Cauliflower (Brassica oleracea L.) Seed Vigour: Imbibition Effects

By means of a machine vision facility, the process of water-imbibitionin a small seeded brassica species was recorded as the visibleincrease in seed volume. Dry cauliflower seed (Brassica oleracea)showed an immediate rapid phase of imbibition upon the additionof water. This initial phase was associated with the reductionin seedling root growth resulting from the imbibition of coldwater, and the rate of uptake of water at 20?C was negativelycorrelated with subsequent seedling growth. Damage to the testaof dry seed resulted in an increased rate of imbibition anda corresponding decrease in seedling root growth measured onslant boards. This showed that the intact testa of cauliflowerseed is capable of acting as a barrier to water influx and thata high rate of water uptake is damaging to the embryo. Testadamage reduced percentage soil emergence of seeds, as did raisingthe soil moisture content during the imbibition period by wateringimmediately after sowing. Both these treatments were believedto increase imbibition rate. Conditions which encouraged a lowrate of water uptake also improved the rate and uniformity ofemergence. Correlation of mean imbibition rates (measured ina laboratory test) with soil-emergence indicated that the sensitivityto imbibition damage varied between seed lots and interactedwith the absolute rate of water influx to determine the finalpercentage emergence. This factor prevented reliable predictionof seedling performance from the ranked-order of measured imbibitionrates. The significance of these findings to the seed productionand modular transplant raising industries is discussed. Key words: Machine vision, imbibition rate, testa, soil moisture, vigour     

Subcellular Distribution of O-Acetylserine(thiol)lyase in Cauliflower (Brassica oleracea L.) Inflorescence

The subcellular localization of O-acetyiserine(thiol)lyase (EC 4.2.99.8) in nongreen tissue from higher plants has been studied using purified proplastids, mitochondria, and protoplasts from cauliflower (Brassica oleracea L.) buds as a source of subcellular fractions. O-Acetylserine(thiol)lyase has been detected in both organelles (proplastids and mitochondria) and a cytosolic extract obtained by protoplast fractionation. We confirmed these observations, demonstrating that a form of the enzyme different in global charge and separated from others by anion-exchange chromatography corresponded to each subcellular location. Our observations are consistent with the need for cysteine biosynthesis in each subcellular compartment where the synthesis of proteins occurs.     

Serine Transhydroxymethylase of Cauliflower (Brassica oleracea var. botrytis L.): Partial Purification and Properties

Serine transhydroxymethylase (EC 2.1.2.1) has been purified 46-fold from cauliflower (Brassica oleracea var. botrytis L.). The enzyme was completely dependent on the presence of tetrahydrofolic acid for the conversion of serine to glycine. The addition of pyridoxal phosphate gave a large increase in the reaction rate. A double pH optimum was observed with maxima at 7.5 and 9.5. The enzyme is specific for l-serine. The d-isomer is neither a substrate nor an inhibitor. The Michaelis constants for l-serine, tetrahydrofolic acid, and pyridoxal phosphate were 300 μm, 760 μm, and 24 μm, respectively. The addition of K⁺ also stimulated the reaction rate considerably. The effect was quite specific since all other metal ions tested either had very little: influence or were extremely inhibitory.     

Conservation of S-locus for self-incompatibility in Brassica napus (L.) and Brassica oleracea (L.)

 Self-incompatibility (SI) in Brassica is a sporophytic system, genetically determined by alleles at the S-locus, which prevents self-fertilization and encourages outbreeding. This system occurs naturally in diploid Brassica species but is introduced into amphidiploid Brassica species by interspecific breeding, so that in both cases there is a potential for yield increase due to heterosis and the combination of desirable characteristics from both parental lines. Using a polymerase chain reaction (PCR) based analysis specific for the alleles of the SLG (S-locus glycoprotein gene) located on the S-locus, we genetically mapped the S-locus of B. oleracea for SI using a F₂ population from a cross between a rapid-cycling B. oleracea line (CrGC-85) and a cabbage line (86-16-5). The linkage map contained both RFLP (restriction fragment length polymorphism) and RAPD (random amplified polymorphic DNA) markers. Similarly, the S-loci were mapped in B. napus using two different crosses (91-SN-5263×87-DHS-002; 90-DHW-1855-4×87-DHS-002) where the common male parent was self-compatible, while the S-alleles introgressed in the two different SI female parents had not been characterized. The linkage group with the S-locus in B. oleracea showed remarkable homology to the corresponding linkage group in B. napus except that in the latter there was an additional locus present, which might have been introgressed from B. rapa. The S-allele in the rapid-cycling Brassica was identified as the S₂₉ allele, the S-allele of the cabbage was the S ₅ allele. These same alleles were present in our two B. napus SI lines, but there was evidence that it might not be the active or major SI allele that caused self-incompatibility in these two B. napus crosses. Received: 7 June 1996/Accepted: 6 September 1996     

