玉米化感物质异羟肟酸的研究进展

介绍了异羟肟酸在玉米植株中的分布和玉米根系分泌物中异羟肟酸的分析方法．丁布(DIM-BOA)是玉米植株中含量最大的异羟肟酸．不同玉米品种之间异羟肟酸含量的差异很大．种子不含异羟肟酸;但萌发后其含量迅速增加,在萌芽几天后的幼苗植株其含量达最大值,随后逐渐下降;在玉米生长发育的不同时期,幼嫩叶片内异羟肟酸含量始终较高;地上部分异羟肟酸的浓度高于根系．植株异羟肟酸的浓度受生长环境条件影响显著,在紫外辐射、黑暗条件或水分胁迫下其含量明显增加．在各种禾谷类作物中,玉米根系分泌物内含异羟肟酸较高;铁的存在能显著增加玉米根系分泌物中异羟肟酸的含量．     

Malate Dehydrogenase Isoenzymes in Cotton Leaves of Different Ages

Malate dehydrogenase isoenzymes from the blades of different aged leaves of the cotton plant have been investigated. The total extractable malate dehydrogenase activity varied widely between leaves of different ages and different locations on the plant. Malate dehydrogenase zymograms developed from the extracts which contained significantly different levels of enzyme activity appear to indicate the presence of different groups of malate dehydrogenase isoenzymes in leaves of different ages. However, under appropriate conditions of polyacrylamide gel electrophoresis, the same number of malate dehydrogenase isoenzymes with the same relative mobilities were detected in all the leaves studied. These findings are discussed in relation to reports that malate dehydrogenase isoenzymes change with plant development or that they have different roles in the plant.     

红豆杉幼树异龄叶的功能性状

植物叶片功能性状随叶龄的变化体现了植物的生活史策略,反映着植物对有限资源的权衡与配置特征.本研究以红豆杉幼树异龄叶为对象,测定了3个年龄段叶片的14个功能性状,分析红豆杉叶片老化过程中生态策略的调整方式.结果 表明:1年生叶的比叶面积显著大于2、3年生叶,3年生叶的叶厚、叶面积、叶体积、叶鲜重和叶干重显著大于1、2年生...     

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.     

Movement and feeding patterns of Epilachna cucurbitae Richards (Coleoptera:Coccinellidae) on pumpkin and zucchini plants2

The oviposition patterns of adults and the movement and feeding patterns of larvae of Epilachna cucurbitae on two species of cucurbits, Cucurbita maxima cv Queensland Blue and C. pepo cv Blackjack, were studied in the field and laboratory. The physical and nutritional characteristics of host plant leaves of different ages were described. Younger leaves had higher nitrogen contents but were less abundant, smaller and had higher trichome densities than older leaves. The development of first instar larvae was delayed by the leaf hairs on young and mature pumpkin leaves which prevented larvae from reaching the leaf surface to feed First instal larvae developed more quickly on leaves rich in nitrogen. Neither the total developmental time of larvae nor the size of pupae was affected by leafage because larvae on poor quality leaves compensated by eating more. Female beetles oviposited on all but the youngest and oldest leaves of the host plant. The trichomes on young leaves prevented females from attaching eggs to the leaf surface. First instar larvae remained where they hatched, but older larvae were more mobile, Changing feeding sites frequently and moving progressively to younger, more nutritious leaves. Final instar larvae moved onto adjacent vegetation to pupate. The adaptive significance of these patterns is discussed in relation to the nutritional value, hairiness and abundance of host plant leaves of different ages and the physical limitations of different larval instars.     

芦荟属3种植物不同叶龄、不同部位叶内蒽醌类物质含量及其变化的研究

用植物化学技术研究了3种芦荟属植物不同叶龄和不同部位叶中蒽醌类物质的含量及其变化。结果表明,被研究的芦荟属3种植物叶中主含的蒽醌类物质有：芦荟素或高那特芦荟素,芦荟宁和芦荟苦素。其中,中华芦荟和木立芦荟主含芦荟素;海莱芦荟主含高那特芦荟素。叶各部位详细分析的结果表明,蒽醌类物质在植株上部的嫩叶中的含量要高于下部老叶;同一叶中,叶尖高于叶中部,叶基含量最低;而叶缘含量高于叶的中央部分。在同一叶的横切面上,蒽醌类物质的含量在维管柬区最高,同化薄壁组织部分次之,储水组织部分最低。芦荟属植物在同一个植物体不同的叶之间,以及同一叶不同的位置间有规律的累积蒽醌类物质有重要的生物学意义。它是保证芦荟属植物在原产地的干旱和半干旱生活环境中得以良好生存的适应反应和化学防御机制。     

