珍稀濒危植物堇叶紫金牛对持续干旱的生理响应

采用盆栽控水法,研究了珍稀濒危植物堇叶紫金牛(Ardisia violacea)在持续干旱条件下的生理响应。随着持续干旱时间的延长,堇叶紫金牛应对持续干旱的阶段可分为适应期、轻度干旱期、中度干旱期和重度干旱期。在适应期和轻度干旱期,堇叶紫金牛叶片游离脯氨酸和可溶性糖含量稳定在一个较低水平,可溶性蛋白质含量先下降后快速上升,细胞膜系统和抗氧化酶系统能主动进行生理调节;中度干旱期,丙二醛(MDA)含量和质膜相对透性迅速升高,细胞膜系统受损加剧,游离脯氨酸、可溶性糖含量均急剧增加,对抵御干旱起到重要的渗透调节作用。在轻度干旱期和中度干旱期,光合色素中叶绿素a和叶绿素b含量显著提高,以抵抗干旱胁迫。重度干旱期,细胞膜系统、抗氧化酶SOD、游离脯氨酸和可溶性糖含量上升,但MDA略微下降,这时可能达到植物耐受干旱的极限,不再发生膜脂过氧化作用。综上表明,堇叶紫金牛具有较强的耐旱性,RWC为49.94%是细胞膜系统、抗氧化酶系统和渗透调节物质含量变化的拐点,渗透调节和抗氧化酶系统的主动适应是其耐旱的主要机制。     

抽穗期不同程度水分胁迫对水稻产量和根叶渗透调节物质的影响

抽穗期是水稻生长对干旱胁迫比较敏感的时期,而渗透调节是作物适应逆境的重要生理机制之一。以水稻品种丰华占为实验材料,在人为控制水分的盆栽条件下,对水稻生长的抽穗期分别进行不同时间长短的控水处理,研究干旱胁迫对水稻干物质积累、产量、根系及叶片渗透调节物质的变化规律及其生理调节机制。结果表明,不同程度干旱胁迫后叶片水势均显著下降,除长期控水处理（12d）的可溶性糖含量下降外,其余控水处理（3～9d）的根系和叶片的有机渗透调节物质可溶性糖、游离氨基酸、脯氨酸均大幅度上升,而且水分胁迫程度越高,上升幅度越大,根系与叶片表现一致,但叶片的渗透调节能力大于根系,而根系的反应比叶片更迅速和敏感。短期干旱胁迫（3d和6d）再复水后根系和叶片的有机渗透调节物质含量可恢复到对照水平,而长期干旱胁迫（9d和12d）则不能。除长期干旱（控水12d）造成无机离子显著下降外,其他不同程度的干旱胁迫后根系和叶片的无机离子K^＋、Ca^2＋、Mg^2＋等含量则变化不大或轻微下降。水分胁迫后水稻根系、茎叶和穗干物质积累显著下降,抽穗期短期控水（3d）对产量没有明显影响,而控水6,9,12d分别使产量下降12．09％,48．55％,58．30％。不同控水处理均显著增加叶片的水分利用效率,控水时间越长,水分利用效率越高。研究结果表明了水稻在抽穗期经受短期干旱胁迫能有效地进行渗透调节,产量影响较小,而有机渗透调节物质比无机离子对干旱胁迫的反应更为敏感。     

干旱胁迫下2种香蕉幼苗叶片和根的主要渗透调节物质的变化

本文研究了不同干旱胁迫下抗旱性不同的帝王蕉和粉蕉幼苗叶片和根系的可溶性蛋白质和可溶性糖主要渗透调节物质的含量变化。结果表明:2种香蕉幼苗叶片可溶性蛋白质和可溶性糖含量随着干旱胁迫程度的增加而显著增多;根系可溶性蛋白质和可溶性糖含量并未持续上升,而是重度胁迫低于中度胁迫,但仍高于对照和轻度胁迫。干旱胁迫后,除帝王蕉根系可溶性糖含量外,帝王蕉根系可溶性蛋白质、粉蕉根系可溶性蛋白质和可溶性糖含量在3个胁迫程度下增加幅度均大于叶片增加幅度,且粉蕉较帝王蕉更能适应干旱胁迫环境。本文将为香蕉抗旱品种选育和栽培提供一定的理论依据和实践意义。     

