Cloning of Ten Peroxidase (<Emphasis Type="Italic">POD</Emphasis>) Genes from <Emphasis Type="Italic">Tamarix Hispida</Emphasis> and Characterization of their Responses to Abiotic Stress

Plant peroxidases (PODs) have been ascribed a variety of biological functions, including hydrogen peroxide detoxification, lignin biosynthesis, hormonal signaling, and stress response. In the present study, ten POD genes, including three ascorbate peroxidases (class I PODs) and seven secretory peroxidases (class III PODs), were cloned from Tamarix hispida. The roles of the ten POD genes were addressed under different abiotic stress conditions, and gene expression profiles in roots, stems, and leaves were evaluated using real-time quantitative reverse-transcribed polymerase chain reaction. Our results showed that the relative abundance of the PODs was markedly different in roots, stems, and leaves, indicating that POD activity differs in these three organs. ThPOD1 and ThPOD8 were the most and least abundant, respectively, in all organs. The expression profiles in response to abiotic stresses were organ specific. All of the genes were highly induced by drought, salt, salt–alkaline, CdCl₂, and abscisic acid (ABA) treatments in at least one organ. Five ThPOD genes were induced in roots, stems, and leaves under all of the studied stress conditions, indicating that they are closely associated with abiotic stress. Our results demonstrate that the ten plant peroxidases are all expressed in leaves, stems, and roots, that they are involved in different abiotic stress responses, and that they are controlled by an ABA-dependent stress signaling pathway.     

续随子ElFAD2基因的序列及表达特性分析

为了研究油酸脱氢酶(FAD2)基因ElFAD2对续随子(Euphorbia lathyris L.)中不饱和脂肪酸合成的调控作用,该研究在续随子转录组数据的基础上经筛选获得ElFAD2基因序列,并对其序列及表达特性进行分析。序列分析结果显示,ElFAD2基因全长1 907 bp,ORF长1 152 bp,共编码383个氨基酸,包含有典型的脂肪酸去饱和酶结构域。续随子ElFAD2蛋白理论等电点为8.08,属于稳定蛋白,包含4个跨膜区和3个保守的组氨酸簇。基于FAD2的系统发育分析表明,续随子与同科植物乌桕(Triadica sebifera L.)的亲缘关系最近。荧光定量PCR分析发现,ElFAD2基因在不同器官中均有表达,且在花后15 d的种子中表达量最高,在叶与花后30 d及45 d种子中的表达量相当,而在根、茎、花中的表达量最低。该研究结果为深入探讨续随子ElFAD2基因的生物学功能提供了基础数据,也为解析续随子种子中脂肪酸合成的分子机制奠定了基础。     

Nickel distribution in the hyperaccumulator Alyssum serpyllifolium Desf. spp. from the Iberian Peninsula

Abstract

The relative concentration and distribution of nickel (Ni) in vegetative tissues (leaves, stems and trichomes) and reproductive organs (seeds) was studied using energy-dispersive X-ray microanalysis (EDXS) and scanning electron microscopy (SEM) in two previously studied Ni-hyperaccumulator subspecies of Alyssum serpyllifolium Desf. growing naturally in ultramafic soils of the Iberian Peninsula: A. serpyllifolium ssp. lusitanicum Dudley & P. Silva and A. serpyllifolium ssp. malacitanum Rivas Goday ex G. López. Both taxa showed that Ni accumulates preferentially in the leaves, exhibiting a homogeneous distribution on both epidermis surfaces. The highest Ni concentrations were found inside the epidermal cells and at the base of trichome stalks. Ni accumulation in seeds was lower than in the vegetative organs. The location of Ni in these plants allows us to postulate that its accumulation is a protection mechanism against external stress.     

A synopsis of the genus <Emphasis Type="Italic">Poteranthera</Emphasis> (Melastomeae: Melastomataceae) with the description of a new,apparently pollinator deceiving species

A synopsis of the annual genus Poteranthera is presented here. Three species are recognized including the newly described Poteranthera windischii. Poteranthera is characterized by its annual life cycle, generally linear leaves that have conspicuous gland-tipped hairs on the lamina margin, 5-merous flowers with a constriction at the level of the torus, one cycle of stamens reduced to staminodia or absent altogether, three locular ovary, and reniform seeds with a foveolate testa. The flowers of the new species P. windischii are strongly heterandrous, where the usual set of stamens that bees harvest pollen from is reduced to staminodia and the stamen set that deposits pollen on the bee has large yellow ventral appendages that possibly function as pollen mimics and result in deceit pollination. This hypothesis is supported by experiments that have demonstrated innate preferences of female bees for yellow, UV absorbing colors in flowers. Species of Poteranthera are extremely rare, known from very few specimens and possibly highly endangered.