乙烯在植物生长发育和抗病反应中的作用及其生物合成的反义抑制

乙烯是迄今为止所发现的 5大类植物激素之一 ,它广泛存在于植物体中 ,对植物的生长发育 ,特别是植物的成熟和衰老起着十分重要的调节作用。研究还发现 ,乙烯参与逆境条件 (热害、冷害、旱害、涝害、盐害、紫外线和重金属离子等 )下植物的胁迫反应 ,影响到植物体内一系列胁迫反应的开始和植物抗性的变化。近年来又发现乙烯参与植物的抗病反应 ,尤其是转反义乙烯形成酶基因植物的抗病性研究倍受重视。人们虽然在转反义乙烯形成酶基因植物的抗病性方面做了大量的工作 ,积累了相当多的资料 ,发现植物的抗病性与乙烯密切相关 ,但由于该研究尚处在初期 ,研究还不系统 ,乙烯在植物抗病反应中的作用机理也不十分清楚 ,因此需要系统整理和更加深入细致的研究。反义基因技术的成功应用 ,不仅为深入研究乙烯在植物体内的作用机理提供了方便 ,也为培育植物新品种提供了快速有效且专一性极强的育种新途径。本文将系统介绍乙烯在植物生长发育中的作用以及利用反义基因技术控制乙烯的生物合成、从而达到控制植物生长和发育之目的研究进展 ,重点叙述乙烯在植物抗病作用以及转反义乙烯形成酶基因植物的抗病性研究的最新进展 ,同时对倍受重视的反义基因技术的原理及特点也做较为全面和细致的介绍。     

Effect of fruit maturity on efficiency of 1-methylcyclopropene to delay the ripening of bananas

Three bunches of unripe ‘Williams’ banana fruit of different maturity, 173, 156 and 71 days from bunch emergence, were harvested. Fruit from the top, bottom and middle hands from each bunch were fumigated for 24 h with 1-methylcyclopropene (1-MCP) at 0, 5, 50 or 500 nl l⁻¹ at 20^oC. All fruit were then stored at 20^oC in air containing 0.1 μl l⁻¹ ethylene and the time taken for each fruit to ripen (green life) was noted. The green life of fruit treated with 500 nl l⁻¹ 1-MCP varied with fruit maturity. In the two most mature bunches it was 27.9±2.3 days, 4-fold longer than fruit fumigated with 0 nl l⁻¹ 1-MCP (6.7±0.6 days). In the least mature bunch, green life was 39.7±3.0 days, 1.5-fold longer than fruit fumigated with 0 nl l⁻¹ 1-MCP (25.7±2.5 days). Most fruit treated with 500 nl l⁻¹ 1-MCP showed an unacceptable uneven skin colouration when ripe. There was no significant effect on green life of 1-MCP at 50 nl l⁻¹ and 5 nl l⁻¹. Other fruit from these bunches were not exposed to 1-MCP and were held in ethylene-free air until ripe. In the two most mature bunches, these fruit had a significantly shorter green life (11.2±5.6 days in hand 1; 18.9±4.1 days in hands 4 and 6) than fruit that were fumigated with 500 nl l⁻¹ 1-MCP. In the least mature bunch, however, these fruit had a significantly longer green life (56.0±5.9 days) than 1-MCP treated fruit. Since the effectiveness of 1-MCP varied with fruit maturity and in any commercial consignment there is a mixture of fruit maturity, it is concluded that 1-MCP has limited commercial potential for the storage of unripe ‘Williams’ bananas.     

Plant oil emulsion modifies internal atmosphere, delays fruit ripening, and inhibits internal browning in Chinese pears

'Laiyang Chili’ and ‘Ya Li’ (Pyrus bertschneideri Reld) pears were treated with 3, 6, and 9% emulsions of commercial or refined (reduced -tocopherol levels) plant (soybean, corn, peanut, linseed, and cottonseed) oils at harvest an stored at 0°C for 6 months. Effects of oil treatments on ethylene production, respiration, fruit firmness, fruit color, soluble solid content (SSC), titratable acids (TA), internal browning (IB), and internal CO₂, O₂, and ethanol were studied. At the same concentration, oil treatments induced similar responses regardless of their sources or their -tocopherol concentrations. In both cultivars, ethylene production and respiration in fruit treated with 9% oils were lower in early storage and higher in late storage than that in the controls. Oils at 6% reduced IB, at 9% inhibited IB completely, and at 3% was not effective after 6 months at 0°C and 7 days at 20°C. Plant oil treatment maintained fruit color, firmness, SSC, and TA in a concentration-dependent manner during storage. In the first 4 months storage, 9% corn oil-treated fruit contained similar partial pressure of CO₂ and O₂ as the controls. After 5 months storage, oil-treated fruit contained higher partial pressure of CO₂ and lower levels of O₂ than the controls. When held at 20°C for 7 days, changes of internal CO₂ and O₂ were slower but partial pressure of CO₂ were higher, and O₂ were lower, in 9% corn oil-treated fruit than in the controls. Internal ethanol was not affected by oil treatment compared with control, either during storage or 7 days at 20°C. No off-flavor was detected in either oil-treated and control fruit by sensory evaluation.     

