Changes in activity of lysine decarboxylase in winter triticale in response to grain aphid feeding

Changes in lysine decarboxylase (LDC) activity caused by Sitobion avenae (F.) feeding on two winter triticale cultivars (cvs) were studied. The aphid fecundity and values of intrinsic rate of natural increase showed that cv Witon was less susceptible to S. avenae than cv Tornado. The grain aphid feeding on more susceptible triticale caused a decrease in the LDC activity, with exceptions of root tissues after two weeks of the feeding. In case of less susceptible cv Witon reduction of the LDC activity was observed only during initial period of S. avenae feeding. Later the aphid infestation induced activity of the LDC within tissues of cv Witon.     

Effect of L-3,4-dihydroxyphenylalanine, ornithine and γγ-aminobutyric acid on winter wheat resistance to grain aphid

The association between the concentrations of L-3,4-dihydroxyphenylalanine (L-DOPA), ornithine, and γ-aminobutyric acid (GABA) in winter wheat cultivars with their antibiotic resistance to the grain aphid Sitobion avenae (F.) (Hom., Aphididae) was studied. The antibiosis was measured under field conditions using the intrinsic rate of natural increase ( r _m ). The content of the studied non-protein amino acids was estimated in flag leaf at the beginning of anthesis growth stage. Highly significant negative correlations were found between the r _m values and concentrations of L-DOPA (r = −0.937) and ornithine (r = −0.907), but not with GABA (r = −0.363). The contribution of these allelochemicals to the resistance of the plants to insects is discussed.     

Expression of the insecticidal lectin from snowdrop (Galanthus nivalis agglutinin; GNA) in transgenic wheat plants: effects on predation by the grain aphid Sitobion avenae

Transgenic wheat plants containing the gene encoding snowdrop lectin (Galanthus nivalis agglutinin; GNA) under the control of constitutive and phloem-specific promoters were generated through the particle bombardment method. Thirty-two independently derived plants were subjected to molecular and biochemical analyses. Transgene integration varied from one to twelve estimated copies per haploid genome, and levels of GNA expression from 0 to ca. 0.2% of total soluble protein were observed in different transgenic plants. Seven transgenic plants were selected for further study. Progeny plants from these parental transformants were selected for transgene expression, and tested for enhanced resistance to the grain aphid (Sitobion avenae) by exposing the plants to nymphal insects under glasshouse conditions. Bioassay results show that transgenic wheat plants from lines expressing GNA at levels greater than ca. 0.04% of total soluble protein decrease the fecundity, but not the survival, of grain aphids. We propose that transgenic approaches using insecticidal genes such as gna in combination with integrated pest management present promising opportunities for the control of damaging wheat pests.     

高粱抗高粱蚜的生化基础

高粱中的可溶性总氮、可溶性总糖和绝大部分游离氨基酸,特别是必需氨基酸,在感性品种中的含量显著地比抗性品种中的含量高.感性品种叶液微偏酸,抗性品种近中性.多元回归分析表明,高梁对高粱蚜Melanaphis sacchari(Zehntner)的抗性与可溶性总氮、可溶性总糖和游离氨基酸的含量呈反相关.     

Resistance to the aphids Sitobion avenae and Rhopalosiphum padi in Gramineae in relation to hydroxamic acid levels

Aribiotic resistance to the aphid Sitobion avenae was assessed in relation to levels of hydroxamic acids (Hx) in a wide genetic range of cultivars and species of Triticum. Within hexaploid and tetraploid Triticum material, total plant concentrations of Hx explained a significant proportion of the variation in intrinsic rate of increase (r_m) of S. avenae. Significant correlations were also found between resistance to Rhopalosiphum padi and Hx levels. Although the concentrations of Hx in whole plants declined during seedling growth, concentrations of Hx in newly-emerging leaves remained high in plants of all ages, including in the emerging flag leaves of mature plants. When the mean relative growth rate of S. avenae over three days was used instead of r_m and the control of environmental conditions was improved, a higher proportion of the variation in aphid performance was explained by Hx concentrations in six cultivars.     

