Seed germination and seedling fitness in Mesua ferrea L. in relation to fruit size and seed number per fruit

Effect of fruit size and seediness (seed number per fruit) was examined on germination and early growth of seedlings in Mesua ferrea L. Fruiting incidence (number of fruited trees in a population) and fruit loading (number of fruits per tree) vary from one year to the other, and were greater in 1997 than in 1998. Seeds from large fruits (> 40 g) are preferred for forestry plantations and those from small fruits (< 40 g) are discarded, despite a greater proportion of small fruits (63.2 %) than large fruits (36.8 %). A fruit, large or small in size, may contain one, two, three or four seeds. The germination percentage of seeds increased from 1-seeded through 4-seeded fruits both in laboratory and greenhouse conditions, and both in case of large and small fruits. Conversely, the mean seed weight and germination time decreased along this gradient, i.e. seeds from 1-seeded fruits were the heaviest and required maximum time for germination, and the seeds from 4-seeded fruits were the lightest and required minimum time for germination. The seeds from small fruits were lighter in weight, achieved lower germination percentages and required greater germination time than the seeds from large fruits in all four seeded categories. Seedlings from seeds from 1-seeded fruits survived better and with stronger vigour after 1 year of growth than seedlings from 2-, 3- and 4-seeded fruits. Further, seedling survival and vigour were greater for seeds from large rather than small fruits.     

草木灰对四种松属种子发芽和幼苗生长的影响

火干扰不仅影响森林生态系统的结构与功能,而且影响群落更新与演替。为了研究草木灰对4种松属种子萌芽和幼苗生长的影响,在湖南省株洲市黄丰桥林场采集马尾松、云南松、湿地松和火炬松种子,以马尾松次生林火烧迹地的草木灰为基质,设置对照和3个草木灰处理,进行播种试验及生长观测。结果表明:(1)草木灰处理下4个物种的种子发芽率比对照试验低,并呈现随草木灰含量的增加而降低的趋势,低草木灰含量处理马尾松种子发芽率不及对照一半,中、高草木灰含量处理发芽率更低;云南松、湿地松和火炬松种子发芽率规律类似于马尾松,而高草木灰含量处理发芽率为0。(2)培养皿播种平均发芽时间比花盆播种长,无论草木灰处理还是培养条件(培养皿或花盆),马尾松和云南松种子平均发芽时间比湿地松和火炬松短。(3)4个物种种子播种14周后,对照试验中马尾松和云南松幼苗死亡率最低,而火炬松和湿地松幼苗死亡率相对增加。(4)播种14周后不同试验处理4个物种幼苗生长差异不明显。火炬松、湿地松、云南松和马尾松幼苗的单株平均干重分别达0.038、0.031、0.027、0.024 g。各物种叶干重按降序排列依次是火炬松(0.026 g)湿地松(0.019 g)云南松(0.017 g)马尾松(0.016 g),根和茎的干重比重相当,约占对应物种幼苗叶干重的三分之一。研究表明以草木灰为培养基质,马尾松和云南松种子的发芽率较高,平均发芽时间较短,更适合作为火烧迹地植被恢复先锋树种,为火干扰后选择人工促进天然更新树种提供参考。     

外源甲醇对油菜种子萌发和幼苗生长的影响

以中国南、北2个主要栽培品种‘玉油二号’和‘秦油二号’油菜种子为供试材料,采用溶液培养方法研究了0~2 000mmol·L-1甲醇溶液处理下,油菜种子萌发、幼苗生长特征及其相关生理生化指标的变化。结果表明:(1)10~1 000mmol·L-1甲醇处理的油菜种子萌发指标(发芽率、发芽势、发芽指数、活力指数)和幼苗生长指标(幼芽及幼根长度、鲜重、根冠比)均比对照显著增加,而甲醇溶液浓度为2 000mmol·L-1时油菜种子萌发和幼苗生长受到显著抑制;两个油菜品种种子萌发和幼苗生长在甲醇溶液处理下均表现为相同的变化趋势,但也存在品种的差异,‘秦油二号’生长受影响程度低于‘玉油二号’。(2)随着甲醇溶液浓度的增加,油菜种子萌发指标和幼苗生长指标表现出先增加后降低的趋势,并在甲醇溶液浓度为100mmol·L-1时均达到最大值,继续高于此浓度后促进作用即减弱以至消失,甚至产生抑制作用。(3)随着甲醇处理溶液浓度的增加,油菜幼苗叶片的叶绿素含量呈先增后降的趋势,而同期叶片的MDA和过氧化氢含量却呈先降后升的相反趋势,且均在相同的100mmol·L-1浓度下分别达到最大或者最低值。研究认为,适宜浓度的甲醇溶液能够促进油菜种子萌发和幼苗生长。     

