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Starch degradation, abscisic acid and vesicular trafficking are important elements in callose priming by indole‐3‐carboxylic acid in response to Plectosphaerella cucumerina infection
Author(s) -
Gamir Jordi,
Pastor Victoria,
SánchezBel Paloma,
Agut Blas,
Mateu Diego,
GarcíaAndrade Javier,
Flors Víctor
Publication year - 2018
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14045
Subject(s) - callose , priming (agriculture) , abscisic acid , arabidopsis , biology , microbiology and biotechnology , biochemistry , mutant , chemistry , botany , gene , germination
Summary A fast callose accumulation has been shown to mediate defence priming in certain plant–pathogen interactions, but the events upstream of callose assembly following chemical priming are poorly understood, mainly because those steps comprise sugar transfer to the infection site. β‐Amino butyric acid ( BABA )‐induced resistance in Arabidopsis against Plectosphaerella cucumerina is known to be mediated by callose priming. Indole‐3‐carboxylic acid ( ICOOH , also known as I3 CA ) mediates BABA ‐induced resistance in Arabidopsis against P. cucumerina . This indolic compound is found in a common fingerprint of primed metabolites following treatments with various priming stimuli. In the present study, we show that I3 CA induces resistance in Arabidopsis against P. cucumerina and primes enhancement of callose accumulation. I3 CA treatment increased abscisic acid ( ABA) levels before infection with P. cucumerina . An intact ABA synthesis pathway is needed to activate a starch amylase ( BAM 1 ) to trigger augmented callose deposition against P. cucumerina during I3 CA ‐ IR . To verify the relevance of the BAM 1 amylase in I3 CA ‐ IR , knockdown mutants and overexpressors of the BAM 1 gene were tested. The mutant bam1 was impaired to express I3 CA ‐ IR, but complemented 35S:: BAM 1‐ YFP lines in the background of bam1 restored an intact I3 CA ‐ IR and callose priming. Therefore, a more active starch metabolism is a committed step for I3 CA ‐ IR , inducing callose priming in adult plants. Additionally, I3 CA treatments induced expression of the ubiquitin ligase ATL 31 and syntaxin SYP 131 , suggesting that vesicular trafficking is relevant for callose priming. As a final element in the callose priming, an intact Powdery Mildew resistant4 ( PMR 4 ) gene is also essential to fully express I3 CA ‐ IR .