3种地被竹对大气臭氧胁迫的光合生理响应

以美丽箬竹(Indocalamus decorus)、黄条金刚竹(Pleioblastus kongosanensis f.aureostriatus)、白缟椎谷笹竹(Sasa glabra f.albostriata)3种优良地被观赏竹为试材,用开顶式同化箱(OTCs)模拟大气O3浓度,研究了不同O3浓度胁迫(环境背景大气、100nL L-1和150 nL L-1)对竹子光合生理指标的影响。结果表明,随着大气O3浓度的升高,美丽箬竹叶片叶绿素含量先升高后降低,黄条金刚竹呈相反变化规律,白缟椎谷笹竹呈下降趋势;它们的叶片类胡萝卜素含量变化不明显。美丽箬竹的Pn日均值先缓慢升高后降低,黄条金刚竹先略有升高后急剧降低,白缟椎谷笹竹逐渐降低;大气O3浓度升高明显影响3种竹的光合参数日变化进程;大气O3浓度为100 nL L-1时,美丽箬竹的光合作用未受到抑制,黄条金刚竹和白缟椎谷笹竹则出现明显的抑制效应;大气O3浓度达150 nL L-1时,3竹种的光合生理都受到严重的伤害。耐受O3胁迫能力存在种间差异,美丽箬竹明显高于黄条金刚竹、白缟椎谷笹竹。     

3种地被类观赏竹对大气臭氧浓度倍增的生理响应

运用开顶式同化箱(OTCs)模拟环境背景大气O3浓度(CK,40~45 nL.L-1)的倍增1倍(TR-1,92~106nL.L-1)和倍增2倍(TR-2,142~160 nL.L-1)情景,分析美丽箬竹、黄条金刚竹和白缟椎谷笹竹叶片脂质过氧化、抗氧化酶和渗透调节物质等生理指标的变化,以明确竹子对大气O3浓度倍增的生理响应规律及耐受O3胁迫能力的种间差异性,为园林观赏竹种选育和应用提供参考。结果表明:(1)大气O3浓度倍增45 d时,随着O3浓度的升高,3种地被类观赏竹叶片O2.-和MDA含量、相对电导率、SOD活性均表现出增大趋势。叶片POD活性、可溶性糖含量美丽箬竹呈下降趋势,而黄条金刚竹和白缟椎谷笹竹呈升高趋势。叶片可溶性蛋白含量美丽箬竹和白缟椎谷笹竹呈下降趋势,黄条金刚竹呈升高趋势。(2)大气O3浓度倍增1倍时,美丽箬竹和黄条金刚竹未表现出伤害症状,而白缟椎谷笹竹表现出明显的伤害症状;大气O3浓度倍增2倍时,3种地被类观赏竹叶片活性氧含量大量积累,抗氧化系统遭到破坏,膜脂过氧化加剧,影响正常的生理代谢和生长发育。(3)主成分分析表明,叶片MDA含量是反映地被类观赏竹耐受O3胁迫最重要的生理指标,耐受O3胁迫能力表现为美丽箬竹>黄条金刚竹>白缟椎谷笹竹。     

3种林下灌木竹种地上竞争的可塑性响应

林下灌草层物种种群内竞争是森林生态系统发育和演替研究的重要组成部分。通过模拟去除边缘效应, 对3种赤竹属灌木竹种——铺地竹(Sasa argenteastriatus)、菲黄竹(S. auricoma)、菲白竹(S. fortunei)3种植物对地上竞争的可塑性响应研究。研究发现: (1)3种赤竹属竹种的垂直结构和器官(根、茎和叶)表征了在进化尺度上3种植物内源的相似性和表型可塑性差异; (2)根冠比表明在高密度条件下菲黄竹投入到地上部生物量大于低密度条件, 菲白竹类似, 铺地竹则相反, 3物种在向最大生长速率进化的过程中, 遇到生理(光合)和分配之间的交换关系而产生的矛盾选择; (3)菲黄竹与菲白竹较慢的光合速率, 表明在生理上已经对高密度处理产生可塑性变化, 并且这种可塑性是以缩短叶寿命为代价的。     