Signalling molecules and blast pathogen attack activates rice OsPR1a and OsPR1b genes: A model illustrating components participating during defence/stress response

Recently the rice (Oryza sativa L.) OsPR1a and OsPR1b genes were primarily characterized against jasmonic acid, ethylene and protein phosphatase 2A inhibitors. The dicot PR1 are recognized as reliable marker genes in defence/stress responses, and we also propose OsPR1 as marker genes in rice, a model monocot crop genus. Therefore, to gain further insight into the expression/regulation of OsPR1 genes, we characterized their activation against signalling molecules such as salicylic acid (SA), abscisic acid (ABA) and hydrogen peroxide (H₂O₂), and the blast pathogen Magnaporthe grisea. Here, we report that SA and H₂O₂ strongly induced the mRNA level of both OsPR1 genes, whereas ABA was found to be moderately effective. These inductions were specific in nature and required a de novo synthesized protein factor. A potential interaction amongst the signalling molecules in modulating the expression of OsPR1 genes was observed. Moreover, a specific induction of OsPR1 expression in an incompatible versus compatible host-pathogen interaction was also found. Finally, based on our present and previous results, a model of OsPR1 expression/regulation has been proposed, which reveals their essential role in defence/stress responses in rice and use as potent gene markers.     

两种云杉种子萌发和幼苗生长对环境因子的适应性

青海云杉是我国沙区通过种子育苗引种成功的物种。通过对不同储藏时间青海云杉和沙地云杉种子生活力测定、种子萌发对温度、光照、水盐胁迫以及幼苗生长对水盐胁迫和沙埋的响应实验,比较两种种子萌发和幼苗生长对环境因子适应性,为沙地云杉在我国沙区广泛引种提供参考。结果表明:1)在2年的储藏过程中,沙地云杉和青海云杉种子生活力分别由79%和72%下降了19%和5%; 2)沙地云杉和青海云杉种子适宜萌发温度分别为15—30℃和10—30℃,最适萌发温度分别为25℃(72%)和25/15℃(69%),除10℃和10/30℃外,两种种子萌发率在各温度下没有显著差异; 3)沙地云杉种子萌发光照条件为14 h光照/8 h黑暗交替(67%),青海云杉为24 h光照(61%)或24 h黑暗(61%); 4)水势在-2.7—0 MPa时,2种云杉的IGR(初始萌发率)、RGR(恢复萌发率)、ISL(初始幼苗长度)和RSL(恢复幼苗长度)均没有显著差异; 5) NaCl浓度在200 mmol/L和250 mmol/L,青海云杉种子IGR显著大于沙地云杉,NaCl浓度在0—450 mmol/L,青海云杉和沙地云杉种子RGR没有显著差异,当NaCl浓度为50 mmol/L和100 mmol/L,青海云杉ISL显著大于沙地云杉; 6)在0.5—2.0 cm沙埋深度时,青海云杉出苗率显著高于沙地云杉,沙地云杉最适沙埋深度0.5 cm,青海云杉为0.5—1.5 cm。因此,青海云杉种子萌发和幼苗生长比沙地云杉有更强的环境适应性,但只要采取合理的播种时间、播种深度和水分管理等措施,沙地云杉会和青海云杉一样在我国沙区大面积引种育苗。     

