“绿色革命”新进展:赤霉素与氮营养双重调控的表观修饰助力水稻高产高效育种

以半矮秆育种为代表的“绿色革命”极大地提高了作物产量,但也带来氮营养利用效率降低的严重问题。“绿色革命”主要基于调控赤霉素的代谢和信号转导而实现。前期的研究发现,赤霉素信号转导关键因子DELLA蛋白通过调控GRF4而负调控氮素的吸收利用,为半矮秆品系氮利用效率低的问题提供了解决方案。最近的一项研究进一步揭示了GA信号途径与氮响应交叉互作的新机制。该研究发现水稻(Oryza sativa)NGR5是氮素调控分蘖数目的一个关键基因,其表达受氮诱导。通过招募PRC2,NGR5对D14和OsSPL14等分蘖抑制基因所在位点进行H3K27me3甲基化修饰,从而抑制其表达。而在半矮秆背景下超表达NGR5可以提高低氮水平下的水稻产量。NGR5同时也被发现为赤霉素受体GID1的一个新靶标,受到其负调控。该研究发现了调控赤霉素信号通路的新机制,并对高产高效的新一代“绿色革命”育种实践具有重要启示。     

Comparison of the roles of neurohormones in the regulation of blood distribution from the hearts of American and Japanese lobsters

The decapod cardiovascular system consists of a single ventricle that pumps blood into seven arteries; previous work has shown that the outflow distribution patterns of intact animals are variable. In the present study, flow recordings were made from pairs of arteries in semi-isolated hearts whilst different cardioactive hormones were infused into the heart. Each hormone (5-hydroxytryptamine, octopamine, dopamine, proctolin and F1) changed the outflow pattern, heart rate and ventricular pressure in a unique way. The probable sites of hormone action are the cardioarterial valves located at the origin of each artery except one, the dorsal abdominal. Outflow from the dorsal abdominal is controlled downstream by valves located at the origin of the segmental lateral arteries. The responses to a particular hormone were sometimes different between the hearts of American and Japanese lobsters. Accepted: 11 May 1998     

Soil and plant tests for available sulfur in wetland rice soils

Summary Soil tests, plant performance, and plant tissue analyses were used to study the availability of sulfur to wetland rice in 30 Philippine soils. The critical concentrations of available sulfur by the calcium phosphate, lithium chloride, ammonium acetate, and hydrochloric acid extractions were 9, 25, 30, and 5 mg/kg, respectively. The critical total sulfur limits were 0.11% in the shoot at maximum tillering 0.055% in the straw at maturity, and 0.065% in the grain. The critical N:S ratio was 15 in the shoot at maximum tillering, 14 in the straw at maturity, and 26 in the grain. The critical sulfate-sulfur limit was 150 mg/kg in the shoot at maximum tillering and 100 mg/kg in the straw at maturity. The critical sulfate-sulfur/total sulfur percentage ratio was 15% in the shoot at maximum tillering and the straw at maturity. Plant performance, judged by appearance and yield of dry matter, straw, and grain, was generally poorer in the sulfur deficient soils than in the other soils. Although the calcium phosphate and ammonium acetate methods gave a better correlation between plant performance and available sulfur than the others, all four methods separated sulfur-deficient soils from non-deficient ones. The hydrochloric acid method merits further study because it is simple and versatile.     

Functional assignment to JEV proteins using SVM

Identification of different protein functions facilitates a mechanistic understanding of Japanese encephalitis virus (JEV) infection and opens novel means for drug development. Support vector machines (SVM), useful for predicting the functional class of distantly related proteins, is employed to ascribe a possible functional class to Japanese encephalitis virus protein. Our study from SVMProt and available JE virus sequences suggests that structural and nonstructural proteins of JEV genome possibly belong to diverse protein functions, are expected to occur in the life cycle of JE virus. Protein functions common to both structural and non-structural proteins are iron-binding, metal-binding, lipid-binding, copper-binding, transmembrane, outer membrane, channels/Pores - Pore-forming toxins (proteins and peptides) group of proteins. Non-structural proteins perform functions like actin binding, zinc-binding, calcium-binding, hydrolases, Carbon-Oxygen Lyases, P-type ATPase, proteins belonging to major facilitator family (MFS), secreting main terminal branch (MTB) family, phosphotransfer-driven group translocators and ATP-binding cassette (ABC) family group of proteins. Whereas structural proteins besides belonging to same structural group of proteins (capsid, structural, envelope), they also perform functions like nuclear receptor, antibiotic resistance, RNA-binding, DNA-binding, magnesium-binding, isomerase (intra-molecular), oxidoreductase and participate in type II (general) secretory pathway (IISP).     

Persistence of occluded viruses in the nests of the paper waspPolistes hebraeus (Hym.: Vespidae)

Bioassays were used to study the infectivity of cytoplasmic polyhedrosis viruses (CPVs), nuclear polyhedrosis viruses (NPVs) and entomopoxviruses (EPVs) contained in 16 nests of the paper waspPolistes hebraues F. in Réunion Island. Several virosis were propagated from 6 nest contents in 5 Lepidoptera:Catopsilia thauruma Saalmüller,Catopsilia florella F.,Callixena versicolora Mabille,Polydesma umbricola Boisduval andEagris sabadius Boisduval. Each of the previous species supported the development of one or two virosis and therefore, wasp nests must be considered as accumulating centres where infectivity of occluded entomoviruses is preserved. The accurate origin of the virosis propagated through bioassays was searched for using ecological investigations on similar natural diseases, REN analysis and a cross-transmission test onSpodoptera mauritia Boisduval. The nuclear polyhedrosis and one cytoplasmic polyhedrosis appearing in bioassays can be assigned respectively to viruses produced byC. thauruma andC. versicolora; the other virosis must be considered as developing in alternate or substitution hosts. Wasp nests could therefore be used to detect the presence of specific viruses in an environment and to collect new virus isolates.     