Distribution of hydroxamic acids in zea mays tissues

The hydroxamic acid content of leaves of cereals correlates well with resistance to aphids. In maize these compounds were absent from xylem exudates and guttation drops. Lateral veins of leaves of 7-day-old maize plants contained 8 mmol/kg fr. wt. while the entire leaf contained only 4.2 mmol/kg fr. wt. In leaves of 20-day-old plants, these amounts decreased by ca one-third. In mesocotyls, the cortex and central vascular cylinder contained 1.3 and 2.2 mmol/kg fr. wt, respectively. In 12-day-old wheat plants, the complete leaves and their veins contained 2.4 and 6.4 mmol/kg fr. wt respectively. Thus, the concentration of hydroxamic acid was always higher in the vascular bundles.     

Senescence-related gene expression profiles of rosette leaves of Arabidopsis thaliana: leaf age versus plant age

Abstract: Senescence is a form of programmed cell death (PCD) which leads to the death of whole organs, e.g., leaves or flowers, and eventually to the death of entire plants. Like all forms of PCD, senescence is a highly regulated and energy consuming process. Senescence parameters, like protein content, chlorophyll content, expression of photosynthesis-associated genes or senescence-associated genes (SAGs), reveal that senescence occurs in old leaves derived from young plants (6 week old) as well as in young leaves derived from older plants (8 week old), indicating that it is governed by the actual age of the leaves. In order to analyse the differential gene expression profiles during leaf senescence, hybridizations of high-density genome arrays were performed with: i) individual leaves within the rosette of a 6-week-old plant and ii) leaves of the same position within the rosette but harvested from plants of different ages, ranging from 5 to 8 weeks. Cluster and genetree analyses, according to the expression pattern revealed that genes which are up-regulated with respect to the age of the entire plant, showed completely different expression profiles with respect to the age of the individual leaves within one rosette. This was observed even though the actual difference in leaf age was approximately the same. This indicates that gene expression appears to be governed by different parameters: i) the age of the individual leaf and ii) the age and developmental stage of the entire plant.     

Mutual support and selection between branches of damaged plants

Snow (1931) showed that the fate of a branch of a plant that had suffered local herbivory could be determined by correlative effects of other branches. This neglected work was continued in the current study, herbivory being simulated by the removal of leaves of different ages from pea plants with two branches. A damaged branch was suppressed when an undamaged alternative branch was present; otherwise the damage never prevented continued development. The removal of mature leaves had a smaller effect than the removal of immature, expanding leaves. When leaves were removed from both branches it was the branches that suffered less damage to their immature leaves that continued shoot development. Branches from which all photosynthetic leaves were repeatedly removed developed only when they retained their immature leaves and remained dominant, inhibiting the development — but not the photosynthesis — of the other branch on the same plant. Accounting for these results requires mechanisms that compare the different branches of the plant and select for development the ones that have the greatest potential for future, rather than present, photosynthesis. It is concluded that a compartmentalized or sectorial distribution of essential substrates can be modified by correlative relations that are probably mediated by hormones.     

Hydroxamic acids in Secale cereale L. and the relationship with their antifeedant and allelopathic properties

Contents of the hydroxamic acids 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA), and 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) in leaves and roots of 14 cultivars of rye, Secale cereale L., were determined. Dynamics of accumulation in three cultivars were evaluated. DIBOA was the main cyclic hydroxamic acid in leaves but the contents differed significantly between the cultivars. Both DIBOA and DIMBOA were present in the roots. Maximum concentration of DIBOA in leaves and DIMBOA in roots was reached between 48-54 h and 54-72 h after germination, respectively. Antifeedant activity of DIBOA towards the aphid Rhopalosiphum padi and the feeding behavior were studied by electronic recording in barley leaves treated with different contents of DIBOA. The deleterious activity of DIBOA could arise by starvation and/or a toxic effect. Additionally, allelopathic potential of pure DIBOA and aqueous extracts of leaves and roots of rye (Tetra-Baer) on the germination of lettuce (Lactuca sativa) and rye (Tetra-Baer) seeds was evaluated. A high percentage of germination inhibition of pure DIBOA and the extracts of leaves and roots was observed. The activity is in agreement with the contents of hydroxamic acids in the plants. The substrates had no allelopathic effect on rye seeds.     

