First Report of Fusarium proliferatum Infecting Carnation (Dianthus caryophyllus L.) in China

In 2011, a wilt disease has been detected on carnation (Dianthus caryophyllus L.) cultivar ‘Light Pink Barbara’ in Kunming, Yunnan, China. A Fusarium sp. was consistently recovered from pieces of symptomatic tissues on Petri dishes containing potato dextrose agar (PDA). On the basis of morphological characteristics and molecular identification by DNA sequencing of ribosomal DNA internal transcribed spacer (rDNA ITS) and partial translation elongation factor‐1α (TEF) gene region, following their phylogenetic trees construction, the putative causal agent was identified as Fusarium proliferatum (Matsushima) Nirenberg, and its pathogenicity was finally confirmed by Koch's postulates. To our knowledge, this is the first report of a wilt disease caused by F. proliferatum on carnation in China.     

香石竹DcSKP1基因克隆及表达分析

SKP1基因是SCF E3泛素连接酶蛋白复合物的核心成分,参与多种生物过程。然而,香石竹SKP1基因还未被克隆,该文利用RT-PCR结合RACE技术,从香石竹(Dianthus caryophyllus)的花药中分离克隆了1个减数分裂相关基因SKP1的全长cDNA序列,命名为DcSKP1(GenBank登录号为MK931293)。结果表明:(1)DcSKP1基因cDNA全长序列为962 bp,含有1个长度为567 bp的ORF,该基因编码188个氨基酸。(2)蛋白序列比对显示,DcSKP1中存在一个高度保守TPEE基序,还具有Skp1_POZ结构域和Skp1结构域,并与拟南芥的SKP1聚集在一个分支上。(3)利用荧光定量PCR对香石竹DcSKP1基因表达模式进行研究,发现DcSKP1基因在各个组织部位都有表达,在花药中的表达量高于茎、叶组织,且在幼小的花药中表达量最高,随着花药发育的进程表达量下降。由此推测,DcSKP1基因可能在香石竹减数分裂中具有重要作用。     

Cytokinins in cut carnations. X. The effect of stem length and holding time on the transport and metabolism of [8-14C]6-(benzylamino)purine

Stem length and to a lesser extent holding time influenced the transport of [8-¹⁴C]6-(benzylamino)purine (BA) within the carnation flower ( Dianthus caryophyllus L.). A stem length of 40 cm as compared to one of 10 cm resulted in a lower amount of BA reaching the carnation flower head when the flowers were held in solution for 3 to 24 h. There was also a slight delay in cytokinin movement from, as well as increased metabolism within, the stem tissues. Consequently levels of radioactivity and the nature of metabolites produced in the upper floral components were influenced by movement through the stem. In the flower head the receptacle was the strongest sink for flowers with 10 cm stem lengths. A metabolite tentatively identified as ribosyl-benzylaminopurine [9R]BA was the major compound formed in all flower components. This metabolic step appeared to be reversible. Various minor stable metabolites and possible breakdown products were also produced.     

The biosynthesis of Caryophyllaceae-like cyclic peptides in Saponaria vaccaria L. from DNA-encoded precursors

Cyclic peptides (CPs) are produced in a very wide range of taxa. Their biosynthesis generally involves either non‐ribosomal peptide synthases or ribosome‐dependent production of precursor peptides. Plants within the Caryophyllaceae and certain other families produce CPs which generally consist of 5–9 proteinogenic amino acids. The biological roles for these CPs in the plant are not very clear, but many of them have activity in mammalian systems. There is currently very little known about the biosynthesis of CPs in the Caryophyllaceae. A collection of expressed sequence tags from developing seeds of Saponaria vaccaria was investigated for information about CP biosynthesis. This revealed genes that appeared to encode CP precursors which are subsequently cyclized to mature CPs. This was tested and confirmed by the expression of a cDNA encoding a putative precursor of the CP segetalin A in transformed S. vaccaria roots. Similarly, extracts of developing S. vaccaria seeds were shown to catalyze the production of segetalin A from the same putative (synthetic) precursor. Moreover, the presence in S. vaccaria seeds of two segetalins, J [cyclo(FGTHGLPAP)] and K [cyclo(GRVKA)], which was predicted by sequence analysis, was confirmed by liquid chromatography/mass spectrometry. Sequence analysis also predicts the presence of similar CP precursor genes in Dianthus caryophyllus and Citrus spp. The data support the ribosome‐dependent biosynthesis of Caryophyllaceae‐like CPs in the Caryophyllaceae and Rutaceae.     

