RESUMO
Rice blast caused by Magnaporthe oryzae is one of the most devastating rice diseases worldwide. To understand the genetic diversity of indica landrace accessions and identify simple sequence repeat (SSR) markers that are associated with blast resistance, a population of 276 indica landraces from across the world was constructed. This population was then used to evaluate the blast-resistance phenotype through artificial inoculation under controlled conditions in 2012 and 2013. The genetic diversity and association of the population with resistance were analyzed by examining the phenotype for 160 SSR markers distributed on 12 rice chromosomes. The 276 accessions were classified into seven groups using model- and distance-based cluster analyses. Associations between SSR markers and blast resistance showed that 26 SSR markers were significantly associated with blast resistance in 2012 and 2013 (P < 0.01) and that the phenotypic variation ranged from 2.68 to 13.11%. Nineteen of the markers associated with blast resistance were located in regions where genes or quantitative trait loci (QTLs) have been previously reported, and seven were newly identified in this study. These results indicate that marker-trait association has potential advantages over classical linkage analysis and QTL mapping, and that these markers could be used for marker-assisted selection in rice blast-resistance-breeding programs.
Assuntos
Resistência à Doença/genética , Oryza/genética , Doenças das Plantas/genética , Mapeamento Cromossômico , Cromossomos de Plantas/genética , Análise por Conglomerados , Genes de Plantas , Estudos de Associação Genética , Ligação Genética , Variação Genética , Interações Hospedeiro-Patógeno , Magnaporthe/fisiologia , Repetições de Microssatélites , Oryza/microbiologia , Melhoramento Vegetal , Doenças das Plantas/microbiologia , Locos de Características QuantitativasRESUMO
Bodao, a japonica landrace from the Taihu Lake region of China, is highly resistant to most Chinese isolates of Magnaporthe oryzea, a form of rice blast. To effectively dissect the influence of genetics on this blast resistance, a population of 155 recombinant inbred lines (F2:8) derived from a cross of Bodao x Suyunuo was inoculated with 12 blast isolates. Using a quantitative trait locus (QTL) mapping approach, 13 QTL on chromosomes 1, 2, 9, 11, and 12 were detected from Bodao. Five QTL, including qtl11-1-1, qtl11-3-7, qtl11-4-9, qtl12-1-1, and qtl12-2-3, have not been previously reported. The qtl11-3-7 and qtl11-4-9 may be the two main effective QTL and resistant to 7 and 9 isolates, respectively. The results of the present study will be valuable for the fine mapping and cloning of these two new resistance genes.
Assuntos
Cromossomos de Plantas/imunologia , Oryza/genética , Doenças das Plantas/imunologia , Imunidade Vegetal/genética , Locos de Características Quantitativas/imunologia , China , Mapeamento Cromossômico , Cromossomos de Plantas/química , Cruzamentos Genéticos , Magnaporthe/imunologia , Oryza/imunologia , Oryza/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologiaRESUMO
In the studies of modern epidemiology, exposure in a short term cannot fully elaborate the mechanism of the development of diseases or health-related events. Thus, lights have been shed on to life course epidemiology, which studies the exposures in early life time and their effects related to the development of chronic diseases. When exploring the mechanism leading from one exposure to an outcome and its effects through other factors, due to the existence of time-variant effects, conventional statistic methods could not meet the needs of etiological analysis in life course epidemiology. This paper summarizes the dynamic path analysis model, including the model structure and significance, and its application in life course epidemiology. Meanwhile, the procedure of data processing and etiology analyzing were introduced. In conclusion, dynamic path analysis is a useful tool which can be used to better elucidate the mechanisms that underlie the etiology of chronic diseases.
Assuntos
Doença Crônica/epidemiologia , Estudos Epidemiológicos , Modelos Teóricos , Humanos , Fatores de Risco , TempoRESUMO
Two simple cerebral ischemic models of mice were used for studying brain energy metabolism and the effects of drugs. Model one is partial occlusion of the left carotid artery and total occlusion of the right one including the vagus. The behavior of the animals appeared splaying of the contralateral extremities, circling around counterclockwise and in a comatose motionless state. Following the designated ischemic time, the animals were put into liquid N2. Model two is decapitation induced ischemia of mouse brain. The whole animal (control) and the severed head were rapidly frozen in liquid nitrogen 0, 10, 30, 60 s after decapitation. Brain samples were powdered at liquid N2 temperature, extracted and determined for ATP, phosphocreatine (Pcr) and lactic acid (LA). The data from model one indicate that after an ischemic period of 10 min, brain LA level increased significantly compared with values from the sham operated group, while no significant alteration was observed in brain ATP, and Pcr level. At 180 min of ischemia, levels of ATP and Pcr were considerably reduced while LA level increased significantly. The degree of symptoms induced by brain ischemia showed good correlation with brain energy metabolism. In model 2 brain LA level was found to be increased, while ATP and Pcr levels decreased after whole brain ischemia. However, brain ATP and Pcr levels were increased and LA level was decreased significantly in the normal and ischemic animal after administration of phenobarbital (225 mg/kg ip). LA level decreased significantly in the unischemic mice treated with Rb1 (100 mg/kg ip). It is indicated that both models of cerebral ischemia were simple and sensitive methods for studying brain ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)