林线树种太白红杉种子萌发的生理生态特性

 太白红杉(Larix chinensis)是太白山的高山林线树种。通过在人工气候室内的试验,研究了太白红杉种子在6种不同的光照与温度组合处理条件下的萌发特性。结果表明：在恒温和变温两种条件下,交替光照对于种子吸胀后的脱落酸（ABA）和赤霉素 (GA)有刺激作用。在恒温条件下,持续光照对于种子吸胀后的生长素 (IAA)有刺激作用,而变温条件下交替光照对生长素有刺激作用。细胞分裂素（CTK）的变化情况与IAA相反。光照条件相同时,恒温条件下的植物激素含量要高于变温条件下的含量,说明恒温对于各种激素有刺激作用。在25 ℃环境下种子的萌发率高于在12 ℃环境下的萌发率,说明温度对于种子的萌发有重要作用。太白红杉种子的萌发受交替光照（12 h光照/12 h黑暗）的刺激;恒温（25 ℃）条件下的种子萌发率高于变温（12 ℃/25 ℃）条件下的种子萌发率。实验结果反映了内源激素在太白红杉种子萌发过程中起着重要作用。     

椭圆叶花锚种子内源激素对储藏的响应及其与种子萌发的关系

内源激素作为调控种子萌发与休眠的主要内因一直备受关注,但其随环境条件改变的变化规律及其对种子萌发的调节机制一直缺乏普遍接受的理论或假说。本研究以广泛分布于青藏高原东北缘高寒草甸的椭圆叶花锚种子为研究材料,分析不同储藏条件和时间对椭圆叶花锚种子内源激素含量的影响,及其与种子萌发的关系。结果表明:不同储藏条件下,椭圆叶花锚种子中内源激素含量随储藏时间变化差异显著;常温条件下,储藏时间对内源激素的绝对含量及各生长促进物与抑制物的比值(IAA/ABA除外)均有较显著的影响,而在冷藏条件下,储藏时间仅对GAs、IAA、ABA和促进物总量有较显著的影响;储藏条件和时间对椭圆叶花锚种子的萌发率均有极显著影响;常温储藏条件下种子萌发率大约是冷藏条件下的4倍,且种子存在休眠循环;椭圆叶花锚种子萌发并不是促进类激素或抑制类激素绝对含量的升降调节的;种子萌发与GAs含量显著正相关、与IAA含量显著负相关,CTK的含量达到一定高度的时候,萌发率才能达到最高。因此,本研究中各内源激素的作用关系,与Khan提出的三因子学说相一致,即CTK与ABA相拮抗,减轻或消除ABA的萌发抑制作用,从而使GAs的作用表现出来。     

3,4-二羟基苯乙酮胁迫对天山云杉种子萌发过程中内源植物激素含量变化的影响

3,4-二羟基苯乙酮(DHAP)是天山云杉(Picea schrenkiana ssp. tianschanica)叶和凋落物中存在的主要自毒物质, 是导致天山云杉林天然更新障碍的原因之一。为了解释自毒物质发生作用的生理机制, 该文设计多个浓度梯度的DHAP溶液处理天山云杉种子, 以发芽率和发芽势为种子萌发参数, 运用反相超高效液相色谱(UPLC)分析技术, 检测了种子萌发过程中内源植物激素玉米素(ZT)、赤霉素(GA₃)、吲哚乙酸(IAA)和脱落酸(ABA)含量水平的变化。研究结果表明: DHAP处理对天山云杉种子萌发影响具有浓度效应, 表现为5.0 mmol·L^-1 > 0.1 mmol·L^-1 > 1.0 mmol·L^-1 >对照, 即5.0 mmol·L^-1 DHAP处理组对种子萌发的抑制作用最强、0.1 mmol·L^-1 DHAP处理组次之、1.0 mmol·L^-1 DHAP处理组最弱; DHAP处理组的种子内源ZT、GA₃浓度水平降低, ABA含量升高, GA₃浓度峰值出现时间延迟, IAA浓度在高浓度(5.0 mmol·L^-1 DHAP)处理组短时间内(3-6天)过量积累, 1.0和5.0 mmol·L^-1 DHAP处理组的种子内源ABA浓度峰值出现时间延迟; DHAP处理种子萌发1-6天时, ZT/(GA₃+IAA)比值降低, IAA/ZT、ABA/ZT比值增大; ABA/(ZT + GA₃ + IAA)比值在0.1 mmol·L^-1 DHAP处理组增大, 在5.0 mmol·L^-1 DHAP处理组降低。DHAP处理引发种子内源激素含量水平及激素含量间比值变化, 可能是抑制、延迟天山云杉种子萌发的主要原因。     

