Screening for plant transporter function by expressing a normalized Arabidopsis full-length cDNA library in Xenopus oocytes

Background  

We have developed a functional genomics approach based on expression cloning in Xenopus oocytes to identify plant transporter function. We utilized the full-length cDNA databases to generate a normalized library consisting of 239 full-length Arabidopsis thaliana transporter cDNAs. The genes were arranged into a 96-well format and optimized for expression in Xenopus oocytes by cloning each coding sequence into a Xenopus expression vector.     

Kinome profiling of Arabidopsis using arrays of kinase consensus substrates

Background  

Kinome profiling aims at the parallel analysis of kinase activities in a cell. Novel developed arrays containing consensus substrates for kinases are used to assess those kinase activities. The arrays described in this paper were already used to determine kinase activities in mammalian systems, but since substrates from many organisms are present we decided to test these arrays for the determination of kinase activities in the model plant species Arabidopsis thaliana.     

A rapid and versatile combined DNA/RNA extraction protocol and its application to the analysis of a novel DNA marker set polymorphic between Arabidopsis thaliana ecotypes Col-0 and Landsberg erecta

Background  

Many established PCR-based approaches in plant molecular biology rely on lengthy and expensive methods for isolation of nucleic acids. Although several rapid DNA isolation protocols are available, they have not been tested for simultaneous RNA isolation for RT-PCR applications. In addition, traditional map-based cloning technologies often use ill-proportioned marker regions even when working with the model plant Arabidopsis thaliana, where the availability of the full genome sequence can now be exploited for the creation of a high-density marker systems.     

An improved method for preparing Agrobacterium cells that simplifies the Arabidopsis transformation protocol

Background  

The Agrobacterium vacuum (Bechtold et al 1993) and floral-dip (Clough and Bent 1998) are very efficient methods for generating transgenic Arabidopsis plants. These methods allow plant transformation without the need for tissue culture. Large volumes of bacterial cultures grown in liquid media are necessary for both of these transformation methods. This limits the number of transformations that can be done at a given time due to the need for expensive large shakers and limited space on them. Additionally, the bacterial colonies derived from solid media necessary for starting these liquid cultures often fail to grow in such large volumes. Therefore the optimum stage of plant material for transformation is often missed and new plant material needs to be grown.     

A rapid and robust method of identifying transformed Arabidopsis thaliana seedlings following floral dip transformation

Background  

The floral dip method of transformation by immersion of inflorescences in a suspension of Agrobacterium is the method of choice for Arabidopsis transformation. The presence of a marker, usually antibiotic- or herbicide-resistance, allows identification of transformed seedlings from untransformed seedlings. Seedling selection is a lengthy process which does not always lead to easily identifiable transformants. Selection for kanamycin-, phosphinothricin- and hygromycin B-resistance commonly takes 7–10 d and high seedling density and fungal contamination may result in failure to recover transformants.     

High throughput generation of promoter reporter (GFP) transgenic lines of low expressing genes in Arabidopsis and analysis of their expression patterns

Background  

Although the complete genome sequence and annotation of Arabidopsis were released at the end of year 2000, it is still a great challenge to understand the function of each gene in the Arabidopsis genome. One way to understand the function of genes on a genome-wide scale is expression profiling by microarrays. However, the expression level of many genes in Arabidopsis genome cannot be detected by microarray experiments. In addition, there are many more novel genes that have been discovered by experiments or predicted by new gene prediction programs. Another way to understand the function of individual genes is to investigate their in vivo expression patterns by reporter constructs in transgenic plants which can provide basic information on the patterns of gene expression.     

Effects of growth retarding treatments on apple tree growth,fruit maturation and fruit abscission

SUMMARY

Eight days after petal fall in 1991, mature 'Delicious'/MM. 106 apple trees and four days after petal fall in 1992, mature 'McintoshVMM. 106 were ringed, scored, root pruned (1 m from the trunk, two sides, 30 cm deep), or treated with ethephon (500 mg 1¹). Only ringing and scoring reduced vegetative growth. Ethephon advanced fruit maturation and fruit abscission, but root pruning did not affect the trees or fruit significantly. Mature 'Cort-land'/M.7a apple trees were root pruned 8 d after petal fall in 1991 and/or at full bloom in 1992. Root pruning reduced shoot growth, even in the year after treatment. Fruit abscission was reduced in 1991 and 1992 by root pruning in 1991, but root pruning in 1992 had no impact on abscission, in 1992. In an additional experiment, mature 'Mcintosh'/ MM.106 were root pruned 4 d after petal fall in 1991 or root pruned both in 1991 and at full bloom in 1992. Growth and preharvest fruit abscission were reduced in both the year of root pruning and the year after.     