乙烯抑制剂在采后观赏植物中的应用研究进展

乙烯作为植物衰老激素在观赏植物及切花开花衰老过程中起着关键性的调节作用。利用乙烯抑制剂控制乙烯作用就成为延长观赏植物观赏寿命和提高其观赏价值的主要途径和经济有效的方法,是采后观赏植物研究的主要方向之一。在此,综述了近年来在采后观赏植物研究和生产实践中广为应用的几种乙烯抑制剂,并简要说明了其特点和作用原理。     

植物切花乙烯致衰机理与化学调节

乙烯是引起切花采后衰老的主要激素。综述了针对植物体内乙烯的生物合成途径及其作用机理的研究现状，从保持切花体内水分平衡、降低呼吸速率、抑制乙烯的产生和作用等方面提出了利用糖类、有机酸、STS、GA3、1—MCP等化学物质调控切花衰老的主要措施，并对切花保鲜的研究方向进行了展望。     

油桃后熟衰老期间几个生理指标的变化

以溶质油桃秦光和不溶质油桃阿姆肯为材料 ,研究了果实采后成熟衰老期间呼吸强度、乙烯释放速率、果肉硬度和膜透性变化的特点。结果表明 ,秦光和阿姆肯具有呼吸高峰和乙烯释放高峰 ,是典型的跃变型果实。果实硬度在跃变前快速下降 ,且膜透性的变化早于乙烯释放高峰。阿姆肯采后寿命长于秦光 ,膜透性、果实硬度的变化比秦光缓慢 ,但果实乙烯释放速率显著高于同期的秦光果实。     

乙烯释放剂克服香石竹试管苗玻璃化的研究

用香石竹(Diamthus caryphyllus L.)为试验材料,乙烯前体ACC和乙烯释放剂乙烯利为生长调节剂进行试验。试验结果表明,ACC对克服香石竹试管苗玻璃化有显著效果,并能一次成苗,正常试管苗的诱导频率达98％。从外部形态观察,茎叶充实度好,根系发达;茎横切面显微观察,茎内厚壁组织发达,细胞排列紧密;生理指标测定结果,蛋白质、干物质、叶绿素含量均高于玻璃苗,干物质为玻璃苗的1.7倍,叶绿素为玻璃苗的5.5倍。乙烯利培养的试管苗生长情况与ACC培养的相近。添加ACC、乙烯利的培养瓶中,乙烯释放量明显高于对照,说明乙烯对克服香石竹试管苗玻璃化有良好作用。     

聚乙烯醇渗调对台湾相思树种子活力的影响

用浓度为3％或5％的聚乙烯醇（PVA）水溶液浸种处理台湾相思树（Acocia canfusa Merr.）种子，其效果与聚乙二醇（PEG）相似，均能提高种子的发牙势、发芽率和活力指数，以及根的活力，呼吸速率、细胞色素氧化酶的活性和乙烯的释放量，初步证实了种子的活力指数与根的活力、呼吸速率、细胞色素氧化酶的活性和乙烯的释放量，有明显的相关性。根据对相关系数显著性“t”测定，其结果差异显著。     

高温胁迫下温州蜜柑内源乙烯和脱落酸的释放及其与落花落果的关系

 高温胁迫对温州蜜柑的热伤害首先表现在细胞膜透性增大，随后出现内源乙烯和脱落酸（ABA）的释放高峰，启动了纤维素酶的活力，从而加速了柑桔花和幼果的脱落速率。本研究结果还表明，异常高温对柑桔花和幼果的危害主要是代谢性的，当高温胁迫使花和幼果细胞电解质泄漏率大于对照1倍时将导致严重落花落果而减产。     

低压条件下“拳杏”果实的乙烯代谢

在4℃±1℃,大气压力分别为101 324.7,66 661.0和13 332.2 Pa的贮藏条件下,研究了“拳杏”果实的乙烯代谢,结果表明:低压抑制了果实内源乙烯的产生,ACC和蛋氨酸含量减少,EFE活性降低,对MACC含量影响不大。低压处理14d恢复常压后,内源乙烯逐渐升高。低压处理21d恢复至常压,14d内,乙烯变化不大。低压处理未看到EFE活性“高峰”。低压对ACC含量的抑制作用是可逆的,一旦恢复至常压,含量就上升。低压贮藏有延缓果实硬度下降的作用。