外源信号物质对肉苁蓉种子萌发与吸器形成内源激素水平变化的影响

利用外源信号物质氟草敏（norflurazon）和2,6-二甲氧基对苯醌（2,6-DMBQ）分别诱导肉苁蓉种子萌发与吸器形成,研究它们在此过程中对内源激素脱落酸（ABA）、赤霉素（GA3）、吲哚乙酸（IAA）、玉米素核苷（ZR）水平变化的影响。结果表明：在诱导肉苁蓉种子萌发时,经norflurazon处理0～168h后,种子中ABA水平呈现显著降低的变化趋势,GA3、IAA、ZR水平呈现显著升高的变化趋势。在诱导肉苁蓉种子萌发体吸器形成时,经2,6-DMBQ处理0～72h后,肉苁蓉种子萌发体ABA水平变化不显著,GA3、IAA、ZR水平均呈现显著升高的变化趋势。表明在肉苁蓉种子萌发与吸器形成中外源信号物质nor-flurazon和2,6-DMBQ能影响内源激素水平的变化。     

光照对沙芥种子萌发中生理生化指标的影响

以沙芥种子为实验材料,以24h黑暗处理为对照,研究了光照对其萌发过程中主要贮藏物质、内源激素和酚酸类物质含量的影响。结果表明：光照处理的沙芥种子的萌发指标均明显低于黑暗处理,且萌发过程中脂肪和淀粉的降解、淀粉酶活性、可溶性糖的增加也显著低于黑暗处理;在萌发的前2d,光照处理的种子ABA、酚酸类物质总量、没食子酸、对羟基苯甲酸、咖啡酸、香豆酸和肉桂酸含量均高于黑暗处理。     

珍稀濒危植物珙桐种子休眠萌发过程中内源激素的变化

珙桐是我国特有珍稀濒危植物,休眠期长且具二次休眠现象。将处于休眠萌发过程中的珙桐种子依据胚根长度划分为4个阶段,利用高效液相色谱(HPLC)测定各阶段种子及其内果皮中ABA(脱落酸)、GA(赤霉素)、KT(细胞分裂素)、IAA(3-吲哚乙酸)4种内源激素含量,分析其比值动态变化,并与幼苗阶段进行比较。结果显示:未破壳种子的内果皮中内源激素含量以ABA最高,其次是GA、IAA、KT,随着种子破壳后四种激素含量显著降低。除ABA外,种子中GA、IAA和KT含量随着胚根的伸长逐渐升高,但仍低于幼苗阶段。此外,随着胚根伸长,种子中GA/ABA、IAA/ABA、KT/ABA比值逐渐增大,其中以GA/ABA的变化最显著。因此,珙桐种子的休眠和萌发可能主要受ABA和GA的平衡和拮抗来调控。     

大果白刺种子内源激素含量研究

目的：探究大果白刺种子萌发过程中内源激素的变化。方法：通过HPLC测定低温层积后大果白刺种子内源激素含量的变化。结果：大果白刺种子GA₃含量显著提高，而ABA、IAA、ZR和ETH含量均显著下降。GA₃/ABA值显著提升，IAA/ABA和ZR/ABA值呈现下降趋势。结论：GA₃含量和GA₃/ABA值较高，ABA、IAA、ZR、ETH含量和IAA/ABA、ZR/ABA值较低，证明各种内源激素含量及其比值是制约其种子休眠的重要因素。     

4PU-30对水稻叶片衰老与内源激素的调控

4PU－30能显著地延缓水稻叶片衰老。根据叶片衰老过程中内源激素含量的变化,可明确减缓水稻叶片衰老期间内源ABA含量的增加和内源ZRs、GAs和IAA含量的减少,使叶片中保持有较低水平的ABA与较高水平的ZRs、GAs和IAA,是4PU－30延缓水稻叶片衰老的主要调控机理。     

