播娘蒿对双氟磺草胺的抗性水平及靶标抗性分子机理

为明确麦田杂草播娘蒿对双氟磺草胺的抗性水平及靶标抗性分子机理,采用整株-剂量响应法测定了播娘蒿对双氟磺草胺的抗性水平,通过克隆测序进行了靶标乙酰乳酸合成酶(ALS)基因序列比对分析,并通过测定靶标酶离体活性,分析了抗性和敏感种群播娘蒿ALS对双氟磺草胺的敏感性。结果显示,与敏感种群TS 相比,抗性种群G₁₃₀ 对双氟磺草胺产生了高水平抗性,抗药性指数为108.6;在G₁₃₀种群中随机抽取100株,对其ALS基因进行测序,比对分析发现,33%植株ALS 的第197位脯氨酸突变为苏氨酸,40%植株ALS 的第574位色氨酸突变为亮氨酸,27%植株的ALS 同时存在上述两种突变。ALS 离体活性测定结果表明,双氟磺草胺对抗性种群ALS 的活性抑制中浓度为敏感种群的137.8倍。这说明,播娘蒿抗性种群ALS 关键位点氨基酸的突变可能是导致其对双氟磺草胺产生高水平抗性的重要原因之一。     

Wild tuber-bearing species ofSolanum and incidence ofPhytophthora infestans (Mont.) de Bary on the Western slopes of the volcano Nevado de Toluca. 5. Type of resistance toP. infestans

Summary Plants of wildSolanum species (S. demissum (dms), S. verrucosum (ver), S. iopetalum (iop), S. brachycarpum (bra), and an unidentified species (unsp), from the natural habitat were inoculated in the laboratory withPhytophthora infestans race 0, to see if major genes for resistance were present, and with the most complex and aggressive race available in an attempt to reveal the level of general resistance. No plant with a susceptible reaction to race 0 was found in 120 plants ofdms, and 34 plants ofunsp. Plants with a hypersensitive reaction to race 0 and susceptible plants were found inver. When infected with a complex aggressive isolate of the fungus 73.5% of the WSS plants were susceptible. It was concluded that WSS in the area possess both complex race specific resistance and a high level of general resistance, whose effects cannot yet be separated.     

Genetic Transformation of a High Molecular Weight Glutenin (Glu-1Dx5) to Rice cv. Fatmawati

Abstract

In order to improve rice dough functionality, we co-transformed the Glu-1Dx5 gene encoding a high molecular weight (HMW) glutenin subunit Dx5 from bread wheat, Triticum aestivum L. and either bar gene conferring resistance to herbicide bialaphos or hpt gene conferring resistance to hygromycin B to rice callus cells of cv. Fatmawati. We molecularly characterized 9 plants regenerated from bialaphos-containing medium and 63 plants from hygromycin-containing medium. The Glu-1Dx5 gene was detected by PCR analysis in 15 transgenic T₀ plants. Further analysis of T₁ and T₂ plants revealed that some transgenic plants carried the Glu-1Dx5 gene. Analysis of the endosperm extracts of T₂ plants by SDS-PAGE revealed the existence of a protein similar in size to the wheat Glu-1Dx5 gene product, suggesting successful expression of the transgene. These plants will be incorporated into breeding program for further assessment of their benefits.     

Resistance to <Emphasis Type="Italic">Potato virus Y</Emphasis> in a Multitrait Potato Breeding Scheme without Direct Selection in Each Generation

In an experimental breeding scheme to improve late blight (Phytophthora infestans) and white potato cyst nematode (Globodera pallida) resistance of tetraploid potato over three generations of crossing and selection, 15 clones survived the final selection, and these were derived from 15 great-grandparents. There was no direct selection for resistance to Potato virus Y (PVY), but 14 out of the 15 great-grandparents were resistant to PVY and three had extreme resistance. Thirteen of the 15 descendants had PVY resistance and one extreme resistance. This was within the range expected for a random (unselected) sample from the genotypes of the great-grandparents. Hence, we found no evidence for any positive or negative association between PVY resistance and the attributes selected. The conclusion is that laborious selection is not required in every generation when many parents have PVY resistance, including some with more than one copy of a PVY resistance gene or resistance at more than one locus. However, in the future, determining the major virus resistance genes present in potential parents in each generation using diagnostic molecular markers would prevent susceptible × susceptible crosses being made and maximise the number of resistant × resistant ones.     