油茶叶片营养元素、叶脉密度及生理指标随树龄变化规律及其与产量的相关性

该研究关注了不同树龄油茶叶片的营养元素含量、叶脉密度及生理指标,旨在了解它们随树龄的变化规律及其对产量的影响。结果表明：(1)不同树龄间金属或稀土元素含量差异显著;大部分元素随树龄的增加表现为先增后减的变化趋势,但不同元素达到最大含量的树龄不尽相同;(2)叶脉呈网络状分布,根据叶脉直径大小分为粗、中、细三个等级;粗、中叶脉密度随树龄的变化不明显,细叶脉密度随树龄呈先增后减变化趋势。(3)叶绿素、MDA、可溶性糖、可溶性蛋白质含量以及POD活性等生理指标均随树龄的变化,表现出各自变化规律。(4)叶绿素含量、POD活性、稀土元素总量以及细叶脉密度与产量表现出明显正相关关系(P<0.05, P<0.01)。该研究结果丰富了油茶的基础资料,可为油茶的栽培与管理提供些许参考,并提示人们可以利用叶片的部分营养、生理、结构指标来跟踪监测植株状态和预测产量。     

UHPLC-Q-Orbitrap HR-MS-Based Metabolomics for Profiling the Sida rhombifolia Metabolites with Different Plant Organs and Cultivation Ages

Plant organs and cultivation ages can result in different compositions and concentration levels of plant metabolites. The metabolite profile of plants can be determined using liquid chromatography. This study determined the metabolite profiles of leaves, stems, and roots of Sida rhombifolia at different cultivation ages at 3, 4, and 5 months post-planting (MPP) using liquid chromatography-mass spectrometry/mass spectrometry (LC/MS/MS). The results identified that 41 metabolites in S. rhombifolia extract for all plant organs and cultivation ages. We successfully identified approximately 36 (leaves), 22 (stems), and 18 (roots) compounds in all extract. Using principal component analysis (PCA) with peak area as the variable, we clustered all sample extracts based on plant organs and cultivation ages. As a result of PCA, S. rhombifolia extracts were grouped according to plant organs and cultivation ages. In conclusion, a clear difference in the composition and concentration levels of metabolites was observed in the leaves, stems, and roots of S. rhombifolia harvested at 3-, 4-, and 5-MPP.     

Catalase activity and isozyme pattern of the metalloenzyme system, superoxide dismutase, as a function of leaf development during growth of Pisum sativum L. plants

The catalase activity and the isozyme pattern of the metalloenzyme system superoxide dismutase (SOD) have been determined in pea ( Pisum sativum L., cv, Lincoln) leaves of different ages (apical, middle and lower), during several stages of plant development. Pea seedlings were grown in full nutrient solution in a phytotron. Catalase activity was determined polarographically, and superoxide dismutase isozymes (Mn-SOD, Cu, Zn-SOD I and Cu, Zn-SOD II) were separated by acrylamide gel electrophoresis and their relative amounts quantified by densitonietry. The results indicate that the relative amounts of SOD isozymes are slightly different in leaves of different ages during plant growth and, interestingly, each molecular form of SOD shows a clearly distinct pattern during plant development. These changes in the relative percentages of SOD isozymes could be due to the induction of the distinct molecular forms of SOD by the metals Mn, Cu and Zn, translocated to the different leaves as a result of plant development. The relative percentage of the Mn-SOD isozyme showed a similar pattern to that of catalase activity, suggesting a possible link between these two metalloenzymes at subcellular level, both cooperating to remove the toxic effects of O^-₂ and H₂O₂.
An additional conclusion is that before a certain metalloenzyme can be used as a marker to assess the plant micronutrient status, it is essential to have a detalled study of its activity pattern in leaves of different age during plant development.     

Variation of DIMBOA and related compounds content in relation to the age and plant organ in maize

We report the variation of all 1,4-benzoxazin-3-one derivatives content detectable in maize with plant age in roots and aerial parts. Our results show that the concentration of hydroxamic acids, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one glucoside (DIMBOA-Glc) and its 8-methoxylated analogue (DIM2BOA-Glc) is high after seed germination and then decreases with plant age. Nevertheless, these compounds continue to be biosynthesised during 6-10 days after germination. Variation in concentration of N-O-methylated DIMBOA-Glc (HDMBOA-Glc) is similar to the one of hydroxamic acids in aerial parts. On the contrary, in roots, its concentration remains relatively stable with plant age. After 10 days, HDMBOA-Glc becomes the main compound in roots. This compound is also present in higher concentration than hydroxamic acids in the oldest leaf of 20-day-old maize. The presence of four other DIMBOA related compounds in maize plants depends on variety, age and tissue. The role of these compounds in plant resistance to aphids is discussed.     