MITE转座子在不同甘蓝型油菜品种中的多态性研究

微型反向重复转座因子(MITE)在真核生物基因组中普遍存在,其活动能够在物种内形成丰富的多态性,在基因组进化和基因调控中均发挥重要作用。该研究利用286对不同MITE家族侧翼序列筛选的特异引物,对101个中国油菜、27个加拿大油菜和29个合成油菜品系(共157个品系)的基因组DNA进行多态性研究,以明确MITE家族的插入/缺失多态性以及在不同油菜品种之间插入的遗传多样性,进而探讨他们之间的亲缘关系。结果显示：(1)286对引物中筛选出60对条带清晰重复性高的多态性引物,多态性比例21.0%;其中Stowaway like家族和Tourist like家族特异引物的多态性比例分别为24.6%和20.0%。(2)PCR扩增结果显示,60对多态性引物对中国、加拿大、合成油菜品系的基因组DNA分别扩增出4 029、1 044、1 087条清晰可辨的条带。(3)UPGMA聚类显示,中国油菜品种间遗传相似系数在0.59~0.95,加拿大油菜品种间遗传相似系数在0.73~0.95;合成油菜品种间遗传相似系数值在0.64~0.93。研究表明,MITE在基因组中大量随机插入,形成种内丰富的多态性,利用MITE家族引物检测不同地区的油菜种质资源的多态性,可为油菜的育种找到许多尚未被开发的遗传变异。     

Purification and properties of Pinus taeda arginase from germinated seedlings

In germinated loblolly pine (Pinus taeda L.) seeds arginine accumulates in the seedling during its growth immediately following germination. The enzyme arginase (L-arginine amidinohydrolase, EC 3.5.3.1) is responsible for hydrolyzing this arginine into ornithine and urea. Loblolly pine arginase was purified to homogeneity from seedling cotyledons by chromatographic separation on DE-52 cellulose, Matrex Green and arginine-linked Sepharose 4B. The enzyme was purified 148-fold and a single polypeptide band was identified as arginase. The molecular mass was determined to be 140 kDa by FPLC, while the subunit size was shown to be 37 kDa by SDS-PAGE, predicting a homotetramer holoprotein. Removal of manganese from the enzyme abolishes catalytic activity, which can be restored by incubating the protein with Mn²⁺. Antibodies, raised against the arginase subunit, are able to immunotitrate arginase activity and are monospecific for arginase on immunoblots.     

模拟干旱胁迫对巴东木莲种子萌发和芽苗生长的影响

巴东木莲原生种群天然更新差,林下鲜见更新幼苗或幼树.为探究其种子萌发和芽苗在生长期对干旱胁迫的耐受性,该文以巴东木莲种子为材料,采用不同质量浓度的聚乙二醇(PEG-6000)模拟干旱胁迫,分析干旱胁迫对其种子萌发、芽苗生长及其相关的生理生化指标的影响.结果表明:(1)不同质量浓度的PEG溶液对巴东木莲种子萌发和芽苗生长...     

Characterization of natural rubber biosynthesisin Ficus benghalensis

Natural rubber was identified for the first time in the latex of Ficus benghalensis, and the rubber biosynthetic activity in latex and rubber particles was investigated. ¹³C NMR analysis of samples prepared by successive extractions with acetone and benzene confirmed that the benzene-soluble residues were natural rubber, cis-1,4-polyisoprene. The rubber content in the latex of F. benghalensis was approximately 17 %. Gel permeation chromatography revealed that the molecular mass of the natural rubber from F. benghalensis was approximately 1 500 kDa. The high rubber content and large molecular size suggest that F. benghalensis is a good candidate for an alternative rubber source. Examination of latex serum from F. benghalensis by SDS-polyacrylamide gel electrophoresis revealed a small number of proteins with major proteins of 31 and 55 kDa in size. The 31-kDa protein was predominant in catalytically-active rubber particles. Determination of metal ion concentration in latex and a comparison of the effect of ethylenediamine-tetraacetic acid on in vitro rubber biosynthesis in F. benghalensis, F. carica and Hevea brasiliensis suggest that the divalent metal ion present in latex serum is an important physiological factor controlling the rubber biosynthetic activities in these plant species. Microscopic examination revealed that the rubber in F. benghalensis occurred in a series of laticifer cells located in concentric zones in the inner bark of stems and branches.     

