河南主推小麦品种对低温胁迫的生理响应及耐寒性分析

为探讨不同小麦品种对春季低温胁迫的响应,以郑麦366、郑麦7698、矮抗58等12个河南省主推小麦品种为试验材料,研究了拔节期低温(-6℃)和孕穗期低温(0℃)处理对不同小麦品种叶片生理指标、产量及其构成要素的影响,分析了寒害级别与各生理指标增幅之间的相关性。结果表明,幼穗发育进程慢的强耐寒性小麦品种的叶片中可溶性糖含量、可溶性蛋白含量、脯氨酸含量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性在低温条件下的增幅大于幼穗发育进程快的弱耐寒性品种,丙二醛(MDA)含量的增幅表现出相反的趋势。拔节期和孕穗期低温处理,使供试小麦品种的有效穗数、穗粒数、千粒重以及产量均下降,拔节期低温对有效穗数和千粒重的影响更为严重,孕穗期低温对穗粒数和产量的影响更为严重。拔节期低温引起的小麦叶片可溶性蛋白含量、脯氨酸含量、SOD活性、CAT活性和MDA含量的增幅与小麦所受寒害级别呈显著或极显著相关;孕穗期低温引起的小麦叶片可溶性糖含量、可溶性蛋白含量、SOD活性、POD活性、CAT活性和MDA含量的增幅与小麦所受寒害级别呈显著或极显著相关。这些结果说明,不同小麦品种的耐寒性强弱在拔节期和孕穗期的表现并不一致,与寒害水平显著相关的生理指标也有差异,应结合两个时期的综合表现评价小麦品种春季的耐寒性。     

拔节期霜冻胁迫对不同小麦品种源库特性的影响

为给小麦耐霜冻品种选育和抗霜冻丰产栽培提供理论依据,以半冬性偏冬性品种济麦22、半冬性品种舜麦1718和半冬性偏春性品种西农585为材料,在拔节期(幼穗药隔期)通过移动式人工霜冻箱模拟霜冻胁迫(-5～-3℃,5 h),研究霜冻胁迫对小麦源库特性的影响。结果表明,霜冻胁迫下,小麦幼穗冻伤率为31.4%～61.9%,穗粒数、穗数、千粒重和产量较对照分别降低8.4%～12.6%、3.2%～6.1%、0.8%～10.7%和19.7%～41.9%,耐霜冻能力表现为济麦22舜麦1718西农585。霜冻胁迫后,孕穗期和抽穗期各品种平均单茎叶面积分别减少15.5%和17.0%,叶面积指数分别减少19.5%和21.1%;霜冻胁迫初期光合速率下降28.5%～42.1%,孕穗后耐霜品种济麦22的光合速率提高3.6%～16.7%;叶片MDA含量显著提高;孕穗至成熟期生长率(CGR)比对照明显降低9.6%～22.0%,其中耐霜品种济麦22生长率降幅小,净同化率和粒叶比却分别提高26.9%和11.4%。小麦籽粒直径极显著降低,籽粒蛋白质含量提高1.3%～11.0%,面筋强度和沉降值稳定或提高。正常生长条件下小麦源库关系属库限制型,霜冻胁迫下属源库互作型。综上,霜冻胁迫打破了小麦原来源库平衡,显著降低了小麦的库容量和源强度,选择种植抗霜冻稳产品种或通过栽培措施调节高穗粒库容量和叶源活性,可减少霜冻导致的产量损失。     

不同阶段夜间增温对小麦生长特性及产量的影响

全球变暖表现出夜间增温幅度大于白天的非对称性增温特性,为明确不同阶段夜间增温对小麦生长发育特征及产量的影响,以扬麦18为试验材料,采用被动式增温装置分别对小麦分蘖期至拔节期(NW_(T-J))、拔节期至孕穗期(NW_(J-B))、孕穗期至开花期(NW_(B-A))三个不同阶段进行夜间增温处理,以不增温为对照(NN),研究不同阶段夜间增温对小麦生长发育特性、旗叶衰老特性及产量的影响。结果表明,不同阶段夜间增温均能提高小麦花后0～15 d旗叶面积和叶绿素含量;显著提高灌浆前期小麦旗叶的超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,降低花后0～15 d小麦旗叶丙二醛(MDA)含量;显著增加成熟期小麦干物质的积累量,提高小麦产量,其中,NW_(J-B)处理下小麦产量增加幅度最大,较NN(对照)提高了8.75%。本试验条件下,拔节期至孕穗期夜间增温提高了花后0～15 d小麦旗叶面积、叶绿素含量和抗氧化酶活性,降低了灌浆前期小麦旗叶膜脂过氧化程度,最终增加了小麦的干物质积累量和产量。     