小叶锦鸡儿幼苗非结构性碳水化合物积累及分配对干旱胁迫的响应

以2年生小叶锦鸡儿幼苗为研究对象,采用盆栽控水法,设置适宜水分、轻度、中度和重度胁迫处理(即田间持水量的80%、60%、40%和20%),探讨小叶锦鸡儿幼苗在干旱胁迫历时15、30、45和60 d各器官非结构性碳水化合物(NSC)的响应规律。结果表明:不同干旱胁迫处理程度与时间对小叶锦鸡儿幼苗叶片、茎、粗根和细根可溶性糖、淀粉及总NSC含量均具有显著交互作用。轻度胁迫下,各器官可溶性糖、淀粉及总NSC含量在胁迫30 d时均显著低于适宜水分处理,细根可溶性糖和粗根淀粉含量在胁迫60 d时显著高于适宜水分处理。中度胁迫下,随着胁迫时间延长,茎和粗根可溶性糖含量先低于适宜水分处理,而后逐渐增加;与轻度胁迫处理相比,叶片、茎和细根可溶性糖含量增加,茎和粗根淀粉含量降低。重度胁迫下,各器官淀粉含量在胁迫15 d时显著低于适宜水分处理;在胁迫60d时显著高于适宜水分处理。以上结果说明,小叶锦鸡儿幼苗通过调整各器官NSC积累及分配应对不同干旱环境。     

栓皮栎幼苗对土壤干旱胁迫的生理响应

以栓皮栎一年生盆栽苗为实验材料,采用称重控水的方法,设置不同土壤水分胁迫梯度,系统分析其幼苗在不同干旱胁迫条件下的生理生化响应特征,以探索栓皮栎耐旱特性.结果显示:(1)栓皮栎幼苗叶片中3种保护酶(SOD、POD、CAT)活性在对照(CK,土壤相对含水量19.5％～21.5％)条件下保持稳定,而中度干旱(T2,9.5％～11.5％)和重度干旱(T3,5.5％～7.5％)条件下,随着胁迫时间的延长呈先增高后降低的趋势,且变化的幅度在不同胁迫强度下存在差异.(2)在整个干旱胁迫过程中,各胁迫处理叶片丙二醛(MDA)含量均呈上升趋势,不同胁迫强度的变化幅度不同;叶片中的可溶性蛋白含量和根系活力随着干旱胁迫程度的增强呈先增高后降低的趋势.(3)栓皮栎幼苗叶片的脯氨酸含量随着干旱胁迫时间的延长表现出先增加后降低的趋势;叶片叶绿素a、叶绿素b、总叶绿素含量以及叶绿素a/b值均呈逐渐降低的趋势.研究表明,栓皮栎幼苗在短期和轻度干旱胁迫下通过提高自身的保护酶活性、增加可溶性蛋白和脯氨酸含量、提高根系活力等来抵御干旱环境的伤害,从而表现出较强的耐旱特性;而在重度干旱胁迫条件下,栓皮栎幼苗自我调节能力丧失,体内代谢紊乱,导致保护酶活性、可溶性蛋白、脯氨酸含量和根系活力等下降,从而受到干旱伤害.     