油菜花粉发育相关基因RALFbn的克隆与表达分析

根据美国NCBI数据库中快速碱化因子(RALF)类基因序列的已知信息,克隆了油菜的快速碱化因子基因RALFbn,对其核酸序列及预测蛋白进行了生物信息学分析,并在油菜多种组织内观测其表达情况.结果表明:(1)经克隆获得油菜RALFbn基因的cDNA序列全长为510 bp,无内含子,编码79个氨基酸.(2)生物信息学分析发现,油菜RALFbn蛋白具有RALF类蛋白保守的“YIXY”区和4个保守的半胱氨酸残基,并且含有N豆蔻酰化位点、酪氨酸激酶Ⅱ磷酸化位点、蛋白激酶C磷酸化位点、和酪氨酸激酶磷酸化位点等多个生物活性位点,说明该蛋白在油菜中潜在的生理调节能力较为活跃.(3) RT-PCR检测RALFbn基因在油菜生殖器官中的表达结果发现,RALFbn主要在油菜雄蕊中表达,而在雌蕊、花瓣和萼片中没有表达.提示RALFbn基因极可能与油菜雄蕊中花粉的发育相关.     

Gene expression in the soybean seed axis during germination and early seedling growth

Copy-DNA clones have been obtained that distinguish eight messenger mRNAs, moderately abundant in the axes of the germinating soybean (Glycine max (L.) Merr.) seedling. These clones have been used to characterize the size of the mRNAs and to anlyze the accumulation of the mRNAs at different time points and in different parts of the axis during germination and early seedling growth. Three of the mRNAs accumulate to a substantial level by 9 h, a time point before either the beginning of growth or the accumulation of polyribosomes. Four other mRNAs reach a substantial level only at 24 h, a period when rapid seedling growth is occurring. Those mRNAs whose accumulation begins at 24 h were found only in the top (hypocotyl) half of the 24-h seedlings, while the remaining mRNAs were present also in the bottom half of the seedlings in different amounts. By 44 h, the bottom 0.5 cm of the seedlings, i.e., the region of meristematic growth, had little or none of the mRNAs, with the exception of one mRNA. These temporal and spatial observations indicate that many of the mRNAs are not involved simply in the general maintenance of ongoing cell proliferation, but that they may be related to differentiation during early seedling formation. Further, the early accumulating mRNAs may be functioning in regulating the onset of seedling growth.Abbreviations cDNA copy DNA - poly(A)⁺RNA polyadenylated RNA     

The role of M cells in Salmonella infection

Intestinal M cells, the specialised antigen-sampling cells of the mucosal immune system, are exploited by Salmonella and other pathogens as a route of invasion. Salmonella entry into M cells and colonisation of Peyer’s patches involve mechanisms critical for infection of cultured cells as well as factors not accurately modelled in vitro.     