增温对北疆灌区冬小麦生长、光合和产量的影响

为了解北疆灌区冬小麦生理和产量对气温升高的响应,以自然生长为对照(CK),采用远红外辐射器模拟增温(FATI)的方法,从起身期后对冬小麦进行夜间增温(T12)、全天增温(T24)处理,分析了不同增温对冬小麦生长、光合和产量的影响。结果表明,与CK相比,增温后小麦株高和干物质总积累量变化不明显,绿叶面积在开花期前后分别增大和下降,穗部干物质的分配比例降低。增温虽然对小麦净光合速率、气孔导度、胞间CO_2浓度有一定的影响,但缺乏规律性。增温后小麦穗粒数和千粒重均略有下降,T24和T12处理分别增加和减少了穗数,分别导致小麦产量下降1.7%和18.9%,其中T12处理减产效应明显。这说明增温会引起冬小麦功能叶片过早衰老,减少光合产物向穗部的输送,不利于产量形成。     

黄淮麦区小麦品种抗倒春寒鉴定及其评价方法构建

小麦抗倒春寒特性与发育进程和体内生理指标密切相关。为筛选小麦品种抗倒春寒指标,建立小麦春季抗寒性评价方法,以郑麦7698、矮抗58、石麦19等11份黄淮麦区小麦品种为材料,于小麦二棱期、小花分化期、雌雄蕊分化期、药隔期和四分体期在人工气候室,对试验材料进行低温处理,于6、12和18 h后观察幼穗的受冻情况,测定每个小麦品种的可溶性糖、可溶性蛋白、丙二醛（MDA）含量以及超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性,并对产量性状进行测定。结果表明,幼穗冻害级别以二棱期最低,药隔期最高。进一步对小花分化期、雌雄蕊分化期、药隔期和四分体期低温处理后小麦叶片的生理指标进行比较,发现药隔期低温处理18 h后小麦叶片的可溶性糖含量以及CAT和SOD活性的平均降幅显著高于其他三个时期,分别为32.33%、38.22%和45.20%,MDA含量的平均增幅显著高于其他三个时期,为84.73%。幼穗冻害级别与药隔期低温处理12 h后的可溶性糖含量、SOD活性和MDA含量的变幅均呈极显著相关。这些结果说明,药隔期为小麦抗倒春寒鉴定的最佳生育期,可溶性糖含量、SOD活性和MDA含量可作为小麦抗倒春寒鉴定的生理指标;基于以上3项生理指标的隶属函数综合值对不同品种进行抗寒性评价,综合值（D值）为0.65<D≤1.00、0.40<D≤0.65和0.00<D≤0.40的小麦品种分别为强、中等和弱抗寒类型。     

孕穗期低温对冬小麦光合、干物质转运和产量的影响

为探明低温对冬小麦光合作用、干物质转运和产量的影响,以西农979、小偃22和商麦5226为试验材料,在孕穗期进行不同强度的低温处理,测定光合特性、干物质积累、转运和分配及产量等性状变化。结果表明：(1)低温处理后,供试品种叶片净光合速率、蒸腾速率和气孔导度均显著下降,胞间CO₂浓度显著增加。(2)低温处理降低了开花期和成熟期单株干物质积累量、籽粒干物质积累量、茎秆+叶鞘+叶片干物质积累量、花前干物质转运量、干物质转运效率、干物质贡献率、花后干物质积累量和籽粒干物质分配比例。茎秆+叶鞘+叶片干物质分配比例、穂轴+颖壳干物质分配比例和花后干物质贡献率较对照有不同程度的增加。(3)低温处理显著降低了单株产量和穗粒数,连续3 d低温处理下西农979、小偃22、商麦5226单株产量分别下降38.2%、48.5%和75.9%,连续6 d低温处理下依次下降62.7%、76.6%和87.5%;低温胁迫也降低了单株穂数和千粒质量。孕穗期低温处理降低了小麦光合性能、营养器官干物质积累量和向籽粒的转运与分配,导致穗粒数和千粒质量大幅下降,是造成小麦减产的主要原因。综合来看,3个品种的孕...     