Chloroplast DNA phylogeography of Fagus crenata (Fagaceae) in Japan

 CpDNA variation in Japanese beech, Fagus crenata (Fagaceae), was studied in 45 populations distributed throughout the species' range. Two cpDNA regions were sequenced: the non-coding region between the trnL (UAA) 5′exon and trnF (GAA), and the trnK region (including matK). Thirteen distinct cpDNA haplotypes were recognized and each haplotype was found to be geographically structured. Two major clades (I and II+III) were revealed in phylogenetic analyses among the haplotypes using F. sylvatica as an outgroup. The haplotypes of Clade I were distributed mainly along the Japan Sea side of the Japanese Archipelago, while those of Clade II+III occurred chiefly along the Pacific Ocean side. Consequently, the distribution of the two major cpDNA clades suggests that there were two migration routes in the history of F. crenata; one along the Japan Sea and the other along the Pacific Ocean side of the Japanese Islands. Received March 19, 2001 Accepted November 22, 2001     

Rice G protein γ subunit qPE9-1 modulates root elongation for phosphorus uptake by involving 14-3-3 protein OsGF14b and plasma membrane H+-ATPase

Heterotrimeric G protein is involved in plant growth and development, while the role of rice (Oryza sativa) G protein γ subunit qPE9-1 in response to low-phosphorus (LP) conditions remains unclear. The gene expression of qPE9-1 was significantly induced in rice roots under LP conditions. Rice varieties carrying the qPE9-1 allele showed a stronger primary root response to LP than the varieties carrying the qpe9-1 allele (mutant of the qPE9-1 allele). Transgenic rice plants with the qPE9-1 allele had longer primary roots and higher P concentrations than those with the qpe9-1 allele under LP conditions. The plasma membrane (PM) H⁺-ATPase was important for the qPE9-1-mediated response to LP. Furthermore, OsGF14b, a 14-3-3 protein that acts as a key component in activating PM H⁺-ATPase for root elongation, is also involved in the qPE9-1 mediation. Moreover, the overexpression of OsGF14b in WYJ8 (carrying the qpe9-1 allele) partially increased primary root length under LP conditions. Experiments using R18 peptide (a 14-3-3 protein inhibitor) showed that qPE9-1 is important for primary root elongation and H⁺ efflux under LP conditions by involving the 14-3-3 protein. In addition, rhizosheath weight, total P content, and the rhizosheath soil Olsen-P concentration of qPE9-1 lines were higher than those of qpe9-1 lines under soil drying and LP conditions. These results suggest that the G protein γ subunit qPE9-1 in rice plants modulates root elongation for phosphorus uptake by involving the 14-3-3 protein OsGF14b and PM H⁺-ATPase, which is required for rice P use.     

Changes in DTPA-iron and management of iron chlorosis in rice nurseries

Summary On a Typic Ustochrept soil incorporation of 10 tons/ha of a green manure plus submergence for 10 days followed by raising upland nursery checked iron chlorosis. In contrast, presubmergence with and without FYM and iron sulfate or pyrite were a failure. Nor weekly sprays with 3.0% iron sulfate were found very effective. The success of green manure plus submergence was associated with the mobilization of soil iron as a result of intense reduction and its subsequent retention in available form at a sufficient high level during the growth of upland nursery.     

Rice straw decomposition in rice-field soil

Rice straw, buried in a rice-field during the dry season decomposed at a rate of 0.0075 day-1. Seventy five percent of the biomass, 70 percent carbon, 50 percent nitrogen and 30 percent phosphorus remained after 139 days of decomposition. Rice straw decomposition furnished 33% N and 8% P of the total nitrogen and phosphorus provided by man.     

Spider mites of sugarcane in Australia: a review of grass-feeding Oligonychus Berlese (Acari: Prostigmata: Tetranychidae)

Abstract In many areas of the world, spider mites are significant pests of sugarcane. Australia is currently fortunate in lacking the most destructive species, and usually suffers only sporadic damage. Herein, we provide a key to the genera of spider mites associated with sugarcane, review the most significant genus, Oligonychus Berlese, and provide a key to the species of grass-feeding Oligonychus in the Australasian region. The species O. araneum Davis, O. digitatus Davis, O. grypus Baker and Pritchard, O. orthius Rimando, and O. oryzae (Hirst) are redescribed, while the Australian O. zanclopes sp. n. Beard and Walter from sugarcane and rice, O. turbelli sp. n. Beard and Walter, O. ephamnus sp. n. Beard and Walter and O. festucolus sp. n. Beard and Walter from other grasses, are newly described. Previous records of O. grypus in Australia appear to be misidentifications of what is described here as the new species O. zanclopes .