, RAPDs and AFLPs. Markers located closer to the PMR locus, OPO06(1100y) (0.5 cM), OPT06(480) (3.3 cM) and AGG/CAA(125) (5.5 cM), were cloned and converted into SCAR markers. Markers AH1R(850) and AHR(920y) were found to be allelic and converted into the co-dominant marker ScAH1 (16.3 cM). Two previously known DNA markers, ScOPE16(1600) and A5(420y,) were mapped at 9.6 and 23.0 cM from the PMR locus, respectively. The novel markers identified in this study are currently being transferred to a new F2 mapping population derived from a cross between the induced PMR mutant line F(er1mut2) and a more genetically distant susceptible line of Pisum sativum var. arvense.
- Identification of DNA markers linked to an induced mutated gene conferring resistance to powdery mildew in pea (Pisum sativum L.)Publication . Pereira, G.; Marques, C.; Ribeiro, R.; Formiga, S.; Damâso, M.; Tavares Sousa, M.; Farinhó, M.; Leitão, J. M.We have recently induced two powdery mildew (Erysiphe pisi Syd) resistant mutants in Pisum sativum L. via ethylnitrosourea (ENU) mutagenesis. Both mutations (er1mut1 and er1mut2) affected the same locus er1 that determines most of the identified natural sources of powdery mildew resistance (PMR) in this crop. The mutated gene er1mut2 was mapped to a linkage group of 16 DNA markers combining three main strategies: near isogenic lines (NILs) analysis, bulked segregant analysis and genetic mapping of randomly identified polymorphic markers, together with three DNA-markers techniques: ISSR, RAPDs and AFLPs. Markers located closer to the PMR locus, OPO061100y (0.5 cM), OPT06480 (3.3 cM) and AGG/CAA125 (5.5 cM), were cloned and converted into SCAR markers. Markers AH1R850 and AHR920y were found to be allelic and converted into the co-dominant marker ScAH1 (16.3 cM). Two previously known DNA markers, ScOPE161600 and A5420y, were mapped at 9.6 and 23.0 cM from the PMR locus, respectively. The novel markers identified in this study are currently being transferred to a new F2 mapping population derived from a cross between the induced PMR mutant line F(er1mut2) and a more genetically distant susceptible line of Pisum sativum var. arvense. © Springer Science+Business Media B.V. 2009.
- Molecular characterization of Phaseolus vulgaris L. genotypes included in Bulgarian collection by ISSR and AFLP (TM) analysesPublication . Svetleva, D.; Pereira, G.; Carlier, Jorge; Cabrita, L.; Leitão, J. M.; Genchev, D.Seventy-eight (33 Bulgarian and 45 foreign) common bean (Phaseolus vulgaris L.) genotypes included in Bulgarian collection were screened for ISSR (Inter Simple Sequence Repeats) and AFLP (TM) (Amplified Fragment Length Polymorphism) markers. ISSR analysis was performed with 13 primers, and 55 (36.7%) out of the 150 bands observed were polymorphic. One hundred and sixty-four AFLP (TM) fragments were obtained with three primer combinations, of which 54 (32.9%) were polymorphic. UPGMA (Unweighted Pair Group Method Arithmetic Averages) analysis was performed using DICE coefficient and dendrograms were constructed using either the data from each method (ISSR and AFLP (TM)) separately or combined in a single joint matrix. Despite some genetic heterogeneity observed in both pools (Middle American origin: M and Andean origin: A) the genotypes were separated in to main groups: one gathering genotypes mainly from pool M and the other more genotypes from pool A. Moreover, Bulgarian genotypes were spread over the two groups suggesting that they are not subject to genetic erosion and that the Phaseolus genetic diversity is conserved. (c) 2006 Elsevier B.V. All rights reserved.
- Two powdery mildew resistance mutations induced by ENU in Pisum sativum L. affect the locus er1Publication . Pereira, G.; Leitão, J. M.The alkylating compounds and strong mutagens methylnitrosourea (MNU) and ethylnitrosourea (ENU) were used to widen the genetic variability of pea (Pisum sativum L.) via experimental mutagenesis. Amongst multiple mutations of agronomical interest, for the first time two mutations conferring broad-range resistance to powdery mildew (Erysiphe pisi Syd.) were induced in pea. Mutagenic treatments were carried out on seedlings using a technique that ensures very high mutagenic efficiency. Two-hour exposure of cv. Solara seedlings to chemical mutagens resulted in almost non noticeable lethality and sterility in the M1 generation and very high mutation rates: similar to 9% families with visible mutations in the M2 generation. The influence of the cell cycle phase on the process of mutagenesis was studied in cv. Frilene using a previously developed technique for synchronization of shoot apical meristem cells. The cell cycle phase at which cells were treated apparently did not influence the lethality and sterility in the M1 generation, while the visible mutation rate, assessed in the M2 generation, showed a clear cell cycle dependency. Seedlings treated at the G2 and M phases gave rise to progenies exhibiting the highest mutation rate, over 50% of M2 families with visible mutations. The powdery mildew resistant (PMR) mutant S(er1mut1) was induced by treatment of cv. Solara seedlings for 2 h with ENU, while the PMR mutant F(er1mut2) was induced by treatment of cv. Frilene seedlings with the same chemical mutagen for 1 h during the G2 phase of the cell cycle. The genetic analysis of the novel PMR mutant lines showed that both resistances are inherited as monogenic recessive traits. The performed genetic complementation analyses revealed that both mutations affect the same locus-er1, which determines most of the natural sources of PMR in pea. A project aiming at the isolation of the powdery mildew resistance mutated gene via map based cloning is currently under way.