苗期紫花苜蓿株体对不同地区垂穗披碱草种子萌发生长的化感作用

以发芽率、苗长、根长、苗干重、根干重变化为种子萌发和幼苗生长参数,研究苗期紫花苜蓿(Medicago sativa)植株浸提液对不同地区垂穗披碱草(Elymus nutans)种子萌发生长的化感作用。结果表明:地上部浸提液对LS、DX垂穗披碱草种子发芽率具有明显的促进作用,而对GS、KMX、LKZ、LZ地区垂穗披碱草种子发芽率均表现为抑制作用,其中对GS垂穗披碱草种子发芽率的抑制作用最强,在14.5%和5.5%浓度处理时抑制率分别为57.89%、55.26%;苗长方面,浸提液5.5%浓度对垂穗披碱草苗长的抑制率顺序为:LZNQDXLSKMXQHGSLKZ,14.5%处理时抑制率顺序为:LZKMXLKZNQGSQHDXLS,其中抑制率最高的为LZ垂穗披碱草,在14.5%和5.5%浓度处理时抑制率分别为33.03%、28.97%;根长方面,5.5%处理对垂穗披碱草根长的抑制率顺序为:QHNQLZKMX、GSLKZDX、LS,14.5%处理时抑制率顺序为:GSQH、NQLZLSKMXDXLKZ,其中在高浓度下抑制率最高的为GS垂穗披碱草,抑制率为57.69%;地上部浸提液对LKZ、LZ垂穗披碱草苗干重均具有促进作用,高浓度浸提液对NQ垂穗披碱草苗干重产生促进作用(RI0),而对KMX、DX垂穗披碱草苗干重均表现为抑制作用;根干重方面,浸提液对LS、QH、GS、NQ、LKZ垂穗披碱草根干重均有明显的抑制作用,而对KMX、DX垂穗披碱草根干重产生促进作用,高浓度浸提液对LZ垂穗披碱草的根干重产生促进作用。从根浸提液的作用来看,根浸提液除对LS、DX垂穗披碱草种子发芽率和根干重、GS垂穗披碱草种子发芽率和苗干重及NQ垂穗披碱草根干重具有促进作用外(P 0.05),对其余地区垂穗披碱草的各项指标均有明显的抑制作用(RI0)。所有以上结果表明,紫花苜蓿植株浸提液对垂穗披碱草种子萌发生长的作用具有一定的浓度效应。不同地区垂穗披碱草对紫花苜蓿地上部浸提液的敏感性趋势总体为:GSQHLSKMXNQLKZLZ,最不敏感或有促进作用的是DX垂穗披碱草;对根浸提液的敏感性趋势总体为:QHNQLZKMX,根浸提液对LS、GS、LKZ、DX垂穗披碱草种子萌发生长具有促进作用。紫花苜蓿植株不同部位浸提液对垂穗披碱草种子萌发生长的化感效应顺序为:地上部根。     

盐磷胁迫对木麻黄和台湾相思种子萌发及幼苗生长的影响

恶劣环境下,人工海防林因面临养分胁迫而经营困难。为探讨盐、磷胁迫对主要海防林树种木麻黄和台湾相思种子萌发及生长的影响,该研究分别用不同浓度的NaCl(盐)和KH₂PO₄(磷)溶液处理种子和浇灌幼苗,测定种子萌发和幼苗生长指标。结果表明：(1)高盐胁迫显著抑制种子萌发,对幼苗生长有一定影响,但两种植物影响程度不同;台湾相思种子萌发耐盐性高于木麻黄,前者相对盐害率最大值为23.03%,后者为89.15%;随着盐浓度增加,木麻黄和台湾相思种子的发芽率、发芽势、发芽指数和活力指数均降低,对应最大值分别为38.70%、34.67%、18.70、0.055和76.67%、62.22%、48.46、6.11。(2)两种植物的株高和根长随盐浓度增加而降低,木麻黄和台湾相思株高分别为12.29～6.01 mm和48.27～17.33 mm,根长分别为8.57～1.45 mm和33.41～5.88 mm;台湾相思根、茎、叶生物量及根冠比均随盐浓度的增加逐渐减小,木麻黄各处理差异较小。(3)台湾相思的种子和幼苗较木麻黄更耐低磷环境,二者最适磷浓度存在差异;木麻黄种...     

