Effects of Short-term Red Radiation and Choline Compounds on Cytokinin Content, Chlorophyll Accumulation and Photomorphogenesis in Wheat Seedlings

Effects of choline compounds (2-chloroethyltrimethylammonium chloride and 2-ethyltrimethylammonium chloride) as well as red radiation (R) pulse on the dynamics of cytokinin changes, growth and chlorophyll (a + b) accumulation were studied during the growth and greening of etiolated wheat seedlings (Triticum aestivum L., var. Mironovskaya-808). The seedlings were grown for 120 h in the dark and then exposed for 72 h to white light. Pre-treatment of caryopses with cholines and pre-irradiation of etiolated seedlings with R inhibited elongation of both coleoptile and first leaf; but the same factors accelerated these growth responses when seedlings were exposed to white light. Chlorophyll (Chl) accumulation and the first leaf appearance from coleoptile were accelerated by the pre-treatments as well. Far-red radiation (FR) reversed all effects of R but choline pre-treatment eliminated partly R/FR photoreversibility. Two compounds with high cytokinin activity (tested on a fresh weight basis by the bioassay with Amaranthus caudatus L.) were found in shoots and first leaves. One of them had R_f, UV absorbance spectrum and the biological activity similar to N⁶-(Δ²-isopentenyl)adenosine. Another cytokinin-like substance was not identified with the used standards. Stimulation of greening by R pulse and cholines was accompanied with accelerated accumulation of both cytokinin-like substances. We conclude that the influence of R and cholines on the concentration of substances with cytokinin activities detected in the leaves might be involved in the stimulation of Chl accumulation.     

小麦籽粒干物质积累的动态QTL定位

以波兰小麦品系‘XN555’与普通小麦品系‘中13’杂交产生的99个F10重组自交系(RILs)为材料,构建了包含241个SSR分子标记的A、B染色体组14个连锁群的遗传图谱,并采用Logistic方程拟合籽粒灌浆过程,对粒重增长的缓慢增长期、快速增长期和平稳期进行千粒重条件QTL和非条件QTL定位分析。结果显示:(1)在小麦A、B染色体组上共检测到5个非条件QTL和5个条件QTL。(2)在小麦粒重缓慢增长期和快速增长期各有2个非条件QTL,平稳期有1个非条件QTL,它们分别位于2B、3A、3B和7A染色体上,单个QTL可解释表型变异的9.66%～15.18%。(3)在小麦粒重快速增长期检测到1个条件QTL,平稳期检测到4个条件QTL,涉及1A、2B、5B和7B染色体,单个QTL可解释表型变异的13.01%～29.27%。(4)于2B染色体Xbarc361～Xwmc422标记区间距Xbarc361标记0.05cM处,在粒重快速增长期同时检测到一个条件QTL和非条件QTL,且在平稳期检测到一个非条件QTL。研究表明,小麦不同灌浆时期粒重增长相关QTL的数量和遗传效应各不同,同一QTL在不同灌浆时期的遗传效应也不同,即QTL的表达具有时序选择性。     

Effects of Storage Temperature and Wounding on Cytokinin Levels in Potato Tubers

The level of butanol-soluble cytokinin in potato tubers (Solanumtuberosum L.) decreased greatly after harvest of the tubers,remained low during rest-period and then began to increase priorto the end of the period. In warm-stored tubers (25?C) the levelrose faster than in cold-stored ones (4?C). On the other hand,the level of water-soluble cytokinin, which was high duringthe rest-period, decreased after the rest was broken. Wounding the tubers caused an increase in butanol-soluble cytokinin.The increase in cytokinin within the first 24 hr after woundingwas smaller in warm-stored tubers than in cold-stored ones andwas decreased with increasing storage time of the tubers. Thelevel of water-soluble cytokinin decreased by wounding. Theseresults suggest that water-soluble cytokinin is a storage formand that the level of butanol-soluble cytokinin is regulatedby an interconversion between the two. (Received February 6, 1982; Accepted May 13, 1982)     