燕麦AsRBP1基因克隆及表达特性分析

为了给AsRBP1基因在小麦抗逆转基因分子育种中的应用奠定理论基础,采用同源克隆方法从燕麦中克隆、获得AsRBP1基因,其cDNA序列全长447 bp,编码148个氨基酸.AsRBP1在氨基端具有典型的RNA识别基序(RNA-Recognition Motif,RRM),在羧基端富含甘氨酸,其含量达35.8％.系统进化树分析表明,AsRBP1与拟南芥AtGR-RBP7亲缘关系很近.实时荧光定量聚合酶链式反应(Real-time PolymeraseChain Reaction,RT-PCR)分析该基因的表达特性表明,AsRBP1明显受到外源脱落酸(Abscisic acid,ABA)与低温的诱导,同时对干旱和高盐胁迫也做出响应.由此,推测该基因属于GR-RBPs基因家族成员,可能参与逆境胁迫应答,在增强植物的抗逆性中发挥着重要的作用,可以为小麦抗逆分子育种提供优良候选抗逆基因资源.     

Transgenic potatoes expressing anErwinia pectate lyase gene — results of a 4-year field experiment

Summary Four potato lines of cv. Désirée that express the pectate lyase (PL) isoenzyme 3 ofErwinia carotovora subsp.atroseptica were examined in a 4-year field experiment with respect to plant development, tuber yield and resistance of tuber tissue toErwinia soft rot. The PL3 degrades plant cell wall pectin into unsaturated oligogalacturonates eliciting plant defence responses. In one line, enzyme expression was controlled by the CaMV 35S promoter (C) and in three lines it was driven by the potato patatin B33 promoter (D). Plant development of the D-lines in field plots was not distinguishable from that of the non-transgenic counterpart. Also tuber yield was not too different. By contrast, plants of the C-line were smaller than those of the nontransformed counterpart and also showed reduced tuber yield. There were no significant differences in dry mass, starch and protein content of tuber tissue between PL transgenic and non-transgenic potatoes. But compared with the latter, field-grown tubers expressing the PL displayed an enhanced resistance toErwinia soft rot. Thus, average rotting caused byEc-bacteria was diminished in tubers of PL-transgenic lines by 34.1%. The resistance of tubers toEc soft rot was significantly correlated with the PPO activity in tuber tissue.     

Transgenic potato plants expressing oxalate oxidase have increased resistance to oomycete and bacterial pathogens

Summary Potato (cv. Bintje) was transformed with a gene encoding an oxalate oxidase from wheat under the control of the CaMV35S promoter. Transgenic potato plants produced high constitutive levels of H₂O₂ as visualized by 4-chloro-l-naphtol staining. The resistance of these plants was tested againstPhytophthora infestans. An increased level of resistance to the disease was marked by a reduced number of lesions as well as by a decreased number of sporangia formed per lesion. In addition, oxalate oxidase overexpressing plants also exhibited improved resistance toStreptomyces reticuliscabiei, the causal agent of netted scab. Increased expression of oxalate oxidase had no effect on the interaction withErwinia carotovora. These experiments show that overexpression of oxalate oxidase represents a potentially interesting approach for protection of potato to pathogens.     

Quinclorac Resistance in Echinochloa crus-galli from China

Echinochloa crus-galli is a major weed in rice fields in China, and quinclorac has been long used for its control. Over-reliance of quinclorac has resulted in quinclorac resistance in E. crus-galli. Two resistant(R) E. crus-galli populations from Hunan, China were confirmed to be at least 78-fold more resistant to quinclorac than the susceptible(S) population. No difference in foliar uptake of 14 C-labelled quinclorac was detected between the R and S plants. However, a higher level of 14 C translocation and a lower level of quinclorac metabolism were found in the R plants. Basal and induced expression levels of β-cyanoalanine synthase(β-CAS) gene and β-CAS activity were not significantly different between the R and S plants. However, the induction expression of 1-aminocyclopropane-1-carboxylic acid oxidase(ACO1) gene by quinclorac treatment was evident in the S plants but not in the R plants. Quinclorac resistance in the two resistant E. crus-galli populations was not likely to be related to foliar uptake, translocation or metabolism of quinclorac, nor to cyanide detoxification via β-CAS. Thus, target-site based quinclorac signal reception and transduction and regulation of the ethylene synthesis pathway should be the focus for further research.     