乌鲁木齐周边3种野生灌木对干旱胁迫的响应

木本猪毛菜（Salsola arbucula）、刺旋花（Convolvulos tragacanthoides）和刺木蓼（Atraphaxis spinosa）为乌鲁木齐周边植被组成的重要种,在维持荒漠生态系统的稳定中发挥着重要作用,是植被恢复过程中潜在的候选植物种。该文以盆栽控水法,分析比较了3种野生灌木在不同干旱胁迫下的生理生长特征的差异。结果表明,干旱胁迫下3种灌木均表现出良好的耐旱能力。在生长方面,刺旋花生长受到的影响最小,重度胁迫下其生物量与适宜水分处理相比仅减少9.7%,根系极发达,根冠比大。木本猪毛菜受抑制严重,重度干旱时株高和基茎增量为适宜水分处理的17.85%和21.63%。生理方面,刺旋花叶片叶绿素含量最高,膜系统受破坏较小,渗透调节可以通过可溶性糖的积累来实现。木本猪毛菜膜系统受破坏较小,脯氨酸的积累对渗透调节起重要作用。刺木蓼的脯氨酸和可溶性糖两种渗透调节物质均起重要作用。总之,木本猪毛菜和刺木蓼在轻度干旱下表现良好,刺旋花则能够在重度干旱下保持植物体正常的生理代谢功能,表现出对干旱环境较强的适应能力。     

干旱胁迫对枇杷生理特性及生长的影响

以3年生‘大五星’枇杷嫁接苗为试验材料,通过盆栽控水试验设置4个水分处理梯度:对照(CK)、轻度胁迫(LS)、中度胁迫(MS)和重度胁迫(SS),研究不同程度土壤干旱对枇杷幼树的生长和生理特性的影响。结果显示:(1)枇杷的株高、地上和地下生物量随干旱胁迫的增强呈下降趋势。(2)在轻度和中度胁迫下叶片叶绿素含量增加,随着土壤水分的减少,叶绿素含量和叶片相对含水量(LRWC)均显著下降。(3)叶片净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)随着干旱胁迫的加剧均显著下降,其中Gs下降幅度最大,而胞间CO2浓度(Ci)则表现为先下降后上升,重度胁迫时叶片的水分利用率(WUE)最低。(4)干旱的加重使叶片超氧化物歧化酶(SOD)和过氧化物酶(POD)的活性呈现先增加后降低的趋势,过氧化氢酶(CAT)活性在轻度胁迫下最为活跃但在重度胁迫时显著降低,丙二醛(MDA)含量在中度胁迫第10天开始显著升高。(5)随干旱胁迫的加剧游离脯氨酸(Pro)含量增加且在重度胁迫第10天达到最大值,而可溶性蛋白(SP)含量在胁迫后期与对照无显著差异,可溶性糖(SS)含量在重度胁迫后期达到峰值且与对照差异显著。研究表明,在轻度和中度干旱胁迫下,枇杷叶片光合作用受到抑制,但能够积极调控抗氧化酶的活性和渗透调节物质的含量等来增强耐受性,而重度胁迫下,叶片膜系统和光合系统受到损伤,枇杷生长受到严重抑制。     

辣椒开花结果期对干旱胁迫的形态与生理响应

在遮雨网室选用抗旱性较强的农城椒二号和抗旱性较弱的陕蔬2001,研究辣椒在轻度、中度和重度干旱胁迫下不同时间的生长、产量、渗透调节物质、保护酶活性的变化规律及其生理调节机制。结果表明:随干旱胁迫时间的延长,辣椒的株高、分枝数、叶面积、单位面积产量、叶绿素含量和叶片相对含水量的抗旱系数呈下降趋势,下降速率与干旱胁迫程度呈正相关,与品种的抗旱性呈负相关;脯氨酸、丙二醛含量和细胞膜透性相对值随干旱胁迫时间的延长呈上升趋势;POD、SOD、CAT活性和可溶性蛋白相对值随着干旱胁迫时间的延长先升高后下降,抗旱性强的材料增加幅度低于抗旱性弱的材料;可溶性糖含量的相对值在轻度和中度干旱胁迫下呈上升趋势,在重度干旱胁迫下呈上升—下降趋势,且抗旱性强的材料上升速度大于抗旱性弱的材料。相关分析表明,干旱胁迫下,产量与株高、分枝数、叶片叶绿素含量、叶面积、叶片相对含水量抗旱系数呈显著正相关;与细胞膜透性、CAT活性和可溶性蛋白含量抗旱系数呈显著负相关。主成分分析表明,用作辣椒抗旱性鉴定的主要指标是单株产量、株高、叶面积、分枝数、可溶性蛋白、可溶性糖、MDA、叶绿素含量和细胞膜透性及叶片相对含水量,叶片POD、SOD、CAT活性、脯氨酸含量可做为辣椒抗旱性鉴定的次要鉴选指标。     