乙酰胆碱对管花肉苁蓉种子萌发及其内源IAA和ABA含量的影响

检测不同浓度乙酰胆碱对管花肉苁蓉种子发芽率和内源吲哚乙酸(IAA)和脱落酸(ABA)含量影响的结果表明:适宜浓度(1.0~3.0mmol·L~(-1))的乙酰胆碱可促进肉苁蓉种子萌发,并改变内源IAA和ABA含量。1.0mmol·L~(-1)乙酰胆碱是促进肉苁蓉种子萌发的临界点。     

温水浸种对杜仲种子萌发过程中保护酶活性及内源激素含量变化的影响

探讨杜仲（Eucommia ulmoides Oliver）种子萌发过程中保护酶活性及内源激素含量的变化，为其种子破眠及萌发不同时期采取有效处理措施，从而提高出苗率提供参考。利用室温（CK）、40℃、50℃、60℃和70℃不同水温，探讨温水浸种对杜仲种子萌发的影响。种子萌发进程中，利用常规生理生化方法测定种子内超氧化物歧化酶（SOD）、过氧化物酶（POD）活性和丙二醛（MDA）含量，以及酶联免疫法测定赤霉素（GA₃）、吲哚乙酸（IAA）、脱落酸（ABA）和玉米素核苷（ZR）含量。结果表明：①温水浸种处理能提高了杜仲种子的发芽率及发芽势，其中以50℃温水处理最为显著。②与室温浸种处理相比，50℃温水浸种处理提高了种子内SOD及POD活性，减轻了质膜氧化损伤程度，致使MDA含量的持续下降，从而促使种子朝向有利于萌发的方向发展。此外，50℃温水浸种处理在提高种子内促进生长内源GA₃、IAA及ZR含量的同时，并降低了抑制生长的内源ABA含量，致使GA₃/ABA、IAA/ABA和ZR/ABA值均明显高于室内浸种处理，最终促进了杜仲种子的萌发。     

细叶楠种子休眠与萌发对低温层积的生理响应

细叶楠(Phoebe hui Cheng ex Yang)是我国特有的珍贵树种,种子具有生理休眠特性。本文以细叶楠种子为实验材料,研究不同低温层积处理时间(0、20、40、60 d)对细叶楠种子发芽率、营养物质(淀粉、可溶性糖、可溶性蛋白)、过氧化物酶(POD)以及内源激素脱落酸(ABA)、赤霉素(GA₃)、生长素(IAA)、玉米素核苷(ZR)的影响,分析细叶楠种子萌发与其生理指标的相关性。结果显示：(1)低温层积可以有效打破细叶楠种子的休眠,且处理60 d效果最佳。(2)在低温层积过程,细叶楠种子萌发时间缩短,发芽率提高;种子内淀粉含量降低,可溶性糖和可溶性蛋白含量升高;POD活性上升;ABA含量下降,GA₃、IAA含量增加,而ZR含量先上升后下降。(3)细叶楠种子休眠的解除与萌发与其体内营养物质含量、POD活性以及内源激素含量的变化密切相关。     

Transition from hormonal to nonhormonal regulation as exemplified by seed dormancy release and germination triggering

It is generally believed that seed dormancy release is terminated by germination and that this process is controlled by phytohormones. Most attention was paid to gibberellins (GAs) because treatment with GAs is most frequently applied for seed dormancy breaking. The review characterizes the hormonal regulation of seed dormancy and its release, as exemplified by arabidopsis seeds possessing non-deep physiological dormancy. Dormancy release occurs under the influence of low temperature and/or illumination with red light. Two main trends are typical of this process: (1) a decrease in ABA content and blocking of signal transduction from ABA, and (2) GA synthesis and activation of GA signaling pathway. Dormancy release ends with the GA-induced syntheses of some proteins, enzymes in particular, required for the start of germination. Quiescent seeds are capable of realizing the germination program without hormonal induction, due to nothing but seed hydration. In imbibing seeds, the triggering role of water lies in the successive activation of basic metabolic systems after attaining the water content thresholds characteristic of these systems and in preparing cells of embryo axial organs for germination. Thus, seed dormancy release is controlled by phytohormones, whereas subsequent germination manifesting itself as the initiation of cell elongation in embryo axes is controlled by water inflow.     

