AUTHOR=Backer Robert , Mahomed Waheed , Reeksting Bianca J. , Engelbrecht Juanita , Ibarra-Laclette Enrique , van den Berg Noëlani 

TITLE=Phylogenetic and expression analysis of the NPR1-like gene family from Persea americana (Mill.)

JOURNAL=Frontiers in Plant Science

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2015.00300

DOI=10.3389/fpls.2015.00300

ISSN=1664-462X

ABSTRACT=<p>The NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 (NPR1) forms an integral part of the salicylic acid (SA) pathway in plants and is involved in cross-talk between the SA and jasmonic acid/ethylene (JA/ET) pathways. Therefore, NPR1 is essential to the effective response of plants to pathogens. Avocado (<italic>Persea americana</italic>) is a commercially important crop worldwide. Significant losses in production result from Phytophthora root rot, caused by the hemibiotroph, <italic>Phytophthora cinnamomi</italic>. This oomycete infects the feeder roots of avocado trees leading to an overall decline in health and eventual death. The interaction between avocado and <italic>P. cinnamomi</italic> is poorly understood and as such limited control strategies exist. Thus uncovering the role of NPR1 in avocado could provide novel insights into the avocado – <italic>P. cinnamomi</italic> interaction. A total of five <italic>NPR1</italic>-like sequences were identified. These sequences were annotated using FGENESH and a maximum-likelihood tree was constructed using 34 NPR1-like protein sequences from other plant species. The conserved protein domains and functional motifs of these sequences were predicted. Reverse transcription quantitative PCR was used to analyze the expression of the five <italic>NPR1</italic>-like sequences in the roots of avocado after treatment with salicylic and jasmonic acid, <italic>P. cinnamomi</italic> infection, across different tissues and in <italic>P. cinnamomi</italic> infected tolerant and susceptible rootstocks. Of the five <italic>NPR1</italic>-like sequences three have strong support for a defensive role while two are most likely involved in development. Significant differences in the expression profiles of these five <italic>NPR1</italic>-like genes were observed, assisting in functional classification. Understanding the interaction of avocado and <italic>P. cinnamomi</italic> is essential to developing new control strategies. This work enables further classification of these genes by means of functional annotation and is a crucial step in understanding the role of NPR1 during <italic>P. cinnamomi</italic> infection.</p>