58份鲜食玉米品种对瘤黑粉病和丝黑穗病的抗性评价

2020-2022年通过田间人工接种,对58份鲜食玉米品种进行抗性鉴定和评价,明确玉米品种对瘤黑粉病和丝黑穗病的抗性差异。结果表明,58份鲜食玉米中未检测出高抗(HR)瘤黑粉病品种,1份品种原玉糯999表现抗病(R),占比1.7%;福甜73、白甜糯3号、白玉糯2020、甘糯2020等4份材料表现中抗(MR),占比6.9%;27份品种表现感病(S),占比46.6%;26份品种表现高感(HS),占比44.8%。对丝黑穗病鉴定结果表明,未发现高抗(HR)和抗病(R)品种,仅1份品种永糯321表现中抗(MR);其余20份和37份材料分别表现感病(S)和高感(HS),分别占鉴定材料的34.5%和63.8%。     

Factors that impact on the ability of biofumigants to suppress fungal pathogens and weeds of strawberry

This research aimed at identifying factors that improve the efficacy of biofumigants for soil disinfestation against strawberry (Fragaria×ananassa) pathogens and weeds. In laboratory bioassays, volatiles released from the macerated roots of a Brassica rapa/Brassica napus biofumigant crop were six times more effective at suppressing the growth of the strawberry pathogen Rhizoctonia fragariae than shoots. Furthermore, the toxicity of the volatiles from the biofumigant crop to R. fragariae increased as plant developmental stage progressed. These results related to the release of higher quantities and greater diversity of isothiocyanates (ITCs) from the roots of mature biofumigant plants than from their shoots. Separate bioassays showed that volatiles from the biofumigant crop suppressed the growth of six different soil-borne pathogens (Alternaria alternata, Colletotrichum dematium, Cylindrocarpon destructans, Fusarium oxysporum, Pythium ultimum, Phytophthora cactorum, and R. fragariae) of strawberry and seven Trifolium spp. (clover) weeds. The suppression of Trifolium spp. by biofumigant volatiles did not relate to their seed size, but might relate to their hard-seededness or genotype. In the field, rotary incorporation of the biofumigant crop did not produce detectable levels of ITCs in soil; reduce the survival of the strawberry pathogens, P. cactorum and C. destructans; or affect populations of culturable soil microflora. Yet, it suppressed the growth of emerging weeds by 40% and the growth of P. cactorum by 20%. We hypothesise that allelochemicals other than ITCs, such as nitriles, or other biological mechanisms might also play a role in biofumigation. A key to improving the efficacy of biofumigation in the field seems to lie in the development of application technologies that can macerate and incorporate biofumigants evenly in soils, in addition to incorporating biofumigants under optimal edaphic conditions for release of ITCs.     

Progress in Mapping and Cloning Qualitative and Quantitative Resistance Against <Emphasis Type="Italic">Phytophthora infestans</Emphasis> in Potato and Its Wild Relatives

Cultivated potato is susceptible to many pests and pathogens, none of which is more of a threat to potato agriculture than the late blight disease, caused by the oomycete Phytophthora infestans (Mont.) de Bary. To date all efforts to thwart this most adaptive of pathogens have failed, and early attempts to deploy ‘R genes’ introgressed from the wild Mexican hexaploid Solanum demissum ended in abject failure. With the advent of facile gene mapping and cloning, allied to knowledge of plant resistance gene structure, renewed efforts are leading to mapping and isolation of new sources of late blight resistance in potato wild species, many of which are being performed under the auspices of the BIOEXPLOIT project (Sub-project 2). We document recent advances in late blight resistance gene mapping and isolation, and postulate how these genes, allied to knowledge of pathogen effectors and their recognition specificity, may greatly enhance our chances of halting the progress of late blight disease in potato crops worldwide.     

Resistance toErwinia carotovora subsp.atroseptica in second backcross populations of somatic hybrids betweenSolanum tuberosum andS. brevidens

Summary Eleven clones obtained from a cross between cv. Katahdin and fusion products betweenSolanum tuberosum and the non tuber-bearing speciesS. brevidens, were backcrossed again withS. tuberosum (clone AR80-127-5). Small tubers harvested from 583 seedlings of these second backcross (BC2) populations were screened for tuber tissue resistance toErwinia carotovora subsp.atroseptica under aerobic conditions. After multiplication in the field. BC2 clones again were screened for soft rot resistance under aerobic as well as anaerobic conditions. In general, the resistance of the BC2 populations was reduced in comparison with the BC1. Variation for resistance was found within the BC2 populations, but there was no correlation between the results of the three tests performed. Four BC2 populations were also screenned for resistance to blackleg in the field. Significant differences were found between populations for mean percentage of diseased plants, but these differences could not be explained by the resistance of the parental clones.     