雪花莲凝集素基因转化小麦及转基因小麦抗蚜性的研究

雪花莲凝集素对具有刺吸式口器的同翅目害虫具有毒杀作用。用基因枪法将1个新的雪花莲凝集素(GNA)基因转入普通春小麦品种中-60634和生产上正在推广的冬小麦高产品种——豫麦66中,分别获得了转基因小麦植株。抗蚜实验证明,转化gna基因的小麦植株对我国北方冬麦区的主要麦蚜——麦长管蚜和禾谷缢管蚜的抗性效果不尽相同。对禾谷缢管蚜,在接种当代即表现出明显的毒杀作用。对麦长管蚜,则表现为虫体发育减缓并且降低了其所生产的若蚜成活率。在自然放养条件下,gna基因则对这两种麦蚜的取食均起到了一定的抑制作用。     

Shifts in host plant resistance to the cabbage aphid (Brevicoryne brassicae) exhibited by Brussels sprout plants

Seven cultivars of Brussels sprouts from different sources were tested for their relative degrees of resistance to the cabbage aphid (Brevicoryne brassicae) by estimating the Potential Increase Rate of aphid infestations. The cultivars Winter Harvest and Early Half Tall were selected as susceptible and resistant respectively and tested further. Glasshouse experiments indicated that the resistance of Winter Harvest to the aphids increased with age.
These relative levels of resistance were confirmed by population counts in the field. Aphid numbers were initially significantly higher on Winter Harvest than on Early Half Tall although significance was lost as the season progressed at a time when the characteristics responsible for the resistance mechanism ceased to be distinguishable between the two cultivars.
Analysis of the amino acid content of leaf tissues collected at monthly intervals through the aphid season enabled 'risk rating' predictions of aphid resistance to be made. These conformed with the shifts towards greater resistance as the plants aged noted in the glasshouse trials and endorsed the part played by amino acids in the mechanism of resistance. Total amino acid concentrations reached a peak during September and October then declined with generally lower levels of amino acids in Early Half Tall than Winter Harvest. This cultivar also possessed a greater concentration of those amino acids known to be favourable to B. brassicae although the difference between the two had diminished considerably by the end of September.
Analyses of the mustard oil glycoside levels in mature glasshouse-grown plants did not indicate a difference between the cultivars.     

Costs and benefits of hydroxamic acids-related resistance in winter wheat against the bird cherry-oat aphid, Rhopalosiphum padi L.

Estimations of infestation by the bird cherry-oat aphid (Rhopalosiphum padi) as well as measurements of grain yield in 26 Hungarian winter wheat cultivars under field conditions were correlated with the concentration of hydroxamic acids (Hx) in seedlings of those cultivars. The significant inverse relationship between infestation ratings and Hx levels in wheat showed that Hx, despite their decreased accumulation at later plant phenological stages, may be able to confer resistance against aphid infestation in the field. Since no significant relationship was found between grain yield and Hx levels in plants it is suggested that Hx accumulation does not impose a cost to the plant in terms of yield. These findings support earlier claims stressing the potential of Hx as breeding targets for aphid resistance in wheat.     

Relationship between Water Soluble Carbohydrate Content,Aphid Endosymbionts and Clonal Performance of Sitobion avenae on Cocksfoot Cultivars