撑绿杂交竹和硬头黄竹克隆生长特性比较

以撑绿杂交竹(Bambusa pervariabilis × Dendrocalamopsis daii)和硬头黄竹(Bambusa rigida)为研究对象, 探讨了两种丛生竹生物量分配及克隆生长特性。结果表明, 硬头黄竹秆生物量比例显著高于撑绿杂交竹, 枝和叶生物量比例显著低于撑绿杂交竹, 硬头黄竹具有更高的养分同化效率。硬头黄竹与撑绿杂交竹的繁殖率无明显差异, 但其退笋率显著低于撑绿杂交竹, 表明硬头黄竹具有更高的繁殖效率。此外, 与撑绿杂交竹相比, 硬头黄竹的成竹根茎更长, 资源开拓性更强。两种丛生竹的新竹生长与母竹数量、大小和年龄结构具显著相关性。硬头黄竹产生的竹笋质量高, 具有较高的成竹率, 生长策略类似K对策; 撑绿杂交竹产生的竹笋数量多, 但退笋率较高, 类似r对策。硬头黄竹和撑绿杂交竹的成竹数(成竹胸径)与母竹数量(母竹胸径)间存在线性相关关系, 可以用线性模型模拟。     

CO2浓度升高对三种地被类观赏竹生理特性的影响

运用开顶式气室(OTCs)模拟大气CO₂浓度升高(500、700 μmol·mol^-1)情景,以环境背景大气为对照,研究CO₂浓度升高对3种地被类观赏竹(美丽箬竹、黄条金刚竹和白缟椎谷笹竹)叶片的膜脂过氧化和抗氧化系统的影响及其种间差异.结果表明: 试验进行103 d后,500 μmol·mol^-1CO₂浓度下,3种地被类观赏竹的叶片超氧阴离子含量、丙二醛(MDA)含量、相对电导率和可溶性糖含量总体上没有发生明显的变化,但叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性有一定程度的改变;700 μmol·mol^-1 CO₂浓度下,3个竹种的叶片MDA含量和相对电导率没有发生明显变化,但对叶片超氧阴离子含量、可溶性糖含量和SOD、POD、CAT、APX活性的影响较为明显.不同竹种对CO₂浓度升高环境的适应能力为美丽箬竹＞黄条金刚竹＞白缟椎谷笹竹.     

CO2浓度升高对三种地被类观赏竹生理特性的影响

运用开顶式气室(OTCs)模拟大气CO₂浓度升高(500、700 μmol·mol^-1)情景,以环境背景大气为对照,研究CO₂浓度升高对3种地被类观赏竹(美丽箬竹、黄条金刚竹和白缟椎谷笹竹)叶片的膜脂过氧化和抗氧化系统的影响及其种间差异.结果表明: 试验进行103 d后,500 μmol·mol^-1CO₂浓度下,3种地被类观赏竹的叶片超氧阴离子含量、丙二醛(MDA)含量、相对电导率和可溶性糖含量总体上没有发生明显的变化,但叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性有一定程度的改变;700 μmol·mol^-1 CO₂浓度下,3个竹种的叶片MDA含量和相对电导率没有发生明显变化,但对叶片超氧阴离子含量、可溶性糖含量和SOD、POD、CAT、APX活性的影响较为明显.不同竹种对CO₂浓度升高环境的适应能力为美丽箬竹＞黄条金刚竹＞白缟椎谷笹竹.     

竹子叶绿体基因组SSR分子标记的开发及其应用

为探讨观赏竹叶片异质性的机理,根据麻竹(Dendrocalamus latiflorus)和绿竹(Bambusa oldhamii)叶绿体基因组序列开发SSR分子标记。结果表明,在麻竹和绿竹叶绿体基因组中分别存在87和86个SSR位点,其中三核苷酸重复类型最多,其次为单核苷酸重复类型。根据SSR位点设计21对引物,其中11对引物对6竹种能够扩增出稳定、清晰的条带,且具有多态性,引物有效率达到52.4%。聚类分析表明,6竹种可分为两大类群,与形态学分类结果基本一致。有4对引物在菲白竹(Pleioblastus fortunei)和白纹椎谷笹(Sasaella glabra f.albo-striata)的花叶中具有多态性,可作为区分观赏竹叶片异质性的分子标记。     