干旱胁迫及复水对香樟幼树生理特性及生长的影响

通过盆栽和持续干旱处理研究了轻度干旱(持续干旱2~4d)、中度干旱(持续干旱6~8d)和重度干旱胁迫(持续干旱10~16d)及复水对香樟(Cinnamomum camphora)幼树生理特性和生长的影响,为香樟育苗、造林及合理的水分管理提供理论依据。结果显示:(1)干旱胁迫下香樟幼树地径生长量(Zd)和树高生长量(Zh)受到了抑制;轻度、中度干旱处理(土壤体积含水量从正常状态下降到7%)下叶片相对含水量(LRWC)与对照差异不显著,重度干旱处理(土壤体积含水量下降到3%)下显著低于对照。(2)轻度、中度干旱处理的超氧阴离子和过氧化氢含量与对照无显著差异,重度干旱处理较对照显著上升。(3)在活性氧酶促清除系统中,超氧化物歧化酶(SOD)、过氧化物酶(POD)活性在轻度干旱时显著上升,而过氧化氢酶(CAT)活性在重度干旱时才显著上升,在复水48h后3种酶活性均恢复到对照水平。(4)在轻度、中度干旱处理中叶片丙二醛(MDA)含量无显著变化,而在重度干旱下显著升高,且复水48h后未见显著降低。(5)在渗透调节物质中,轻度干旱时可溶性蛋白(SP)含量开始显著升高,中度干旱时可溶性糖(SS)含量显著升高,重度干旱时脯氨酸(Pro)含量显著上升;复水48h后Pro含量显著降低,而可溶性蛋白和可溶性糖含量无显著变化。研究发现,香樟幼树在轻度干旱胁迫下能通过自身抗氧化酶系统和渗透调节物质维持正常生长,而在中度和重度干旱胁迫条件下,其水分生理状况变差,膜系统遭受伤害,酶活性受到抑制,最终导致其形态生长和地上部分生物量积累受限。     

不同生育期水分胁迫对水稻根叶渗透调节物质变化的影响

 干旱是限制水稻(Oryza sativa)作物产量的主要生态因子之一,渗透调节是作物适应干旱逆境的生理机制之一。在人为控制水分的盆栽条件下, 对水稻生长的分蘖期、幼穗分化期、抽穗期、结实期分别进行水分胁迫,研究水稻根系及叶片渗透调节物质的变化规律。结果表明, 不同生育期 干旱胁迫后叶片水势均显著下降,根系和叶片的有机渗透调节物质如可溶性糖、游离氨基酸、脯氨酸和无机渗透调节物质包括K⁺、Mg²⁺等含量 均大幅度上升,而且幼穗分化期和抽穗期这两个对水分胁迫最敏感的时期上升幅度最大,其中又以有机渗透调节物质变化最显著。不同生育期渗 透调节大小的顺序为：抽穗期>幼穗分化期>结实期>分蘖期,反映了不同生育时期渗透调节能力的差异。同时幼穗分化期和抽穗期水分胁迫结束 后再复水后根系和叶片的有机渗透调节物质含量仍长期明显高于对照,而无机离子则变化规律比较复杂,有的升高有的则降低。叶片的渗透调 节能力大于根系,无论是叶片或根系都是K⁺对渗透调节的贡献最大;其次是Ca²⁺, 6 种渗透调节物质含量大小排列顺序为K⁺ > Ca²⁺ >可溶性糖 > Mg²⁺ > 游离氨基酸 > 脯氨酸。     