Evaluation of Abiotic Stress Resistance in Mutated Populations of Cauliflower (Brassica oleracea var. botrytis)

An efficient in vitro screening method has been developed for cauliflower to create NEU and NMU induced mutant lines selected on hydroxyproline containing medium. Mutant lines and control plants were sub-cultured many times on maintenance medium and stored at 5°C for 2 years and then tested for salt and hydroxyproline resistance as in vitro and in vivo plants. In vitro shoot tips were also sub-cultured to media containing hydroxyproline and NaCl for 28 days and then assessed for their leaf proline content. Non-acclimated and acclimated in vivo plants were also assessed for resistance to freezing. Populations of control and selected lines were created by mass pollination and subsequently tested for their NaCl and frost resistance. Control plants had little or no NaCl or hydroxyproline resistance whilst selected plants showed varying degrees of resistance. In vitro and in vivo responses of selected lines were correlated. Leaf proline content was increased markedly in the mutant lines and the greatest proline contents occurred following NaCl stress with the most respondent line having 100-fold levels compared to the controls. Both non-acclimated and acclimated selected lines showed improved frost resistance over controls. Improvements in frost resistance were heritable but improvements in NaCl resistance were not. The results clearly demonstrated that NaCl, frost and hydroxyproline resistance were stable traits over repeated in vitro sub-cultures and prolonged low temperature storage. A complete range of mutants with single, double or triple resistance traits were produced. The level of resistance however was not necessarily correlated with the level of proline and some lines showed resistance without elevated proline. It is concluded that elevated proline is not essential for improved resistance to abiotic stress in cauliflower, but where it does occur it does improve resistance.     

外源茉莉酸甲酯对干旱胁迫下狭叶黄芩光合和生理特性的影响

以狭叶黄芩为试验材料,测定了不同浓度(0.1、0.5、1、2 mmol·L^-1)茉莉酸甲酯对干旱胁迫下(15%,PEG-6000)狭叶黄芩表型特征、光合以及生理特性的影响。结果外源施加茉莉酸甲酯增强了狭叶黄芩的净光合速率、气孔导度和蒸腾速率。有效降低了狭叶黄芩受伤害等级。可以有效缓解降低了胞间CO2浓度,其中施用2 mmol·L^-1茉莉酸甲酯9 d后对狭叶黄芩的净光合速率、蒸腾速率、气孔导度、胞间CO2浓度的影响最为显著。处理组的游离脯氨酸含量低于CK。可溶性蛋白含量在前6 d的处理中低于CK,而在6 d以后的处理中显著高于CK。外源施加茉莉酸甲酯能够提高SOD、POD、CAT活性。对狭叶黄芩的光合参数和生理指标的研究结果表明,经外源施加的茉莉酸甲酯处理能够有效减缓干旱胁迫对狭叶黄芩的不良影响。     

Modification of Phospholipid Catabolism in Microsomal Membranes of [gamma]-Irradiated Cauliflower (Brassica oleracea L.)

Acceleration of membrane deterioration has been observed recently during storage of [gamma]-irradiated cauliflower (Brassica oleracea L., Botrytis group). In the present study, the activity of microsome-associated lipolytic enzymes was investigated in cauliflower florets exposed to 0 or 4 kilograys of [gamma] radiation and stored for 8 d at 13[deg]C. Radiolabeled breakdown products obtained from the metabolism of (16:0/18:2*)-phosphatidylcholine and (16:0/16:0)-phosphatidyl-[N-methyl-3H]choline by microsomal membranes indicated that phospholipase D (EC 3.1.4.4), phosphatidic acid phosphatase (EC 3.1.3.4), and lipolytic acyl hydrolase were associated with the membranes. The rate of phosphatidylcholine catabolism by the membranes increased slowly in control cauliflower during storage. [gamma] irradiation caused an immediate rise in phosphatidylcholine catabolism that remained higher than that of the controls during subsequent storage. Collectively, the data suggest that enhancement of membrane lipolytic activity results from free-radical-induced stress. Rapid increase of the membrane-associated phospholipase D activity may be a key event leading to accelerated membrane deterioration following [gamma] irradiation.     

