AUTHOR=Sun Lei-Ming , Fang Jin-Bao , Zhang Min , Qi Xiu-Juan , Lin Miao-Miao , Chen Jin-Yong 

TITLE=Molecular Cloning and Functional Analysis of the NPR1 Homolog in Kiwifruit (Actinidia eriantha)

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.551201

DOI=10.3389/fpls.2020.551201

ISSN=1664-462X

ABSTRACT=<p>Kiwifruit bacterial canker, caused by the bacterial pathogen <italic>Pseudomonas syringae</italic> pv. <italic>actinidiae</italic> (Psa), is a destructive disease in the kiwifruit industry globally. Consequently, understanding the mechanism of defense against pathogens in kiwifruit could facilitate the development of effective novel protection strategies. The <italic>Non-expressor of Pathogenesis-Related genes 1</italic> (<italic>NPR1</italic>) is a critical component of the salicylic acid (SA)-dependent signaling pathway. Here, a novel kiwifruit <italic>NPR1</italic>-like gene, designated <italic>AeNPR1a</italic>, was isolated by using PCR and rapid amplification of cDNA ends techniques. The full-length cDNA consisted of 1952 base pairs with a 1,746-bp open-reading frame encoding a 582 amino acid protein. Homology analysis showed that the AeNPR1a protein is significantly similar to the VvNPR1 of grape. A 2.0 Kb 5′-flanking region of <italic>AeNPR1a</italic> was isolated, and sequence identification revealed the presence of several putative cis-regulatory elements, including basic elements, defense and stress response elements, and binding sites for WRKY transcription factors. Real-time quantitative PCR results demonstrated that <italic>AeNPR1a</italic> had different expression patterns in various tissues, and its transcription could be induced by phytohormone treatment and Psa inoculation. The yeast two-hybrid assay revealed that AeNPR1a interacts with AeTGA2. Constitutive expression of <italic>AeNPR1a</italic> induced the expression of pathogenesis-related gene in transgenic tobacco plants and enhanced tolerance to bacterial pathogens. In addition, <italic>AeNPR1a</italic> expression could restore basal resistance to <italic>Pseudomonas syringae</italic> pv. <italic>tomato</italic> DC3000 (Pst) in <italic>Arabidopsis</italic><italic>npr1-1</italic> mutant. Our data suggest that <italic>AeNPR1a</italic> gene is likely to play a pivotal role in defense responses in kiwifruit.</p>