Emanuele Scialò

Ciclo: XXXVII ciclo-PON

Data inizio: 31/10/2022

Curriculum: Agroalimentari

Borsa: UniCT

Titolo tesi: Unveiling the Transcriptional Impact of SNP-Priming on Drought Resilience in Citrus

Abstract:

Water stress is one of the most critical environmental factors causing unpredictable agricultural losses worldwide, especially in semi-arid regions like southern Italy and Spain, where citrus trees are cultivated. Water stress triggers the accumulation of reactive oxygen species (ROS), leading to secondary oxidative stress in plant cells. Priming is a process in which plants, after being exposed to mild stress or chemical treatments, enhance their ability to respond more effectively to future stresses, improving both resilience and tolerance. Rootstocks resilient to abiotic stress are a widely used strategy to improve drought tolerance in many plant species, including Citrus spp. This project aims to evaluate the effects of sodium nitroprusside-priming (SNP-priming) on citrus plants subjected to drought stress. Initial research focused on physiological changes and transcriptomic rearrangements in two citrus rootstocks (Carrizo citrange and Bitters C22) exposed to PEG-induced drought. Stress levels were assessed by measuring leaf malonyl dialdehyde (MDA) and hydrogen peroxide (H₂O₂) content, followed by RNA sequencing and de novo assembly. Weighted Gene Correlation Network Analysis (WGCNA) was used to link gene expression to MDA and H₂O₂ levels. Plant visual inspection and MDA and H₂O₂ contents clearly indicate that Bitters is more tolerant than Carrizo towards PEG-induced drought stress. RNA-Seq analysis and WGCNA identified transcription factors significantly correlated with MDA and H₂O₂ levels in Carrizo, selected as candidate genes for drought tolerance. Successively, the effects of SNP-priming on citrus plants subjected to drought stress were assessed. The effects of priming were evaluated on Bitters C22 subjected to water scarcity, as being more promising than Carrizo in terms of drought tolerance. Primed Bitters C22 plants showed significantly higher drought tolerance than non-primed ones. The RNA-seq analysis revealed that priming, followed by drought stress, regulated a broad spectrum of stress responses, enhancing photosynthetic efficiency, reallocating energy, and reinforcing external barriers and xylem vessels. Additionally, auxin regulation was activated, while ethylene pathways were repressed. Finally, three candidate genes were functionally characterised by ectopic expression in tomato plants. The candidate genes (DREB3, AITR5 and NF-YA1) were successfully cloned through Gateway Cloning technology, and tomato plants were transformed using Agrobacterium-mediated transformation. Unfortunately, only 2 plants (DREB3 and AITR5) were successfully transformed. T1 plants selected under kanamycin pressure showed a healthy phenotype as wild type, at least under normal growing conditions. To our knowledge, this is the first study correlating transcriptomic data with priming-induced drought tolerance in citrus

Tutor: Lo Piero

Data Conseguimento Titolo: 29/03/2021

Linkedin:

Email: emanuele.scialo@phd.unict.it

Periodi all'estero- Sede e data: John Innes Centre, Norwich, UK. 27/09/2022 - 31/07/2023

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