采后猕猴桃果实乙烯产生的变化及其与衰老的关系

中华猕猴桃和美味猕猴桃果实在衰老期间的乙烯释放速度和呼吸强度前期逐渐上升,后期下降,呈峰型变化。降低温度和改变气体成分,可推迟高峰的出现。衰老期间原果胶/总果胶的比值不断下降,果肉硬度随之降低。美味猕猴桃的内源乙烯含量和呼吸强度皆低于中华猕猴桃。原果胶/总果胶的比值和果肉硬度的变化可作为猕猴桃果实衰老的一种标志。     

ABA 和乙烯对荔枝果实成熟和着色的调控

 荔枝果实幼果期ABA 含量很高, 之后下降, 在转红前1 周急剧上升, 形成一个峰值。果皮、果肉乙烯释放量的变化与ABA 相似, 但其跃变发生在ABA 之后, 且跃变较小。伴随着乙烯的跃变, 有一个糖代谢和转化酶活性的跃变。于转熟前用STS 处理荔枝果实, 导致果实转色和成熟延迟。果实发育后期, ABA 急剧增加可能诱导了乙烯的合成, 乙烯启动果实成熟, 果皮转红着色。     

Enzymes of Ammonia Assimilation and Transamination in Relation to Hybrid Vigour in Pearl Millet (Pennisetum americanum L. Leeke)

Changes in the activities of enzymes of ammonia assimilation viz., glutamate dehydrogenase (GDH), glutamine synthetase (GS) and glutamate synthase (GOGAT), together with the activities of glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) were analysed in the topmost fully expanded leaf of pearl millet (Pennisetum americanum L. Leeke) hybrid BJ-104 , and its parents, J-104 and 5141-A , during the entire period of growth in field. Ammonia assimilation enzymes showed strong ontogenic trends and the hybrid attained activities either equal to the better (male) parent or showed better parental heterosis. In contrast to this both GOT and GPT activities were slightly higher than the poor (female) parent. The role of these enzymes in relation to chlorophyll synthesis and transport of metabolites from cellular compartments of C₄ plants, are discussed. Surveying the literature on attempts to propose biochemical criteria for hybrid vigour, it is proposed that there cannot be a universal criterion, rather rate limiting steps in different cultivars should be searched.     

蔗糖和乙烯利对唐菖蒲切花开放的影响

[目的]为了找出唐菖蒲(Gladiolus hybridus)保鲜液中合适的蔗糖浓度,探寻乙烯利对唐菖蒲切花的影响。[方法]进行不同糖浓度保鲜液试验和不同用量乙烯利的催花试验。[结果]唐菖蒲能耐受20%的蔗糖浓度,且该处理的小花开放总数最多、花径最大,盛花期最长。而低糖处理(2%～6%)的花枝在瓶插后期花径减小,盛花期明显缩短。唐菖蒲切花在经过乙烯利处理后没有明显的呼吸跃变现象,小花开放速度比较均匀,但是高浓度乙烯利处理的花枝前期开放速度较快,后期小花无法正常展开,花瓣变色、坏死,比对照的盛花期减少了2 d左右。[结论]唐菖蒲保鲜液中添加高浓度的蔗糖(10%～20%)比低浓度(2%～8%)的保鲜效果好。唐菖蒲虽然没有明显的呼吸跃变现象,但是属于乙烯敏感类型,高浓度的乙烯会对其造成明显伤害。     

不同处理方法对辣椒采后贮藏特性的影响

分别采用热处理、1-MCP处理、乙烯处理尖椒.结果显示,各处理均引起了采后辣椒膜损伤,同时热处理和1-MCP处理可以抑制乙烯生成和呼吸高峰,延迟叶绿素降解,起到延长贮藏期的目的.     

杆菌肽合成分子机制及高产策略

杆菌肽是一种非核糖体肽类的广谱抗菌素,目前广泛应用于农业和医药。过去,杆菌肽的生产水平增长缓慢。近年来国内外对杆菌肽的生物合成及调控的分子机制研究取得较大突破,为其育种和生产工艺优化、提高产量和质量、满足市场需求奠定基础。综述了国内外相关文献,重点关注杆菌肽生物合成基因簇及调节分子机制,兼顾其产量提高策略的报道,为今后开展相关育种研究、发酵工艺优化和提高杆菌肽的产量提供依据。     

‘阿蒂擎天’凤梨谷胱甘肽-S-转移酶基因的克隆与乙烯诱导表达特性的初步分析

以阿蒂擎天凤梨乙烯处理和不处理的植株为材料建立的抑制性差减杂交文库中,筛选到的一个被乙烯诱导并与已知植物谷胱甘肽-S-转移酶(GST)同源的cDNA片段,通过RACE技术得到该基因的全长cDNA序列。序列分析表明,该基因可能属于thioredoxin-likesuperfamily和GSTC_family superfamily两个超家族中的成员。利用半定量RT-PCR检测该基因的表达量在乙烯处理后先会在1h显著升高,然后随时间逐步降低,说明乙烯作为一种逆境胁迫相关激素,可在短时间内诱导凤梨中GST的表达。推测其在受到外源乙烯信号诱导后,一方面可能参与了植物体内的解毒作用,另一方面可能参与了花青素的合成调控和运输。本实验中的GST作为观赏凤梨中一个新发现的GSTs家族成员,对于研究热带花卉中GSTs家族的特点和提高其抗逆性和品质具有重要的理论意义和实用价值。     

Ethylene

Abstract

Ethylene is a simple gaseous hormone that is involved in many aspects of plant growth and development. Two physiological responses that are commonly controlled by ethylene, fruit ripening and flower senescence, have been given the most significant attention in terms of crop improvement using the tools of modern plant molecular biology and biotechnology. Fortunately, the wealth of research on ethylene biosynthesis and signaling pathway has been providing tools for the genetic control of ethylene effects. Today, manipulation of ethylene biosynthesis and signaling is one of the most promising approaches to improve crops through genetic engineering. In this review we will discuss current status and future directions of transgenic techniques to control ethylene effects with a primary focus on flower senescence.     

Diversity and Biosynthetic Potential of Culturable Microbes Associated with Toxic Marine Animals

Tetrodotoxin (TTX) is a neurotoxin that has been reported from taxonomically diverse organisms across 14 different phyla. The biogenic origin of tetrodotoxin is still disputed, however, TTX biosynthesis by host-associated bacteria has been reported. An investigation into the culturable microbial populations from the TTX-associated blue-ringed octopus Hapalochlaena sp. and sea slug Pleurobranchaea maculata revealed a surprisingly high microbial diversity. Although TTX was not detected among the cultured isolates, PCR screening identifiedsome natural product biosynthesis genes putatively involved in its assembly. This study is the first to report on the microbial diversity of culturable communities from H. maculosa and P. maculata and common natural product biosynthesis genes from their microbiota. We also reassess the production of TTX reported from three bacterial strains isolated from the TTX-containing gastropod Nassarius semiplicatus.