濒危植物巴东木莲种子休眠与萌发特性的研究

巴东木莲(Manglietia patungensis)为我国特有种, 属国家重点保护植物。为找出其生殖环节中的致危因素, 作者对巴东木莲种子休眠与后熟过程中的形态和萌发特性进行了研究。结果表明, 巴东木莲种胚发育不完全可能是种子休眠的主要原因, 在其后熟过程中胚不断分化、发育成熟; 种皮具有较好的透性, 与休眠的关系不大; 种子不同部位均存在萌发抑制物, 胚乳中高含量的萌发抑制物是影响胚萌发的重要因素。内源激素ABA和IAA在巴东木莲种子休眠与萌发过程中起着重要作用, ABA是引起休眠的关键因素, IAA有助于种子的萌发, IAA/ABA相对含量的变化对种子的休眠和萌发产生重要影响。巴东木莲种子的休眠是由种子本身的形态和生理特点引起的综合休眠, 在4℃低温保湿条件下才能完成其形态和生理后熟过程, 而自然条件下, 巴东木莲种子成熟时正值秋季少雨, 很容易失水而不能完成其后熟过程而失去生活力, 这可能是导致该物种自然更新困难的重要原因。     

Gibberellin requirement for Arabidopsis seed germination is determined both by testa characteristics and embryonic abscisic acid

The mechanisms imposing a gibberellin (GA) requirement to promote the germination of dormant and non-dormant Arabidopsis seeds were analyzed using the GA-deficient mutant ga1, several seed coat pigmentation and structure mutants, and the abscisic acid (ABA)-deficient mutant aba1. Testa mutants, which exhibit reduced seed dormancy, were not resistant to GA biosynthesis inhibitors such as tetcyclacis and paclobutrazol, contrarily to what was found before for other non-dormant mutants in Arabidopsis. However, testa mutants were more sensitive to exogenous GAs than the wild-types in the presence of the inhibitors or when transferred to a GA-deficient background. The germination capacity of the ga1-1 mutant could be integrally restored, without the help of exogenous GAs, by removing the envelopes or by transferring the mutation to a tt background (tt4 and ttg1). The double mutants still required light and chilling for dormancy breaking, which may indicate that both agents can have an effect independently of GA biosynthesis. The ABA biosynthesis inhibitor norflurazon was partially efficient in releasing the dormancy of wild-type and mutant seeds. These results suggest that GAs are required to overcome the germination constraints imposed both by the seed coat and ABA-related embryo dormancy.     

梾木种子低温层积过程中内源激素含量的动态变化特征

应用酶联免疫吸附测定法(ELISA)研究了梾木种子低温层积过程中内源激素含量的动态变化,分析了内源激素与种子休眠与发芽的关系。结果表明:(1)梾木种子中IAA含量在层积处理初期剧烈降低,持续一段时间后又显著升高,但后期下降,且IAA/ABA也出现同样的变化;种子中ABA含量在层积处理前期较高,但随着处理时间的延长趋于下降;种子内GA1/3含量以及GA1/3/ABA均随层积处理时间的延长逐渐增大;种子内ZRs和iPAs含量的变化相对较为平稳,尽管有一定的波动,但整体呈渐趋增高趋势。(2)梾木种子发芽率及发芽势在未经层积处理以及处理时间少于90d的条件下均为0,但随着层积处理时间的延长二者明显上升,层积处理的时间长短对梾木种子萌发有显著影响。(3)相关分析表明,梾木种子内GA1/3含量与种子的发芽率、发芽势均呈显著正相关关系,相关系数分别为0.688、0.662;种子内GA1/3/ABA增大有利于种子休眠解除和萌发。     