花后渍水时长对小麦根系形态和抗氧化酶活性及产量的影响

为研究花后渍水对小麦根系形态特征和衰老特性及产量的影响,以小麦品种齐民7号和淮麦44为试验材料,采用柱栽试验方法,在开花期设置0 d(W0)、3 d(W3)、6 d(W6)和9 d(W9)四个渍水时长,分析了不同渍水处理间小麦根系平均直径、总根长、根干重和根系衰老相关酶活性及产量的差异。结果表明,在整个测定时期,W3处理的小麦根系平均直径、总根长、根干重、丙二醛(MDA)含量、超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性与W0处理无显著差异,但成熟期千粒重和产量显著低于W0处理。花后21 d, W6和W9处理的根系平均直径、总根体积、总根长、根干重、CAT和SOD活性显著低于W0和W3处理,POD活性和MDA含量显著高于W0和W3处理。成熟期不同处理之间穗数无显著差异,W9处理的穗粒数显著低于其他处理,千粒重和产量表现为W9W6W3W0。齐民7号各处理的穗粒数和产量均显著高于淮麦44,但W3处理下,齐民7号的产量损失显著低于淮麦44。随渍水时长的增加,两品种的产量损失均显著增加,渍水9 d时最终产量损失均达到51%以上,品种之间无显著差异。这说明本试验条件下,开花期渍水胁迫会加快小麦根系衰老,进而影响籽粒灌浆,最终导致产量降低,且渍水时间越长,其影响越大。     

吉花3号对四粒红衰老特性与产量性状改良研究

在田间试验条件下,系统研究了花生新品种吉花3号和其亲本四粒红农艺性状、衰老特性及产量性状的差异。结果表明,新品种吉花3号明显改善了植株性状,叶面积指数显著提高,且保持较高叶面积指数和叶绿素含量的时间较长;功能叶片的SOD、POD酶活性和脯氨酸含量明显提高,MDA含量明显降低。吉花3号的单株生产力较高,荚果增产32.87%,经济系数提高了0.12。吉花3号在农艺性状、抗早衰特性及丰产性上明显优于亲本,生产中可作为四粒红的替代种植品种。     

隔年深耕对夏玉米花后叶片衰老和子粒产量的影响

通过田间定位试验,研究不同耕作方式对华北小麦、玉米一年两熟农作区夏玉米开花后叶片衰老生理特性及产量的影响。结果表明,秸秆还田和隔年深耕可以显著提高玉米叶片各生育期SOD、POD活性,且MDA含量一直保持在较低水平,维持了叶片后期较高的生理功能,最终产量表现为秸秆还田与隔年深耕相结合时产量高于其他处理,起到良好的增产效果。     

播后镇压和冬前灌溉对土壤条件和冬小麦生育特性的影响

为揭示冬灌和镇压的作用,以冬小麦品种石新828和石麦12号为材料,研究了冬灌和镇压措施对麦田土壤水热条件和冬小麦生育特性的影响。结果表明,与不冬灌相比,冬灌条件下,冬季和春季土壤含水量提高,土壤温度较稳定。与不镇压相比,镇压处理的冬前和起身期土壤含水量及冬前夜间土壤温度提高。冬灌处理冬小麦在越冬后各时期的总茎数、LAI、干物质积累量有所降低,开花期叶片光合速率显著下降,灌浆后期叶片SPAD值下降也较快,每穗总小穗数、结实小穗数、穗粒数和产量均减少。镇压使小麦开花前干物质积累量减少,但对成熟期干物质积累量影响不显著,因为开花后光合速率提高,叶片SPAD值下降较缓慢,开花后干物质积累较多。镇压处理成熟期的单位面积穗数降低,但由于穗粒数和千粒重提高,镇压与不镇压的产量差异不显著。从本研究结果看,冬灌是一项防冻保苗的有效措施,与播后镇压配合可减缓冬季低温和温度剧烈变化对小麦的不利影响。     