亚硒酸钠对矮脚黄白菜农药残留和重金属积累的影响

采用盆栽试验考察了不同浓度和pH的亚硒酸钠溶液对矮脚黄白菜啶虫脒残留和重金属积累的影响。结果表明,亚硒酸钠溶液在浓度为1 mg/L且pH 7.0时对矮脚黄白菜促生效果显著优于对照和其它处理,叶绿素含量最高;在5 mg/L且pH 6.5时,啶虫脒和重金属Cd、Pb含量均显著下降;浓度为10 mg/L时对降低重金属含量的效果不明显。本研究表明,亚硒酸钠在降低植物农药残留和重金属积累方面具有一定的应用潜力。     

干旱与氧化胁迫对小麦根氧化还原状态和叶片ABA积累的影响

通过分析一氧化氮(nitric oxide,NO)、活性氧(reactive oxygen species,ROS)和干旱胁迫对小麦根氧化还原状态和叶片脱落酸(abscisic acid,ABA)积累的影响,探讨了干旱胁迫下NO和H2O2调节ABA合成的可能机制。结果表明:干旱胁迫处理初期小麦根还原型谷胱甘肽含量降低、抗氧化酶活性发生振荡变化,细胞氧化还原状态向氧化型转变。NO和H2O2能模拟干旱胁迫的作用使细胞状态向氧化型转变,还可以使小麦叶片ABA积累量上升。干旱胁迫下NO和H2O2对ABA合成的调节作用可能是通过调节细胞氧化还原状态进行。     

Effects of Low Temperature on Growth and Nutrient Accumulation in Rye (Secale cereale) and Wheat (Triticum aestivum)

Rye (Secale cereale cv. Rheidol) and wheat (Triticum aestivumcv. Mardler) were grown at shoot/root temperatures of 20/20°C (warm grown, WG plants), 8/8 °C (cold grown, CG plants)and 20/8 °C (differential grown, DG plants). Plants fromcontrasting growth temperature regimes were standardized andcompared using a developmental timescale based on accumulatedthermal time (°C d) at the shoot meristem. Accumulationof dry matter, nitrogen and potassium were exponential overthe time period studied (150–550 °C d). In rye, therates of plant dry matter and f. wt accumulation were linearlyrelated to the temperature of the shoot meristem. However, inwheat, although the rates of plant dry matter and f. wt accumulationwere temperature dependent, the linear relationship with shootmeristem temperature was weaker than in rye. The shoot/rootratio of rye was stable irrespective of growth temperature treatment,but the shoot/root ratio of wheat varied with growth temperaturetreatment. The shoot/root ratio of DG wheat was 50% greaterthan WG wheat. In both cereals, nutrient concentrations anddry matter content tended to be greater in organs exposed directlyto low temperatures. The mean specific absorption rates of nutrientswere calculated for the whole period studied for each species/temperaturecombination and were positively correlated with both plant shoot/rootratio and relative growth rate. The data suggest that nutrientuptake rates were influenced primarily by plant demand, withno indication of specific nutrient limitations at low temperatures. Nutrient accumulation, relative growth rate (RGR), rye, Secale cereale cv. Rheidol, temperature, thermal time, Triticum aestivum cv. Mardler, wheat     

Effects of Temperature on Photosynthesis by Maize and Wheat

Maize and wheat plants were grown in controlled environmentswith day temperatures of 13, 18, 23, or 28 ?C. Leaves from maizegrown at 23 ?C photosynthesized faster than leaves from maizegrown at 13 or 18 ?C and, except when measured at 28 ?C, fasterthan leaves from maize grown at 28 ?C;leaves of maize grownat13 ?C were yellow and photosynthesized at insignificant rates.Leaves from wheat grown at 18 ? or 13 ?C had faster rates ofphotosynthesis than leaves from wheat grown at 23 or 28 ?C.The best rates for maize were faster than the best rates forwheat when the measurements were made at 23 or 28 ?C but at13 or 18 ?C the best rates for maize were not significantlybetter than the best rates for wheat. Leaves of maize that developedin the environment with 23 ?C as the day temperature did notrapidly lose their green colour when transferred to the environmentwith the day temperature of 13 ?C and the rate of photosynthesisof these leaves did not decline rapidly. However, new leavesexpanding in the cooler conditions were yellow and not effectivein photosynthesis. At 13 or 18 ?C maize, a C4 plant, which photorespiresslowly, did not photosynthesize more effectively than wheat,which photorespires rapidly. The maize did not produce its mosteffective leaves at 13 or 18 ?C and its optimum temperaturefor photosynthesis was 23?C or higher. It may therefore be consideredill-adapted to the temperate climate.     

