Rootstock-Mediated Variation in Tomato Vegetative Growth Under Drought, Salinity and Soil Impedance Stresses

Abstract

There is increasing interest in using novel rootstocks to confer resistance to abiotic stresses in horticultural species, and to understand the physiological mechanism(s) conferring these responses. The same scion (Solanum lycopersicum cv. Boludo F1, Monsanto) was grafted onto 144 different rootstocks: six accessions from S. lycopersicum (cv cerasiforme) and S. pimpinellifolium, selected for drought tolerance (sourced from AVRDC); nine introgression lines from S. lycopersicum x S. pennellii and x S. habrochaites, selected for high root/shoot ratio, salinity and drought tolerances (sourced from TGRC); and a population of 129recombinant inbred lines (RILs) derived from a salt sensitive genotype of S. lycopersicum var.Cerasiforme and a salt tolerant line from S. pimpinellifolium L. (sourced from IVIA). Plants were grown in greenhouses in hydroponics (salinity stress) or soil (soil drying or high soil mechanical impedance) for 2-5 weeks (during the vegetative stage), and shoot fresh weight (SFW) was recorded at the end of each experiment. Although rootstock effects on SFW were significantly correlated in the soil drying and impedance assays, no significant correlations were detected between SFW under salinity and SFW under the other stresses. Indeed, the best rootstocks for drought stress were different to those that were the best for salinity and high soil impedance. For each abiotic stress, some graft combinations had higher SFW (up to 90% more) than the self-grafted commercial cultivar Boludo F1. The search for genetic factors contributing to this variation will be the objective of a future study.

Root-to-Shoot Hormonal Communication in Contrasting Rootstocks Suggests an Important Role for the Ethylene Precursor Aminocyclopropane-1-carboxylic Acid in Mediating Plant Growth under Low-Potassium Nutrition in Tomato

“…Shoot biomass of the non-grafted scion was reduced by 30% under low-K compared to control conditions (Albacete et al, 2015a). The H rootstocks produced 40–50% more SFW than the L ones, while low-K decreased ( HcLk ) or increased ( LcHk ) shoot biomass by 25–30%, compared to control conditions (Figure 1A, Table S1).…”

“…The use of RILs has proven to be a useful tool for these and other purposes (Albacete et al, 2009, 2015a,b; Estañ et al, 2009; Asins et al, 2010). Using 114 RILs from a S. lycopersicum × S. pimpinellifolium cross as rootstocks of a commercial tomato cultivar generate a 2.5-fold variation in the vegetative growth of the scion growing under low-K supply (1 mM; Albacete et al, 2015b).…”

“…Although gaining insights into the regulatory mechanisms of plant responses to K deficiency in Arabidopsis may lead to improvements in K utilization efficiency (KUE), the transfer of this knowledge into crop species through conventional breeding or biotechnological approaches is still a scientific challenge that need to be addressed in order to implement a “more-with-less” agriculture. As alternative, grafting provides a tool to explore and exploit new and existing genetic variability through regulating root-shoot interactions governing a range of physiological responses, including tolerance to abiotic stresses such as drought, salinity, and nutrient deficiency (Ghanem et al, 2011; Pérez-Alfocea, 2015; Albacete et al, 2015a). Grafting can enhance nutrient uptake and/or utilization efficiency in vegetables (Rouphael et al, 2008b; Colla et al, 2010; Salehi et al, 2010; Savvas et al, 2010), thus contributing to reduce the amount of fertilizers and production costs.…”

“…However, the mechanisms underlying the rootstock-mediated growth improvement in response to K deprivation have not been elucidated. The availability of RIL populations derived from crosses between the cultivated tomato Solanum lycopersicum and wild species such as Solanum pimpinellifolium , provides a powerful tool to identify the physiological and genetic determinants of the rootstock-mediated improvement of crop performance (Albacete et al, 2009, 2015a; Estañ et al, 2009; Asins et al, 2010). In the present study, we selected four groups of contrasting RILs on the basis of their high ( H ) or low ( L ) induced vigor to the scion under control ( c ) and low K ( k ) conditions to gain insights into the hormonal and nutritional components involved in the rootstock-mediated adaptation to low-K supply.…”

Screening Pepper Genotypes to Obtain Tolerant Rootstocks to Salt and Water Stress: Physiological and Agronomical Responses of the Grafted Plants

“…Moreover, some accessions behaved as tolerant to both stresses, ranking theirself as the most interesting plant material for further research. Few studies can be found in which a rootstock can tolerate both water scarcity and salinity, and mainly are done in woody plants, such as grapevine (Walker et al 2002;Meggio et al 2014) and citrus (García-Sánchez et al, 2007;Rewald et al, 2012;Syvertsen et al, 1988), finding only some in tomato (Albacete et al, 2015). None of the studied 277 | C h a p t e r 8 accessions belong C. frutescens and C. pubescens shown tolerances to both water and salt stress screening experiments, being discarded in the next experiments.…”