Field observations on nitrogen catch crops. I. Potential and actual growth and nitrogen accumulation in relation to sowing date and crop species

In temperate climates with a precipitation surplus during autumn and winter, nitrogen catch crops can help to reduce nitrogen losses from cropping systems by absorbing nitrogen from the soil and transfer it to a following main crop. The actual and potential accumulation of dry matter and nitrogen in catch crops were studied in the field during four seasons with winter rye (Secale cereale) and forage rape (Brassica napus ssp. oleifera (Metzg.) Sinsk) or oil radish (Raphanus sativus spp. oleiferus (DC.) Metzg.). Sowing dates were end of August and three and six weeks later. Potential nitrogen accumulation, Y (g m^-2), could be summarized with Y = 96 –0.34 X, where X is the day number in the year of the sowing date (range: late August till end of September). Species were compared in their performance, looking at differences in specific leaf area, leaf weight ratio, leaf area ratio, light extinction and persistence during frost. The rate of dry matter accumulation in intervals of 14 days appeared to be determined primarily by the amount of radiation intercepted. A regression, forced through the origin, gave as a common slope 1.12 g dry matter accumulated per MJ intercepted global radiation, irrespective of season, species, sowing date or nitrogen treatment (period from ca. day 250 to day 310). From this result the inference is made that leaf expansion is a key process, determining the performance of catch crop species under varying environmental conditions.     

Solute accumulation and decreased photosynthesis in leaves of potato plants expressing yeast-derived invertase either in the apoplast, vacuole or cytosol

Potato (Solanum tuberosum cv. Désirée) plants expressing yeast invertase directed either to the apoplast, vacuole or cytosol were biochemically and physiologically characterised. All lines of transgenic plants showed similarities to plants growing under water stress. Transformants were retarded in growth, and accumulated hexoses and amino acids, especially proline, to levels up to 40-fold higher than those of the wild types. In all transformants rates of CO₂ assimilation and leaf conductance were reduced. From the unchanged intercellular partial pressure of CO₂ and apoplastic cis-abscisic acid (ABA) content of transformed leaves it was concluded that the reduced rate of CO₂ assimilation was not caused by a limitation in the availability of CO₂ for␣the ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco). In the transformants the amount of Rubisco protein was not reduced, but both activation state and carboxylation efficiency of photosynthesis were lowered. In vacuolar and cytosolic transformants this inhibition of Rubisco might be caused by a changed ratio of organic bound and inorganic phosphate, as indicated by a doubling of phosphorylated intermediates. But in apoplastic transformants the pattern of phosphorylated intermediates resembled that of leaves of water-stressed potato plants, although the cause of inhibition of photosynthesis was not identical. Whereas in water-stressed plants increased contents of the phytohormone ABA are supposed to mediate the adaptation to water stress, no contribution of ABA to reduction of photosynthesis could be detected in invertase transformants. Received: 29 May 1996 / Accepted: 30 December 1996     

Somatic embryogenesis and Agrobacterium-mediated transformation system for scented geraniums (Pelargonium sp. `Frensham')

Plant regeneration via somatic embryogenesis was achieved from leaf petioles of Pelargonium sp. `Frensham' cultured on Murashige and Skoog medium containing 15 μM N⁶-benzyladenine, and 5 μM α-naphthaleneacetic acid (NAA). More than 80% of these somatic embryos converted into plants when isolated and cultured on Murashige and Skoog medium supplemented with 15 μM NAA. Stable transgenic plants were obtained by co-cultivation of the petioles (prior to culture) with Agrobacterium tumefaciens strains LBA4404 (harbouring a binary vector pBI121 carrying the nptII and gus genes) and LBG66 (harbouring a binary plasmid pJQ418 carrying the gus/int:nptII fusion gene). Transformants were selected using kanamycin and transformation was verified by β-glucuronidase histochemical assay and polymerase chain reaction. Southern analysis further confirmed the integration of these genes into the genome of transgenic plants. We report here for the first time, an Agrobacterium-mediated model transformation system coupled with regeneration via somatic embryogenesis for production of transgenics in Pelargonium sp. Received: 20 September 1996 / Accepted: 13 November 1996     

