Introgression of Xa4, Xa7 and Xa21 for resistance to bacterial blight in thermosensitive genetic male sterile rice (Oryza sativa L.) for the development of two-line hybrids     

Loida M. Perez  Edilberto D. Redo?a  Merlyn S. Mendioro  Casiana M. Vera Cruz  Hei Leung 《Euphytica》2008,164(3):627-636

Bacterial blight (BB) of rice caused by X. oryzae pv. oryzae is a major production constraint in commercial hybrid rice production in the Philippines because most of the parental lines used in hybrid production do not carry resistance genes against the pathogen. In this study, three bacterial blight resistance genes, Xa4, Xa7 and Xa21, were introgressed to a temperature-sensitive genetic male sterile (TGMS1) line. A three-way cross of AR32-19-3-3/TGMS1//IRBB4/7 (PR36944) was made to produce 1,364 F₂ plants carrying various combinations of Xa4, Xa7 and Xa21. Individual plants were characterized for reaction to bacterial blight PXO61 (race 1), PXO86 (race 2), PXO99 (race 6) and pollen sterility. Of 144 F₂ plants demonstrating resistance against PXO61, PXO86 and PXO99, 22 exhibited highly resistant phenotypes with mean lesion lengths ranging from 0.37–2.97 cm. Analysis of disease reaction identified 20 potential TGMS F₂ plants containing Xa4, Xa7 and Xa21 while 78 plants with Xa4 + Xa7. Phenotypic and polymerase chain reaction (PCR) analyses confirmed PR36944-450, PR36944-473 and PR36944-700 as homozygous for Xa7 and Xa21 and highly resistant to all three Xoo races. Fertility of PR36944-450 and PR36944-700 was restored at permissive temperature in a growth chamber. BB-resistant TGMS lines should facilitate breeding two-line hybrids in the tropics.  相似文献   

Pot2在稻瘟病菌群体结构分析中的应用     

何月秋  唐文华 《华中农业大学学报》2000,19(4):317-321

利用稻瘟病菌的一段倒位重复序列Ｐｏｔ２设计的一对引物直接对稻瘟病菌的ＤＮＡ进行ＰＣＲ扩增。根据带型相似性大于８０％为度可将国际水稻所一个稻瘟病圃上的３１０个菌株划分６个宗亲群（ｌｉｎｅａｇｅ）。这些依分子标记划分的宗亲群与品种的遗传背景有密切关系,而且各宗亲群在水稻不同生育期有不同的波动方式。  相似文献   

Technical efficiency of carp production in India: a stochastic frontier production function analysis   总被引：1，自引：0，他引：1  

K R Sharma  & P S Leung 《Aquaculture Research》2000,31(12):937-947

This paper aims to examine the levels and determinants of technical efficiency in carp pond culture in India. The stochastic production frontier technique involving the model for technical inefficiency effects is applied separately to samples of semi‐intensive/intensive and extensive carp producers interviewed during 1994–95. The results showed significant technical inefficiencies in carp production in India, especially among extensive farms. The mean technical efficiencies for semi‐intensive/intensive and extensive sample farms were estimated to be 0.805 and 0.658 respectively. By operating at full technical efficiency levels, the semi‐intensive/intensive farms could, on average, increase their production from about 3.4 Mt ha^?1 to 4.1 Mt ha^?1. Likewise, the extensive farms could increase their production from 1.3 Mt ha^?1 to 1.9 Mt ha^?1. Much of these efficiency gains would come from improvement in the adoption of recommended fish, water and feed management and monitoring practices. Besides expanding production area, the results indicated several other possibilities for increasing carp production in India by increasing yields per hectare, such as: (1) increased intensification of carp culture (i.e. moving from extensive to semi‐intensive or intensive systems); (2) improvement in technical efficiency at the farm level; and (3) technological progress. However, the realization of these potentials will depend on continuous efforts by the government in ensuring an adequate supply of inputs, technology transfer and development and adequate provision of research, extension and credit services in aquaculture.  相似文献   

Potent interaction between thyrotropin releasing hormone (TRH) and human pancreatic growth hormone releasing factor (hpGRF) in stimulating chicken growth hormone (cGH) in vivo: Hypothalamic noradrenergic mediation in TRH stimulation of cGH release     

F.C. Leung  J.E. Taylor  C.A. Ball 《Domestic animal endocrinology》1985,2(4):183-190

The interaction of human pancreatic growth hormone releasing factor (hpGRF) and thyrotropin releasing hormone (TRH) on chicken growth hormone (cGH) release in vivo and possible noradrenergic involvement on TRH-induced stimulation of cGH in vivo were examined. Four-week old cockerels (1 kg) were injected intravenously with hpGRF (1.0 μg/bird), TRH (0.1 μg/bird), or hpGRF (1.0 μg/bird) in combination with TRH (0.1 μg/bird). Five min after the injection, blood samples were collected and serum concentrations of cGH were determined by a homologous RIA. The results showed that hpGRF and TRH were potent stimulators of cGH release, 5- and 6-fold over the control birds, respectively, and that hpGRF and TRH administered in combination produced a synergistic stimulation of cGH release (>20 fold). In separate experiments, pretreatment with alpha-methyl-para-tyrosine (250 mg/bird) for 2 hours resulted in complete suppression of the TRH stimulatory effect on cGH release but not the stimulatory effect of hpGRF. Pretreated with phenoxybenzamine hydrochloride (20 mg/bird) or diethyl-dithiocarbamate (500 mg/bird) also resulted in complete suppression of TRH-induced cGH release. These results indicate that hpGRF acts directly at the pituitary and TRH acts at the hypothalamus in addition to the pituitary in stimulating cGH release, possibly mediated through the noradrenergic neurons. HpGRF and TRH were potent releasers of cGH and their stimulation was potentiated when administered together.  相似文献   

