Vectoring ability of aphid clones of Rhopalosiphum padi (L.) and Sitobion avenae (Fabr.) and their capacity to retain barley yellow dwarf virus

Vectoring ability of four aphid clones, Rp-M and Rp-R26 of Rhopalosiphum padi and Sa-R1 and Sa-V of Sitobion avenae, to transmit barley yellow dwarf (PAV, MAV and RPV) luteoviruses (BYDV) was compared in controlled conditions. Significant differences between highly efficient vectors (HEV), Rp-M and Sa-Rl, and poorly efficient vectors (PEV), Rp-R26 and Sa-V, were found in transmission of their specific viruses with acquisition and inoculation access periods (AAP, IAP) of 5 days. BYD-RPV was occasionally transmitted by both clones of S. avenae. None of 150 tested apterous adults of the Rp-R26 transmitted BYD-MAV, while 10% of transmission was observed from those of the Rp-M in a parallel test. An improved ELISA and immuno-PCR were adapted to test for viruses in aphids. The results obtained by the improved ELISA indicated there was a good correlation between virus detection in single aphids of HEV clones after a 5 day AAP and virus transmission by them. In contrast, the percentages of virus-carrying aphids of PEV clones were generally higher than those of their transmission rates. BYD-MAV and BYD-RPV were also detected by the improved ELISA in single aphids of their PEV clones, with the exception of BYD-RPV in those of Sa-V. However, after a 2-day IAP, the improved ELISA in most cases failed to detect these viruses in single aphids of PEV clones. Detection by immuno-PCR demonstrated that all three viruses could be acquired and retained by the aphids of both HEV and PEV clones. But, as visualised from electrophoretic bands, after the 2-day IAP the amplified products from aphid extracts of PEV clones were reduced. The detection in a batch of nine aphids by the improved ELISA revealed that virus content in PEV clones decreased more rapidly than that in HEV clones during transmission. Thus, the difference in transmission efficiency of the aphid clones within species was not caused by an inability to acquire virus, but was determined by variation in vectoring ability between them. This was due to differences in ability to prevent the passage of virions from haemocoel to salivary duct and/or different capacities for the retention of BYDV.     

稻鱼鸭复合生态经济效益的初步研究

试验表明．稻鱼鸭种养共生,水稻增产 １０％以上,同时增收鲜鱼 １０３６．５ ｋｇ· ｈｍ－２,成鸭２３８．９～４８９．３ ｋｇ·ｈｍ－２;水稻土壤全Ｎ、Ｐ、Ｋ和有机质含量分别增加２７．９、 ４４． ３、６． ５和 ２８． ２％,提高了土壤肥力;水稻植株虫口量最少．稻鱼鸭共生大大提高了稻田 的产出和效益．属良性循环的高效复合生态农业．     

Simulating the rice yield change in the middle and lower reaches of the Yangtze River under SRES B2 scenario

As one of the most important crops in China, rice accounts for 18% of the country’s total cultivated area. Increasing atmospheric CO₂ concentration and associated climate change may greatly affect the rice productivity. Therefore, understanding the impacts of climate change on rice production is of great significance. This paper aims to examine the potential impacts of future climate change on the rice yield in the middle and lower reaches of the Yangtze River, which is one of the most important food production regions in China. Climate data generated by the regional climate Model PRECIS for the baseline (1961–1990) and future (2021–2050) period under IPCC SRES B2 scenario were employed as the input of the rice crop model ORYZA2000. Four experimental schemes were carried out to evaluate the effects of future climate warming, CO₂ fertilization and water managements (i.e., irrigation and rain-fed) on rice production. The results indicated that the average rice growth duration would be shortened by 4 days and the average rice yield would be declined by more than 14% as mean temperature raised by 1.5 °C during the rice growing season in 2021–2050 period under B2 scenario. This negative effect of climate warming was more obvious on the middle and late rice than early rice, since both of them experience higher mean temperature and more extreme high temperature events in the growth period from July to September. The significance effect of the enhanced CO₂ fertilization to rice yield was found under elevated CO₂ concentrations in 2021–2050 period under B2 scenario, which would increase rice yield by more than 10%, but it was still not enough to offset the negative effect of increasing temperature. As an important limiting factor to rice yield, precipitation contributed less to the variation of rice yield than either increased temperature or CO₂ fertilization, while the spatial distribution of rice yield depended on the temporal and spatial patterns of precipitation and temperature. Compared to the rain-fed rice, the irrigated rice generally had higher rice yield over the study area, since the irrigated rice was less affected by climate change. Irrigation could increase the rice yield by more than 50% over the region north of the Yangtze River, with less contribution to the south, since irrigation can relieve the water stress for rice growing in the north region of the study area. The results above indicated that future climate change would significantly affect the rice production in the middle and lower reaches of the Yangtze River. Therefore, the adverse effect of future climate change on rice production will be reduced by taking adaptation measures to avoid disadvantages. However, there is uncertainty in the rice production response prediction due to the rice acclimation to climate change and bias in the simulation of rice yield with uncertainty of parameters accompanied with the uncertainty of future climate change scenario.     