茉莉酸甲酯对花生幼苗生长和抗旱性的影响

经过茉莉酸甲酯处理的花生幼苗,在形态、解剖和生理上都发生变化,其中以１２５ｍｇ／Ｌ处理最显著。处理后的植株幼苗矮化,叶小而厚,叶片贮水细胞大、蒸腾减弱、内源脱落酸和脯氨酸含量增多、过氧化物酶活性加大。由于水分的丧失减少,叶片水分的贮存增加,从而提高幼苗的抗旱性。     

GA_3对老化花椰菜种子活力和几种相关生理生化性状的影响

用10、50、100、150和200mg·L-15种浓度赤霉素（GA3）溶液处理于10℃冰箱中贮藏5年的花椰菜老化种子。结果表明,100mg·L-1GA3浸种22h的效果最佳,老化种子的发芽率、发芽势、活力指数、根长均有提高,畸形苗率下降;过氧化物酶（POD）、过氧化氢酶（CAT）和脱氢酶活性提高,可溶性蛋白和叶绿素含量也提高,种子浸出液的电导率和丙二醛（MDA）含量则下降。另外,100mg·L-1GA3处理后的种子在温度为25℃条件下贮藏时间不宜超过25d。     

Modelling Nitrogen Content and Distribution in Cauliflower (Brassica oleracea L.botrytis )

A model of nitrogen uptake and distribution is presented whichdescribes these processes in relation to the amount of availablesoil nitrate and the rate of plant growth. Nitrogen uptake iseither sink or source limited. Sink limitation is based on maximumN-concentrations of plant compartments. The N-uptake model iscombined with a photosynthesis model based on the productivity-nitrogenrelationship at the single-leaf level. The model is parameterizedusing cauliflower as an example crop. Applied to an independentdata set, the combined model was able to predict leaf, stemand inflorescence nitrogen concentrations with correlation coefficientsbetween predicted and simulated values of 0.89, 0.66 and 0.86,respectively. The influence of nitrogen supply and light intensityon leaf nitrate-N could also be predicted with good accuracy(r² = 0.87). Dry matter production based on the productivity-Nrelationship and the partitioning into leaf, stem and inflorescencewas also reproduced satisfactorily (r² = 0.91, 0.93 and 0.92,respectively). Copyright 2000 Annals of Botany Company Brassica oleracea L. botrytis, cauliflower, nitrogen, nitrate, nitrogen supply, nitrogen uptake, nitrogen distribution, model     

Primary Structure of Cytochrome b(5) from Cauliflower (Brassica oleracea L.) Deduced from Peptide and cDNA Sequences

Cytochrome b₅ is a microsomal protein that functions as an intermediate electron donor in fatty acid desaturation and other oxidation/reduction reactions. cDNA clones were isolated from cauliflower (Brassica oleracea L.) by using oligonucleotides based on the partial amino acid sequence of the protein. The deduced amino acid sequence of the polypeptide exhibited approximately 30% sequence identity with the homologous protein from vertebrates.     

干旱胁迫下冠菌素对玉米幼苗光合参数和内源激素含量的影响

采用沙培称重法研究冠菌素对玉米幼苗光合参数及内源激素系统影响的结果表明,干旱胁迫下,0.01μmol·L-1冠菌素显著增加玉米幼苗茎基部粗、根长、干鲜重、光合速率、蒸腾速率和气孔导度,降低胞间二氧化碳浓度,提高幼苗的ABA和1-氨基环丙烷-1-羧酸(ACC)含量。叶片与根中ABA/GA3大时耐旱性增大。     

花椰菜BobACT基因的克隆及其作为内参基因的研究

实时荧光定量PCR技术是探索植物基因功能和调节机理的有效手段。选择合适的内参基因是获得实时荧光定量PCR准确性数据的必备条件。ACT基因高度保守且表达稳定,常作为内参基因被广泛应用。为了获得花椰菜ACT基因,以转录组测序和RT-PCR方法为手段克隆得到花椰菜肌动蛋白基因Actin。该基因等电点为5.395,理论分子量为41.77 kD;其cDNA开放阅读框长1134 bp,编码氨基酸377个,GenBank登录号为MG598643。Wolf Psort分析发现,BobActin蛋白亚细胞定位于细胞质基质中。Motif Scan分析显示,BobActin蛋白质的氨基酸序列4～377位为Actin保守结构域。进化分析表明,同源序列基因编码的蛋白质与同为十字花科的甘蓝、芜菁和油菜同源蛋白的相似性达到90%以上,具有高度的保守性。在此基础上,设计了1对荧光定量PCR引物,分析显示,该引物具有较高的特异性和扩增效率,在花椰菜根、茎、花、花球、叶片等不同组织和低温、高温、盐处理、干旱处理、ABA处理等胁迫处理下均能稳定表达,适合在花椰菜基因表达研究中作为内参基因,为开展花椰菜重要功能基因的挖掘、表达模式以及调控机理的研究提供参考。花椰菜在内参基因方面的研究还处于初步阶段,今后可继续克隆其他内参基因,丰富花椰菜的内参基因库,从而进一步提高花椰菜基因表达分析研究的稳定性、重复性和准确性。     