Societal Costs of Late Blight in Potato and Prospects of Durable Resistance Through Cisgenic Modification

In the European Union almost 6 Mha of potatoes are grown representing a value of close to €6,000,000,000. Late blight caused by Phytophthora infestans causes annual losses (costs of control and damage) estimated at more than €1,000,000,000. Chemical control is under pressure as late blight becomes increasingly aggressive and there is societal resistance against the use of environmentally unfriendly chemicals. Breeding programmes have not been able to markedly increase the level of resistance of current potato varieties. New scientific approaches may yield genetically modified marker-free potato varieties (either trans- and/or cisgenic, the latter signifying the use of indigenous resistance genes) as improved variants of currently used varieties showing far greater levels of resistance. There are strong scientific investments needed to develop such improved varieties but these varieties will have great economic and environmental impact. Here we present an approach, based on (cisgenic) resistance genes that will enhance the impact. It consists of five themes: the detection of R-genes in the wild potato gene pool and their function related to the various aspects in the infection route and reproduction of the late blight causing pathogen; cloning of natural R-genes and transforming cassettes of single or multiple (cisgenic) R-genes into existing varieties with proven adaptation to improve their value for consumers; selection of true to the wild type and resistant genotypes with similar qualities as the original variety; spatial and temporal resistance management research of late blight of the cisgenic genetically modified (GM) varieties that contain different cassettes of R-genes to avoid breaking of resistance and reduce build-up of epidemics; communication and interaction with all relevant stakeholders in society and transparency in what research is doing. One of the main challenges is to explain the different nature and possible biological improvement and legislative repercussions of cisgenic GM-crops in comparison with transgenic GM-crops. It is important to realize that the present EU Directive 2001/18/EC on GM crops does not make a difference between trans- and cisgenes. These rules were developed when only transgenic GM plants were around. We present a case arguing for an updating and refinement of these rules in order to place cisgenic GM-crops in another class of GM-plants as has been done in the past with (induced) mutation breeding and the use of protoplast fusion between crossable species.     

Overexpression of a Maize SPS Gene Improves Yield Characters of Potato under Field Conditions

Abstract

We analyzed the yield characters of field-grown transgenic potato plants (Solanum tuberosum) carrying a maize gene for sucrose-phosphate synthase (SPS), the key enzyme in sucrose synthesis. The SPS activity in the leaves of transgenic plants (line Ag1203) was 2 times that of the control (cv. May Queen). There was no difference in the photosynthetic CO₂ uptake rates between Ag1203 and May Queen plants, and the leaf starch content of Ag1203 was lower. These observations indicate that the introduction of a foreign SPS gene improved the supply of photosynthate from source (leaves) to sink (tubers). Additionally, leaf senescence of the transgenic potato plants was delayed relative to that of May Queen. The average tuber weight and total yield of Ag1203 plants were at least 20% higher, and the tuber sucrose content, which is related to eating quality, was also higher. Increased translocation of photosynthate and longer period of photosynthetic activity in the leaves may have increased the yield of Ag1203. These results suggest that introduction of the SPS gene improved the yield characters and quality of potato tubers under field conditions.     

小麦L699叶片受白粉菌胁迫后蛋白质的差异表达

为从蛋白组学角度认识小麦抗白粉病机制,以含有抗白粉病新基因Pm40的小麦品系L699为材料,采用蛋白质双向电泳和质谱技术(MALDI-TOF-MS)检测小麦叶片接种白粉菌24h后的差异蛋白。结果表明,经PDQuest软件分析,接种白粉菌后小麦叶片中有18个蛋白质斑点表达量上调,38个蛋白质斑点表达量下调。对表达量上调的蛋白质斑点进行质谱分析和数据库检索,共鉴定出15种蛋白质,其中13种参与防御反应、碳水化合物代谢和蛋白质周转。这些差异蛋白与抗病途径、植株生理过程密切相关,在小麦抗白粉病过程中起很重要的作用。     

Fermentation of pearl millet flour with yeasts and lactobacilli:in vitro digestibility and utilisation of fermented flour for weaning mixtures

Single as well as mixed culture fermentations by yeasts (S. diastaticus;S. cerevistiae) and lactobacilli (L. brevis;L. fermentum) at 30 °C for 72 h improved the starch and protein digestibility (in vitro) of pearl millet flour significantly. The flour fermented bySaccharomyces diastaticus, a starch hydrolysing yeast, had the highest starch digestibility whereas fermentation bySaccharomyces cerevisiae enhanced the in vitro protein digestibility of the flour significantly. Weaning mixtures prepared from the fermented flour were also found to be organoleptically acceptable.     