狭叶红景天幼苗对水分及遮阴的生长及生理生化响应

研究植物对水分和遮阴胁迫的响应及其生理机制对制定合理的栽培管理措施十分必要。以红景天属植物为研究对象,设置土壤含水量分别为田间持水量的80%(过湿水分)、70%(正常水分)、60%(轻度干旱)、40%(中度干旱)、20%(重度干旱)5个水分梯度;设置2个遮阴处理,以全光照(遮阴率为0)为对照、黑色遮阴网遮阴(遮阴率为85%),研究狭叶红景天生长及生理生化指标的变化特征。结果表明:在不同水分处理下,与对照相比,叶绿素含量、茎干重和茎重比(SMR)显著增加(P0.05),株高、总生物量、叶面积、叶干重、叶重比(LMR)、比叶面积(SLA)、叶面积比(LAR)和叶面积根干重比(LARMR)增加,根冠比和根重比(RMR)减少;随着干旱程度加剧,丙二醛(MDA)、脯氨酸(Pro)和可溶性糖(Ss)含量增加,超氧化物歧化酶(SOD)活性总体呈先增加后减小的趋势。在遮阴处理下,株高、SMR、SLA、LAR和LARMR显著增加(P0.05),叶绿素SPAD值和叶面积增加,总生物量、根干重、根冠比和LMR显著减少(P0.05),茎干重和叶干重减少,MDA含量显著增加,Pro含量略有下降,Ss含量减少。在水分胁迫下,狭叶红景天中度干旱时通过增加酶活性抵御伤害,重度干旱超过其阈值,SOD活性下降,植物体受到伤害,Ss可能是主要的渗透调节物质。在遮阴处理下,狭叶红景天通过增加SLA避免遮阴伤害。狭叶红景天在受到环境胁迫时会通过形态改变、调节MDA含量、抗氧化酶活性和渗透调节物质来保证自身正常的生长发育。     

Seed biopriming with drought tolerant isolates of Trichoderma harzianum promote growth and drought tolerance in Triticum aestivum

Green house study was aimed to investigate the effect of seed biopriming with drought tolerant isolates of Trichoderma harzianum, viz. Th 56, 69, 75, 82 and 89 on growth of wheat under drought stress and to explore the mechanism underlying plant water stress resilience in response to Trichoderma inoculation. Measurements of relative water content, osmotic potential, osmotic adjustment, leaf gas exchange, chlorophyll fluorescence and membrane stability index were performed. In addition, analysis of the phenolics, proline, lipid peroxidation and measurements of phenylalanine ammonia‐lyase activity were carried out. Seed biopriming enhanced drought tolerance of wheat as drought induced changes like stomatal conductance, net photosynthesis and chlorophyll fluorescence were delayed. Drought stress from 4 to 13 days of withholding water induced an increase in the concentration of stress induced metabolites in leaves, while Trichoderma colonisation caused decrease in proline, malondialdehyde (MDA) and hydrogen peroxide (H₂O₂), and an increase in total phenolics. A common factor that negatively affects plants under drought stress conditions is accumulation of toxic reactive oxygen species (ROS), and we tested the hypothesis that seed biopriming reduced damages resulting from accumulation of ROS in stressed plants. The enhanced redox state of colonised plants could be explained by higher l ‐phenylalanine ammonia‐lyase (PAL) activity in leaves after 13 days of drought stress in Trichoderma treated plants. Similar activity was induced in untreated plants in response to drought stress but to a lower extent in comparison to treated plants. Our results support the hypothesis that seed biopriming in wheat with drought tolerant T. harzianum strains increased root vigour besides performing the process of osmoregulation. It ameliorates drought stress by inducing physiological protection in plants against oxidative damage, due to enhanced capacity to scavenge ROS and increased level of PAL, a mechanism that is expected to augment tolerance to abiotic stresses.     