Pharmacokinetics of Marine-Derived Drugs

Marine organisms represent an excellent source of innovative compounds that have the potential for the development of new drugs. The pharmacokinetics of marine drugs has attracted increasing interest in recent decades due to its effective and potential contribution to the selection of rational dosage recommendations and the optimal use of the therapeutic arsenal. In general, pharmacokinetics studies how drugs change after administration via the processes of absorption, distribution, metabolism, and excretion (ADME). This review provides a summary of the pharmacokinetics studies of marine-derived active compounds, with a particular focus on their ADME. The pharmacokinetics of compounds derived from algae, crustaceans, sea cucumber, fungus, sea urchins, sponges, mollusks, tunicate, and bryozoan is discussed, and the pharmacokinetics data in human experiments are analyzed. In-depth characterization using pharmacokinetics is useful for obtaining information for understanding the molecular basis of pharmacological activity, for correct doses and treatment schemes selection, and for more effective drug application. Thus, an increase in pharmacokinetic research on marine-derived compounds is expected in the near future.     

La pourriture fongique des tubercules de pomme de terre en atmosphère contrôlée

Résumé Fusarium culmorum et, dans une moindre mesure,F. avenaceum, F. sambucinum, Colletotrichum coccodes etCylindrocarpon sp. ont été isolés de tubercules entreposés en atmosphère contr?lée (AC) et atteints de pourriture grave. Des expériences d'inoculation de tubercules avec 10 espèces ou variétés fongiques et conservation en AC à 8 et 10°C ont montré que: 1) les champignons non pathogènes en atmosphère normale (ex.:Cylindrocarpon sp.) le devenaient en AC, 2) ceux qui étaient faiblement pathogènes en atmosphère normale étaient nettement plus virulents en AC (ex.:F. culmorum), 3) les espèces ou variétés virulentes en conditions d'air normales (Fusarium sulphureum etPhoma exigua var.foveata) ne provoquaient pas de pourriture plus grave en AC et leur activité pouvait même être légérement freinée.

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Summary The extensive rotting of tubers which occurred during storage trials in controlled atmospheres has led to a mycological and pathological study of the rots. The most frequently isolated species wasFusarium culmorum althoughF. avenaceum, F. Sambucinum, Coletotrichum coccodes and aCylindrocarpon sp. were also present. Tubers of cvs Bintje and Ulla were inoculated with 19 isolates of 10 fungal species or varieties associated with rotting of stored tubers (Table 1). The tubers were incubated at 8 or 10°C in normal or controlled (2% O₂:1% CO₂, 2% O₂:6% CO₂, 2% O₂:12% CO₂, 6% O₂:6% CO₂) atmospheres and the extent of rotting was determined a month later (Tables 2 and 3 and Fig. 2). Species which were weakly virulent in a normal atmosphere (variousFusarium spp. andPhoma exigua var.exigua) were clearly more aggressive in the controlled atmosphere and this was especially evident in the case ofF. culmorum. Species ot pathogenic in a normal atmosphere under experimental conditions (Colletotrichum coccodes, Cylindrocarpon sp.,Phoma eupyrena) caused rotting in the controlled atmosphere. The two species which were virulent in a normal atmosphere (F. sulphureum andP. exigua var.foveata) were also virulent in the controlled atmosphere and in some cases the extent of rotting was even less. As a general rule, rotting caused by weakly virulent fungi was greater in both cultivars in the controlled than in a normal atmosphere.

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Zusammenfassung Eine starke F?ulnis von in Kontrotrollierter Atmosph?re gelagerten Kartoffelknollen veranlasste eine mykologische und pathologische Untersuchung. Der am h?ufigsten isolierte Pilz warFusarium culmorum. F. avenaceum, F. sambucinum, Colletotrichum coccodes undCylindrocarpon sp. wurden ebenfalls bestimmt. Neunzehn St?mme von 10 Pilzsorten oder-Arten welche bei Lagerf?ulnis vorkommen (Tab. 1) wurden auf Knollen der Sorten Bintje und Ulla inokuliert. Die Lagerung wurde bei 8 oder 10°C under Normalbedingungen oder kontrollierter Atmosph?re durchgeführt (2% O₂:1% CO₂, 2% O₂:6% CO₂, 2% O₂:12% CO₂, 6% O₂:6% CO₂). Der F?ulnisgrad (Abb. 1) wurde nach einem Monat bonitiert. Die Ergebnisse sind in den Tabellen 2 und 3 dargestellt und in der Abb. 2 illustriert. Unter in Normalbedingungen nur schwach virulente Arten (verschiedeneFusarien undPhoma exigua var. exigua) waren deutlich aktiver in kontrollierter Atmosph?re. Dies was besonders der Fall fürF. culmorum. Pilze, die im Versuch unter Normalbedingungen nicht pathogen waren (Colletotrichum coccodes, Cylindrocarpon sp., Phoma eupyrena), haben unter kontrollierter Atmosph?re Sch?den verursacht. Hingegen werden die beiden unter Normalbedingungen sehr pathogenen Arten (F. sulphureum undP., exigua var.foveata), durch kontrollierte Atmosph?re wenig beeinflusst. Es wurde sogar in einigen F?llen eine gewisse Verringerung des F?ulnisbefalls beobachtet. Ganz allgemein haben die getesteten kontrollierten Bedingungen die Entwicklung der Pilzf?ulnis an beiden Kartoffelsorten gef?rdert, speziell durch Pilzarten, welche unter Normal-bedingungen wenig Sch?den verursachen.