Aphids feed on plant phloem sap, rich in sugars but poor in essential amino acids. However, sugars cause osmotic regulation problems for aphids, which they overcome by hydrolysing the sugars in their gut and polymerising the hydrolysis products into oligosaccharides, excreted with honeydew. Aphids harbour primary bacterial endosymbionts, which supply them with essential amino acids necessary for survival. They also harbour secondary (facultative) endosymbionts (sfS), some of which have a positive impact on life history traits, although it is not yet known whether they also play a role in providing effective tolerance to differing levels of water soluble carbohydrates (WSCs). We investigated the relationship between WSC content of cocksfoot cultivars and performance of clones of the English grain aphid Sitobion avenae F. We evaluated how clone genotype and their sfS modulate performance on these different cultivars. We therefore examined the performance of genetically defined clones of S. avenae, collected from different host plants, harbouring different sfS. The performance was tested on 10 Dactylis glomerata L. cultivars with varying WSC content. D. glomerata is known as a wild host plant for S. avenae and is also commercially planted. We found that high WSCs levels are responsible for the resistance of D. glomerata cultivars to specific S. avenae clones. The minimum level of WSCs conferring resistance to D. glomerata cultivars was 1.7% dw. Cultivars with a WSC content of 2.2% or higher were resistant to S. avenae and did not allow reproduction. Our results further indicate that sfS modulate to some extend host plant cultivar adaptation in S. avenae. This is the first study revealing the importance of WSCs for aphid performance. Cocksfoot cultivars with a high content of WSCs might be therefore considered for aphid control or used for resistance breeding in this and other grass species, including cereals.     

3个新引进小麦品种对麦长管蚜抗性的初步研究

以小偃-22和Amigo(美国)为对照对麦长管蚜在3个新引进小麦品种Astron、Batis和Xanthos(德国)上的抗蚜性进行了测定。在室内控制条件下,麦长管蚜在5个品种上的发育历期(DD)、体重差(dW)、相对日均体重增长率(MRGR)和生殖力(F)的测定结果表明,Astron、Xanthos与Amigo、小偃-22的抗性水平相当,均优于Batis;在大田自然条件下,通过对不同品种在不同生育期的感蚜指数以及感蚜量动态曲线的监测分析表明,Astron、Xanthos在我国的抗蚜水平与抗性品种Amigo的抗蚜性水平相当,优于Batis和小偃-22。可初步说明Astron、Xanthos在我国也具有较好的抗蚜性,可作为我国抗蚜育种材料。     

不同冬小麦品种在3种质地土壤中氮代谢特征及利用效率分析

为明确不同土壤质地条件下不同品种冬小麦(Triticum aestivum)的氮代谢和利用特征, 筛选与土壤质地相适宜的高产和氮高效利用的优质小麦品种, 采用大田试验的方法, 在同一生态类型区砂土、壤土和黏土3种质地土壤上, 以当地生产上大面积应用的强筋小麦‘郑麦366’ (‘ZM366’)和中筋小麦‘矮抗58’ (‘AK58’)、‘周麦22’ (‘ZM22’)为材料, 系统地研究了土壤质地对不同冬小麦品种主要生育时期叶片氨同化关键酶谷氨酰胺合成酶(GS)活性、游离氨基酸含量、花前和花后不同器官氮素积累和分配、氮素再分配等氮代谢过程及产量、品质和氮素利用效率等的影响。结果表明: 在这3种土壤质地上, 不同品种冬小麦旗叶GS活性和游离氨基酸含量均呈倒“V”型变化特征。各品种小麦旗叶GS活性、游离氨基酸含量大小及达到最大值的时期不一样, 砂土条件下峰值早于壤土10天左右出现, 且在5月22日已检测不到GS活性和游离氨基酸含量。花前和花后小麦地上部及各器官氮积累量(NA)、氮再分配量(NR)、成熟期籽粒产量和氮素当季利用率(NUE)均以壤土上为最高。氮素转运率(NRE)、花前再分配氮素对籽粒氮素的贡献率(NRC)、氮素生理效率(NPE)、氮收获指数(NHI)以砂土上为最高。其中, 砂土上NRC达82.46%-95.84%, 是花后的7倍左右; 壤土和黏土条件下花后吸收的氮素在籽粒氮素的积累中占有较大的比例, 贡献率分别为36.6%和29.2%。同一土壤质地上3个品种比较, 在砂土上, GS活性、游离氨基酸含量、籽粒产量、蛋白质含量及NUE和NPE以‘郑麦366’最高, 而壤土上以‘矮抗58’最高, 黏土上则以‘周麦22’最高。因此, 在生产上应培育和选择与土壤质地相适应的小麦品种, 砂土地种植‘郑麦366’, 壤土条件下种植‘矮抗58’, 黏土条件下种植‘周麦22’, 可以在获得较高产量和品质的同时, 提高氮素利用效率。     

