Glutamine Synthetase Activity and Foliar Nitrogen Volatilization in Response to Temperature and Inhibitor Chemicals

In soyabeans (Glycine max (L.) Merr.), glutamine synthetase(GS) activity was greater at 28 °C than at 35 °C. Thereverse was true for foliar-N loss. In field-grown plants at29 °C, the GS activity was higher and foliar-N loss waslower in soyabeans than in Amaranthus palmeri (S.) Wats. Methioninesulphoximine, a GS inhibitor, and 6-diazo-5-oxo-L-norleucine,a glutamate synthase inhibitor, significantly increased foliar-Nloss from soyabeans. The data suggest that conditions conduciveto decreased GS or glutamate synthase activity may result inincreased foliar-N loss. Palmer amaranth, Amaranthus palmeri, soyabean, Glycine max, methionine sulphoximine, 6-diazo-5-oxo-L-norleucine     

Temperature Response of Vernalization in Wheat: A Developmental Analysis

The vernalization response of wheat ( Triticum aestivum L.)was reinterpreted from a developmental perspective, using currentconcepts of the developmental regulation of wheat morphologyand phenology. At temperatures above 0 °C, the effects ofthe process of vernalization per se in wheat are confoundedby the effects of concurrent vegetative development. These effectsare manifested by differences in the number of leaves initiatedby the shoot apex prior to floral initiation, which in turnaffects the subsequent rate of development to ear emergenceand anthesis. Leaf primordia development during vernalizationand total leaf number at flowering were used to develop criteriato define both the progress and the point of saturation of thevernalization response. These criteria were then used to reinterpretthe results of Chujo ( Proceedings of the Crop Science Societyof Japan 35 : 177–186, 1966), and derive the temperatureresponse of vernalization per se for plants grown under saturatinglong day conditions. The rate of vernalization increased linearlywith temperature between 1 and 11 °C, such that the timetaken to saturate the vernalization response decreased from70 d at 1 °C to 40 d at 11 °C. The rate declined againat temperatures above 11 °C, and 18 °C was apparentlyineffective for vernalization. Total leaf number at saturation,however, increased consistently with temperature, as a resultof the balance between the concurrent processes of leaf primordiuminitiation and vernalization. Total leaf number at saturationincreased from 6 at 1 °C to 13.3 at 15 °C, which inturn influenced the time taken to reach ear emergence. The advantagesof using this developmental interpretation of vernalizationas the basis for a mechanistic model of the vernalization responsein wheat are discussed. Triticum aestivum L.; wheat; vernalization; rate; temperature; primordia; leaf number; flowering     

叶面喷施茉莉酸甲酯对马铃薯微型薯生长及产量的影响

以‘云薯505’马铃薯(Solanum tuberosum ‘Yunshu 505’)为材料,测定马铃薯块茎发育初期四个阶段茉莉酸含量,并以叶面喷施方式,研究茉莉酸甲酯对马铃薯生长和块茎产量的影响。结果表明,马铃薯块茎膨大过程中,茉莉酸的积累水平不断升高。在微型薯生产中,使用100 μmol·L^-1茉莉酸甲酯在结薯期以不同频率喷施叶面,测量并统计植株、块茎性状及产量变化。结果表明,与对照(CK)相比,1次·d^-1处理茎粗增加36.1%,2次·d^-1处理的叶绿素含量降低20.1%。此外,植株的叶色、茎色、花色、株型等生长性状及块茎大小整齐度、薯形、皮色、肉色、薯皮类型、芽眼深浅、裂薯率、大薯空心率等块茎性状在各组间没有显著差异。2次·d^-1、1次·d^-1、1次·2d^-1、CK四种处理的植株存活率分别为45.57%、100.00%、100.00%、87.29%;前三种喷施频率处理折合产量较CK分别增加-15.61%、8.77%、12.11%。综合分析,马铃薯在块茎形成初期茉莉酸积累水平不断升高,以1次·2d^-1频率叶面喷施100 μmol·L^-1茉莉酸甲酯,马铃薯微型薯的产量增加最大且不影响生长。     