Effects of concanavalin A on the progesterone production by bovine steroidogenic luteal cells in vitro          下载免费PDF全文

FC Destro  I Martin  FDC Landim‐Alvarenga  JCP Ferreira  JL Pate 《Reproduction in domestic animals》2016,51(5):848-852

The aim of this study was to evaluate the effects of concanavalin A (CONA) on the progesterone (P4) production by bovine steroidogenic luteal cells (LCs) in vitro. Luteal cells were collected during the mid‐luteal stage (at 10–12 days following ovulation) and processed in the laboratory. Luteal cells were grown for 7 days in a humid atmosphere with 5% CO₂, with or without 10% foetal bovine serum, and were subjected to the following treatments: control: no treatment; CONA (10 μg/ml); LH (100 μg/ml); CONA + LH; LH (100 μg/ml) + prostaglandin F2α (PGF2α) (10 ng/ml); CONA + LH + PGF2α. Samples of the culture media were collected on days 1 (D1) and 7 (D7) for P4 quantification. The cells were counted on D7 of culture. Differences between treatments were considered statistically significant at p < .05. Culture in the presence of CONA decreased the P4‐secreting capacity of LCs on D7 of culture, particularly in the absence of serum. The cell numbers did not change between treatments.  相似文献   

Magnetic resonance imaging used for the evaluation of water presence in wood plastic composite boards exposed to exterior conditions     

Marek Gnatowski  Rebecca Ibach  Mathew Leung  Grace Sun 《Wood material science & engineering》2015,10(1):94-111

Abstract

Two wood plastic composite (WPC) boards, one experimental and one commercial, were exposed to exterior conditions and evaluated non-destructively using a clinical magnetic resonance imaging (MRI) unit for moisture content (MC) and distribution. The experimental board was exposed in Vancouver, British Columbia, for more than 8 years, and the commercial board was exposed near Hilo, Hawaii, for 2 years. Both boards were characterized in terms of wood content, density, water uptake properties and voids content. The experimental board was additionally destructively analysed for water absorption of the WPC and MC calculated based on the wood content for verification of MRI results. MRI detected the presence of free water and its distribution in both of the WPC boards. Fibre saturation in the experimental board was found to be about 22–24%, in comparison to 25–30% present in most wood species. There was good correlation between the detection of free water by MRI and by destructive testing. Magnetic resonance images showed various major points of water entry in the WPC boards such as the support area, the cut ends, the dripping edge and the sides of the boards. For the experimental board, significant water entry also occurred at the upper exposed surface.  相似文献   

Development of a Clean Biodiesel Fuel in Hong Kong Using Recycled Oil     

Leung  Dennis Y.C. 《Water, air, and soil pollution》2001,130(1-4):277-282

All fuel usage produces air pollutants, causing local and trans-boundary air pollution and acid rain problems. Biodiesel is a clean renewable fuel with properties similar to diesel but produced from renewable resources such as vegetable oils and animal fats. Although this fuel has been developed some two to three decades ago, it is not commonly used, mainly due to the higher production cost involved. Due to the increasing concern on environmental protection, a lot of researches on the usage of this fuel are conducted in recent years. To study the characteristics of this fuel, a special biodiesel fuel is produced using waste cooking oil and animal fat from restaurants as feedstock. Reusing of these wastes has both the benefit of producing a cleaner fuel and waste cycling. Tests of the fuel with different proportions of diesel have been conducted on various diesel engines and the results obtained are encouraging. The environmental benefits and suitability of this fuel to Hong Kong to reduce air pollution problems are discussed based on the assessment results.  相似文献   

Quantification of two polyacetylenes in Radix Ginseng and roots of related Panax species using a gas chromatography-mass spectrometric method     

Liu JH  Lee CS  Leung KM  Yan ZK  Shen BH  Zhao ZZ  Jiang ZH 《Journal of agricultural and food chemistry》2007,55(22):8830-8835

A sensitive method for quantitating the pharmacologically active polyacetylenes panaxynol and panaxydol in Radix Ginseng was developed using a capillary gas chromatography-mass spectrometric (GC-MS) method. The detection mode of selected ion monitoring (SIM) allowed sensitive and selective quantitation of the two compounds in ginseng. Method validation showed that the GC-MS method has much lower detection and quantitation limits than the high-performance liquid chromatography (HPLC)-UV method. This indicates that GC-MS is particularly useful for the analysis of polyacetylene compounds, which have relatively low abundances compared with ginsenosides in ginseng. Based on the quantitative results of different types of ginseng herbs, it was found that the panaxydol and panaxynol contents were higher in forest ginseng than in cultivated ginseng. This method was further applied to the quantitative analyses of panaxynol and panaxydol in Radix Notoginseng and American ginseng. The ratio of panaxydol to panaxynol can be utilized as a marker for differentiating ginseng, notoginseng, and American ginseng. This study introduces the first GC-MS method for the quantitative analysis of polyacetylenes in herbs of the Panax genus.  相似文献   

Polymorphisms of 5' flanking region of chicken prolactin gene   总被引：9，自引：0，他引：9  

Liang Y  Cui J  Yang G  Leung FC  Zhang X 《Domestic animal endocrinology》2006,30(1):1-16

  相似文献   

Oestrogen and Progesterone Receptor Gene Expression in Canine Oocytes and Cumulus Cells Throughout the Oestrous Cycle     

JSA Gonçalves  CI Vannucchi  FC Braga  FF Paula-Lopes  MP Milazzotto  MEOA Assumpção  JA Visintin 《Reproduction in domestic animals》2009,44(S2):239-242

  相似文献