Discovery of English grain aphid (Hemiptera: Aphididae) biotypes in China

The English grain aphid, Sitobion avenae (F.) (Hemiptera: Aphididae), is an important pest insect of wheat, Triticum aestivum (L.), in China. Grain aphid biotypes are necessary to breed aphid-resistant wheat varieties; however, none have currently been identified. Here, we describe a method to identify grain aphid biotypes and survey the aphid biotype variation in the wheat growth area of China. Clones of S. avenae were collected from 11 locations in China and used to establish culture populations. These populations were then used to assess the resistance of 12 wheat varieties. Based on resistance responses, seven differential hosts were selected to identify the biotype of S. avenae: Amigo, 'Fengchan No. 3', Zhong 4 wumang, JP1, L1, 885479-2, and 'Xiaobaidongmai'. S. avenae was ultimately classified into five biotypes: EGA I, EGA II, EGA III, EGA IV, and EGA V. These methods provide a mechanism to detect the variation and evolution of grain aphids in different wheat-growing locations and also allow for selection of appropriate aphid-resistant germplasm for wheat breeding of commercial wheat cultivars.     

Seasonal changes in the free amino acids of oat and barley phloem sap in relation to plant growth stage and growth of Rhopalosiphum padi

The concentrations and composition of free amino acids in phloem sap from two cultivars of oats and barley, both susceptible to the aphid Rhopalosiphum padi, were determined by means of high performance liquid chromatography. Sap was collected from excised aphid stylets at three developmental stages (seedlings, tillering plants and plants undergoing stem elongation) from plants given or not given fertiliser and grown outdoors. In connection, the growth of individual R. padi nymphs was estimated at the same phenological stages on plants grown in the greenhouse. The content of free amino acids was consistently higher in seedlings than in plants at the early tillering stage. Only in seedlings did the addition of fertiliser increase amino acid levels. Barley phloem sap contained more free amino acids than that of oats when fertiliser was added and at later developmental stages. Phloem sap of oats and barley showed similar patterns in their composition of free amino acids at the seedling stage, but as the plants grew older the patterns became increasingly different. Plants given fertiliser had higher amounts of dicarboxylic amino acids (glutamic and aspartic acid) than unfertilised plants. The concentrations of γ-amino butyric acid, glycine, histidine, and methionine were very low in all treatments. The relative growth rates of R. padi nymphs were low when amino acid content was low and vice versa. The results are discussed in relation to host plant suitability and plant resistance mechanisms.     

Metabolic changes associated with cold-acclimation in contrasting cultivars of barley

Cereal plants become more resistant to freezing when first exposed to a period of cold-acclimation. Many physiological and molecular changes have been shown to occur at low temperatures, but the role and the contribution of each to frost resistance is still poorly understood. Two cultivars of barley ( Hordeum vulgare L.), the winter barley Onice and the spring barley Gitane, were acclimated under controlled conditions under an 8-h photoperiod at 4°C (light) and 2°C (dark) for 21 days. Changes in free proline, ABA, water-soluble carbohydrates and free fatty acids were measured to assess their involvement in cold-acclimation and to explain the different frost-resistant capacities of the two cultivars. Exposure of barley plants to low temperature resulted in an equal increase in proline in both cultivars. During the first days of cold acclimation, ABA levels showed a peak in the frost-resistant cultivar, lasting about 24 h, followed by a decrease. The water soluble carbohydrates reached their highest content after 3 days of hardening, although after 14 to 21 days of acclimation the carbohydrate content was similar to that of unhardened plants. The frost-resistant Onice had a much higher free fatty acid content than the frost-sensitive Gitane. Furthermore in Onice 86% of free farty acids was represented by unsaturated molecular species. Inolenic acid alone being 71%. In contrast, in the frost-sensitive cultivar only 31% of free fatty acids was unsaturated and a large amount of 9-oxo-nonanoic acid, a product present in the linolenic acid cascade, was also detected.
The ABA content after 2 days of hardening and the free fatty acid composition were clearly different between the two cultivars and may explain, at least in part, the different frost-resistant capacities of Onice and Gitane.     