Reduced sedoheptulose-1,7-bisphosphatase levels in transgenic tobacco lead to decreased photosynthetic capacity and altered carbohydrate accumulation

Transgenic tobacco (Nicotiana tabacum L. cv. Samsun) plants with reduced levels of the Calvin cycle enzyme sedoheptulose-1,7-bisphosphatase (SBPase; EC 3.1.3.37) were produced using an antisense construct in which the expression of a tobacco SBPase cDNA clone was driven by the cauliflower mosaic virus (CaMV) promoter. The reduction in SBPase protein levels observed in the primary transformants correlated with the presence of the antisense construct and lower levels of the endogenous SBPase mRNA. No changes in the amounts of other Calvin cycle enzymes were detected using Western blot analysis. The SBPase antisense plants with less than 20% of wild-type SBPase activity were observed to display a range of phenotypes, including chlorosis and reduced growth rates. Measurements of photosynthesis, using both light-dosage response and CO₂ response curves, of T1 plants revealed a reduction in carbon assimilation rates, which was apparent in plants retaining 57% of wild-type SBPase activity. Reductions were also observed in the quantum efficiency of photosystem II. This decrease in photosynthetic capacity was reflected in a reduction in the carbohydrate content of leaves. Analysis of carbohydrate status in fully expanded source leaves showed a shift in carbon allocation away from starch, whilst sucrose levels were maintained in all but the most severely affected plants. Plants with less than 15% of wild-type SBPase activity were found to contain less than 5% of wild-type starch levels. The results of this preliminary analysis indicate that SBPase activity may limit the rate of carbon assimilation. Received: 23 February 1997 / Accepted: 2 May 1997     

Recovery of transgenic rice plants expressing the rice dwarf virus outer coat protein gene (S8)

 The coding region of the eighth largest segment (S8) of the rice dwarf virus (RDV) was obtained from a RDV Fujian isolate. It was then cloned into pTrcHisA for expression in E. coli and into vector pE3 for plant transformation. By using callus derived from mature rice embryos as the target tissue, we obtained regenerated rice plants after bombardment of the former with plasmid pE3R8 containing the RDV S8 gene and the marker gene neomycin phosphotransferase (NPT II). Southern blotting confirmed the integration of the RDV S8 gene into the rice genome. The expression of the outer coat protein in both E. coli and rice plants was confirmed by western blotting. The recovery of transgenic rice plants expressing S8 gene is an important step towards studying the function of the RDV genes and obtaining RDV-resistant rice plants. Received: 1 March 1996 / Accepted: 2 August 1996     

胚胎发育早期转基因的PCR检测研究

转基因在受精卵中的整合时间对于转基因动物的建立十分重要。采用ＷＡＰ基因调控序列指导的人Ｇ－ＣＳＦ基因为构件,对小鼠受精卵进行显微注射。对培养至１细胞期、２细胞期和８细胞期的胚胎进行ＰＣＲ检测。结果表明,三个时期转基因的检出率分别为１００％、７７．７７％和４４．４４％。说明随着培养时间的增加,转基因逐渐丢失。     

春小麦水分利用效率日变化及其生理生态基础的研究

采用光合速率和蒸腾速率之比 (Pn/Tr)表示植物水分利用效率 (WUE) ,发现在两种不同水分处理下春小麦拔节期 .WUE日变化中都有上午高于下午值 ,且 8∶0 0～ 1 0∶0 0为明显峰值的特征 ,这种特征与Pn、Tr日变化存在的上、下午值不对称性和反向性 (Pn为上午高于下午 ,Tr相反 )紧密相关 ,水分胁迫处理中 ,Pn、Tr值均有降低 ,但不同品种的WUE反应不一 .研究表明 ,叶水势 ( ψw)、气孔阻力 (Rs)等生理因素和空气相对湿度 (RH)、光照 (Q)及冠层温度 (Tc)等生态因子 ,通过对Tr和Pn的不同影响而同WUE显著相关 ,40 %RH是WUE变化的一个重要阈值 .     