Unraveling Physiological and Metabolomic Responses Involved in Phlox subulata L. Tolerance to Drought Stress

Metabolic responses are important for plant adaptation to abiotic stress. To investigate the responses of Phlox subulata L. to drought stress, we analyzed its physiological and metabolic changes using gas chromatography-mass spectrometer. Based on the physiological indices, P. subulata L. has tolerance to drought to some degree. Our results showed that there were a total of 30 key metabolites induced by drought stress, including amino acids, organic acids, sugars and sugar alcohols, nucleic acid and its derivatives, and other organic compounds. The glutamic acid-mediated proline biosynthesis pathway is continuously upregulated under drought stress, which could regulate osmotic pressure and maintain intracellular environmental stability. More secondary metabolites are used to increase glycolysis and tricarboxylic acid cycle, to accelerate energy production and to enhance the glutamic acid-mediated proline biosynthesis pathway, which are necessary to increase osmotic regulation. Prolonged drought stress induced progressive accumulation of compatible osmolytes, such as proline and inositol, sugars, and amino acids. Therefore, drought caused systemic alterations in metabolic networks involving transamination, TCA cycle, gluconeogenesis/glycolysis, glutamate-mediated proline biosynthesis, shikimate-mediated secondary metabolisms, and the metabolism of pyrimidine. These data suggest that plants may utilize these physiological and metabolomic adjustments as adaptive responses in the early stages of drought stress. These results deepen our understanding of the mechanisms involved in P. subulata L. drought tolerance, which will help improve the understanding of drought’s effects on plant systems.

     

PEG模拟干旱胁迫对糜子幼苗生理特性的影响

以'榆糜1号'和'榆糜3号'为试验材料,采用PEG模拟水分胁迫方法,研究了干旱胁迫对糜子幼苗生理生化特性的影响.结果显示,(1)2品种幼苗叶片的细胞电解质外渗率、叶片的MDA含量、游离脯氨酸含量和可溶性糖含量均在胁迫2 d后逐渐上升,但保护酶SOD和POD的活性均呈先升高后降低的变化趋势,2品种幼苗在不同强度PEG胁迫下总体变化趋势基本一致,且各胁迫处理间差异显著(P<0.05).(2)2品种在相同处理下差异显著(P<0.05),其中,10%～30 0A PEG胁迫8 d时,'榆糜3号'比'榆糜1号'的细胞电解质外渗率、叶片的MDA含量增加幅度小,而游离脯氨酸含量和可溶性糖含量增加幅度较大,但保护酶SOD和POD的活性下降幅度较小,说明相同渗透胁迫下'榆糜1号'比'榆糜3号'叶片的细胞膜透性增加幅度大,但渗透调节物质增加较少,细胞膜系统受干旱伤害会更大,其抗旱性相对较弱.综合各项生理指标的分析认为,'榆糜3号'具有较强的抗旱能力.     

Rhizospheric Bicarbonate Improves Glucose Metabolism and Stress Tolerance of Broussonetia papyrifera L. Seedlings under Simulated Drought Stress

Russian Journal of Plant Physiology - Heavy concentrations of bicarbonates present throughout karst ecosystems necessitate identification of the role of $${text{HCO}}_{3}^{ - }$$ in plant growth,...     

Impact of Rice Husk Biochar on Drought Stress Tolerance in Perennial Ryegrass (Lolium perenne L.)

Journal of Plant Growth Regulation - In a water shortage crisis, the landscape management of perennial ryegrass, a common lawn grass, is a major challenge. An organic material that can help to...     

Patterns of Endopolyploidy During Seedling Development in Cabbage (Brassica oleracea L.)

Flow cytometric analysis of nuclear DNA contents of somatictissues of cabbage (Brassica oleracea L.) has revealed extensiveendopolyploidization, resulting in tissues that comprise mixturesof cells with different DNA contents, ranging from 2C to 16C.Patterns of endopolyploidy are specific to each developmentalstage. Multiple polyploidy was not present in the embryos ofdry seeds. Rapid endoreduplication occurred in the radicle andthe hypocotyl of the embryos during seed germination. Furtherendoreduplication cycles were detected in all tissues exceptthose of the shoot tips. In five cabbage cultivars tested, seedlingscontained cells of four ploidy levels, corresponding to 2C,4C, 8C and 16C. Multiploidy may be an integral part of differentiationprograms in cabbage plants. The biological significance of endoreduplicationin cabbage plants is discussed. Copyright 2001 Annals of BotanyCompany Cabbage (Brassica oleracea L.), endopolyploidy, endoreduplication, flow cytometry