Genetic transformation of Populus trichocarpa genotype Nisqually-1: a functional genomic tool for woody plants

We report here the Agrobacterium-mediated genetic transformation of Nisqually-1, a Populus trichocarpa genotype whose genome was recently sequenced. Several systems were established. Internodal stem segments from vigorously growing greenhouse plants are the explants most amenable to transformation. For the most efficient system, approximately 40% of the stem segments infected with pBI121-containing Agrobacterium tumefaciens C58 produced transgenic calli, as confirmed by beta-glucuronidase (GUS) staining. The regeneration efficiency of independent transgenic plants was approximately 13%, as revealed by genomic Southern analysis. Some transgenic plants were produced in as little as 5 months after co-cultivation. This system may help to facilitate studies of gene functions in tree growth and development at a genome level.     

不同调控序列控制下的GUS基因在水稻和毛白杨愈伤组织中的瞬时表达

用CaMV35S启动子、玉米Ubil启动子、TMVΩ增强子(Ω序列)以及拟南芥18S rRNA基因同源序列构建的6种GUS基因表达载体分别转化水稻和毛白杨愈伤组织,研究不同调控序列对外源基因表达的调控作用.结果表明:(1)在水稻中,以独立Ubil启动子驱动下的GUS基因表达水平为最高,CaMV35S启动子附加18SrRNA基因同源序列调控下的GUS基因为最低.而在毛白杨中,则呈相反趋势;(2)在水稻中,CaMV35S-Ubil复合启动子的表达活性比独立CaMV35S启动子提高了近1.5倍.而在毛白杨中,前者比后者的低;(3)Ubil启动子附加Ω序列,使GUS基因在毛白杨中的表达水平提高一倍以上.但CaMV35S-Ubil复合启动子附加Ω序列,对GUS基因在毛白杨及水稻愈伤组织中的表达活性均没有明显的增强作用.     

胡杨披针形叶与宽卵形叶的超微结构与光合特性的差异

以胡杨的披针形叶和宽卵形叶作为实验材料,对其细胞超微结构、光合酶活性、稳定碳同位素组成进行了比较研究。结果表明,两种叶片都是等面叶,角质层厚,具皮下层和孔下室,含较多的粘液细胞,表现出明显的旱生结构特点;两种叶片均具有不整齐的维管束鞘细胞,Rubisco／PEPC值与小麦的接近,δ^13C值分别为-27．9‰和-26．7‰,位于C3植物的δ^13C值的范围内,表明两种叶片的碳同化途径均为C3途径;然而宽卵形叶较披针形叶的旱生结构更发达,叶肉细胞的线粒体数目及液泡中的泡状物质较多,Rubisco／PEPC值较低而δ^13C值较高,表明宽卵形叶比披针形叶具有更强的抵抗逆境的能力。此外,还对两种叶片对胡杨适应其盐碱化生境的能力的贡献作了初步探讨。     

正交设计在毛白杨栽培技术研究中的应用

对毛白杨苗木进行药物催根、不同根幅、植坑大小、栽植深度和不同肥料5个因子3位级正交试验，结果表明：最佳栽培方案是：根幅25～30cm，栽植穴直径60cm,根颈栽深60cm，追施氮肥。     

rol-Gene expression in transgenic aspen (Populus tremula) plants results in accelerated growth and improved stem production index

Stem and trunk growth, axillary bud break and branching habits are extremely important parameters of wood production in forest trees. The possibility of altering tree form by transformation with genes responsible for hormone biosynthesis and/or activity is most attractive. We examined four different phenotypically selected transgenic clones of a model tree –Populus tremula– expressing rol genes from Agrobacterium rhizogenes under their native promoters. Several of the observed phenotypic modifications were correlated with rol-gene expression, including breaking of stem apical dominance which resulted in the development and branching of up to four axillary buds per explant, as compared to a lack of axillary bud break in a uidA (β-glucuronidase-encoding)-transgenic aspen line and control (non-transformed) plants. rol-Transgenic plants also exhibited a higher cumulative stem length and enhanced growth rate, and hence a higher stem production index. During their first and second years in the greenhouse, rol-transgenic aspen plants exhibited enhanced growth and delayed winter dormancy relative to non-transformed plants. Although initially rol-transgenic plants had smaller, wrinkled leaves, these changes were not observed in the 2-year-old plants, which exhibited a phenotypically true-to-type leaf shape. Received: 13 September 1998 / Accepted: 15 April 1999     

Geographic structure in metabolome and herbivore community co‐occurs with genetic structure in plant defence genes

Plant–herbivore interactions vary across the landscape and have been hypothesised to promote local adaption in plants to the prevailing herbivore regime. Herbivores that feed on European aspen (Populus tremula) change across regional scales and selection on host defence genes may thus change at comparable scales. We have previously observed strong population differentiation in a set of inducible defence genes in Swedish P. tremula. Here, we study the geographic patterns of abundance and diversity of herbivorous insects, the untargeted metabolome of the foliage and genetic variation in a set of wound‐induced genes and show that the geographic structure co‐occurs in all three data sets. In response to this structure, we observe local maladaptation of herbivores, with fewer herbivores on local trees than on trees originated from more distant localities. Finally, we also identify 28 significant associations between single nucleotide polymorphisms SNPs from defence genes and a number of the herbivore traits and metabolic profiles.     

Altered GAI activity of hybrid aspen has minimal effects on the performance of a polyphagous weevil,Polydrusus sericeus

Genetically modified plants can have unintended effects on herbivores, even when the transgene is not explicitly devised for pest protection. These effects may lead to altered ecological relationships in areas where transgenic plants are deployed. We tested several genetically‐modified hybrid aspen clone INRA 717‐IB4 [Populus tremula L. ×P. alba L. (Salicaceae)] lines expressing transgenic constructs with altered gibberellic acid expression for their effects on a polyphagous insect, Polydrusus sericeus (Schaller) (Coleoptera: Curculionidae). Longevity, egg production, and leaf consumption were measured in laboratory assays. Only male longevity was negatively affected by foliage from genetically modified trees, and in no case was oviposition or leaf consumption significantly altered. The importance of males in population dynamics varies among species, but we do not have evidence it is a major driver in this system. Contrary to our hypothesis of increased performance on modified foliage, adult P. sericeus were rarely affected by GM foliage, suggesting that not all genetic modifications that alter secondary metabolism in plants will necessarily have a strong effect on specific insect‐plant relations, supporting the view that evaluations continue to require case by case analysis.