一氧化氮、乙烯和赤霉素在打破杜梨种子休眠中的相互作用

【作者】 宋要强；

【导师】 惠伟；

【作者基本信息】 陕西师范大学 ， 植物学， 2010， 硕士

【摘要】 近十年的研究表明一氧化氮(NO)作为一种新的信号分子在植物体内广泛存在,并在植物各种生理活动中起着重要的调控作用,研究发现NO在打破种子休眠中也起着重要作用。种子休眠原因多种多样,许多生物因素和非生物因素都可以调控植物种子休眠。许多科学家已经证明在一些植物种子的休眠中乙烯(ET)和赤霉素(GA)起着重要的调控作用。杜梨是蔷薇科植物,广泛用于梨的砧木,其种子存在着较深度的休眠,需要长期的低温层积才能萌发,费时费力而且损失严重。本研究以处于休眠状态的杜梨种子为实验材料,经NO、ET和GA以及它们的抑制剂处理,在培养过程中对它们的发芽率和芽长度进行统计,并用气相色谱对乙烯释放量进行测定,研究NO、ET和GA在杜梨休眠中的相互关系。研究结果如下：1.外源NO可以打破杜梨种子休眠,显著提高萌发率。1、5、10、20 mM的一氧化氮供体硝普钠(SNP)处理都能促进杜梨种子萌发,提高萌发率。但是过高浓度的SNP处理会抑制芽的生长,甚至引起芽的死亡,其中10mM的SNP处理在促进萌发中效果较好,而且对芽的生长没有造成伤害。NO清除剂PTIO可以逆转SNP的作用维持种子休眠。在打破杜梨种子休眠中,NO合成有一氧化氮合酶(NOS)途径而没有硝酸还原酶(NR)途径参与。2.外源乙烯可以打破杜梨种子休眠,显著提高萌发率。0.5、1、2、5 mM的乙烯利(ETH)处理都可以提高杜梨种子的萌发率,以2 mM和5 mM两个浓度效果比较好,但过高浓度的乙烯利强烈抑制杜梨芽的生长,结果表明：2mM是打破杜梨休眠促进萌发的最佳浓度。乙烯作用抑制剂1-甲基环丙烯(1-MCP)可以逆转外源乙烯的作用,降低萌发率。3.GA参与打破杜梨种子休眠过程。外源GA处理对带皮杜梨种子没有显著的影响,但是对去皮种子打破休眠效果显著。GA合成抑制剂多效唑可以强烈延长杜梨种子休眠、抑制萌发。4.NO通过促进内源乙烯的积累打破杜梨种子休眠,在打破杜梨种子休眠中乙烯处于NO信号通路的下游。1-MCP处理可以逆转SNP的作用,而PTIO对乙烯的效果作用不大。乙烯可以诱导自身的合成,乙烯的积累可以打破杜梨种子的休眠,经10 mM SNP处理后杜梨种子内源乙烯的释放量有了显著提高,而且PTIO和1-MCP都可逆转这种作用。5.在打破杜梨种子休眠中乙烯和GA是协同关系,协同打破杜梨休眠,而且GA是乙烯打破休眠必需的。GA抑制剂可以阻止乙烯的作用,乙烯抑制剂可以部分抑制GA的作用。6.根据本实验结果,我们提出在打破杜梨种子休眠中NO、乙烯和GA三者之间的信号关系：NO处于乙烯信号通路的上游,能够促进乙烯的积累；乙烯和GA是协同关系,协同打破杜梨种子休眠,而且GA在乙烯打破休眠中是必需的。更多还原

【Abstract】 Nearly a decade of research shows that NO as a new signaling molecule in plants is widespread, and plays an important role in regulating a variety of physiological active-ties in plants, many scien-tists found that NO plays an important role in breaking seed dormancy. the reasons of seed dormancy are very variegated, many biological factors and abiotic factors can control seed dormancy. It has been proved that ethylene (ET) and Gibberellin acid (GA) play an important role in regulating seed dormancy of some plants. Pyrus betulifolia Bunge is a species of the Rosaceae, its seed is a dormant seed, Dormancy can be breaked by Long-term cold stratification, consuming time and bring-ing a serious loss. In this study, the Pyrus betulifolia Bunge dormant seeds as expert-menttal material, we treated its seeds with NO, ET, GA and their inhibitors, calculate and measure percentage of germina-tion, shoot length, release of ethylene content in the training process, hope to find effects and rela-tionship of NO, ET and GA on seed dormancy of Bunge. The results as follows:1. Exogenous NO can break seed dormancy for germination of Pyrus betulifolia Bunge.1,5,10, 20 mmol/L of Sodium nitroprusside(SNP) treatment all broke its seed dormancy. But the high con-centration of SNP treatment inhibited the growth of buds, even leaded to the death of buds.10 mmol/Lof SNP treatment was better in promoting germination, and didn’t harm the growth of the bud. NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazo-line-l-oxyl-3-oxide(PTIO) reversed the role of SNP and main-tained seed dormancy. In Breaking the dormancy of Pyrus betulifolia Bunge seed NO came from Nitric oxide synthase(NOS) but not Nitrate reductase(NR) pathway.2. Exogenous ethylene broke Pyrus betulifolia Bunge seed dormancy, increased germination rate significantly.0.5,1,2,5 mmol/L of ethephon treatment all improved the germination rate of its seed,2 and 5 mmol/L were better, but the high concentra-tion of ethephon was strongly inhibited the growth of Pyrus betulifolia Bunge buds. The results showed that 2mmol/L was optimal concen-tration to break dormancy and promote germination of Pyrus betulifolia Bunge seed. Inhibitor of ethylene action 1-Methylcyclopropene(1-MCP) can reverse the role of exogenous ethephon and reduced germina-tion rate.3. GA involved in the process of breaking Pyrus betulifolia Bunge seed dormancy.2 mmol/L exogenous GA treatment had little effect on the seeds with testa of Pyrus betulifolia Bunge, but broke seed dormancy of peeled seed. GA synthesis inhibitor paclobutrazol strongly inhibited the germination of seeds of Pyrus betulifolia Bunge.4. Breaking Pyrus betulifolia Bunge seed dormancy by NO involved the stimulation of ethylene production. Ethylene was at the downstream of NO signaling pathway in breaking Pyrus betulifolia Bunge seed dormancy.1-MCP treatment reversed the SNP effect, while PTIO had little effect on ethylene. Ethylene induced its own synthesis, ethylene accumulation broke the dormancy of Pyrus betulifolia Bunge seed. By the treatment of 10 mmol/L SNP, endogenous ethylene production of Pyrus betulifolia Bunge seed had significantly increased, both PTIO and 1-MCP reversed the effect.5. Ethylene and GA were synergy in Pyrus betulifolia Bunge seeds, collaborative breaking its dormancy, and GA was necessary for ethylene to break dormancy. The inhibitors of GA could reverse the role of ethylene, ethylene inhibitors could partially inhibit the role of GA.6. According to the experimental results, it was proposed the signals relations of NO, ET and GA in breaking the dormancy of Pyrus betulifolia Bunge seeds:NO was in the upstream signaling pathway of ethylene, promoting the accumulation of ethylene; ethylene and GA was the systematic relationship, synergy breaking the dormancy of its seed, and GA was necessary for ethylene to break dormancy.更多还原