Race-specificity of temperature-sensitive genes for resistance to Puccinia striiformis in Triticum dicoccoides

Summary Twenty-four entries of wild emmer possessing temperature-sensitive genes for resistance to yellow rust were studied in the seedling stage, at two temperature-profiles, with 15 pathogenic races from 11 countries in South America, Africa, Asia and Europe. It was shown that the majority of the resistance genes in these wild emmer entries were race-specific. In most of these entries a more resistant reaction was displayed at the higher temperature-profile; however in three entries a shift in reaction towards resistance was observed with certain races but towards susceptibility with some of the other races, suggesting that two different kinds of temperature-sensitive genes were involved in each of these entries. The similarity of temperature-sensitive genes occurring in wild emmer and in cultivated wheat is discussed.     

Characterization of the durable resistance to yellow rust in old winter wheat cultivars in the Netherlands

Summary Winter wheat cultivars released in the Netherlands before 1930 carried durable resistance to yellow rust. Cultivars released in the period between 1930 and 1950 often were durably resistant while recent cultivars infrequently showed durable resistance. This durable resistance was not difficult to transfer to new cultivars. Twenty nine older cultivars with durable resistance and eight recent non-durably resistant cultivars were tested in the seedling stage and in the adult plant stage against 12 West-European yellow rust races and against some non-European races in the seedling stage only. The adult plant tests were carried out in race nursery tests in the Flevopolder. Per race nursery all 37 cultivars, planted in hills of about 20 plants on both sides of the highly susceptible cv. Michigan Amber, were exposed to one race.The infection type of each cultivar-race combination was scored on 0 to 9 scale once in the seedling stage and twice in the adult plant stage. In the race nurseries the percentage leaf area affected was evaluated three times to be used to calculate the area under the disease progress curve (AUDPC). This AUDPC multiplied with the mean infection type in the field gave the susceptibility index (SI).The infection types were classified into resistant (R), intermediate (I) or susceptible (S) when the infection types were 0 to 3, 4 to 6 or 7 to 9, respectively. Four categories of resistance were discerned on the basis of the three infection type scores: 1) RRR, overall resistance; complete or near-complete resistant at all stages. 2) SRR, adult plant resistance, complete- or near-complete resistant at the adult plant stage only. 3) SRS and SSR, temperature sensitive resistance, the resistance changed from the one evaluation data to the other. 4) SSS and an SI lower than that of Michigan Amber, partial resistance.The frequencies of overall, adult plant and temperature sensitive resistance were 1.4, 52 and 54% in the older cultivars and 40, 62 and 22% in the recent ones, respectively. Among the older cultivars all had a fair to high level of partial resistance, the SI being on average only 20% of that of Michigan Amber, while most cultivars also seemed to carry temperature sensitive resistance. The partial resistance of the recent cultivars was of a much lower level with a mean SI compared to that of Michigan Amber of 61%. Partial resistance was highly correlated (r = –0.94) with the mean resistance scores from the Dutch Recommended Cultivars Lists. It was concluded that partial resistance and temperature sensitive resistance were the major components of the durable resistance in the older cultivars.     

Discovery of a new gene causing dark green cotyledons and pathway of pigment synthesis in lentil (Lens culinaris Medik)

A new gene is reported which functions as a master gene for synthesis of the pigments determining cotyledon colour in lentil. This gene is different from the two earlier reported genes which are responsible for synthesis of yellow (gene Y) and brown (gene B) pigments. Double recessive homozygous condition of these two genes results into loss of both pigments and, consequently, produces light green cotyledons. The new gene, in contrast, produces dark green cotyledons in recessive condition irrespective of the dominance or recessive state of the Y and B genes. It is hypothesized that the new gene for dark green cotyledon colour (Dg) acts at an earlier stage in the biosynthesis of the two cotyledon-specific pigments, which are derived from a common precursor, whose synthesis is blocked when Dg mutates to its recessive condition. This revised version was published online in August 2006 with corrections to the Cover Date.     