马铃薯HSP17.7基因的克隆及其对高温逆境的响应

热激蛋白和植物对高温的响应密切相关,同时在植物生长发育调控和逆境抵抗等方面具有重要作用。该研究克隆了马铃薯热激蛋白基因StHSP17.7(GenBank登录号为XP_006350804.1),对其全长cDNA序列进行了相关生物信息学分析,并利用qRT-PCR分析StHSP17.7基因在高温胁迫下的差异表达特性。结果显示:(1)StHSP17.7全长755bp,包含465bp开放阅读框,编码154个氨基酸。(2)StHSP17.7分子质量约为17.62kD,等电点7.91,为亲水性蛋白,C端含有保守序列Ⅰ和Ⅱ组成的ACD结构域,属于典型的sHSPs家族成员。(3)系统进化分析发现马铃薯小分子热激蛋白归为12个亚家族,其中StHSP17.7与马铃薯HSP17.6蛋白亲缘关系较近,属于小分子热激蛋白C的Ⅰ类家族成员;基因结构分析显示,在马铃薯48个sHSP基因中,StHSP17.7基因不含内含子,含1个内含子的基因有23个,占47.9%。(4)qRT-PCR分析显示,高温能够快速诱导StHSP17.7基因表达,且基因表达量呈爆发式变化,在24h达到最高值。研究表明,StHSP17.7基因明显参与了马铃薯对高温的响应。     

Response of Winter Wheat Seedlings Respiration to Long-Term Cold Exposure and Short-Term Daily Temperature Drops

Russian Journal of Plant Physiology - The effects of a long-term (6-day) exposure to low positive temperature (4°С, LT treatment) and short-term (3 h per a day for 6 days) daily...     

冬季小麦叶片光合作用对温度响应方式的变化

冬季田间生长的小麦离体叶片净光合速率（Ｐｎ）对温度的响应有两种方式。在１２月上旬可以观测到第一种方式。在离体叶片周围空气温度从１０℃逐步升到３０℃后的１ｈ内Ｐｎ逐渐升高,在随后气温逐步降低到１０℃的过程中,Ｐｎ都比先前升温过程中同样温度下的数值高。３０℃下叶片胞间ＣＯ２浓度（Ｃｉ）降低和叶片无机磷含量增高表明,这种响应方式可能起因于一些光合碳同化酶活性的增高。在１２月中旬以后可以观测到第二种方式。Ｐｎ在３０℃下的１ｈ内逐步下降,在随后的降温过程中Ｐｎ都比升温过程中同样温度下的数值低。３０℃下叶片Ｃｉ和膜透性增高表明,这种响应方式可能是适应冬季低温的光合机构膜系统在高温下遭受破坏的结果。     

Leaf Expansion in the Potato, Solanum tuberosum

The effects of a number of manipulative treatments together with the application of the growth hormones IAA and GA on leaf expansion in the potato, variety Majestic, were investigated. It was found that removal of the apex and its surrounding non-expanded leaves resulted in an increase in both the rate and the extent of expansion of Ihe remaining upper leaves on the system. Application of IAA and GA to decapitated shoots showed that the rate of leaf expansion was decreased by IAA both alone and in combination with GA, whereas it was increased by GA treatment. Further investigations indicated that the response of a leaf to GA treatment was determined by the area and position of the leaf al the time of treatment and also by the number of expanding leaves on the system. It is postulated that this is due, at least in part, to competition for some factor or factors, which could be nutrients, within the system.     

Wheat Streak Mosaic Virus-induced Cytoplasmic Expansion and Membrane Proliferation

The cytoplasmic volume of wheat streak mosaic virus-infected cells was significantly greater than that of cells in healthy control tissue. Ultrastructural examination revealed that mainly cellular membranes and ribosomes filled the expanded cytoplasm. Imperfectly spherical inclusions, containing continuous endoplasmic reticulum membranes at the periphery and a mixture of membranes and ribosomes in the centre, were observed near nuclei at early infection stages. The inclusions became larger as infection progressed. Membranes and ribosomes proliferated also throughout the cell, forming a matrix in which organelles and various cytopathic structures were enclosed. Numerous vesicles were observed in the cytoplasm of other WSMV-infected cells. Multi-layered membrane bodies were found at later infection stages. Virus particles were present in the central space of these myelin-like structures. The presence of apparently intermediate stages in myelin-like structure development in chloroplasts suggest that at least some of the myelin-like structures originated from the chloroplasts.     

