Salicylic acid and NIM1/NPR1-independent gene induction by incompatible Peronospora parasitica in arabidopsis

To identify pathogen-induced genes distinct from those involved in systemic acquired resistance, we used cDNA-amplified fragment length polymorphism to examine RNA levels in Arabidopsis thaliana wild type, nim1-1, and salicylate hydroxylase-expressing plants after inoculation with an incompatible isolate of the downy mildew pathogen Peronospora parasitica. Fifteen genes are described, which define three response profiles on the basis of whether their induction requires salicylic acid (SA) accumulation and NIM1/NPR1 activity, SA alone, or neither. Sequence analysis shows that the genes include a calcium binding protein related to TCH3, a protein containing ankyrin repeats and potential transmembrane domains, three glutathione S-transferase gene family members, and a number of small, putatively secreted proteins. We further characterized this set of genes by assessing their expression patterns in each of the three plant lines after inoculation with a compatible P. parasitica isolate and after treatment with the SA analog 2,6-dichloroisonicotinic acid. Some of the genes within subclasses showed different requirements for SA accumulation and NIM1/NPR1 activity, depending upon which elicitor was used, indicating that those genes were not coordinately regulated and that the regulatory pathways are more complex than simple linear models would indicate.     

大豆中L34基因的克隆与表达分析

目的:采用分子手段试图分离与大豆种子低温吸胀相关的基因.方法:利用cDNA-AFLP(cDNA-amplified fragment length polymorphism)和RACE技术从大豆种子胚轴中克隆到一个编码132 kD的全长核糖体蛋白基因,命名为SOL34.结果:序列分析表明,SOL34和苜蓿(gi | 113205273 |)、茄科植物(gi | 48057670 |)及拟南芥(gi | 2500376 |)中L34蛋白基因的同源性分别为95%、95%和90%.半定量RT-PCR结果表明:大豆种子在4℃下吸胀24h内,胚轴中的SOL34被诱导表达,其中当种子低温吸胀6h,SOL34表达量升高非常明显,18h的表达量最大,24h表达量和18h相似;SOL34在大豆不同部位的表达不同,4叶期的大豆幼苗经过低温处理后,根尖中SOL34的表达比非处理材料增强约5倍,同时比胚轴中高约2倍;但是在叶片中,SOL34表达量并没有受到温度的影响,表达量也很弱,说明SOL34在叶片中是组成型表达.结论:结果分析表明,SOL34可能和大豆根的代谢有关.     

Gene flow between arrhenotokous and thelytokous populations of Venturia canescens (Hymenoptera)

In the solitary parasitoid wasp Venturia canescens both arrhenotokously (sexual) and thelytokously (parthenogenetical) reproducing individuals occur sympatrically. We found in the laboratory that thelytokous wasps are able to mate, receive and use sperm of arrhenotokous males. Using nuclear (amplified fragment length polymorphism, virus-like protein) and mitochondrial (restriction fragment length polymorphism) markers, we show the occurrence of gene flow from the arrhenotokous to the thelytokous mode in the field. Our results reinforce the paradox of sex in this species.     

cDNA-AFLP display for the isolation of Peronospora parasitica genes expressed during infection in Arabidopsis thaliana

To identify genes from the obligatory biotrophic oomycete Peronospora parasitica that are expressed during infection in Arabidopsis thaliana we employed cDNA-amplified fragment length polymorphism (AFLP) display. cDNA-AFLP fragments from infected and non-infected leaves were separated in parallel by gel electrophoresis and displayed by autoradiography. Most differential gene fragments were derived from P. parasitica.     

Identification of differentially expressed genes induced by <Emphasis Type="Italic">Bamboo mosaic virus</Emphasis> infection in <Emphasis Type="Italic">Nicotiana benthamiana</Emphasis>by cDNA-amplified fragment length polymorphism

Background  

The genes of plants can be up- or down-regulated during viral infection to influence the replication of viruses. Identification of these differentially expressed genes could shed light on the defense systems employed by plants and the mechanisms involved in the adaption of viruses to plant cells. Differential gene expression in Nicotiana benthamiana plants in response to infection with Bamboo mosaic virus (BaMV) was revealed using cDNA-amplified fragment length polymorphism (AFLP).     

Cloning of differential expression fragments in cauliflower after Xanthomonas campestris inoculation

A near isogenic line (NIL) of Brassica oleracea var. botrytis with resistant and susceptible lines C712 and C731, was used in this study. More than 100 differentially expressed cDNA fragments were obtained from black rot resistant cauliflower plants obtained using cDNA-amplified fragment length polymorphism (AFLP) after infection with the pathogen. Thirteen of these fragments were cloned and subjected to reverse Northern blot analysis using both infected and control cDNA pools. Two positive clones, M2 and M6, were isolated. Northern dot blot and Northern blot analyses showed that M2 was constitutively expressed, whereas M6 contained a gene that was differentially expressed during pathogen infection. Moreover, M6 cDNA fragment was also highly expressed 16–24 h after H₂O₂ treatment. Southern blots showed that M6 is a single copy gene in the cauliflower genome, and encodes a protein with 84 % homology to gene on Arabidopsis chromosome 1. The deduced M6 protein has 91 % positive homology with the Arabidopsis 2A6 protein, which regulates ethylene synthesis; 76 % homology with a 1-aminocyclopropane-1-carboxylate oxidase (ACO), the last enzyme in ethylene synthesis; and 70 % homology with an ethylene induced DNA binding factor. These results suggest that M6 gene fragment is a new H₂O₂ downstream defense related gene fragment and can be induced by Xanthomonas campestris pv. campestris and H₂O₂.