Anthocyanin Accumulation Mediated by Blue Light and Cytokinin in Arabidopsis Seedlings

It has been reported that pigmentation In plants Is stimulated by light and cytoklnln （CTK）; however, the signaling pathways and the relationship between light and CTK Involved In the regulation of anthocyanln accumulation remain to be elucidated. We Investigated （i） the role of blue light （BL） and CTK In anthocyanln accumulation ; and （ii） the relationship between BL and CTK In wild type （WT） and by4 mutants of Arabidopsis thaiiana. Two-d-old seedlings grown on medium with or without klnetln （KT） or zeatln （ZT） In darkness were Irradiated using BL at different fluence rates for 3 d before the anthocyanln content was determined using a spectrophotometrlc method. Anthocyanln accumulation was strongly Induced by BL In WT seedlings but not In hy4 seedlings, which demonstrated that CRY1 Is the main photoreceptor for BL. Both KT and ZT enhanced the response of the WT seedlings to BL In a dose-dependent manner, whereas they were not sufficient to promote anthocyanln eccumulatlon In darkness. In addition, data from experiments using the hy4 mutant showed that the CTK effect of BL was also CRYl-dependent. The results from experiments with three different treatment programs showed that the relationship between BL and KT In anthocyanln accumulation of Arabidopsis seedlings seems neither muItlpllcatlve nor additive coactlon, but rather Interaction. BL Is necessary for anthocyanln accumulation, and KT might be Involved In the BL signaling pathway.     

Effects of Low Temperature on Winter Wheat and Cabbage Leaves

Contents of soluble proteins, proline and chlorophyll in winter wheat (Triticum aestivum cv. Doğu-88) and cabbage leaves (Brassica oleracea convar. acephala) during acclimation to low temperature were investigated. When both of the plants species were cold acclimated, soluble proteins, proline and chlorophyll contents were higher than in the controls (non-acclimated). Also protein patterns differed between the plants at control and cold conditions. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Control of Growth Habit of Marquillo x Kenya Farmer Wheat Dwarf I by Temperature

The Marquillo × Kenya Farmer 1 “grass-clump” dwarf selection of Triticum aestivum L. was grown under continuous 2000 foot candle light and several regimes of alternating 16° and 26° temperatures combined in total cycle lengths of 6, 12, 24, or 48 hr. Plants at 26° grew as normal wheat. Those exposed to 0.25 to 2 hr of 16° per cycle showed typical “grass-clump” dwarf characteristics which were independent of the cycle length. Treatments with 16° exposures of 4 to 8 hr per 24 hr and 12 to 16 hr per 48 hr exhibited vegetative “grass-clump” dwarfness for 40 days but later displayed extensive reproductive development. Longer 16° treatments killed the plants at a very early stage of vegetative development before floral initiation. The data supported an hypothesis that all 4 growth habits were related to the temperature sensitivity of the vegetative meristem. The cessation of meristem development was possibly due to the accumulation of a stable inhibitory substance produced at low temperatures.     