Changes in the hydroxamic acid content of maize leaves with time and after artificial damage; implications for insect attack

The dynamics of hydroxamic acids (Hx) in maize plants were examined, along with the effects on this process of artificial leaf damage. The concentration of Hx in maize (cv. LGH) leaves declined rapidly with age, although young emerging tissue did have relatively high levels. The decline was not entirely due to a growth dilution effect, as the total Hx content in leaves also decreased with age. This effect was less pronounced in isolated leaves. The plant hormone abscisic acid (ABA) accelerated the decline in Hx in isolated maize leaves, while indole acetic acid (IAA) had no apparent effect. Artificial leaf damage on growing plants produced a significant increase in the concentration of Hx relative to undamaged controls. The difference was greatest (about 18%) two days after damage, but seemed to be largely due to a slower rate of decline relative to controls. Isolated maize leaves generally showed a much higher level of increase (20 - 40%). The results are generally consistent with the theory that Hx functions as a defence against insect attack.     

黄土高原子午岭地区人工油松林碳氮磷生态化学计量特征

分析人工植被重建背景下,森林植物、枯落物与土壤的碳(C)、氮(N)、磷(P)化学计量特征有助于深入理解森林生态系统养分循环规律和系统稳定机制。以黄土高原子午岭地区的3个林龄(10、25 a和40 a)的人工油松林为对象,通过测定油松林叶片、枯落物和土壤的碳(C)、氮(N)、磷(P)含量,研究人工油松林不同林龄叶片、枯落物和土壤的化学计量学特征。结果表明,不同林龄油松叶片C、N、P含量分别为538.85—560.54 g/kg、9.00—10.47 g/kg和1.04—1.13 g/kg。在3个林龄油松林中,除叶片C含量外,叶片N、P含量存在显著差异(P0.05);枯落物层以及土壤层的C、N、P含量均存在显著差异(P0.05),且枯落物层含量大于土壤层。随着林龄的增加,叶片C∶N比呈现先减小后增大的变化,N∶P和C∶P比呈显著增加趋势,而枯落物层C∶N、C∶P和N∶P比无显著差异。同时,随着林龄的增加,除10—20 cm土层的C∶N比外,土壤的C∶N比在0—10 cm土层和C∶P和N∶P比在0—10和10—20 cm皆呈显著增加趋势。研究区油松林叶片N∶P比平均值为9.13,低于14,表明油松林生长主要受氮的限制。土壤的N含量与叶片和枯落物层的N含量、以及三者间N∶P比呈显著线性相关(P0.05),充分体现了油松林植物、枯落物与土壤之间的互动关系。研究结果可为我国黄土高原脆弱生态区的生态功能恢复与植被重建提供科学依据。     

Hydroxamic acids affecting barley yellow dwarf virus transmission by the aphid Rhopalosiphum padi

2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), a hydroxamic acid (Hx) occurring in wheat, was shown to deter feeding by the aphid Rhopalosiphum padi (L.), and to reduce BYDV transmission to the plant. Dual choice tests with wheat leaves showed the preferential settlement of aphids on leaves with lower levels of DIMBOA. Electric monitoring of aphid feeding behaviour showed that in seedlings with higher DIMBOA levels fewer aphids reached the phloem and they needed longer times to contact a phloem vessel than in those with lower levels. When aphids carrying BYDV were allowed to feed on wheat cultivars with different DIMBOA levels, fewer plants were infected with BYDV in the higher DIMBOA cultivars than in the lower ones. Preliminary field experiments showed a tendency for wheat cultivars with higher Hx levels to be more tolerant to infection by BYDV than lower Hx level ones.     