     

Marine Pharmacology in 2016–2017: Marine Compounds with Antibacterial,Antidiabetic, Antifungal,Anti-Inflammatory,Antiprotozoal, Antituberculosis and Antiviral Activities; Affecting the Immune and Nervous Systems,and Other Miscellaneous Mechanisms of Action

The review of the 2016–2017 marine pharmacology literature was prepared in a manner similar as the 10 prior reviews of this series. Preclinical marine pharmacology research during 2016–2017 assessed 313 marine compounds with novel pharmacology reported by a growing number of investigators from 54 countries. The peer-reviewed literature reported antibacterial, antifungal, antiprotozoal, antituberculosis, and antiviral activities for 123 marine natural products, 111 marine compounds with antidiabetic and anti-inflammatory activities as well as affecting the immune and nervous system, while in contrast 79 marine compounds displayed miscellaneous mechanisms of action which upon further investigation may contribute to several pharmacological classes. Therefore, in 2016–2017, the preclinical marine natural product pharmacology pipeline generated both novel pharmacology as well as potentially new lead compounds for the growing clinical marine pharmaceutical pipeline, and thus sustained with its contributions the global research for novel and effective therapeutic strategies for multiple disease categories.     

Effects of Micronutrient Deficiencies on Human Health: Its Status in South Asia

SUMMARY

Vitamin A, iodine, and iron deficiencies affect large numbers of people worldwide. A deficiency of one or more of these micronutrients adversely affects the physical and mental abilities of humans. South Asia contains a high percentage of these individuals, not just because of its large population, but also the prevalence of deficiency is higher there than in many other parts of the world. The reasons for the high rates of deficiency in South Asia are many, but they include inadequate availability of micronutrient-rich foods, sub-optimal dietary habits, and high rates of infection. Across the region, national plans vary from (a) increasing availability of appropriate foods, (b) introducing new dietary behaviors, (c) improving health status, and (d) directly addressing deficiency through intervention programs. The extent to which each of the countries is making progress toward the goals of these plans can help in understanding the priorities for future efforts to address micronutrient malnutrition. This article discusses the adverse effects of micronutrient deficiencies in humans with special reference to South Asia.     

Irrigation but not N fertilization enhances seedhead density in plains rough fescue ( F estuca hallii)

Plains rough fescue ( F estuca hallii) is an important forage grass species in western Canada. Seed for use in pastures and ecological restoration is in high demand but supply is limited because F. hallii is an erratic seed producer. Seed producers require an understanding of the factors that influence flowering and seed set in this species. The aim of this study was to assess the effect of irrigation and nitrogen fertilization on the flowering and growth of F. hallii in a native rough fescue prairie in Alberta, Canada. Irrigation had a strong positive effect on seedhead density, whereas fertilization had limited effects on growth and reproduction of F. hallii. These results demonstrate that under field conditions, available moisture is likely to be a key factor driving flowering and seed production in F. hallii.     