珙桐幼苗生理生化指标对重金属铅、镉胁迫的响应

铅和镉在土壤中表现出很强的毒性,严重危害植物的生长发育。该研究着眼于中国特有濒危珍稀植物珙桐,探究盆栽实验条件下其抗氧化酶活性、丙二醛(MDA)以及游离脯氨酸、可溶性蛋白对不同浓度重金属铅、镉胁迫的响应规律。结果表明:(1)不同浓度铅处理下,珙桐幼苗MDA浓度均显著高于对照组,而镉胁迫条件下除10 mg·kg~(-1)浓度外,其余处理组MDA浓度也显著高于对照组,表明了铅和镉污染加剧了珙桐膜脂过氧化进程。(2)游离脯氨酸随着铅、镉浓度的增加,表现出先增加后降低的现象,分别在铅浓度≥800 mg·kg~(-1)和镉浓度≥20 mg·kg~(-1)处理下显著低于对照组。可溶性蛋白浓度随着铅浓度的增加也表现出先增后减的规律,其浓度在镉胁迫下均显著高于对照组。可溶性蛋白和游离脯氨酸的增加可以提高珙桐抵抗低浓度重金属危害的能力,高浓度重金属对珙桐则产生抑制作用。(3)随着铅和镉浓度的增加,珙桐抗氧化酶活性也表现出先增加后降低的特征,表明了低浓度重金属(铅浓度≤600 mg·kg~(-1),镉浓度≤5mg·kg~(-1))容易激活珙桐抗氧化应激反应,有效地减少重金属的危害,高浓度的重金属则会抑制抗氧化酶活性。(4)通过相关性和主成分分析表明,珙桐幼苗中抗氧化酶、游离脯氨酸可以较好地反映珙桐对两种重金属胁迫的响应规律。     

3种土壤类型下红椿幼苗对铅胁迫的光合响应

采用盆栽试验,研究钙质紫色土、酸性紫色土和冲积土3种土壤类型上生长的红椿幼苗在不同浓度(0、200、450、2 000mg·kg-1)铅(Pb)胁迫下的光合生理响应,探讨红椿在不同土壤类型下Pb污染的生态适应性,为木本植物的重金属修复提供理论依据。结果表明:(1)3种土壤类型下,红椿幼苗叶片叶绿素a、叶绿素b及叶绿素总量随Pb胁迫浓度的增大呈总体降低的趋势,叶绿素含量在钙质紫色土上受Pb胁迫的影响不大,而在酸性紫色土和冲积土上降低明显。(2)不同土壤类型的红椿光合响应曲线变化趋势十分相似,红椿幼苗叶片的净光合速率均随Pb胁迫程度的加大呈先增加后降低的趋势且差异显著,并在Pb浓度为200和2 000mg·kg-1时光合速率分别达到最大值和最小值。(3)随着Pb胁迫浓度的增大,红椿的最大光合速率、表观量子利用效率、光补偿点等光合生理指标都发生了显著改变,说明Pb胁迫严重影响红椿幼苗的光合作用。研究表明,高浓度的铅抑制红椿幼苗叶片叶绿素的合成,从而抑制光合作用的强度,且铅胁迫的浓度越高,叶绿素含量越低,光合作用受到的抑制越强;较低浓度的Pb处理(200和450mg·kg-1)对酸性紫色土和冲积土上红椿的净光合速率影响很小,而对钙质紫色土上红椿的最大净光合速率的抑制最为明显。     

