刺梨GL2同源基因的克隆、系谱树和表达分析

为了观察刺梨果实的果刺细胞学发育过程,该研究以刺梨‘贵农5号''的cDNA为模板,通过RACE克隆获得刺梨中与拟南芥表皮毛形成GL2的同源基因RrGL2,并对该基因进行生物信息学分析和表达分析。结果表明:(1)刺结构在花芽形成早期基部内的细胞首先不断分裂,向外继续发育,中部的细胞变细、变长形成“针”状结构,顶部的细胞逐渐木质化使刺变硬,形成果刺。(2)通过RACE扩增得到RrGL2的cDNA全长2 292 bp,编码763 aa氨基酸。(3)RrGL2具有Homeodomain同源结构域和StAR磷脂酰胆碱转移蛋白的结构域,RrGL2与其他物种编码的GL2氨基酸同源性高度相似,并且系谱树分析揭示刺梨RrGL2和野草莓的GL2密切相关。(4)qRT-PCR分析表明,RrGL2在茎和果实中的表达水平高于其他组织,在花后7周果刺中的表达最高,是3周和5周果刺中的7.87倍和2.10倍。综上结果发现RrGL2的功能与果刺的形成发育密切相关,该研究为刺梨中刺形成的分子机制和育种提供了理论基础。     

Decreased structural defence of an invasive thistle under warming

Plant structural defences play a key role in preventing fitness loss due to herbivory. However, how structural defences are affected by potential climate change is rarely examined. We examined how leaf morphological traits that relate to the structural defence of an invasive thistle, Carduus nutans, change in a warmer climate. We manipulated warming using open-top chambers (OTCs) and examined the morphology of leaves at three different positions (the 5th, 10th and 15th leaves, counted from the top of the plant) in two destructive summer censuses. We found that structural defence traits were different under ambient versus warmed conditions. Prickle densities (both the number of prickles per leaf area and the number of prickles per leaf mass) were significantly lower in plants grown in a warmer climate. Our results suggest that plant structural defences may be reduced under warming, and therefore should be considered when examining species' responses to climate change.     

Interspecific Variation in the Reproductive Response of Acacia Species to Protection from Large Mammalian Herbivores

We quantified the fruit set of four Acacia spp. inside and outside of long-term experimental exclosures in order to examine the fitness consequences of herbivory by large mammals. We found a considerable interspecific variation in the reproductive fitness costs of herbivory in four African Acacia spp. Acacia nilotica and A. brevispica respond to protection from large mammalian herbivores by greatly increasing their seed set. In contrast, there was little or no increase in seed set in A. mellifera and A. etbaica . The reasons for these differences are not known, but may be related to armament morphologies.     

Silica bodies and hooked papillae in lemmas of Melica species (Gramineae: Pooideae)

Melica (sensu lato ) is a genus with approximately 80 species distributed in the temperate regions of both hemispheres. The genus has been better studied morphologically than anatomically, but morphological patterns have led to conflicting subdivisions either into sections, or by segregation of the genus Bromelica . The lemma epidermis is examined here under scanning electron microscopy (SEM) for 40 species of Melica to see if it exhibits characters of systematic significance. Silica bodies and hooked papillae are reported in the lemma for the first time in the genus. Patterns of variation are evident within four structures that terminate in points: prickles, hooks, hooked papillae and macro-hairs. Fourteen qualitative characters for lemma epidermis are used in phenetic analyses. The presence or absence of macro-hairs conflicts with some other patterns, but gives some support to the classification of Papp. Characters associated with the split of the clusters were micro-hairs (straight and geniculate) and the distribution and frequency of prickles in both costal and intercostal zones. As a conclusion, Melica is not a coherent taxonomic grouping and a simple segregation of Bromelica from Melica genus is rejected.  © 2003 The Linnean Society of London , Botanical Journal of the Linnean Society , 2003, 141, 447 – 463.     

Prickly pairs: the proportion of spinescent species does not differ between islands and mainlands

Aims Organisms on islands are thought to escape biotic pressure and lose defensive capabilities. However, broadscale, evidence-based tests of this idea are rare. In this study, we asked: (i) whether the proportion of spinescent plant species differed between islands and mainlands and (ii) whether the proportion of spinescent species increased with increasing island area and with decreasing island distance to mainland.