title: Salt-tolerant rootstock increases yield of pepper under salinity through maintenance of photosynthetic performance and sinks strength.
abstract: The performance of a salt-tolerant pepper (Capsicum annuum L.) accession (A25) utilized as a rootstock was assessed in two experiments. In a first field experiment under natural salinity conditions, we observed a larger amount of marketable fruit (+75%) and lower Blossom-end Root incidence (-31%) in commercial pepper cultivar Adige (A) grafted onto A25 (A/A25) when compared with ungrafted plants. In order to understand this behavior a second greenhouse experiment was conducted to determine growth, mineral partitioning, gas exchange and chlorophyll a fluorescence parameters, antioxidant systems and proline content in A and A/A25 plants under salinity conditions (80 mM NaCl for 14 days). Salt stress induced significantly stunted growth of A plants (-40.6% of leaf dry weight) compared to the control conditions, while no alterations were observed in A/A25 at the end of the experiment. Accumulation of Na(+) and Cl(-) in leaves and roots was similar in either grafted or ungrafted plants. Despite the activation of protective mechanisms (increment of superoxide dismutase, catalase, ascorbate peroxidase activity and non-photochemical quenching), A plants showed severely reduced photosynthetic CO2 assimilation (-45.6% of AN390) and substantial buildup of malondialdehyde (MDA) by-product, suggesting the inability to counteract salt-triggered damage. In contrast, A/A25 plants, which had a constitutive enhanced root apparatus, were able to maintain the shoot and root growth under salinity conditions by supporting the maintained photosynthetic performance. No increases in catalase and ascorbate peroxidase activities were observed in response to salinity, and MDA levels increased only slightly; indicating that alleviation of oxidative stress did not occur in A/A25 plants. In these plants the increased proline levels could protect enzymatic stability from salt-triggered damage, preserving the photosynthetic performance. The results could indicate that salt stress was vanished by the lack of negative effects on photosynthesis that support the maintained plant growth and increased marketable yield of the grafted plants.
authors.affiliation: Instituto Valenciano de Investigaciones Agrarias (IVIA), Departamento de Horticultura, Ctra. Moncada-Naquera km. 4, 5, 46113 Moncada, Valencia, Spain. Electronic address: penella_con@gva.es.
authors.forename: Consuelo
authors.initials: C
authors.lastname: Penella
authors.affiliation: Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy. Electronic address: marco.landi@for.unipi.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Landi
authors.affiliation: Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy. Electronic address: lucia.guidi@unipi.it.
authors.forename: Lucia
authors.initials: L
authors.lastname: Guidi
authors.affiliation: Universitat Politècnica de València, Departamento de Producción Vegetal, Camino de Vera 14, 46020 Valencia, Spain. Electronic address: sergonne@bvg.upv.es.
authors.forename: Sergio G
authors.initials: SG
authors.lastname: Nebauer
authors.affiliation: Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy. Electronic address: elisa.pellegrini@for.unipi.it.
authors.forename: Elisa
authors.initials: E
authors.lastname: Pellegrini
authors.affiliation: Universitat Politècnica de València, Departamento de Producción Vegetal, Camino de Vera 14, 46020 Valencia, Spain. Electronic address: asanbau@prv.upv.es.
authors.forename: Alberto
authors.initials: A
authors.lastname: San Bautista
authors.affiliation: Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy. Electronic address: damiano.remorini@unipi.it.
authors.forename: Damiano
authors.initials: D
authors.lastname: Remorini
authors.affiliation: Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy. Electronic address: cristina.nali@unipi.it.
authors.forename: Cristina
authors.initials: C
authors.lastname: Nali
authors.affiliation: Universitat Politècnica de València, Departamento de Producción Vegetal, Camino de Vera 14, 46020 Valencia, Spain. Electronic address: slopez@prv.upv.es.
authors.forename: Salvador
authors.initials: S
authors.lastname: López-Galarza
authors.affiliation: Instituto Valenciano de Investigaciones Agrarias (IVIA), Departamento de Horticultura, Ctra. Moncada-Naquera km. 4, 5, 46113 Moncada, Valencia, Spain. Electronic address: calatayud_ang@gva.es.
authors.forename: Angeles
authors.initials: A
authors.lastname: Calatayud
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D002212:Capsicum / Q000187:drug effects / Q000502:physiology*; D002374:Catalase / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D008315:Malondialdehyde / Q000378:metabolism; D018384:Oxidative Stress; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000502:physiology; D018520:Plant Shoots / Q000187:drug effects / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology; D011392:Proline / Q000378:metabolism; D054712:Salinity; D055049:Salt Tolerance; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D002734:Chlorophyll; D012965:Sodium Chloride; D008315:Malondialdehyde; D011392:Proline; D002374:Catalase; D013482:Superoxide Dismutase; D000077194:Chlorophyll A
keywords: Antioxidant systems; Capsicum annuum; Chlorophyll fluorescence; Grafting; NaCl stress; Proline