Reduced titer of BNYVV in transgenic sugar beets expressing the BNYVV coat protein

Summary Rhizomania is a disease of sugar beet caused by the furovirus beet necrotic yellow vein virus (BNYVV). Coat protein mediated resistance has been reported for a number of viral diseases. This approach to virus resistance was therefore attempted for control of rhizomania. Two constructs of the coat protein gene of BNYVV were introduced into sugar beet by Agrobacterium-mediated transformation. The mRNA level was estimated to be 0.01% of the poly A⁺ RNA. Expression of the coat protein gene was under the detection limit of our western blotting protocol i.e. below 0.01 g/50 g (0.02% of the total soluble protein). One transformation event per construct was tested in a greenhouse assay and in rhizomania infested soil in a field trial. In the greenhouse assay, transgenic plants showed a strong reduction of virus multiplication when compared to non-transgenic plants. This result was confirmed in the field trial, where a significant difference in virus multiplication was shown between plants with and without the coat protein gene.     

成年鲁西牛肌内前脂肪细胞的分离培养

建立牛肌内前脂肪细胞体外培养方法，旨在更深入地研究组成肌肉内脂肪组织的肌内前脂肪细胞的增殖分化特性及其影响因素。选取来自成年育肥鲁西黄牛第6与第7肋骨间的肌肉内脂肪组织，利用Ⅰ型胶原酶消化法分离获得牛肌内前脂肪细胞。培养出的细胞成分均一，增殖旺盛，分化率高，经形态学动态变化观察、生长曲线、油红O脂肪染色提取法及对胰岛素和地塞米松反应的测定，证明是功能活跃的前脂肪细胞，并在体外重现了其增殖分化过程，同时经染色体核型分析证明体外培养的细胞倍性正常，可以用于后续研究。本试验成功分离得到了成年育肥牛肌内前脂肪细胞，这为下一步研究肌内脂肪的沉积机制，改善牛肉品质奠定了基础。     

中国台湾番茄曲叶病毒侵染引起广东番茄黄化曲叶病

广东汕头番茄(Lycopersicon eseulentum)上发生的黄化曲叶病毒病,田间症状表现为病株明显矮化、病叶褪绿黄化、叶小且卷曲和叶质较脆硬。对该病毒代表分离物(BS)基因组DNA-A克隆和测定结果表明,其全长为2740nt(GenBank acces-sion No.DQ237918),具有菜豆金色花叶病毒属(Begomovirus)病毒基因组典型特征,为闭合环状单链DNA,有6个ORFs,分别位于病毒链上的AV1、AV2及位于互补链上的AC1、AC2、AC3和AC4;在基因AV2与AC1之间有269nt的非编码区。BLAST结果显示,BSDNA-A与Begomovirus中来自亚洲的病毒同源性较高,而与美洲、非洲等地的相对较低;其中与中国台湾番茄曲叶病毒(Tomato leaf curl Taiwan virus,ToLCTWV)DNA-A全序列同源性最高,为97.7%,而二者的AV1、AV2、AC1、AC2、AC3和AC4基因及IR的同源性分别为98.6%、98.0%、98.0%、97.5%、96.3%、98.6%和96.6%,推导编码的6个蛋白的氨基酸序列同源性分别为97.7%、99.1%、97.5%、95.6%、91.8%和99.0%%。全序列系统进化关系树显示,BS与ToLCTWV的亲缘关系最近,并形成一个独立分支,再与广东番茄曲叶病毒G2(Tomato leaf curl Guangdong virus G2,ToLCGDV-[G2]和广东番茄曲叶病毒G3(Tomato leaf curl Guangdong virus G3,ToLCGDV-[G3]形成一个大的分支,而与其它33种Begomovirus病毒的亲缘关系均相对较远。这些结果表明,BS应是ToLCTWV的一个分离物。     

What do artificial nests tells us about nest predation?

Artificial nests are commonly used to evaluate predation, but the assumption that this method mimics predation on natural nests has seldom been tested. Natural and artificial nests of eastern yellow robins (Eopsaltria australis) were monitored in four, 55-ha plots over two breeding seasons. Overall, daily survival rates were higher (P<0.001) for natural (95%/day) than for artificial nests (88%/day). Among plots, daily survival rates for the two types of nests were not correlated with one another (P=0.72) indicating that the spatial pattern of predation on artificial nests did not mimic that for natural nests. Seasonal variation was evident for natural nests in one year, when they were more successful at the beginning and end of the breeding season. No seasonal patterns were observed for artificial nests in either year. Neither natural nor artificial nests showed annual variation in predation. Previous researchers concluded that large birds were important predators on robin nests. In this study, predation by large birds on artificial nests was positively correlated with the numbers of large birds counted on the plots (P=0.04). However, large birds depredated only 16% of artificial nests. Daily survival rates for artificial nests were recalculated using predation by large birds only. These rates were compared with natural nests, but there was still no correspondence in the spatial and temporal patterns of predation for the two types of nests. These results suggest that inferences about predation on natural nests based on artificial nest studies should be avoided.     

