Major gene resistance in Brassica napus (oilseed rape) is overcome by changes in virulence of populations of Leptosphaeria maculans in France and Australia

Resistance of Brassica napus (oilseed rape, canola) conferred by three different major resistance genes has been overcome by changes in virulence of Leptosphaeria maculans populations in France and Australia. In South Australia where B. napus cultivars with major gene resistance derived from Brassica rapa ssp. sylvestris were grown extensively, resistance was rendered ineffective within 3 years of commercial release of the cultivar. Disease severity was higher on cultivars with sylvestris-derived resistance than cultivars with polygenic resistance. This Australian situation is compared to that in France, where resistance conferred by the Rlm1 gene was overcome nation-wide in 5 years under commercial cropping practices, and also where a source of resistance introgressed into B. napus from B. juncea was rendered inefficient in 3 years in experimental field plots near Rennes.     

cDNA clone of a putative peanut (Arachis hypogaea L.) trypsin inhibitor has homology with peanut allergens Ara h 3 and Ara h 4

Trypsin inhibitors are pathogenesis-related (PR) proteins, which play an important role in the plant defense mechanism against insects and pathogens. Peanut trypsin inhibitors are low molecular mass seed storage proteins. Like peanut allergens, they are stable to acid and heat, resistant to digestion, and can have a negative impact on human health. In peanut, five Bowman-Birk trypsin inhibitors (BBTI) have been isolated and amino acid sequences published. However, to date, no peanut BBTI sequence is available at both the cDNA and the genomic levels. The objectives of this investigation were (i) to synthesize degenerate oligonucleotides based on conserved regions of published amino acid sequences of BBTI, BII, and BIII; (ii) to isolate, sequence, and analyze at least one positive peanut trypsin inhibitor cDNA clone using the synthesized (32)P-labeled oligonucleotides as probes; and (iii) to determine its trypsin inhibitory activity. Thirty-two degenerate oligonucleotides DNA primers of 24 nucleotides each were synthesized based on the published amino acid sequences of peanut BBTI, and two were selected as probes to screen a peanut Lambda gt 11 cDNA library. Three putative positive clones were isolated, purified, and subcloned, and one was sequenced. Sequence analysis revealed a partial cDNA clone of 643 bp with a start codon. This clone shares 93 and 96% nucleotide sequence homology with peanut allergens Ara h 3 and Ara h 4 cDNA clones, respectively. A trypsin inhibitor assay revealed that peanut allergen Ara h 3 has a trypsin inhibitory activity of 11 238 TIA/mg protein. We concluded that peanut allergen Ara h 3 may also function as a trypsin inhibitor.     

转录因子OsHOX4过量表达及T1代转基因植株中纯合系鉴定

OsHOX4基因是属于水稻植物同源结构域(HD-Zip)转录因子家族的一个成员。本研究利用农杆菌介导法将OsHOX4基因转入籼稻(Oryza sativa ssp.indica)IR64中,获得54株过量表达植株。我们利用southern杂交分析确定了各个株系的拷贝数后,利用TAIL-PCR方法对4个不同的单拷贝株系进行了研究,并在其中找出T-DNA在3个单拷贝株系染色体上的插入位点(分别为染色体5,8,10)。根据T-DNA在各个株系的插入位点分别设计特异性引物,从T1代转基因株系里鉴定出纯合的植株。我们观察到OsHOX4过量表达植株的分蘖数明显高于野生型,株高比野生型明显的变矮,在同一个株系的纯合和杂合的转基因植株表型也有很大的差异。在TAIL-PCR分析基础上,为从T1代转基因作物中鉴定出纯合的植株提供了方法和理论依据。     

The Effect of Training on the Jumping Parameters of Inexperienced Warmblood Horses in Free Jumping

Seven Warmblood horses without sport experience were trained and filmed four times during free jumping, with a 1-month interval between each investigation. Jumping parameters were measured on selected frames by means of video image analysis. Linear and angular parameters describing takeoff, landing, and lifting of limbs above the obstacle were studied. Statistical analysis revealed that the following parameters were affected by training: hind limbs distances at takeoff and landing, lifting of the limbs above the obstacle, and the angle of bascule.     

Feasibility Study of a Fish By-Product Recovery Plant with a Processing Capacity of 1,000 kg/Day

ABSTRACT

This study evaluates the feasibility of producing hamburger, silage, and leather using fish by-products in a medium-sized recovery plant with total capacity of processing up to 1,000 kg/day of whole fish. The average volume of fish by-products generated daily was 673 kg. The investment necessary to introduce these three technologies was US$47,193.13 in 1 year. The average cost to produce 1 kg of hamburger, silage, and leather was 1.24, 0.17, and US$1.77, respectively. The return of the investment was 56.16%, and the net present value US$570,582.16. The investment pay back was realized in 3.88 years, with a benefit/cost relationship of 1.31. For all the studied scenarios, sale price variations most influenced the economical parameters analyzed.     

A 10-year Survey of Populations of Leptosphaeria maculans in France Indicates a Rapid Adaptation Towards the Rlm1 Resistance Gene of Oilseed Rape

Leptosphaeria maculans, the cause of stem canker of oilseed rape (OSR), exhibits gene-for-gene interactions with its host plant. The race structure of L. maculans was assessed on the basis of the analysis of 1011 isolates collected in France between 1990 and 2000, with regards to three AVR genes, AvrLm1, AvrLm2 and AvrLm4. The effect of selection pressure, due to large-scale cropping of Rlm1 cultivars, on the evolution of races of the fungus was also evaluated. The results revealed a scarcity or complete absence of isolates harbouring AvrLm2, whereas isolates harbouring AvrLm4 were present at a variable level, that was as high as 17.2–31.2% depending on the sample year and location. When obtained from rlm1 cultivars, isolates harbouring AvrLm1 always represented more than 83% of the populations until the 1997–1998 growing season. As a consequence, the Rlm1 cultivars had been highly efficient at controlling the disease and were grown on an estimated 43.7% of the total French acreage in OSR in 1998–1999. However, the increased commercial success of Rlm1 cultivars was paralleled by a decrease in the proportion of isolates harbouring AvrLm1 in 1997–1998 and 1998–1999. This resulted in less than 13% of isolates harbouring AvrLm1 in populations being collected from rlm1 cultivars in 1999 and 2000, and contributed to the loss of efficiency of the Rlm1 resistance in the field. The present study is an illustration of one round of a `boom and bust' cycle that occurred for a pathosystem where it has never been reported before. These data and the high evolutionary potential of L. maculans are fully supportive of one pathogen species with a high risk of breaking down resistance genes in OSR and suggest that the development of integrated strategies aiming at maximising the durability of novel resistance is now a priority for this pathosystem.     

水稻OsHOX6启动子的组织特异性表达

【目的】研究水稻HD-ZipⅠ转录因子家族的成员OsHOX6基因启动子的表达。【方法】通过构建水稻OsHOX6基因启动子与GUS基因融合表达载体,利用农杆菌(Agrobacterium)介导,以未成熟水稻胚作为试验材料,转化到水稻IR64,通过PCR检测和潮霉素抗性筛选出阳性的转基因植株,从不同组织取样品,进行X-Gluc染色并观察。【结果】转基因植株的叶、根、茎、花等器官经过X-Gluc染色后,主要在侧根、花粉以及组织损伤部分出现蓝色斑点,其它组织均未检测出蓝色斑点,观察根解剖结构,绿色斑点集中在根内皮层。【结论】 水稻OsHOX6基因启动子能够驱动GUS基因,在转基因水稻侧根和花粉上特异表达。