NPR1 as a transgenic crop protection strategy in horticultural species

The NPR1(NONEXPRESSOR OF PATHOGENESIS RELATED GENES1)gene has a central role in the long-lasting,broad-spectrum defense response known as systemic acquired resistance(SAR).When overexpressed in a transgenic context in Arabidopsis thaliana,this gene enhances resistance to a number of biotic and abiotic stresses.Its position as a key regulator of defense across diverse plant species makes NPR1 a strong candidate gene for genetic engineering disease and stress tolerance into other crops.High-value horticultural crops face many new challenges from pests and pathogens,and their emergence exceeds the pace of traditional breeding,making the application of NPR1-based strategies potentially useful in fruit and vegetable crops.However,plants overexpressing NPR1 occasionally present detrimental morphological traits that make its application less attractive.The practical utility of NPR-based approaches will be a balance of resistance gains versus other losses.In this review,we summarize the progress on the understanding of NPR1-centered applications in horticultural and other crop plants.We also discuss the effect of the ectopic expression of the A.thaliana NPR1 gene and its orthologs in crop plants and outline the future challenges of using NPR1 in agricultural applications.

An Efficient Intragenic Vector for Generating Intragenic and Cisgenic Plants in Citrus

Genetic transformation has become a promising tool for improvement of a variety of crop species. However, transferring genes across species, the presence of selectable marker genes, and bacteria-derived vector backbone sequences have raised considerable health and environmental concerns. Intragenic vector system-based intragenesis/cisgenesis is a new method using transgenic approach to achieving traditional breeding objectives but circumventing many of the associated shortcomings. We report here the development of an intragenic vector by assembling a T-DNA-like fragment and a buffering sequence following the left border from Citrus clementina into the backbone of the binary vector pCB302. Recovery of citrus regenerants is performed under non-selective conditions and positive intra-/cisgenic regenerants were identified through PCR analysis. Transformation efficiencies obtained in Arabidopsis and “Duncan” grapefruit were ~3% and ~0.67%, respectively, demonstrating the potential of the system for development of “foreign DNA-free” intra-/cisgenic citrus cultivars.

Monitoring gene expression by cDNA array

A new method designated cDNA array was developed by hybridization of quantitatively arrayed DNA samples isolated randomly from a cDNA library with probes reverse-transcribed from mRNAs of different sources or treatments. The gene expression patterns of 1 000 randomly chosen clones from an Arabidopsis library were analyzed with green seedlings versus suspension cells and seedlings irradiated under UV light. Northern blot and sequence analysis of some differentially expressed clones confirmed the results revealed by cDNA array, indicating that this method is efficient and reliable to monitor gene expression.

A direct link between BR and SA signaling: Negative regulation of TGA4 by BIN2

It is well known that plantgrowth,development,and response to environmental stresses are harmonized through theaction of a suite of growth and defense signaling molecules.Brassinosteroid(BR)is a steroid hormone that regulates plant growth and development.