title: Transcriptomic Changes Drive Physiological Responses to Progressive Drought Stress and Rehydration in Tomato.
abstract: Tomato is a major crop in the Mediterranean basin, where the cultivation in the open field is often vulnerable to drought. In order to adapt and survive to naturally occurring cycles of drought stress and recovery, plants employ a coordinated array of physiological, biochemical, and molecular responses. Transcriptomic studies on tomato responses to drought and subsequent recovery are few in number. As the search for novel traits to improve the genetic tolerance to drought increases, a better understanding of these responses is required. To address this need we designed a study in which we induced two cycles of prolonged drought stress and a single recovery by rewatering in tomato. In order to dissect the complexity of plant responses to drought, we analyzed the physiological responses (stomatal conductance, CO2 assimilation, and chlorophyll fluorescence), abscisic acid (ABA), and proline contents. In addition to the physiological and metabolite assays, we generated transcriptomes for multiple points during the stress and recovery cycles. Cluster analysis of differentially expressed genes (DEGs) between the conditions has revealed potential novel components in stress response. The observed reduction in leaf gas exchanges and efficiency of the photosystem PSII was concomitant with a general down-regulation of genes belonging to the photosynthesis, light harvesting, and photosystem I and II category induced by drought stress. Gene ontology (GO) categories such as cell proliferation and cell cycle were also significantly enriched in the down-regulated fraction of genes upon drought stress, which may contribute to explain the observed growth reduction. Several histone variants were also repressed during drought stress, indicating that chromatin associated processes are also affected by drought. As expected, ABA accumulated after prolonged water deficit, driving the observed enrichment of stress related GOs in the up-regulated gene fractions, which included transcripts putatively involved in stomatal movements. This transcriptomic study has yielded promising candidate genes that merit further functional studies to confirm their involvement in drought tolerance and recovery. Together, our results contribute to a better understanding of the coordinated responses taking place under drought stress and recovery in adult plants of tomato.
authors.affiliation: National Research Council of Italy, Institute of Biosciences and Bioresources, Research Division Portici (CNR-IBBR) Portici, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Iovieno
authors.affiliation: National Research Council of Italy, Institute of Biosciences and Bioresources, Research Division Portici (CNR-IBBR) Portici, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Punzo
authors.affiliation: National Research Council of Italy, Institute for Agricultural and Forestry Systems in the Mediterranean (CNR-ISAFoM) Ercolano, Italy.
authors.forename: Gianpiero
authors.initials: G
authors.lastname: Guida
authors.affiliation: National Research Council of Italy, Institute for Agricultural and Forestry Systems in the Mediterranean (CNR-ISAFoM) Ercolano, Italy.
authors.forename: Carmela
authors.initials: C
authors.lastname: Mistretta
authors.affiliation: Department of Agriculture, University of Naples "Federico II," Portici, Italy.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Van Oosten
authors.affiliation: National Research Council of Italy, Institute of Biosciences and Bioresources, Research Division Portici (CNR-IBBR) Portici, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Nurcato
authors.affiliation: Department of Agriculture, University of Naples "Federico II," Portici, Italy.
authors.forename: Hamed
authors.initials: H
authors.lastname: Bostan
authors.affiliation: Department of Agriculture, University of Naples "Federico II," Portici, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Colantuono
authors.affiliation: National Research Council of Italy, Institute of Biosciences and Bioresources, Research Division Portici (CNR-IBBR) Portici, Italy.
authors.forename: Antonello
authors.initials: A
authors.lastname: Costa
authors.affiliation: CREA - Council for Agricultural Research and Economics, Genomics Research Centre Fiorenzuola d'Arda, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Bagnaresi
authors.affiliation: Department of Agriculture, University of Naples "Federico II," Portici, Italy.
authors.forename: Maria L
authors.initials: ML
authors.lastname: Chiusano
authors.affiliation: National Research Council of Italy, Institute for Agricultural and Forestry Systems in the Mediterranean (CNR-ISAFoM) Ercolano, Italy.
authors.forename: Rossella
authors.initials: R
authors.lastname: Albrizio
authors.affiliation: National Research Council of Italy, Institute for Agricultural and Forestry Systems in the Mediterranean (CNR-ISAFoM) Ercolano, Italy.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Giorio
authors.affiliation: National Research Council of Italy, Institute of Biosciences and Bioresources, Research Division Portici (CNR-IBBR) Portici, Italy.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Batelli
authors.affiliation: National Research Council of Italy, Institute of Biosciences and Bioresources, Research Division Portici (CNR-IBBR) Portici, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Grillo
keywords: ABA; RNA sequencing; gene-expression cluster analysis; photosynthesis; proline; stomatal conductance; water stress