甘蓝型油菜苗期生长阶段对NaCl胁迫的生理响应

以甘蓝型油菜自交系2205(强耐盐型)、487(中耐盐型)和1423(敏盐型)为材料,采用土培+水培方法于五叶期研究了0(无盐胁迫,CK)、60 mmol·L-1(低盐)、120 mmol·L-1(中低盐)、180 mmol·L-1(中盐)、240mmol·L-1(高盐)NaCl胁迫后的叶片MDA、可溶性糖、甜菜碱和叶绿素含量的变化特征,为油菜耐盐性评价提供理论依据。结果显示:(1)叶片MDA含量在低盐和中低盐胁迫下降低且显著低于CK,在中盐和高盐胁迫下显著升高,并以品系2205含量最低且升幅最小,品系1423最高且升幅最大。(2)叶片可溶性糖含量在低盐和中低盐胁迫下减少(但2205在中低盐胁迫下显著高于CK),在中盐和高盐胁迫下升高且显著高于CK,并以品系2205含量最高增幅最大且显著高于品系487和1423,品系1423含量最低且增幅最小。(3)叶片甜菜碱含量随NaCl浓度升高增加,品系2205和487在中低以上盐浓度胁迫下显著升高,品系1423仅在高盐胁迫下显著升高,并以品系2205含量最高且增幅最大,1423含量最低且增幅最小。(4)叶片叶绿素含量在低盐和中低盐胁迫下显著增加,且以2205叶片叶绿素含量最高且增幅最大,但在中盐和高盐胁迫下显著减少,并以品系1423含量最低且降幅最高。研究表明,120mmol·L-1以下NaCl胁迫对油菜苗期生长可能有促进作用,180mmol·L-1以上NaCl胁迫则有明显抑制作用,且NaCl浓度越高油菜受伤害越重;油菜苗期生长阶段,NaCl胁迫浓度在120~180mmol·L-1时各生理指标发生显著变化,可能是鉴定耐盐性强弱的适宜浓度;综合分析认为,品系2205具有强的耐盐性,品系1423耐盐性最差,这与之前萌芽期和幼苗期鉴定结果一致。     

甘蓝型油菜PGK基因的克隆与表达分析

为研究甘蓝型油菜磷酸甘油酸激酶(PGK)基因表达特性,在对拟南芥PGK基因家族生物信息学分析的基础上,通过电子克隆方法获得3个甘蓝型油菜PGK基因(BnPGK1、BnPGK2、BnPGK3)。分别设计特异引物,以甘蓝型油菜雄性不育系09A和保持系09B的cDNA为模板克隆BnPGK基因全长序列。根据获得的cDNA序列设计实时荧光定量特异引物,采用实时荧光定量PCR技术,研究油菜雄性不育系与保持系PGK基因表达差异。结果显示:BnPGK基因在甘蓝型油菜雄性不育系09A和保持系09B的根、茎、叶、花蕾中均有表达,属组成性表达。除茎中的BnPGK3外,BnPGK其它基因在根、茎、叶中的表达均表现为09A高于09B,而在花蕾中均为09B高于09A,BnPGK1和BnPGK3在09B中的表达量是09A中的2倍以上。     

沙埋和种子大小对柠条锦鸡儿种子萌发、出苗和幼苗生长的影响

研究了沙埋深度和种子大小对内蒙古毛乌素沙地植被群落中占优势的柠条锦鸡儿(Caragana korshinskii Kom.)种子萌发、出苗、幼苗存活和生长的影响.结果表明,沙埋深度显著影响柠条锦鸡儿的种子萌发率、休眠率、出苗率、幼苗存活率及生物量.在0.5-2cm的浅层沙埋下,种子萌发率、出苗率、幼苗存活率及生物量最高,休眠率最低;沙埋深度≥4 cm时,柠条锦鸡儿的种子萌发率、出苗率、幼苗存活率及生物量随着沙埋深度增加显著降低,而休眠率却显著升高;沙埋深度≥12 cm时,柠条锦鸡儿种子不能够出苗,幼苗也不能够存活.种子大小对柠条锦鸡儿种子萌发率没有显著影响,但对出苗率、幼苗存活率及生物量影响显著.在各个沙埋深度下,不同大小的柠条锦鸡儿种子间的萌发率没有显著差异.当沙埋深度≤6 cm时,不同大小的柠条锦鸡儿种子在同一沙埋深度下的出苗率间没有显著差异;但当沙埋深度≥8 cm时,在同一沙埋深度下,大种子的出苗率显著高于中种子和小种子的出苗率,而中种子和小种子出苗率间没有显著差异.0.5-10 cm的沙埋深度中,除6 cm和8 cm深度下中种子和小种子萌发幼苗的生物量间没有显著差异外,其余深度下,大种子萌发的幼苗的存活率及生物量显著高于同一沙埋深度下中种子萌发的幼苗的存活率及生物量,后者又显著高于小种子萌发的幼苗的存活率及生物量.可能正是种子萌发对沙埋环境的忍耐或响应能力以及种子的多态性提高了柠条锦鸡儿在毛乌素沙地的适合度,为其在流动或半流动沙丘环境中成功定居并形成优势群落奠定了基础.     