不同根部微灌水器对云南红壤和黄沙土水分分布的影响

探索根部微灌水器类型对土壤水分分布的影响和作用规律,是提高根部微灌水效率的有效途径。该文研究了根部微灌水器类型对土壤水分分布的影响。试验采用2种灌溉方式(地上滴灌和根部微灌)、2种灌水器(流量可调式灌水器和内镶贴片式滴灌带),测定各处理在3种灌水时长(5、15和30 min),在2种土壤(云南红壤土和黄沙土)时的土壤水分含量。结果表明:1)灌水器种类与土壤类型、灌水器种类与灌水时长对土壤水分有极显著的交互作用(P0.01),但三者之间没有显著交互作用(P0.05);2)流量可调式灌水器四周配有8个水平出水孔,其灌溉水在2种土壤中向四周渗出的水平宽度都较宽(25 cm左右),而内镶贴片式滴灌带只有1个向下单孔,灌溉水向四周渗出的水平宽度均较窄(16 cm左右);3)在红壤土中,根部微灌内镶贴片式滴灌带的高含水率区域更接近于作物根部区域,而地上滴灌的高含水率区域基本上集中在花盆土壤的上部区域;4)在红壤土中,基质势对灌溉水的运移起主要作用,而在黄沙土中重力势起主要作用;5)在红壤土中,灌水时间越短,土壤面积百分比为70%时对应的区域越集中在较窄的和较低的土壤含水率区段,且各区段是连续的,灌水30 min时,它所对应的土壤含水率区段最宽,土壤水分分布均匀性也最高;在黄沙土中,随着灌水时间的增加,土壤面积百分比为70%时所对应的土壤含水率区段范围大,且黄沙土所对应的分布区段大于红壤土,表明红壤土水分分布不均,而黄沙土水分分布较均匀。该文为提高根部微灌系统使用效率提供理论依据。     

Effect of Selenium on Mineral Content and Nutritive Value of Melilotus officinalis L.

Plants of Melilotus officinalis L. were subjected to two different treatments: a) no selenium (Se), and b) addition of 3 mg Se L^?1 irrigation water for 45 days and samples of leaves, stems and roots were analyzed for Se, potassium (K), sodium (Na), magnesium (Mg), iron (Fe), copper (Cu), calcium (Ca), manganese (Mn) and zinc (Zn). Crude protein (CP) content, neutral detergent fiber (NDF), acid detergent fiber (ADF) and in vitro organic matter digestibility (IVOMD) were also estimated for the aerial plant tissues. In Se-treated plants Se mainly accumulated in leaf tissues, various changes in macronutrient concentrations were detected, while the micronutrient content decreased significantly. In addition, leaf CP, NDF and ADF content decreased, while IVOMD increased, possibly indicating ameliorated nutritive value. According to our findings, M. officinalis could be used either as a dietary supplement, in mixture with non-accumulator species, for livestock feed deficient in Se or for restoration of grasslands in seleniferous soils.     

三种网格的农田防护林防止土壤风蚀的效应研究

在山东省夏津县黄河故道冲积沙地建立土壤风蚀试验区,采用标尺法对3种网格的农田防护林和对照地的土壤风蚀量进行观测,测定结果表明:农田防护林网可明显减少风蚀损失,其中,130m×300m林网相对于对照减少土壤风蚀量81%,260m×300m林网相对于对照减少78%,300m×400m林网相对于对照减少75%,即随着网格面积的增加对风蚀量的影响越来越小。同时,土壤风蚀程度与测定期间日平均风速>4 m/s的出现频率有密切关系,土壤风蚀量与风速之间的最佳拟合关系为幂函数关系,二者之间呈正相关关系,相关系数在0.95以上。黄河故道冲积沙地农田防护林网对5.0~5.9 m/s范围内的风速引起的土壤风蚀防治效果最好。