铅胁迫对3种藓类植物抗氧化酶活性的影响

采用水培实验研究了重金属Pb对3种藓类植物尖叶拟船叶藓(Dolichomitriopsis diversiformis)、湿地匍灯藓(Plagiomnium acutum)和匍枝青藓(Brachythecium procumbens)的抗氧化酶(SOD、POD和CAT)活性的影响.结果表明,(1)在1~200 mg·L-1的铅胁迫浓度范围内,Pb对3种藓类植物的SOD活性均具有显著的促进作用,对Pb胁迫的种间敏感性差异为尖叶拟船叶藓>湿地匍灯藓>匍枝青藓;(2)POD活性对Pb胁迫的反应趋势有一定差别,尖叶拟船叶藓和匍枝青藓的POD活性随Pb浓度的增加先升后降,湿地匍灯藓的POD活性变化较为平缓,种间敏感性差异为匍枝青藓>尖叶拟船叶藓>湿地匍灯藓;(3)在100 mg·L-1时Pb对湿地匍灯藓CAT活性表现为显著促进作用外,其余在低浓度下显示无显著影响,在高浓度下表现为抑制效应,种间敏感性差异为尖叶拟船叶藓>匍枝青藓>湿地匍灯藓.3种藓类植物的抗氧化酶体系中对Pb胁迫的抵抗起关键作用的是SOD,可作为藓类植物受Pb胁迫的敏感生理指标.3种植物中对Pb胁迫的反应较为敏感的是尖叶拟船叶藓.     

In vitro response of promising mulberry (Morus sp.) genotypes for tolerance to salt and osmotic stresses

An in vitro technique for screening mulberry genotypes tolerant to salt and osmotic stress has been standardized.Five mulberry genotypes, namely G2, G3, G4 along with control varieties i.e., S34 and S13, were tested on salt and osmotic stress media. Out of 14 media combinations tested, the optimum responses were observed on Kn 1 mg/l, in the case of G3 genotype, on Kn 2 mg/l with G2 genotype, on BAP 1 mg/l with G4 genotype and on BAP 2 mg/l with S34 and S13 genotypes.With regard to their performance on salt-stress media fortified with NaCl (0.1--2.0%), Na₂CO₃ + NaHCO₃ (pH 8.5--10.0), the data revealed that the genotype G4 ranked the highest in terms of sprouting percentage and shoot length, in comparison to the control variety (S34) at each concentration of NaCl up to 1.0% and pH up to 9.5. However, in the case of osmotic stress condition (media supplemented with 1.0--10.0% PEG),the control variety i.e. S13 itself exhibited the highest sprouting percentage and shoot growth compared to the other test genotypes. The genotype G4 has been screened as a salt tolerant genotype which can be tested under respective in vivo condition.     

Shoot organogenesis and plant regeneration in mulberry (Morus bombycis Koidz): Factors influencing morphogenetic potential in callus cultures

Regeneration of multiple shoots via callus induction and organogenesis was achieved in mulberry (Morus bombycis). Pre-soaked internodal explants in 4.4–8.9 M benzyladenine (BA) formed callus on Linsmaier and Skoog's medium containing 2,4-dichlorophenoxyacetic acid (9.05 M), -naphthaleneacetic acid (2.85 M) and BA (2.2 M). Explants soaked for 48 to 72 h in low levels of BA produced loose and nodular callus that showed regeneration ability. Calluses developed adventitious shoot buds within 3–4 weeks on medium containing BA (8.9 M). Fifteen-week-old calluses developed fewer shoot buds than five-week-old calluses, indicating a decrease in morphogenetic potential with increasing duration of callus cultures. Semi-thin section microscopy was used to evaluate incapability of sustained regeneration. Development of normal shoot bud primordia, due to sub-surface reorganisation, was high in young calluses. The decline in the frequency of shoot bud primordia formation with callus ageing is due to reduced cell division activity in epidermal as well as sub-epidermal layers.     

Shoot growth dynamics and size-dependent shoot fate of a clonal plant,Festuca rubra, in a mountain grassland