Improving Winter Wheat Performance by Foliar Spray of ABA and FA Under Water Deficit Conditions

Foliar spray of antitranspirants triggered plant adaptations to water stress and reduced the negative effects of drought on crop production. This study characterized the influence of exogenous abscisic acid (ABA) and fulvic acid (FA) application on winter wheat (Triticum aestivum L.) by pot experiment during 2012–2013 season and field experiment during 2012–2013 and 2013–2014 seasons in the North China Plain. In the pot experiment, plants were sprayed with FA or ABA under three irrigation levels (deficit, moderate deficit, and full irrigated). Field experiments involved three parts, including concentration and frequency of ABA application as well as the combined application of ABA and FA. Results showed that, compared with non-treated wheat grown under moderate deficit condition, both ABA and FA influenced the biomass allocation above and below ground, which caused the increase in crop harvest index as well as water use efficiency. By analyzing wheat performances in grain yield and transfer ratio of total assimilate (TRA) under different ABA concentrations (ranged from 30 to 60 mg/L) as well as ABA application frequencies (two, three, and four applications), results indicated that ABA worked well with lower concentration and less application frequency. At the heading stage of wheat, spraying FA improved the non-structural carbohydrate content (NCS) in plants. ABA application at the early grain-fill stage decreased residual NCS. In water deficit conditions, combined application of FA (at the heading stage) and ABA (at the early grain-fill stage) significantly improved the TRA and yield performance, and worked better than using separately.     

Temperature Response of Vernalization in Wheat: Modelling the Effect on the Final Number of Mainstem Leaves

This paper outlines a modelling approach which predicts theeffect of both continuous and intermittent low temperature regimeson the final number of leaves in winter wheat. The model takesaccount of the balance between the concurrent processes of leafprimordium initiation and rate of saturation of vernalization,and their response to temperature. The inverse of the time tosaturation of vernalization, at which stage final leaf numberis set, is modelled as a linear function of vernalizing temperature,between 0 and 17 °C. The rate of leaf primordium initiationis modelled using the established linear relationship betweenrate and temperature above 0 °C. Final leaf number is hencethe product of the number of leaf primordia initiated once vernalizationis saturated. In the model, genotypes are characterized by (1)the slope and intercept of the linear response of the rate ofsaturation of vernalization to temperature in the vernalizingrange, and (2) by a development rate towards floral transitionat on-vernalizing temperatures (above 17 °C). The modelis tested against data from experiments where six cultivarsof winter wheat plants of different ages were exposed to a rangeof low temperature regimes, including continuous and intermittentvernalizing temperatures. Overall, the model predicted, withr ²values of 70–90%, the final leaf number across a rangeof six to 21 leaves. Prediction of final leaf number for somecultivars was better in continuous than in intermittent vernalizingregimes. This modelling approach can explain the often-conflictingreports of the effectiveness of different temperatures for vernalization,and the interaction of plant age and vernalization effectiveness. Triticum aestivum L.; wheat; vernalization; rate; temperature; leaf number; modelling; phenology; flowering     

Bean Leaf Expansion in Relation to Temperature

When dwarf Phaseolus vulgaris plants were grown in a controlledenvironment at 20, 25, 30, and 35° C, expansion of the primaryleaves occurred in two phases with an intermediate lag. Varyingrates and duration of expansion were involved, leading to greatestfinal areas at the two intermediate temperatures. Dry weightsof the leaves and leaf areas were similary influenced by temperature,except that the initial rates of increase continued for a longerperiod for weights than for areas. The rates of cell divisionand final numbers of cells were similar from 25 to 35° C,but both were decreased at 20° C. Final cell sizes were,on the other hand, decreased only at the highest temperature.The time trends of cell expansion varied greatly with temperature. Leaf expansion is discussed as a possible consequence of substratesupply, which may be determined by temperature in a number ofways. Cell division and cell expansion are not considered tobe joint direct determinants of leaf expansion. Temperatureinfluences division, with two consequences; the rate interactswith substrate supply to determine size of cells, and finalcell number affects potential leaf area. Cell size is regardedas being secondary to numbers of cells and total material available,although some factors can vary cell size independently of substrate,e.g. water status. An important control of leaf growth, until the attainment ofabout half the final area, may be exercised by way of the leaf.Subsequently, intra-plant competition is likely to dominate.     

Preformed Messenger RNAs and Early Wheat Embryo Germination

Wheat (Triticum aestivum L.) embryo homogenates have been fractionated into three cell fractions from which RNA was extracted and assayed for mRNA content by in vitro translation and by [³H]polyuridylic acid hybridization. In dry embryos the preformed mRNAs are distributed equally between a rapidly sedimenting “pellet” fraction and a cytoplasmic “ribosomal/subribosomal” fraction. During germination 25 to 40% of the total mRNA becomes polyribosomal. The remaining 60 to 75% is retained in the pellet and ribosomal/subribosomal fractions.     