Temporal variation of RAPD-PCR phenotype composition of the grain aphid Sitobion avenae (Hemiptera: Aphididae) on wheat: the role of hydroxamic acids

Hydroxamic acids (Hx) contained in wheat are active mutagens which play an important role in the defence of the plant against aphids. Random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) dominant markers were used to assess genetic variability in the aphid Sitobion avenae (Fabricius) in relation to hydroxamic acid levels in their host-plants. Colonies of aphids belonging to a single RAPD-PCR profile were grown on different host-plants differing in their Hx content under greenhouse conditions. The RAPD-PCR phenotypic pattern showed the appearance of two new RAPD-PCR variants after four to five generations of exposure to wheat cv. Chagual (high Hx levels), one after exposure to wheat cv. Huayún (low Hx levels), and none after exposure to oat (lacking Hx). Differential appearance of new RAPD-PCR aphid phenotypes also occurred on field-grown wheat. While the overall phenotypic 'richness' diminished during the season, the number of RAPD-PCR phenotypes decreased on cv. Huayún and increased on cv. Chagual. The preferential appearance in the field and in the greenhouse of new RAPD-PCR phenotypes of S. avenae on cv. Chagual is discussed on the basis of mutagenesis induced by hydroxamic acids and by the products of their transformation within the aphid. Aphid abundance is interpreted in terms of antixenosis and antibiosis by hydroxamic acids. The appearance on cv. Chagual of phenotypes first detected on cv. Huayún was accounted for by intercrop migrations.     

Characterization of polyphenol oxidase changes induced by desiccation of Ramonda serbica leaves

Resurrection plants are able to dehydrate/rehydrate rapidly without cell damage by a mechanism, the understanding of which may be of ecological importance in the adaptation of crop plants to dry conditions. The o -diphenol oxidase in Ramonda serbica Pan. & Petrov, a rare resurrection plant of the Balkan Peninsula, was characterized in respect to different isoforms, preferable substrates and specific inhibitors. Two anionic isoforms with pI 4.6 and 4.7 were separated from turgid leaves. Three additional anionic isoforms (pI 5.1, 5.3 and 5.6) and three neutral isoforms (pI from 6.8 to 7.4) were induced in desiccated leaves. Based on apparent K_m values, the affinity for reducing substrates decreased as follows: methyl catechol > chlorogenic acid > 3,4-dihydroxyphenylalanine > caffeic acid > pyrogallol. Polyphenol oxidase (PPO) activity was specifically sensitive to diethyldithiocarbamate and also inhibited by KCN, DTT and salicylic hydroxamic acid but with no inhibitory effect of Na₃N. Plants were subjected to drought-to-near complete water loss (approximately 2% relative water content, RWC) and several fold higher PPO activity was detected in desiccated leaves. Ramonda leaves contain high levels of phenolics, which decreased during drought. Rehydration of dry leaves from 2% RWC to 95% RWC led to transient inhibition of PPO in the first few hours. Within a day, the levels completely recovered to those determined in desiccated leaves. The finding of desiccation-induced high activity of PPO and new isoforms, which were also present in rehydrated turgid leaves, indicates a substantial role for PPO in the adaptation mechanism of resurrection plants to desiccation and also to the oxidative stress during rehydration.     

Insect Attraction versus Plant Defense: Young Leaves High in Glucosinolates Stimulate Oviposition by a Specialist Herbivore despite Poor Larval Survival due to High Saponin Content

Glucosinolates are plant secondary metabolites used in plant defense. For insects specialized on Brassicaceae, such as the diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), glucosinolates act as “fingerprints” that are essential in host plant recognition. Some plants in the genus Barbarea (Brassicaceae) contain, besides glucosinolates, saponins that act as feeding deterrents for P. xylostella larvae, preventing their survival on the plant. Two-choice oviposition tests were conducted to study the preference of P. xylostella among Barbarea leaves of different size within the same plant. P. xylostella laid more eggs per leaf area on younger leaves compared to older ones. Higher concentrations of glucosinolates and saponins were found in younger leaves than in older ones. In 4-week-old plants, saponins were present in true leaves, while cotyledons contained little or no saponins. When analyzing the whole foliage of the plant, the content of glucosinolates and saponins also varied significantly in comparisons among plants that were 4, 8, and 12 weeks old. In Barbarea plants and leaves of different ages, there was a positive correlation between glucosinolate and saponin levels. This research shows that, in Barbarea plants, ontogenetical changes in glucosinolate and saponin content affect both attraction and resistance to P. xylostella. Co-occurrence of a high content of glucosinolates and saponins in the Barbarea leaves that are most valuable for the plant, but are also the most attractive to P. xylostella, provides protection against this specialist herbivore, which oviposition behavior on Barbarea seems to be an evolutionary mistake.