The relation of the within-season and between-season patterns of shoot growth were compared in a clonal grass with long-lived shoots,Festuca rubra, in a mown mountain grassland. The growth rate of shoot length from spring to summer in a year was almost constant for each shoot irrespective of spring shoot length each year. The annual shoot growth rate from spring to spring was negatively correlated with the shoot length in the first spring. Shoots of different length and age therefore tended to converge over time to a population of identical shoot size, suggesting an equalizing effect of growth pattern on size structure. Shoot size (shoot length and number of leaves) influenced the fates of shoots. Larger shoots showed an increased incidence of both flowering and formation of intravaginal daughter shoots and a decreased incidence of death in the subsequent time period. The fates of shoots were independent of their age. Although the negatively size-dependent springto-spring annual shoot growth rate acted to decrease shoot size variation, the remaining variation within the shoot population was still sufficient to generate different fates of shoots. These fates were not related to the previous life history of individual shoots. There was a significantly positive effect of the shoot size at initiation on its life expectancy. This was mainly attributable to the positively size-dependent survival rate of shoots in the early stage (<1 year old) of shoot life history. Later on (> 1 year old), shoot size had little effect on the survival rate of shoots. Once small young shoots have survived this early stage (< 1 year old) in life history, they can grow vigorously, little affected by competition regardless of shoot size, and converge to a stable size structure of shoots of similar size. Only shoot size in the early stage ( < 1 year old) of life history is important for the persistence of a shoot population.     

Structural changes in root and shoot ofBacopa monniera in response to salt stress

Various concentrations of salt (NaCI) were shown to have an influence on the differentiation of tissues in the root and stem ofBacopa monniera (L) Wettst. Higher concentrations induced drastic changes in roots grown on salt-supplemented media; epidermal and cortical cells experienced changes in shape, size, and orientation and/or were got disintegrated. A low concentration of salt induced a profuse development of root hairs which gradually disappeared at higher concentrations. Air spaces in the stem cortex were enlarged and xylem cell walls in the vascular ring were thickened.     

Accumulation of terpenoid phytoalexins in maize roots is associated with drought tolerance

Maize (Zea mays) production, which is of global agro‐economic importance, is largely limited by herbivore pests, pathogens and environmental conditions, such as drought. Zealexins and kauralexins belong to two recently identified families of acidic terpenoid phytoalexins in maize that mediate defence against both pathogen and insect attacks in aboveground tissues. However, little is known about their function in belowground organs and their potential to counter abiotic stress. In this study, we show that zealexins and kauralexins accumulate in roots in response to both biotic and abiotic stress including, Diabrotica balteata herbivory, Fusarium verticillioides infection, drought and high salinity. We find that the quantity of drought‐induced phytoalexins is positively correlated with the root‐to‐shoot ratio of different maize varieties, and further demonstrate that mutant an2 plants deficient in kauralexin production are more sensitive to drought. The induction of phytoalexins in response to drought is root specific and does not influence phytoalexin levels aboveground; however, the accumulation of phytoalexins in one tissue may influence the induction capacity of other tissues.     

多年生黑麦草对干旱胁迫下喀斯特异质生境的生长响应策略

在喀斯特地区异质性生境中,土壤水分含量、植物生存空间和养分状况等的综合作用共同影响植物的生理功能和生长发育。以多年生黑麦草(Lolium perenne L.)为研究材料,通过模拟同质(S-S:浅土-浅土)和异质(S-D:浅土-深土)两种小生境,探究3种施水量(对照:W_0、中度干旱:W_1、重度干旱:W_2)条件下植物对异质生境的适应,主要解决以下问题:异质生境下植物是否会主动寻求高水分、厚土壤、或者更宽阔的生长空间来提高其对异质性生境的适应?降雨量的改变是否会导致植物的适应策略发生改变?主要结果如下:(1)只有在重度干旱(W_2)条件下,异质性生境中黑麦草的株高、分蘖数以及地上、地下生物量和地上、根质量分数显著高于同质生境,而在对照(W_0)和中度干旱(W_1)条件下两种生境均无明显差异。(2)在对照降水(W_0)条件下,异质生境中黑麦草浅土区根系生物量、根组织密度较深土区少,比根长、比根面积较深土区大;随着施水量的减少,浅土区根系生物量占整个植株根系生物量的比例呈现先减小、后增大的趋势,深土区的比根长、比根面积逐渐增大,根组织密度逐渐减小。以上结果表明,在异质性生境中黑麦草表现出更强的抵御干旱胁迫能力,且随着干旱程度的加重这种优势更加明显:异质性生境中黑麦草通过将有限的生物量更多的分配在深土区,同时增大深土区根系的根组织密度,使得根系在生长环境好的斑块中大量增生和下扎,使植株获得大量的水分和养分,而浅土区则充分利用较少的资源,通过增大比根长和比根面积、减小根组织密度的方式发展根系,尽可能多地利用浅土区的水分和养分。随着干旱程度的加重,植物在维持浅土区正常生理活动的基础上有限度地增大深土区的生物量;当浅土区比根长、比根面积增大到一定限度时,植物会通过逐渐增大深土区的比根长和比根面积、减小根组织密度的策略来应对干旱胁迫。     