不同生态稻区覆膜旱作稻氮营养生理及抗逆生理特性探讨

不同生态稻区生态环境和栽培管理方式不同,覆膜旱作稻氮营养生理和抗逆生理与常规水作稻有些异同,尤其是体内NO₃^--N和NH₄⁺-N含量及分布差异很大.杭嘉湖平原区覆膜旱作稻生长前期受干热天气影响,其分蘖期、拔节期、孕穗期体内NO₃^--N含量较水作稻有不同程度的降低,而NH₄⁺-N含量则极显著提高;金衢盆地覆膜旱作稻孕穗期体内NO₃^--N含量比常规水作稻高,根部NH₄⁺-N含量则显著降低,茎基部和叶片NH₄⁺-N含量有一定增加.正常气候条件下两生态稻区覆膜旱作稻孕穗期叶片硝酸还原酶(NR)活性和谷氨酰胺合成酶(GS)活性较水作稻均有不同程度的提高;丙二醛(MDA)、可溶性糖及脯氨酸(Pro)含量与水作稻相差不大,表明不同生态稻区的覆膜旱作稻可以通过不同的栽培管理模式,促进生长发育,达到高产目的.     

Excision of a selectable marker in transgenic rice (Oryza sativa L.) using a chemically regulated Cre/loxP system

Removal of a selectable marker gene from genetically modified (GM) crops alleviates the risk of its release into the environment and hastens the public acceptance of GM crops. Here we report the production of marker-free transgenic rice by using a chemically regulated, Cre/loxP-mediated site-specific DNA recombination in a single transformation. Among 86 independent transgenic lines, ten were found to be marker-free in the T₀ generation and an additional 17 lines segregated marker-free transgenic plants in the T₁ generation. Molecular and genetic analyses indicated that the DNA recombination and excision in transgenic rice were precise and the marker-free recombinant T-DNA was stable and heritable.The first two authors contributed equally to the work     

水稻亚种间杂种F1光合特性研究

用绵恢725、蜀恢527和蜀恢881三个籼型恢复系、1个美国稻Lemont和1个爪哇稻香大粒作母本,与1个日本特早熟粳稻Kitaake杂交,研究了5个杂种F1及其亲本的光合生理表现.结果表明,在高光通量密度(Photosynthetic flux density,PFD)条件下,5个杂种F1净光合速率(Pn)明显高于双亲或双亲之一,推测亲本与杂种F1之间不同的Pn同叶片中Rubsico活性有关.杂种F1的比较中,在表观量子效率(ψ)、羧化效率(CE)、CO2补偿点(T)等方面,籼粳亚种间杂种F1(绵恢725/Kitaake、蜀恢527/Kitaake、蜀恢881/Kitaake)对2个亚种内杂种F1香大粒/Kitaake(粳爪交)、Lemont/Kitaake(不同生态型的粳粳交,美国稻属于特殊粳稻)具有明显的优势,而蜀恢881含有粳型血缘,蜀恢881/Kitaake也比典型籼粳亚种间杂种F1绵恢725/Kitaake、蜀恢527/Kitaake优势稍逊一筹.5个杂种F1因为具有不同的遗传差异而表现出不同的光合优势,在这方面,典型籼粳亚种间杂交蜀恢527/Kitaake、绵恢725/Kitaake要优于其他杂交种,说明亲本间遗传差异越大,其杂种F1的光合优势越强.     

Effects of agricultural production on phosphorus losses from paddy soils: a case study in the Taihu Lake Region of China