A method of assessing potato seedling progenies for resistance to the white potato cyst nematode

Summary The resistance expressed by progenies of potato seedlings to the white potato cyst nematode (Globodera pallida) has been assessed on bulk sowings of seedlings and on individual plants raised from tubers, and a positive correlation between the seedling and plant tests has been established. The use of such a seedling test as an addition to other methods of screening is discussed.     

Impact of Different US Genotypes of <Emphasis Type="Italic">Phytophthora infestans</Emphasis> on Potato Seed Tuber Rot and Plant Emergence in a Range of Cultivars and Advanced Breeding Lines

Seed pieces of different potato cultivars and advanced breeding lines (ABLs) from north central US breeding programmes were inoculated with different genotypes of Phytophthora infestans (US-1, US-1.7, US-8, US-11 and US-14). The effect of these genotypes of P. infestans on seed piece rot severity after re-storage was assessed using an image analysis technique. P. infestans genotypes demonstrated variable ability to cause seed piece rot and to reduce plant emergence measured as final plant stand (%) and the relative area under the plant emergence curve (RAUEPC). The US-8 genotype of P. infestans was the most aggressive genotype, as indicated by tuber rot severity across all cultivars/ABLs tested, followed by US-14 in both years. The US-1, US-1.7 and US-11 genotypes were the least aggressive, causing only moderate seed piece rotting across cultivars/ABLs tested. Similar trends were observed in two field experiments, where the US-8 and US-14 genotypes delayed or reduced emergence. Values of final plant stand (%) and RAUEPC demonstrated that the cultivars/ABLs Atlantic, MSJ453-4Y and Torridon were the least susceptible across all P. infestans genotypes. In both experiments cv. Pike was the most susceptible. Other cultivars/ABLs demonstrated variable responses to different genotypes of P. infestans. No symptoms of P. infestans were observed on emerged plants up to 60 days after planting. The variability of susceptibility of tubers to different genotypes of P. infestans has implications for plant breeding efforts in that the major emphasis in the past has been to breed for foliar resistance, with limited emphasis on the reaction of the tuber. Results from this study suggest that highly aggressive genotypes of P. infestans such as US-8 may lead to severe tuber rotting and deterioration of tubers before emergence, but despite this observation the US-8 genotype is still predominant in North America.     

转小麦 TaPDI-A、 TaTRXh-A和 TaPP2Ac-D基因拟南芥植株的主要抗旱性研究

核氧还蛋白（nucleoredoxin,NRX）可通过还原目标蛋白的二硫键来调控其生物活性,在植物的生长发育和抗逆境胁迫中发挥着重要作用。蛋白质二硫键异构酶（protein disulfide isomerase,PDI）、h型硫氧还蛋白（h-type thioredoxin,TRXh）和蛋白磷酸酶2A催化亚基（protein phosphatase 2A catalytic subunit,PP2Ac）是小麦核氧还蛋白TaNRX1的互作蛋白。为了明确TaNRX1互作蛋白的抗旱性功能,本研究在拟南芥中过表达了小麦 TaPDI-A、 TaTRXh-A和 TaPP2Ac-D基因,对野生型和转基因拟南芥的表型和抗旱相关生理指标进行了鉴定。结果表明,干旱胁迫处理后,转 TaPDI-A、 TaTRXh-A和 TaPP2Ac-D基因拟南芥的根长、存活率、脯氨酸含量均大于野生型,离体叶片失水率、丙二醛（MAD）含量均小于野生型。二氨基联苯胺（diaminobenzidine,DAB）对H₂O₂组织定位染色结果表明,干旱胁迫处理后,转 TaPDI-A、 TaTRXh-A和 TaPP2Ac-D基因拟南芥的H₂O₂含量均低于野生型。上述结果说明,TaNRX1的互作蛋白基因 TaPDI-A、 TaTRXh-A和 TaPP2Ac-D增强了拟南芥对于干旱胁迫的抵抗能力。本研究可为小麦抗旱育种提供候选基因和理论基础。