田间不同条件下玉米叶片的气孔阻力及与光合,蒸腾作用的关系

以玉米 1 7个自交系和 1 0个杂交种为试材 ,在田间条件下研究了不同光强、不同叶位、不同生育期、不同源库比例和株间差异状态下的气孔阻力及其与光合 (PH)、蒸腾(TR)和叶片水分利用效率 (WUE)的关系 ,结果表明 ,不同自交系之间RS具有显著的差异 ,相差最大可达 2 .3倍以上 ;光照条件变弱、穗叶位差增加、生育期推延和源 /库比例改变等均可引起RS值的增加 ;在各种情况下导致RS变化的同时也引起TR和PH产生相应的变化 ,RS与TR、PH表现出显著或极显著的负相关 ,且相关系数rRS TR>rRS PH;RS与WUE的相关关系在不同的条件下表现出不稳定性     

The Breeding of Mutant p53 and Neu/erb B2 Dual transgenic Mice: Both of the Genes were Over expressed Specifically in the Mammary Gland

为了研究乳腺癌发生与发展过程中突变型ｐ５３和Ｎｅｕ基因之间的相互作用,我们构建了ｐ５３／Ｎｅｕ双转基因鼠。用５只成年雄性Ｎｅｕ转基因鼠与１０只成年雌性ｐ５３转基因鼠交配,对１５０只雌性杂交后代鼠进行ｐ５３／Ｎｅｕ双转基因鼠的筛选。为此,本实验建立了ＰＣＲ一步鉴定法。即：在同一个反应管内能同时满足小鼠β酪蛋白基因、ｐ５３基因和Ｎｅｕ基因上三个片段（分别为０．５ｋｂ、１．２ｋｂ、１．７ｋｂ）的扩增反应者被断定为双转基因鼠（Ｆｉｇ．１）。传统的Ｓｏｕｔｈｅｒｎ分析（Ｆｉｇ．２）与ＰＣＲ一步法鉴定结果相吻合。证明：该法的准确率为１００％。进一步、随机取样,Ｎｏｒｔｈｅｒｎ分析（Ｆｉｇ．３）表明：双转基因鼠（２号）在哺乳笫二天即出现了ｐ５３基因的高表达。继而、在姓娠笫１０、１７天,哺乳笫１０、２１天也检测到该基因的表达。另外,免疫组化染色也检测到了ｐ５３和Ｎｅｕ蛋白（未展示结果）。     

PREDATION OF THE LADYBEETLE CHILOCORUS KUWANAE ON THE SCALE UNASPIS YANONENSIS

Abstract The prey consumption of ovipositing female adults of the ladybeetle Chilocorus kuwanae on the scale Unaspis yanonensis was found to be significantly greater than that of the male adults. At 25°C one female adult ladybeetle, on average, would consume 42. 7 female scale adult per day while one male adult only destroyed 22. 3 female scale adults. However, after a deprivation of the prey for 48 h, this difference was eliminated. A C. kuwanae female adult had to prey on at least 15 U. vanonensis female adults in order to lay eggs. The funcional responses of the beetle adults to densities of different stages of the scale followed Holling's type 1. The functional responses to female scale adults indicated that the maximum prey consumption went up with the increase in temperature from 16°C to 35°C, and dropped sharply at 37°C. However, temperature did not alter the type of the functional response. Rased on the predation of C. kuwanae adults on U. yanonensis female adults, the minimum critical, optimal and maximum critical temperatures for their attack were estimated to be 10. 6°C, 31. 5°C and 38. 2°C respectively. The increase in predation space or in predator density could result in a reduction in the attack rat-e, but with the increase of predator density, the effect of predation space became much smaller. C. kuwanae adults preferred male pupae to other stages of the scale, and their preference for various stages of the prey was in the order of male pupae, 2nd-instar male nymphs, 2nd-instar female nymphs, adult females and kinstar nymphs.