BABA-Primed Histone Modifications in Potato for Intergenerational Resistance to Phytophthora infestans

Abstract

In this paper we analyzed β-aminobutyric acid (BABA)-primed epigenetic adjustment of potato cv. “Sarpo Mira” to Phytophthora infestans. The first stress-free generation of the potato genotype obtained from BABA-primed parent plants via tubers and seeds showed pronounced resistance to the pathogen, which was tuned with the transcriptional memory of SA-responsive genes. During the early priming phase before the triggering stress, we found robust bistable deposition of histone marks (H3K4me2 and H3K27me3) on the NPR1 (Non-expressor of PR genes) and the SNI1 gene (Suppressor of NPR1, Inducible), in which transcription antagonized silencing. Switchable chromatin states of these adverse systemic acquired resistance (SAR) regulators probably reprogrammed responsiveness of the PR1 and PR2 genes and contributed to stress imprinting. The elevated levels of heritable H3K4me2 tag in the absence of transcription on SA-dependent genes in BABA-primed (F0) and its vegetative and generative progeny (F1) before pathogen challenge provided evidence for the epigenetic mark for intergenerational memory in potato. Moreover, our study revealed that histone acetylation was not critical for maintaining BABA-primed defense information until the plants were triggered with the virulent pathogen when rapid and boosted PRs gene expression probably required histone acetyltransferase (HAT) activity both in F0 and F1 progeny.

A comparison of PTI defense profiles induced in Solanum tuberosum by PAMP and non-PAMP elicitors shows distinct, elicitor-specific responses

“…However, CCF and BABA treatments did not induce SA production, although they up-regulated the PR genes ( PR1 for BABA and CCF and PR2 for BABA only) that are SA pathway activation markers. These results confirm and expand previous reports [ 30 , 31 , 54 , 55 ], who demonstrated that CCF and BABA can activate the SA signaling pathway. Saubeau et al .…”

“…[ 30 ] observed on potato a SA peak 12h after CCF treatment and the PR s genes were up-regulated from 24h-48h [ 31 ]. In the same way, on soybeans, 15 SA pathway genes are up-regulated 24h after BABA treatment [ 55 ]. By contrast, the Ulva extract induced the OPR3 gene and increased OPDA and JA production, as also observed by Jaulneau et al .…”

BABA-Induced DNA Methylome Adjustment to Intergenerational Defense Priming in Potato to Phytophthora infestans

“…It has been well documented that the non-protein amino acid, namely β-aminobutyric acid (BABA), effectively mediates the conditioning of induced plant defense mechanisms leading to enhanced protection against various pathogens (Cohen et al, 2016). Although BABA pre-treatment or other stimuli may prime a plant against future stress (Floryszak-Wieczorek et al, 2015; Meller et al, 2018), there is also evidence that such stress memory establishment is a relatively rare event or priming is reset during the period of stress recovery (Zimmerli et al, 2000; Pecinka et al, 2009; Crisp et al, 2016; Hilker et al, 2016).…”

“…The H3K4me2 epigenetic mark was identified in high numbers on the gene body of StWRKY1, PR1 , and PR2 concomitant with transcript downregulation detected in leaves of primed potato and its descendants before the triggering stress. Moreover, our previous study revealed that the primed state in potato was associated with the transcriptional memory to post-infection histone acetyltransferase (HAT) activation in the next generation after the challenge inoculation with P. infestans (Meller et al, 2018). In the present study, with the same experimental design as mentioned above, we investigated how DNA methylation and demethylation in potato contribute to BABA-primed changes associated with transcriptional memory to improve resistance against the virulent P. infestans MP977.…”

Epigenetic Mechanisms of Plant Adaptation to Biotic and Abiotic Stresses

“…In potato, priming with BABA increased resistance to the oomycete pathogen Phytophthora infestans , the causal agent of late blight disease [ 71 ]. The first unstressed generation of the BABA-primed parent plants showed increased resistance to the P. infestans , probably due to the upregulation of SA-responsive genes.…”