The Effects of Temperature on the Susceptibility of Potato Plants to Infection and Accumulation of Potato Leafroll Virus

Temperature both before and after aphid inoculation with potato leafroll virus (PLRV) greatly influenced the susceptibility of potato plants to infection and virus accumulation, as evaluated with ELISA using cultivars with different ratings for the resistance to PLRV. Pre-incubation at 15 compared to 27 °C increased the susceptibility of plants to infection and a subsequent PLRV accumulation. The virus was detected by ELISA in a greater proportion of plants and reached a higher concentration, when the plants were kept at 27 than at 15 °C after inoculation. The mean ELISA values obtained with PLRV-infected plants in the 15/27 combination of the pre-/post-inoculation temperatures over the period 1—6 wks after inoculation were significantly higher than those in the 27/27, 15/15 and 27/15 treatments, and the values obtained in the 27/27 treatment were significantly higher than those in the 15/15 and 27/15 ones. A hypersensitive-like intolerance reaction to PLRV occurred in the resistant cv. Irga only in the plants kept at 27 °C after inoculation.     

Management of Lesion Nematodes and Potato Early Dying with Rotation Crops

Soil-incorporated rotation/green manure crops were evaluated for management of potato early dying caused by Verticillium dahliae and Pratylenchus penetrans. After two years of rotation/green manure and a subsequent potato crop, P. penetrans numbers were less after ‘Saia’ oat/‘Polynema’ marigold, ‘Triple S’ sorghum-sudangrass, or ‘Garry’ oat than ‘Superior’ potato or ‘Humus’ rapeseed. The area under the disease progress curve (AUDPC) for early dying was lowest after Saia oat/marigold, and tuber yields were greater than continuous potato after all crops except sorghum-sudangrass. Saia oat/marigold crops resulted in the greatest tuber yields. After one year of rotation/green manure, a marigold crop increased tuber yields and reduced AUDPC and P. penetrans. In the second potato crop after a single year of rotation, plots previously planted to marigolds had reduced P. penetrans densities and AUDPC and increased tuber yield. Rapeseed supported more P. penetrans than potato, but had greater yields. After two years of rotation/green manure crops and a subsequent potato crop, continuous potato had the highest AUDPC and lowest tuber weight. Rotation with Saia oats (2 yr) and Rudbeckia hirta (1 yr) reduced P. penetrans and increased tuber yields. AUDPC was lowest after R. hirta. Two years of sorghum-sudangrass did not affect P. penetrans, tuber yield or AUDPC. These results demonstrate that P. penetrans may be reduced by one or two years of rotation to non-host or antagonistic plants such as Saia oat, Polynema marigold, or R. hirta and that nematode control may reduce the severity of potato early dying.     

Effects of Temperature and Photoperiod on Assimilate Partitioning in Potato Plants

The effects of temperature and photoperiod on d. wt partitioningand ¹⁴C translocation were studied in three potato varieties.High temperatures and long days enhanced plant growth in termsof plant height and number of leaves, and also affected d. wtpartitioning between the plant organs. However, no temperatureeffect was noted on total plant d. wt, nor on the export of¹⁴C from the source leaf. Translocation of ¹⁴C to the vegetativeorgans (leaves and stems) was greater at higher temperatures,while translocation to the tubers was less under these conditions.We suggest that, under the temperature regimes studied, themain effect of high temperature is on assimilate partitioningand not on total plant productivity. Differences in responseto high temperatures were observed among varieties, with Norchipshowing the least and Up-to-Date showing the most sensitivity. High temperature, partitioning of assimilates, ¹⁴C-translocation, potato, Solanum tuberosum var. Desirèe, Solanum tuberosum var. Norchip, Solanum tuberosum var. Up-to-Date     

Effect of Temperature on Carbohydrate Metabolism in Potato Plants

The effect of temperature on partitioning of newly fixed ¹⁴Cbetween the various carbohydrate fractions was studied in differentplant organs of three potato varieties. Incorporation of ¹⁴Cinto starch in the tubers was reduced at high temperatures,but the amount of labelled sucrose increased. In all varietiesthe incorporation of ¹⁴C into the cell wall components in theapex of the plant and in the stem, as well as its incorporationinto starch in the stem, was increased at high temperatures.The variety Norchip, which was found to be less sensitive tohigh temperature as indicated by carbon translocation to thetubers, was found to be less affected also in terms of ¹⁴C incorporationinto starch in the tubers. We suggest that high temperatureaffects carbon metabolism in the various plant organs and theresulting changes are associated with the change in the partitioningof assimilates between these organs.