不同水分胁迫对绵毛水苏幼苗形态和生理特性的影响

以绵毛水苏幼苗为试材,以正常供水为对照,研究不同水分胁迫(淹水、渍水、中度干旱、重度干旱)对绵毛水苏形态和生理指标的影响。结果表明:(1)绵毛水苏植株在淹水处理3d后外围叶片坏死,根系死亡,但茎基部有不定根萌生;渍水处理植株地上部始终无明显变化,但部分根系根尖变褐色;干旱处理7d时叶片萎蔫,且重度干旱处理叶片萎蔫程度大于中度干旱。胁迫解除后,除淹水处理在第13天恢复生长外,其余处理均在第2天恢复正常生长。(2)绵毛水苏叶片含水量和根系活力在淹水处理下显著降低,在渍水处理下无明显变化;在干旱胁迫下,叶片含水量迅速下降,而根系活力升高。(3)在各水分胁迫条件下,绵毛水苏植株叶、根的相对电导率和MDA含量均较对照显著升高,且根部受损程度均重于叶片,其中淹水胁迫受损最严重。(4)淹水处理叶片可溶性蛋白含量下降,可溶性糖、游离脯氨酸持续积累;渍水和干旱处理叶和根的可溶性糖、可溶性蛋白和游离脯氨酸均升高。研究认为,绵毛水苏具有较强的渗透调节能力,在渍水和干旱胁迫解除后迅速缓解膜质过氧化伤害,恢复正常生长;绵毛水苏虽不能在长时间淹水条件下生长,但可在渍水条件下正常生长,且能忍受干旱胁迫,可应用于滨水消落带等水分变化较大的区域。     

Improvement in drought tolerance in bread wheat is related to an improvement in osmolyte production,antioxidant enzyme activities,and gaseous exchange

Water deficit stress negatively affects wheat growth, physiology, and yield. In lab and hydroponic experiments, osmotic stress levels (control, −2, −4, −6 and −8 Bars) created by PEG-6000, caused a significant decline in germination, mean germination time, root, shoot, and coleoptile length in both wheat genotypes examined. Germination was inhibited more in Wafaq-2001 than in Chakwal-50. Wafaq-2001 showed a higher susceptibility index based on root and shoot dry weight than did Chakwal-50. Wheat plants exhibited osmotic adjustment through the accumulation of proline, soluble sugars, soluble proteins, and free amino acids, and increased antioxidation activities of superoxide dismutase, peroxidase, catalase, and malondialdehyde. Increasing water deficit stress caused a linear decline in chlorophyll contents, leaf membrane stability, and relative water content in all wheat plants, with Wafaq-2001 showing a more severe negative impact on these parameters with increasing stress levels. The results suggest the possibility of utilizing some of these parameters as quantitative indicators of water stress tolerance in plants. Gas exchange measurements (photosynthesis, transpiration, stomatal conductance), leaf osmotic potential, water potential, and yield attributes decreased more abruptly with increasing water deficit, whereas leaf cuticular wax content increased in both genotypes, with more severe impacts on Wagaq-2001. More reduction in biochemical, physiological, and yield attributes was observed in Wafaq-2001 than was observed in Chakwal-50. Based on these results, we can conclude that Chakwal-50 is a more drought-tolerant genotype, and has excellent potential for future use in breeding programs to improve wheat drought tolerance.     

