Abstract
Diplotaxis tenuifolia L. is of important economic value in the fresh-cut industry for its nutraceutical and sensorial properties. However, information on the molecular mechanisms conferring tolerance of harvested leaves to pre- and postharvest stresses during processing and shelf-life have never been investigated. Here, we provide the first transcriptomic resource of rocket by de novo RNA sequencing assembly, functional annotation and stress-induced expression analysis of 33874 transcripts. Transcriptomic changes in leaves subjected to commercially-relevant pre-harvest (salinity, heat and nitrogen starvation) and postharvest stresses (cold, dehydration, dark, wounding) known to affect quality and shelf-life were analysed 24h after stress treatment, a timing relevant to subsequent processing of salad leaves. Transcription factors and genes involved in plant growth regulator signaling, autophagy, senescence and glucosinolate metabolism were the most affected by the stresses. Hundreds of genes with unknown function but uniquely expressed under stress were identified, providing candidates to investigate stress responses in rocket. Dehydration and wounding had the greatest effect on the transcriptome and different stresses elicited changes in the expression of genes related to overlapping groups of hormones. These data will allow development of approaches targeted at improving stress tolerance, quality and shelf-life of rocket with direct applications in the fresh-cut industries.
Highlights
Plants cope with environmental stresses by coordinately activating and repressing large numbers of genes that modulate their physiology and metabolism to enable survival [1]
BLAST hits were found for 30819 contigs (91%) including 21472 unigenes (Table 2; S3A Table): most of them showed 100% positive alignment and similarity to Arabidopsis thaliana and Arabidopsis lyrata sequences followed by other members of the Brassicaceae (S1A–S1C Fig)
The goal of this study was to reveal the molecular mechanisms of stress responses in rocket through the identification of genes and pathways activated pre- and postharvest
Summary
Plants cope with environmental stresses by coordinately activating and repressing large numbers of genes that modulate their physiology and metabolism to enable survival [1]. In a primary stress response plants immediately activate a set of genes during the first few hours [2]. Their expression is mainly transient and they regulate a class of secondary genes that are associated with defence mechanisms and longer-term responses [3,4]. Gene expression varies temporally and in specificity to the stress imposed. In Arabidopsis ~30% of the transcriptome is induced by stresses and the majority of changes in gene regulation are stimulus-specific, increasing in specificity with the time of exposure to the stress [5]
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