苹果绵蚜对不同苹果品种春梢生长期生理指标的影响

为了筛选培育对苹果绵蚜(Eriosoma lanigerum Hausmann)的抗性品种,实现持续有效治理苹果绵蚜的目的,通过测定红富士、金帅、昭锦108、秦冠、红将军等5种不同苹果品种春梢生长期被苹果绵蚜危害前后枝条内可溶性糖、蛋白质、游离氨基酸、总酚含量以及防御性酶的活性变化,探讨苹果生理指标与抗蚜性的关系。结果表明,被害后可溶性糖含量除红将军外均有所上升,其中红富士上升达13.7%;蛋白质含量除红富士外均有所降低;氨基酸含量均有所上升,其中红将军变化明显,变化率达68.8%。酚类物质是一种重要的抗蚜物质,红富士、昭锦108、秦冠被害后总酚含量均升高,其中昭锦108、秦冠中总酚含量上升率约为红富士的2倍。红富士品种正常枝条内超氧化物歧化酶(Superoxide Dismutase,SOD)、多酚氧化酶(Polyphenol Oxidase,PPO)、过氧化物酶(Peroxidase,POD)以及过氧化氢酶(Catalase,CAT)活性均显著低于昭锦108,被害后各苹果枝条SOD活性均出现上升趋势,除红将军的PPO、POD活性降低外,其他品种均升高;金帅、红富士的CAT活性上升明显,分别为110.8%、45.5%。植物的防御性酶与其抗虫性有密切关系,苹果春梢生长期对苹果绵蚜的抗性与苹果体内的可溶性糖、游离氨基酸、SOD、PPO、POD以及CAT活性均有关,而且不同苹果品种被害后生理指标的变化也与其抗蚜性有一定关系。     

Free amino acid content of phloem sap from Brassica plants in relation to performance of Lipaphis erysimi (Hemiptera: Aphididae)

Cultivars of Brassica juncea, B. napus and B. campestris, differing in host-suitability to the mustard aphid (Lipaphis erysimi pseudobrassicae Kalt.), were analysed for their phloem sap content of free amino acids. Sap was collected from excised mustard aphid stylets and analysed by means of high performance liquid chromatography. Aspartic and glutamic acid were, together with glutamine, the dominating amino acids. All plants had very little glycine, γ-aminobutyric acid (GABA), methionine and tryptophan in their sap. This amino acid pattern closely resembled that of cereals. The total concentration and the individual composition of amino acids were not found to be related to the level of aphid resistance previously found in the investigated Brassica species. However, one B. campestris cultivar, yellow sarson YSB-9, on which the aphids were shown to grow more slowly, had less amino acid content than other B. campestris varieties. The slow population growth of aphids on B. juncea, compared to that on B. campestris, is probably due to other than nutritional factors.     

Photosynthesis, antioxidant activities and transcriptional responses in two sugarcane (Saccharum officinarum L.) cultivars under salt stress

This study analyzes changes in gene expression and the biochemical and physiological properties of the antioxidant system in the leaves of two sugarcane cultivars under salt stress. In both salt-stressed cultivars, no alteration in the foliar nitrogen content was observed; however, there was a reduction in the phosphorus and potassium levels and an increase in the sodium and chloride concentrations. There was also a reduction in gas exchange on the third day under salt stress. Although the content of soluble sugars remained stable in both species, there was a decrease in free amino acids. However, only the RB872552 cultivar displayed a lower leaf protein content compared to the control. The salt stress resulted in higher superoxide dismutase and l-ascorbate peroxidase activities, but only for the RB92579 cultivar. On the other hand, both cultivars were able to maintain lower malondialdehyde contents than the control plants. The gene expression analysis revealed down-regulated expression levels, including the levels of those enzymes linked to higher activities under salt stress. Our results showed that gene induction and leaf antioxidative cycle enzyme activity do not occur at the same time. The variations in gene expression and physiological responses are also discussed.     