Propagation in vitro of the apple rootstock M4: effect of phytohormones on shoot quality

The quality of shoots in cultures of the apple rootstock, M4, was used as a criterion for the selection of an optimum medium. The frequency of shoots in defined shoot clases was monitored for each of five media, which differed in the type and concentration of phytohormone. Media containing BA (1.15 mg l^-1) and IBA (either 0.15 or 0.20 mg l^-1) produced the maximum number of shoots that were desirable for transplantation and acclimatization.     

Intrinsic morphology and spatial distribution of non-structural carbohydrates contribute to drought resistance of two mulberry cultivars

• Drought is one of the most adverse environmental stresses limiting plant growth and productivity. However, the underlying mechanisms regarding metabolism of non-structural carbohydrates (NSC) in source and sink organs are still not fully elucidated in woody trees.
• Saplings of mulberry cv Zhongshen1 and Wubu were subjected to a 15-day progressive drought stress. NSC levels and gene expression involved in NSC metabolism were investigated in roots and leaves. Growth performance and photosynthesis, leaf stomatal morphology, and other physiological parameters were also analysed.
• Under well-watered conditions, Wubu had a higher R/S, with higher NSC in leaves than in roots; Zhongshen1 had a lower R/S with higher NSC in roots than leaves. Under drought stress, Zhongshen1 showed decreased productivity and increased proline, abscisic acid, ROS content and activity of antioxidant enzymes, while Wubu sustained comparable productivity and photosynthesis. Interestingly, drought resulted in decreased starch and slightly increased soluble sugars in leaves of Wubu, accompanied by notable downregulation of starch-synthesizing genes and upregulation of starch-degrading genes. Similar patterns in NSC levels and relevant gene expression were also observed in roots of Zhongshen1. Concurrently, soluble sugars decreased and starch was unchanged in roots of Wubu and leaves of Zhongshen1. However, gene expression of starch metabolism in roots of Wubu was unaltered, but in leaves of Zhongshen1 starch metabolism was more activated.
• These findings revealed that intrinsic R/S and spatial distribution of NSC in roots and leaves concomitantly contribute to drought resistance in mulberry.

     

<Emphasis Type="Italic">In vitro</Emphasis> shoot multiplication through shoot tip cultures of <Emphasis Type="Italic">Decalepis hamiltonii</Emphasis> Wight &; Arn., a threatened plant endemic to Southern India

Summary An efficient and rapid micropropagation system was developed for a food and medicinally important endangered shrub, Decalepis hamiltonii (‘swallow root’), through shoot multiplication. The influence of 2.5–7.5 μM isopentenyladenine (2iP), 4.4–17.7 μM 6-benzyladenine, 2.3–4.7 μM kinetin, 2.8–6.8 μM thidiazuron, and 2.3–11.4 μM zeatin alone and in combination with 0.3–0.9 μM indole-3-acetic acid (IAA) on in vitro multiple shoot production was studied. The maximum number of multiple shoots (6.5±0.4) was induced from shoot tips cultured on agar-based Murashige and Skoog (MS) medium containing 4.9 μM 2iP. But, both zeatin (9.1 μM) and kinetin (4.7 μM) in combination with IAA (0.6 μM) were able to produce a maximum of 5.0±0.4 and 5.1±0.4 multiple shoots, respectively. Further elongation of shoots and adventitious shoot formation was obtained on medium containing 2.5 μM 2iP and 0.3 μM gibberellic acid. Elongated shoots were separated and rooted on MS medium supplemented with 9.8μM indole-3-butyric acid (IBA) and various phenolic compounds within 5–6 wk. Phloroglucinol and salicylic acid interaction with IBA stimulated in vitro rooting of shoots. Successful field transfer was achieved in rooted plantlets.