Control of macaw palm seed germination by the gibberellin/abscisic acid balance

The hormonal mechanisms involved in palm seed germination are not fully understood. To better understand how germination is regulated in Arecaceae, we used macaw palm (Acrocomia aculeata (Jacq.) Lodd. Ex Mart.) seed as a model. Endogenous hormone concentrations, tocopherol and tocotrienol and lipid peroxidation during germination were studied separately in the embryo and endosperm. Evaluations were performed in dry (D), imbibed (I), germinated (G) and non‐germinated (NG) seeds treated (+GA₃) or not treated (control) with gibberellins (GA). With GA₃ treatment, seeds germinated faster and to a higher percentage than control seeds. The +GA₃ treatment increased total bioactive GA in the embryo during germination relative to the control. Abscisic acid (ABA) concentrations decreased gradually from D to G in both tissues. Embryos of G seeds had a lower ABA content than NG seeds in both treatments. The GA/ABA ratio in the embryo was significantly higher in G than NG seeds. The +GA₃ treatment did not significantly affect the GA/ABA ratio in either treatment. Cytokinin content increased from dry to germinated seeds. Jasmonic acid (JA) increased and 1‐aminocyclopropane‐1‐carboylic acid (ACC) decreased after imbibition. In addition, α‐tocopherol and α‐tocotrienol decreased, while lipid peroxidation increased in the embryo during germination. We conclude that germination in macaw palm seed involves reductions in ABA content and, consequently, increased GA/ABA in the embryo. Furthermore, the imbibition process generates oxidative stress (as observed by changes in vitamin E and MDA).     

Role of endogenous hormones,glumes, endosperm and temperature on germination of Leymus chinensis (Poaceae) seeds during development

Aims Leymus chinensis is an original dominant plant in the Songnen grassland, and it has great value for restoration of severely degraded land. However, seeds are dormant, and low germination percentage is a problem for restoring L.chinensis grassland. The mechanism of seed dormancy is not been well understood. The primary aims of the present study were to investigate the dormancy mechanism of L.chinensis seeds (caryopses) with reference to the role of embryo-covering layers, endogenous hormones and temperature.Methods Changes in concentration of the endogenous hormones GA 3, indoleacetic acid (IAA), zeatin riboside (ZR) and abscisic acid (ABA) in L.chinensis seeds from anthesis to maturity were measured by the enzyme-linked immunosorbent assay method. Germination at different stages of maturity were tested at 16/28°C, 5/28°C and 5/35°C for intact seeds with glumes (control), intact seeds with glumes removed (naked-whole seeds) and intact seeds with glumes and one-half of the endosperm removed (naked-half seeds).Important findings Of the four endogenous hormones monitored, only the concentration of ZR differed significantly between the beginning and the end of seed development (increased); the GA 3 /ABA ratio also did not differ. Rank of germination percentage of control at the three temperature regimens was 5/28°C> 16/28°C> 5/35°C. Germination percentage of the naked-half seeds reached 100% under the three temperature regimens. We concluded that dormancy of L.chinensis seeds is not mainly controlled by endogenous hormones. Germination temperature, mechanical resistance of glumes and inhibition of endosperm are the main factors controlling dormancy and germination of L.chinensis seeds.     

Nitric oxide accelerates seed germination in warm-season grasses

The nitric oxide (NO) donor sodium nitroprusside (SNP) significantly promoted germination of switchgrass (Panicum virgatum L. cv Kanlow) in the light and in the dark at 25°C, across a broad range of concentrations. SNP also promoted seed germination in two other warm-season grasses. A chemical scavenger of NO inhibited germination and blocked SNP stimulation of seed germination. The phenolic (+)-catechin acted synergistically with SNP and nitrite in promoting seed germination. Acidified nitrite, an alternate NO donor also significantly stimulated seed germination. Interestingly, sodium cyanide, potassium ferricyanide and potassium ferrocyanide at 200 μM strongly enhanced seed germination as well, whereas potassium chloride was without effect. Ferrocyanide and cyanide stimulation of seed germination was blocked by an NO scavenger. Incubation of seeds with a fluorescent NO-specific probe provided evidence for NO production in germinating switchgrass seeds. Abscisic acid (ABA) at 10 μM depressed germination, inhibited root elongation and essentially abolished coleoptile emergence. SNP partially overcame ABA effects on radicle emergence but did not overcome the effects of ABA on coleoptile elongation. Light microscopy indicated extension of the radicle and coleoptiles in seeds maintained on water or on SNP after 2 days. In contrast, there was minimal growth of the radicle and coleoptile in ABA-treated seeds even after 3–4 days. These data indicate that seed germination of warm-season grasses is significantly influenced by NO signaling pathways and document that NO could be an endogenous trigger for release from dormancy in these species.