夏季苹果新梢生理指标与抗苹果绵蚜的关系

研究苹果生理指标与其对苹果绵蚜(Eriosoma lanigerum Hausmann)抗性的关系,为筛选培育抗性品种,实现持续有效治理苹果绵蚜提供依据.田间调查不同苹果品种对苹果绵蚜的抗性,测定比较各品种正常枝条生理指标,以及被苹果绵蚜危害后生理指标的变化.结果表明,正常枝条中可溶性糖(r=0.99)、蛋白质(r=0.86)含量与感蚜率呈正相关;氨基酸含量与感蚜率呈负相关(r=-0.96);酚类物质和4种酶活性与苹果感蚜率均不存在明显相关性.被害后昭锦108可溶性糖含量有所下降,红富士、金冠分别上升1.4％、7.0％;蛋白质、氨基酸、酚类物质含量均有所下降,其中红富士总酚含量明显下降,达23.5％,总酚下降率与感蚜率呈正相关(r=0.94);超氧化物歧化酶(Superoxide Dismutase,SOD)、过氧化氢酶(Catalase,CAT)活性均上升,其中CAT变化率与感蚜率存在相关性(r=-0.92),昭锦108 CAT活性明显上升,达91.2％;多酚氧化酶(Polyphenol Oxidase,PPO)、过氧化物酶(Peroxidase,POD)活性增减不一;金冠4种酶活性均上升.研究表明,对苹果绵蚜抗性较强的品种:可溶性糖、蛋白质含量较低,游离氨基酸含量较高;受害后可溶性糖含量下降,总酚含量下降率较低,游离氨基酸含量下降率较高.酶活性对抗蚜性的影响不明显.     

Drought‐stress and plant resistance affect herbivore performance and proteome: the case of the green peach aphid Myzus persicae (Hemiptera: Aphididae)

Little is known about the simultaneous effects of drought stress and plant resistance on herbivorous insects. By subjecting the green peach aphid Myzus persicae Sulzer to well‐watered and drought‐stressed plants of both susceptible and resistant peach (Prunus persica), the effects of both stressors on aphid performance and proteomics are tested. Overall, the influence of the water treatment on aphid performance is less pronounced than the effect of host plant genetic resistance. On the susceptible cultivar, aphid survival, host acceptance and ability to colonize the plant do not depend on water treatment. On the resistant cultivar, aphid survival and ability to colonize are higher on drought‐stressed than on well‐watered plants. A study examining the pattern of protein expression aiming to explain the variation in aphid performance finds higher protein expression in aphids on the drought‐stressed susceptible cultivars compared with the well‐watered ones. In the susceptible cultivar, the regulated proteins are related to energy metabolism and exoskeleton functionality, whereas, in the resistant cultivar, the proteins are involved with the cytoskeleton. Comparison of the protein expression ratios for resistant versus susceptible plants reveals that four proteins are down‐regulated in well‐watered plants and 15 proteins are down‐regulated in drought‐stressed plants. Drought stress applied to the susceptible cultivar induces the regulation of proteins in M. persicae that enable physiological adaptation to maintain an almost unaltered aphid performance. By contrast, for aphids on the resistant cultivar subjected to drought stress, the down‐regulation of proteins responds to an induced host susceptibility effect.     

The effect of Furolan on the physiological and biochemical characteristics of ripening winter wheat grain

The effects of the preparation Furolan, (2-furyl-2)-1,3-dioxolane, on the degree of mRNA polyadenylation and the pattern of protein synthesis in the ripening grain of several soft winter wheat (Triticum aestivum L.) cultivars were studied. It was demonstrated that Furolan stabilized mRNA in a cultivar-specific manner, thereby accelerating to various degrees the biochemical processes taking place in the ripening grain. Of the wheat cultivars studied, Krasnodarskaya 99 was the most responsive cultivar with respect to a set of changes in nucleic-protein metabolism; the cultivar Deya was next followed by the cultivar Bat'ko. The cultivar Kroshka did not respond to the treatment with Furolan. The cultivar specificity of this preparation allows its practical application to be optimized.