Application of Streptomyces pactum Act12 Enhances Drought Resistance in Wheat

The use of beneficial microbes to improve drought resistance in crops has great application potential in agricultural production, yet the effects of actinomycetes upon crop resistance to drought are rarely reported. Streptomyces pactum Act12 is a known multi-functional biocontrol agent of soil-borne diseases in several horticultural crops and medicinal plants. Here, we systematically analyzed how Act12 treatment affects drought resistance in drought-sensitive wheat (Triticum aestivum L.) cultivar Xinong 979 by considering both its effects and underlying mechanisms. After seed exposure to a cell-free culture filtrate of Act12, we measured several plant growth variables, osmotic adjustment and antioxidant capacity, cell membrane peroxidation, and drought resistance-related gene expression in wheat seedlings under drought stress conditions simulated by polyethylene glycol 6000. Results showed that, under drought stress, wheat seedling exposure to Act12 cell-free filtrate facilitated plant growth, with significant increases in shoot fresh weight (21.3%), shoot length (10.3%), and root length (13.6%). Act12 treatment also significantly increased total soluble sugar content in wheat leaves while decreasing their malondialdehyde content by 20.5%. Under non-drought conditions, Act12 treatment increased the content of both proline and glutathione in wheat leaves; however, both were lowered in Act12-treated plants compared with non-treated plants at 96 h of drought stress. Further analysis revealed that Act12 treatment increased the content of leaf abscisic acid and upregulated the expression levels of several drought resistance-related genes, such as EXPA2, EXPA6, P5CS, and SnRK2. These results suggest that application of S. pactum Act12 can enhance the osmotic adjustment and antioxidant capacity of plants via induction of abscisic acid accumulation and up-regulation of drought resistance-related gene expression, thereby mitigating drought stress impact in wheat.

     

五唇兰对PEG模拟的干旱胁迫响应研究

为了解干旱对五唇兰(Phalaenopsis pulcherrima)生长的影响,以聚乙二醇(PEG)溶液模拟干旱胁迫,对其叶片的光合色素、渗透调节物质和非结构碳水化合物(NSC)含量变化进行研究。结果表明,随着PEG浓度增加,五唇兰植株含水量和鲜质量逐渐下降,以PEG为13.75%～14.84%时最显著。PEG处理显著降低叶片的叶绿素a和b含量。随着植株含水量的降低,叶片可溶性蛋白、淀粉(St)含量均呈下降趋势,可溶性糖(SS)含量、NSC和SS/St均呈先升后降的趋势。因此,干旱胁迫会影响五唇兰植株的含水量和光合产物的积累;在较低程度干旱胁迫下,可溶性糖在抗旱响应中发挥主要作用;随着干旱胁迫程度加深,五唇兰的生理代谢受到严重影响。     

Photosynthetic pigments and photosynthetic products of endophyte-infected and endophyte-free Lolium perenne L. under drought stress conditions

Endophyte-infected (EI) seeds of Lolium perenne L. were used to attain endophyte-free (EF) population by heating the seeds at 43°C for 15 min and then 57°C for 25 min. Relative water content (RWC), chlorophyll, soluble sugar and starch content of EI and EF populations under normal and drought stress conditions were compared to investigate the effect of endophyte infection on the host plant. Under severe stress, RWC of EI leaf was significantly higher than that of EF leaf, i.e. EI plants took more advantages over EF plants in water-holding ability. Under mild stress, endophyte could enhance soluble sugars in host plants to improve their osmotic ability. With stress intensification, the improvement of endophyte no longer existed, and more photosynthetic products (such as starch) accumulated in EI plants to survive through the undesirable conditions. In the next spring, EI populations will recover more rapidly than EF populations. The biomass of a population is closely related to its photosynthesis. Under severe stress, EI population significantly accumulated more biomass than EF population. As far as photosynthetic pigments were concerned, contents of Chla, Chlb and Car of EI plants were close to those of EF plants, which suggested that endophyte infection didn’t alleviate photosynthetic pigments from being destroyed by drought stress, and endophyte might improve photosynthesis ability of its host plant in other ways. __________ Translated from Acta Ecologica Sinica, 2005, 25 (2) [译自: 生态学报, 2005, 25(2)]