矮败蓝标型小麦不育系的选育与研究

利用蓝粒太谷核不育硬粒小麦89-2343[AABB 4D(MS2)/4E]与普通小麦7739-3(2n=42)杂交、回交所产生的蓝粒可育株与白粒矮败材料杂交、回交,育成了一份矮败蓝粒小麦.选用13份遗传背景不同的白粒普通小麦与之杂交、回交,育成了13份矮败蓝粒小麦.对后代的粒色和育性分离进行分析,蓝粒矮败不育株占22.1%,白粒非矮秆可育株占77.7%,表明蓝粒基因、Ms2和Rht10均位于附加染色体上,且连锁紧密;但不同轮回亲本,矮败蓝粒的传递率有差异,477A的传递率最高,接近50%.细胞学分析表明矮败蓝粒小麦仍为单体附加系;探讨了矮败蓝粒小麦在群体改良和杂种小麦生产中的应用.     

Effect of Water Deficit on Accumulation of Dry Matter, Carbon and Nitrogen in the Kernel of Wheat Genotypes Differing in Yield Stability

Water stress effects on accumulation of dry matter, carbon andnitrogen in grains were analysed in varieties and species ofwheat differing in yield stability. Variable water environmentswere generated using a line source sprinkler system. Althoughlarge fluctuations occurred in the water potentials of the flagleaf and ear, grain growth remained relatively buffered undermoisture stress. Developing grains were at a lower moisturelevel throughout grain growth in plants subjected to moisturestress relative to the unstressed plants. Carbon content decreasedmore than the nitrogen content in the stressed grains of thespecies and varieties. Reduction in the duration of grain growthand the rate of dry weight accumulation induced by water stresswas more prominent in T. aestivum var. C306 and T. sphaerococcum.Grain yield was reduced significantly under water stress, themaximum being in the high yielding cultivar HD2329. Both grainnumber and grain weight were reduced in response to stress,the extent of reduction being different in different genotypes.Copyright1994, 1999 Academic Press Water deficit, yield stability, C and N accumulation, heat degree days     

Methyl Jasmonate and Cytokinin Mitigate the Salinity-Induced Oxidative Injury in Wheat Seedlings

Journal of Plant Growth Regulation - Application of methyl jasmonate (MeJA) has been shown to be effective in improving plant tolerance to various environmental stresses. Present research was...     

Comparative Genome Analysis of Wheat Blue Dwarf Phytoplasma,an Obligate Pathogen That Causes Wheat Blue Dwarf Disease in China

Wheat blue dwarf (WBD) disease is an important disease that has caused heavy losses in wheat production in northwestern China. This disease is caused by WBD phytoplasma, which is transmitted by Psammotettix striatus. Until now, no genome information about WBD phytoplasma has been published, seriously restricting research on this obligate pathogen. In this paper, we report a new sequencing and assembling strategy for phytoplasma genome projects. This strategy involves differential centrifugation, pulsed-field gel electrophoresis, whole genome amplification, shotgun sequencing, de novo assembly, screening of contigs from phytoplasma and the connection of phytoplasma contigs. Using this scheme, the WBD phytoplasma draft genome was obtained. It was comprised of six contigs with a total size of 611,462 bp, covering ∼94% of the chromosome. Five-hundred-twenty-five protein-coding genes, two operons for rRNA genes and 32 tRNA genes were identified. Comparative genome analyses between WBD phytoplasma and other phytoplasmas were subsequently carried out. The results showed that extensive arrangements and inversions existed among the WBD, OY-M and AY-WB phytoplasma genomes. Most protein-coding genes in WBD phytoplasma were found to be homologous to genes from other phytoplasmas; only 22 WBD-specific genes were identified. KEGG pathway analysis indicated that WBD phytoplasma had strongly reduced metabolic capabilities. However, 46 transporters were identified, which were involved with dipeptides/oligopeptides, spermidine/putrescine, cobalt and Mn/Zn transport, and so on. A total of 37 secreted proteins were encoded in the WBD phytoplasma chromosome and plasmids. Of these, three secreted proteins were similar to the reported phytoplasma virulence factors TENGU, SAP11 and SAP54. In addition, WBD phytoplasma possessed several proteins that were predicted to play a role in its adaptation to diverse environments. These results will provide clues for research on the pathogenic mechanisms of WBD phytoplasma and will also provide a perspective about the genome sequencing of other phytoplasmas and obligate organisms.     