An increase in citrus fruit (Kiyomi tangor) abscission induced by ABA is accompanied by an IAA increase in the abscission zone and ethylene production

Summary

Change in IAA concentrations in the peduncle, branch and intervening abscission zone were measured to clarify the involvement of IAA in citrus fruit drop in response to ABA application. Results indicating the importance of an IAA increase in the abscission zone were obtained. One day after application of ABA, the concentration of IAA in the abscission zone showed a temporary increase and then a decrease. The concentration of IAA in the abscission zone was dependent on the concentration of ABA applied. Changes in the production of ethylene, which is involved in the process of abscission and which is induced by IAA, in explants from treated leafy inflorescences, were examined. The fruit-abscission ratios were also investigated in relation to the time required for preparation. Explants sampled 0±1.d after application showed little abscission or ethylene production during the first 24 h incubation. During the next 24 h, almost all the ABA-applied explants abscinded, as did the control, but the former produced 3±4 times more ethylene. ABA-applied explants, sampled 2.d after application, abscinded and produced ethylene markedly during the first 24.h, whereas the control explants did not abscind. Control and ABA-applied explants, sampled 3 d after application, showed no differences in their abscission ratios and ethylene production. These findings indicate that a temporary IAA rise in the abscission zone, observed one day after application, is involved in ethylene production in ABA-induced citrus fruit drop.     

玫瑰切花产量性状遗传参数和选择效率的初步研究

对20个玫瑰品种的切花产量及13个数量性状进行了遗传相关、相关遗传力及通径分析等。结果表明: (1) 单株花蕾数、分枝数、第1个花瓣的长、第2个花瓣的长、花蕾长与单株花蕾产量的遗传相关显著; (2) 单株花蕾数、第2个花瓣的长、分枝数和花蕾长的相关遗传力与单株花蕾产量的遗传力接近, 相关选择效率接近对单株花蕾产量的直接选择效率; (3) 根据决策系数, 花蕾长、单株花蕾数、第2个花瓣的长、分枝数、单蕾花瓣鲜重对单株产量有促进作用。     

A procedure for localisation and electrophysiological characterisation of ion channels heterologously expressed in a plant context

Background  

In silico analyses based on sequence similarities with animal channels have identified a large number of plant genes likely to encode ion channels. The attempts made to characterise such putative plant channels at the functional level have most often relied on electrophysiological analyses in classical expression systems, such as Xenopus oocytes or mammalian cells. In a number of cases, these expression systems have failed so far to provide functional data and one can speculate that using a plant expression system instead of an animal one might provide a more efficient way towards functional characterisation of plant channels, and a more realistic context to investigate regulation of plant channels.     

Effect of IAA gradient between the peduncle and branch on physiological drop of citrus fruit (Kiyomi tangor)

Summary

Changes in indole acetic acid (IAA) concentrations of the peduncle, branch and abscission zone were examined during the physiological fruit-drop period, to investigate the role of endogenous auxin in the peduncle and branch on the physiological drop of the fruit. The effects of 2,3,5-triiodebenzoic-acid (TIBA), applied to the peduncle or branch, on the IAA concentration in each organ and the drop ratio were also investigated. The fruit-drop ratio increased when TIBA was applied to the peduncle (TIBA-P application), whereas it decreased when the application was to the branch (TIBA-B application). Prior to fruit drop, marked IAA accumulation occurred in the abscission zone in the control and after TIBA-P application. An IAA gradient from the branch to the peduncle was found for TIBA-P applications, but a reverse gradient for TIBA-B applications. These results suggest that the reduction of IAA polar transport above the abscission zone is necessary to promote abscission and that both IAA accumulation in the abscission zone and the IAA gradient between the peduncle and branch are involved in abscission.     

Rapid analysis of seed size in <Emphasis Type="Italic">Arabidopsis</Emphasis> for mutant and QTL discovery

Background  

Arabidopsis thaliana is a useful model organism for deciphering the genetic determinants of seed size; however the small size of its seeds makes measurements difficult. Bulk seed weights are often used as an indicator of average seed size, but details of individual seed is obscured. Analysis of seed images is possible but issues arise from variations in seed pigmentation and shadowing making analysis laborious. We therefore investigated the use of a consumer level scanner to facilitate seed size measurements in conjunction with open source image-processing software.     

A rapid biosensor-based method for quantification of free and glucose-conjugated salicylic acid

Background  

Salicylic acid (SA) is an important signalling molecule in plant defenses against biotrophic pathogens. It is also involved in several other processes such as heat production, flowering, and germination. SA exists in the plant as free SA and as an inert glucose conjugate (salicylic acid 2-O-β-D-glucoside or SAG). Recently, Huang et al. developed a bacterial biosensor that responds to free SA but not SAG, designated as Acinetobacter sp. ADPWH_lux. In this paper we describe an improved methodology for Acinetobacter sp. ADPWH_lux-based free SA quantification, enabling high-throughput analysis, and present an approach for the quantification of SAG from crude plant extracts.     

Development of expression vectors based on pepino mosaic virus

Background  

Plant viruses are useful expression vectors because they can mount systemic infections allowing large amounts of recombinant protein to be produced rapidly in differentiated plant tissues. Pepino mosaic virus (PepMV) (genus Potexvirus, family Flexiviridae), a widespread plant virus, is a promising candidate expression vector for plants because of its high level of accumulation in its hosts and the absence of severe infection symptoms. We report here the construction of a stable and efficient expression vector for plants based on PepMV.     

High-throughput <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated barley transformation

Background  

Plant transformation is an invaluable tool for basic plant research, as well as a useful technique for the direct improvement of commercial crops. Barley (Hordeum vulgare) is the fourth most abundant cereal crop in the world. It also provides a useful model for the study of wheat, which has a larger and more complex genome. Most existing barley transformation methodologies are either complex or have low (<10%) transformation efficiencies.