A field plot experiment was conducted on two types of paddy soils in the Taihu Lake Region of China from June 2000 through 2002 to assess phosphorus (P) losses by runoff and drainage flow and the effectiveness of rice–wheat double cropping on reducing P losses from paddy soils. Commercial NPK compound fertilizer and single superphosphate fertilizer were applied to furnish 0, 30, 150, and 300 kg P ha^–1 for rice season trials, and 0, 20, 80, and 160 kg P ha^–1 for wheat season trials. The experiments consisted of four replicates (plots of 5 × 6 m in a randomized block design) of each treatment in Argic stagnic anthrosols (Anzhen site) and six replicates in Cumulic stagnic anthrosols (Changshu site). P30 and P20 treatments (30 and 20 kg P ha^–1 in rice and wheat seasons, respectively) were considered as conventional P application rates in this area. Higher P treatments, such as P150 and P300 for rice and P80 and P160 for wheat, were intended to simulate the status of soil P in ~10–20 years with an application of P30 or P20 kg P ha^–1 each season. Results revealed that the average concentration of total P (TP) in runoff samples was 0.870 mg P l^–1 from P30 plots during the rice season, and 0.763 mg P l^–1 from P20 plots during the wheat season in both years at the Anzhen site, while it was 0.703 and 1.292 mg P l^–1, respectively, at the Changshu site. Average TP load (mass loss) at the Anzhen site with conventional P application rates was 220.9 and 439.5 g P ha^–1 during rice season in 2000/2001 and 2001/2002, respectively, but was 382.3 and 709.4g P ha^–1 during wheat season, respectively. Mass loss at the Changshu site was 140.4 and 165.7 g P ha^–1 during the rice season and 539.1 and 1184.6 g P ha^–1 during the wheat season, respectively. P losses from paddy soils were significantly greater during the wheat season, especially at the Changshu site, indicating that planting rice reduced P. Phosphate fertilizer levels significantly affected P concentrations and P loads in runoff both seasons. Both mean concentrations and average seasonal P loads from the P150/P80 plots were lower than that from the P300/P160 plots, but significantly higher than that from the P30/P20 and P0 plots. This implied that runoff P loads would be greatly increased in 10–20 years as a result of the accumulation of soil P if 50 kg P ha^–1 (rice season plus wheat season) is applied each year.     

一步法RT-PCR克隆水稻线粒体磷转运蛋白基因及其序列特征分析

以水稻广亲和品种Cpslo17幼穗为材料,用一步法RT—PCR（逆转录聚合酶链式反应）克隆了一个长度为1118bp的编码线粒体磷转运蛋白的OsMPT基因。序列分析表明其包含了基因完整的编码序列,编码由368个氨基酸组成的线粒体磷转运蛋白,它与玉米、大豆、Lotus japonicus、Betula pendula、拟南芥的线粒体磷转运蛋白氨基酸序列相似率分别为93．5％,85．6％,83．8％,83．7％,81．1％。氨基酸疏水谱分析显示它有线粒体磷转运蛋白家族高度保守的6个跨膜结构域。水稻线粒体磷转运蛋白N端富含精氨酸（Arginine）、丙氨酸（Alanine）和丝氨酸（Serine）。iPSORT预测其蛋白N端具有定位于线粒体的信号肽序列,进一步分析表明此编码区段有6个外显子和5个内含子。RT—PCR结果表明,OsMPT基因在水稻两个亚种粳稻和籼稻的叶片中均有表达,在Cpslo17营养器官和生殖器官中都有高水平表达。水稻线粒体磷转运蛋白的克隆和表达分析将为研究其结构和生物学功能奠定基础。     

Isolation and transformation of rice aleurone protoplasts

Summary Protoplasts isolated from the aleurone have been used extensively in molecular studies focusing on hormone-mediated regulation of gene expression in barley seed. To extend the use of aleurone protoplasts to other species, we have determined the conditions necessary for the isolation of protoplasts from rice aleurone layers of germinated seed. Many of the common cell wall degrading enzymes used in making protoplasts were tested for their ability to release protoplasts from rice aleurone layers. Cellulysin was found to be the most effective. Transformation of these aleurone protoplasts was accomplished using polyethylene glycol and DNA constructs containing the firefly luciferase reporter gene under the control of two different promoters were tested. Luciferase expression was 24-fold greater when the reporter gene was under the control of the CaMV 35S promoter than when the promoter from the alcohol dehydrogenase 1 gene was used. With the isolation and transformation of aleurone protoplasts from rice, it is now possible to investigate molecular events occurring in this tissue during germination.     

Increased doubled haploid plant regeneration from rice (Oryza sativa L.) anthers cultured on colchicine-supplemented media

Plating rice anthers on a semisolid induction medium containing 250 or 500 mg/l colchicine for 24 or 48 h-incubations followed by transfer to colchicine-free medium and standard anther culture procedures resulted in overall 1.5- to 2.5- fold increases in doubled haploid green plant productions compared to control anther cultures. The addition of colchicine had no detrimental effects on the different anther culture efficiency parameters, but in some treatments led to significant enhancement of anther callusing frequency or callus green plant regenerating ability. The most efficient treatment raised doubled haploid plant recovery from 31% to 65.5%. These results suggest that post-plating colchicine treatment of anthers, since it was found to improve both anther culture efficiency and doubled haploid plant recovery frequency, could be integrated into rice doubled haploid plant production programmes.Abbreviations DH doubled haploid - NAA naphthalenacetic acid - PAS periodic acid Schiff