旱地小麦休闲期覆盖增磷对籽粒蛋白质积累的影响

为探索旱地小麦休闲期覆盖保水配施磷肥高产、优质的技术途径,在山西农业大学闻喜试验基地采用大田试验研究了休闲期覆盖或不覆盖条件下低(75 kg/hm2)、中(112.5 kg/hm2)、高(150 kg/hm2)施磷水平对土壤水分、籽粒蛋白质形成的影响及其生理机制。结果表明:休闲期覆盖后,播种期0-100 cm土壤蓄水量显著提高,达39-42 mm,而开花期60-100 cm土层降低。覆盖后,花后旗叶和籽粒GS和GOGAT活性提高,籽粒游离氨基酸和灌浆后期GMP含量提高,籽粒蛋白质及其组分含量、谷/醇均提高。增加施磷量,开花期20-60 cm、80-100 cm土层蓄水量降低,而花后旗叶和籽粒GS活性提高,且覆盖条件下花后0-15 d、20 d旗叶GOGAT活性,花后5 d、15 d、25-30 d籽粒GOGAT活性,籽粒游离氨基酸含量、籽粒GMP含量提高,籽粒蛋白质及其组分含量、谷/醇、蛋白质产量显著提高,产量提高940-1452 kg/hm2。此外,休闲期覆盖配施磷肥条件下,开花期深层土壤水分与旗叶GS和GOGAT活性密切相关,旗叶和籽粒GS和GOGAT活性均与游离氨基酸含量、谷/醇、蛋白质产量关系密切。总之,旱地小麦休闲期覆盖有利于提高底墒,且配合施磷量150 kg/hm2可促进根系吸收深层土壤水分,提高产量的同时也提高了籽粒蛋白质含量、GMP含量和谷/醇。     

Effects of Cytokinin Preparations on the Pools of Pigments and Proteins of Wheat Cultivars Differing in Their Tolerance to Water Stress

Contents of chlorophylls, carotenoids, soluble leaf proteins, and the key enzyme of carbon metabolism—ribulose bisphosphate carboxylase/oxygenase (RuBisCO; EC 4.1.1.39)—in young seedlings and adult leaves of the wheat Triticum aestivum L. cultivars Mironovskaya 808 and Lyutescens 758, contrasting in their water stress tolerances, were compared under conditions of normal available water supply, water deficiency, and subsequent rehydration. It was discovered that compounds displaying a cytokinin activity (6-benzylaminopurine, thidiazuron, kartolin-2, and kartolin-4) reduced the decreases in contents of chlorophylls, carotenoids, soluble leaf proteins, and RuBisCO, progressing with development of water stress, as well as contributed to their more rapid recovery. These compounds with cytokinin activity also accelerated restoration of the compounds studied to their initial concentrations during rehydration. The kartolin preparations caused a maximal protective effect. Water stress had a more pronounced negative effect on the cultivar Lyutescens 758. Dehydration resulted in a more extensive destruction of seedlings compared to leaves of adult plants.     

Effects of Cytokinin Preparations on the Stability of the Photosynthetic Apparatus of Two Wheat Cultivars Experiencing Water Deficiency

Carboxylase activity of the key enzyme of carbon metabolism, ribulose-bisphosphate carboxylase/oxygenase (RuBisCO; EC 4.1.1.39), and phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31), as well as the intensity of carbon dioxide photosynthetic assimilation in young seedlings and adult leaves of the wheat Triticum aestivum L. cultivars Mironovskaya 808 (a more tolerant) and Lyutestsens758 (a less tolerant), were compared under conditions of progressive water deficiency. The water stress had more pronounced negative effects on all the studied characteristics of the photosynthetic apparatus of the cultivar Lyutestsens758. Its seedlings were more sensitive to water stress. Compounds with a cytokinin activity (6-benzylaminopurine, thidiazuron, kartolin 2, and kartolin 4) played a protective role, increasing the stability of the photosynthetic apparatus under conditions of water deficiency. Preparations of kartolins displayed the maximum protective effect.