甘蓝型油菜BnFLA基因的克隆及表达分析

利用同源克隆法从甘蓝型油菜中获得了1个类成束阿拉伯半乳聚糖蛋白基因(FLA),命名为BnFLA。BnFLA基因开放阅读框长为1 200bp,编码399个氨基酸,分子量为42 885.9Da,等电点为6.37。预测的BnFLA蛋白包含N-端信号肽、2个AGP-like结构域、2个fasciclin-like结构域和C-端GPI-anchor序列。系统进化分析表明BnFLA氨基酸序列与BrFLA17和AtFLA2进化关系较近,一致性分别为98%和87%。qRT-PCR分析表明,BnFLA基因在油菜各组织均有表达,并以下胚轴中表达量最高,其次为子叶,茎秆中表达最少;BnFLA基因的表达受到GA3、BR、IAA、ABA和NaCl的诱导,但受6-BA、蔗糖、低温和PEG抑制。研究认为,油菜中BnFLA基因可能参与激素信号转导途径和非生物胁迫应答。     

人工合成甘蓝型油菜早期世代及其亲本对盐胁迫的生理响应

以白菜‘矮抗青’(基因组AA)和‘中花芥蓝’(基因组CC)及其人工合成异源四倍体甘蓝型油菜(AACC)的早期世代(F1~F4)为实验材料,采用水培方法分别比较它们在100、200mmol/L NaCl处理下的生理指标差异。结果表明:(1)在盐胁迫条件下,‘中花芥蓝’植株的生物量、脯氨酸和叶绿素含量、抗氧化酶(SOD、POD、CAT)活性均最低,而相对电导率、MDA含量则最高。在100mmol/L NaCl处理下,F2代植株的生物量、叶绿素含量、SOD活性最大,MDA含量最低;在200mmol/L NaCl处理下,F4代的生物量、叶绿素含量、POD活性最大,MDA含量最低。研究发现,亲本‘矮抗青’的耐盐特性高于亲本‘中花芥蓝’,它们的杂种后代(异源四倍体)遗传了AA基因组的耐盐特性,从而比二倍体亲本具有更强的抵御盐胁迫的能力。     

南方红豆杉水浸提液对喜树种子发芽和幼苗生长的化感作用

化感作用是影响人工混交林种间关系的重要因素之一。已有研究表明：喜树南方红豆杉混交对喜树生长有明显促进作用,并从混交改善混交林地微气候角度解释了这种促进作用,但未从种间化感作用角度探讨这种作用。为了探究南方红豆杉是否对喜树具有潜在的化感促进作用,从而更全面了解喜树南方红豆杉混交林种间关系,考察了不同浓度（25、50 g/L和100 g/L）的南方红豆杉（Taxus chinensis var.mairei）鲜叶、凋落叶、枝和根水浸提液对喜树（Camptotheca acuminata）种子发芽和幼苗生长的影响。结果表明：（1）南方红豆杉凋落叶浸提液对喜树种子发芽和幼苗生长无显著影响（P>0.05）,而鲜叶、枝和根浸提液对喜树发芽和幼苗生长均具有不同程度的促进作用（P<0.05）,且作用强度大体与浓度呈正相关;（2）100 g/L的南方红豆杉鲜叶、枝和根浸提液浸泡的喜树种子,其发芽率比对照组分别提高8.1%、14.9%和25.6%;（3）南方红豆杉鲜叶浸提液只有在高浓度（100 g/L）时,对喜树幼苗基径生长具有促进作用（P<0.05）,而对其株高、全株干重和净光合速率无显著影响;南方红豆杉根和枝浸提液对喜树幼苗株高、基茎、干重和净光合速率均具有促进作用（P<0.05）,与对照组相比,100 g/L的根和枝浸提液浇灌喜树幼苗,可以使喜树幼苗株高分别提高14.2%和8.4%,基径分别提高19.0%和15.3%,干重分别提高23.1%和15.9%,净光合速率分别提高11.6%和6.1%。研究结果表明,在喜树南方红豆杉混交林中,南方红豆杉对喜树的正向化感作用可能是促进喜树生长的重要因素之一。