Management of Soil Micronutrient Deficiencies in the Rice-Wheat Cropping System

Summary

Within the last three decades, the rice-wheat cropping system has triggered, and with time, aggravated soil micronutrient deficiencies in the Indo-Gangetic Plains (IGP). This has largely been due to the shift from an earlier rice and wheat monoculture with low yielding, long duration indigenous varieties, to an intensive rice-wheat rotation cropping system with short duration modern high yielding varieties on the same piece of land. The problems related to micronutrient deficiency in the IGP are more due to the size of its available pools in the soil rather than its total contents and are greatly influenced by crop management, or rather its mismanagement. Deficiency of zinc is widespread in the IGP, but with the extensive use of zinc sulfate, zinc deficiency has reduced in some areas of the region. Meanwhile, the deficiency of Fe, Mn and B has increased in the IGP. Deficiency of Cu and Mo is location specific and can limit rice and wheat yields. The adoption and spread of the rice-wheat system in permeable coarse textured soils, particularly in the western IGP, not only caused iron deficiency in rice but also resulted in the emergence of manganese deficiency in wheat. In highly calcareous and acidic soils, boron is the next limiting micronutrient in crop production after zinc. Bumper rice and wheat harvests in the past decade, the declining use of organic manures in the region and except for the widespread use of zinc sulfate, a general lack of awareness amongst farmers on micronutrient deficiency problems has contributed to micronutrients limiting rice and wheat yields in the IGP. Approaches to alleviating micronutrient deficiencies include matching the crop removals of the micronutrients with its replenishments through their respective external carriers, supplementation through organic sources and mobilization/utilization through cultivation of micronutrient efficient crop cultivars. Identification of efficient micronutrient carriers and finding the optimum rate, mode and time of its application is important in ameliorating the micronutrient deficiencies. This article reviews the extent of micronutrient deficiency and discusses various management options available to reduce micronutrient deficiency induced crop yield reduction for rice and wheat in the Indo-Gangetic Plains.     

Marine Drugs Regulating Apoptosis Induced by Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL)

Marine biomass diversity is a tremendous source of potential anticancer compounds. Several natural marine products have been described to restore tumor cell sensitivity to TNF-related apoptosis inducing ligand (TRAIL)-induced cell death. TRAIL is involved during tumor immune surveillance. Its selectivity for cancer cells has attracted much attention in oncology. This review aims at discussing the main mechanisms by which TRAIL signaling is regulated and presenting how marine bioactive compounds have been found, so far, to overcome TRAIL resistance in tumor cells.     

Biochemical and morphological characterization of potato clones differing in their resistance to late blight

Summary Morphological and biochemical parameters that could be involved in resistance to late blight were studied in non-infected and in infected potato hybrids resulting from a cross betweenSolanum phureja, resistant toPhytophthora infestans, and a susceptibleSolanum tuberosum. Some morphological differences between resistant and susceptible hybrids, indicating a positive correlation between stem diameter and phloem thickness in the stem and resistance toP. infestans, were observed. The lignin content in the leaves of the resistant hybrid rose upon infection byP. infestans. In the leaves of the susceptible hybrid, a diminution of the lignin content could be observed upon infection byP. infestans. In the same context, peroxidasic activity raised upon infection byP. infestans in both resistant and susceptible hybrids. Further characterization of the hybrid clones based on the polymorphism of peroxidases was attempted using isoelectric focusing.     

Applied Biotechnology to Combat Late Blight in Potato Caused by <Emphasis Type="Italic">Phytophthora Infestans</Emphasis>

Potato is an important crop, grown worldwide. It suffers from many pests and diseases among which late blight, caused by the oomycete Phytophthora infestans, is the worst. The disease is still causing major damage in many potato production areas and control is only possible by applying fungicides frequently. The knowledge on the molecular biology and genetics of the interaction between the plant and the oomycete is developing rapidly. These are relevant fields of study, currently dominated by the discovery of many resistance genes and numerous effector proteins and the analysis of their specific mode of action. These studies may yield essential information needed for the development of durable resistance. The long-term and worldwide effort to breed for resistance so far has had little effect. A novel breeding approach may change this. It is based on cisgenic modification (CM) consisting of marker-free pyramiding of several resistance genes and their spatial and temporal deployment yielding dynamic varieties that contain potato genes only. It is envisioned that this CM approach with potato’s own genes will not only prove societally acceptable but may also result in simplifications in the legislation on use of the CM approach. Various parties in the potato research arena intend to cooperate in this novel approach in a number of developing countries where potato substantially contributes to food security. The use of resources such as land, water and energy improves when the effect of late blight is markedly reduced.     

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.