引种地被石竹光合特征与生理生态因子的关系

以上海地区引种的一年生地被石竹实生苗为材料,研究其苗高生长变化、生物量积累和分配、光合特性及其变化规律,并分析主要生理生态因子对其净光合速率的影响。结果表明:(1)3～6月份为地被石竹苗高生长速生期,生长量为年生长量的65.93%,实生苗各部分器官的生物量总体呈现上升的趋势;3～6月份苗木以地上部分生物量积累为主,其占总生物量的比例从46.89%升至65.60%,6月份以后地下部分生物量所占比例从34.40%升至53.11%。(2)地被石竹叶片净光合速率(Pn)日变化在春季和秋季呈单峰曲线型,而在夏季表现为双峰曲线,且具有典型的光合"午睡"现象。(3)影响光合变化的主要决定生理生态因子:春季为蒸腾速率和气温,夏季为气孔导度和大气CO2摩尔分数,秋季为胞间CO2摩尔分数和光合有效辐射;限制地被石竹Pn日变化生理生态因子:春季为胞间CO2摩尔分数和光合有效辐射,夏季为蒸腾速率和空气相对湿度,秋季为气孔导度和气温。(4)地被石竹具有较高水平的光补偿点(56.94μmol·m-2·s-1)和光饱和点(780.07μmol·m-2·s-1),应属于喜光植物。     

石竹花粉母细胞减数分裂的观察

采用常规压片法对石竹(Dianthus chinensis L.)花粉母细胞减数分裂进行了细胞学观察。结果表明,减数分裂过程中存在二价体提前分离、赤道板外染色体、落后染色体、染色体不均等分离等异常现象,各时期的畸形率都低于3%,石竹的减数分裂过程基本正常,石竹染色体数目2n=2x=30。     

Phylogenetic determinants of potential host shifts in fungal pathogens

Understanding what determines the host range of pathogens and the potential for host shifts is of critical importance to controlling their introductions into new environments. The phylogeny of the hosts has been shown to be important: pathogens are more likely to be infectious on hosts closely related to their host‐of‐origin because of the similar host environments that is shared by descent. The importance of pathogen phylogenies for predicting host range has never been investigated, although a pathogen should also be able to exploit a new host that its close relative can infect. We performed cross‐inoculations using a plant–fungal association and showed that both host and pathogen phylogenies were significant predictors of host range, with at least partly independent effects. Furthermore, we showed that some pathogens were better at infecting novel hosts. Our results should have implications in the context of biological invasions and emergences of new diseases due to globalization.     

Fungitoxic phenols from carnation (Dianthus caryophyllus) effective against Fusarium oxysporum f. sp. dianthi

The phenol compositions of two cultivars of carnation (Dianthus caryophyllus) namely "Gloriana" and "Roland", which are partially and highly resistant, respectively, to Fusarium oxysporum f. sp. dianthi have been investigated with the aim of determining if endogenous phenols could have an anti-fungal effect against the pathogen. Analyses were performed on healthy and F. oxysporum-inoculated in vitro tissues, and on in vivo plants. Two benzoic acid derivatives, protocatechuic acid (3,4-dihydroxybenzoic acid) and vanillic acid (4-hydroxy-3-methoxybenzoic acid), were found within healthy and inoculated tissues of both cultivars, together with the flavonol glycoside peltatoside (3-[6-O-(alpha-L-arabinopyranosyl)-beta-D-glucopyranosyl] quercetin). These molecules proved to be only slightly inhibitory towards the pathogen. 2,6-Dimethoxybenzoic acid was detected in small amounts only in the inoculated cultivar "Gloriana", while the highly resistant cultivar "Roland" showed the presence of the flavone datiscetin (3,5,7,2'-tetrahydroxyflavone). The latter compound exhibited an appreciable fungitoxic activity towards F. oxysporum f. sp. dianthi.