Identifying roles of the scion and the rootstock in regulating plant development and functioning under different phosphorus supplies in grapevine

Abstract

Phosphorus is essential for plant life and plants have developed numerous strategies to maximise phosphate (Pi) acquisition and use under limited Pi supply. Here we have used reciprocal grafting to determine whether the shoot and root have different roles in regulating some of these strategies.Reciprocal grafts of two grapevine genotypes (Vitis vinifera cv. Pinot noir and V. berlandieri x V. rupestris cv. 1103 Paulsen) were produced as well as the corresponding homo-graft controls; the plants were grown in hydroponic culture and subjected to two levels of Pi supply (high (0.6 mM) or low (0.001 mM)). Biomass accumulation, root morphology, and root, stem and leaf organic acid, phosphate, nitrate and sulphate concentrations were measured. The transcript abundance of orthologues of known phosphate starvation induced (PSI) genes from Arabidopsis was also quantified. Under high Pi, the scion genotype had a large impact on plant growth, but the morphology of roots (such as root tip density) was not affected. Low Pi supply affected growth, tissue organic acid concentration, the activity of acid phosphatases released by the roots and the expression of PSI genes. Rootstock genotypes showed differences in root responses to low Pi supply, but the scion also exerted long-distance regulation of rootstock responses to low Pi, for example, modifying PSI gene expression, sulphate acquisition efficiency, the activity of acid phosphatases released by the roots and root organic acid concentrations. This work shows for the first time that the grapevine genotypes differ in their response to low Pi supply and that the scion can modify rootstock responses to the nutrient availability. This work highlights that genetic variation in shootborne signals can regulate root responses to Pi supply and that understanding rootstock responses to the environment must be done considering scion influence. AG, IM, BP and PD executed the experiments and collected data, AG and NC analysed the data, VL, AM, PV and SJC acquired the funding, SJC drafted the manuscript, and all authors made significant intellectual contributions to the design and execution of the work, and revised the manuscript. ReferencesAttia F, Garcia F, Garcia M, Besnard E, Lamaze T. 2007. Effect of rootstock on organic acids in leaves and berries and on must and wine acidity of two red wine grape cultivars 'Malbec' and 'Négrette' (Vitis vinifera L.) grown hydroponically. Acta Horticulturae 754, 473-482.

Characterization of almond scion/rootstock communication in cultivar and rootstock tissues through a RNA-Seq approach

“…Therefore, it is likely that the grafted scion also has an effect on the rootstocks, triggering different mechanisms that could affect the rootstock properties. This reciprocal effect has been already described in other species regarding different traits (regulation of rootstock responses to low Pi and phloem sap metabolites) [42,43]. Here, we reported that hormonal response is affected by the scion, presumably leading to changes in the root architecture.…”

Effects of Scion Variety on the Phosphorus Efficiency of Grafted Camellia oleifera Seedlings

“…This is possible through rootstocks with high P efficiency being able to uptake more ions by efficient root morphologies and root architectures [16,17]. The selection of P-efficient rootstocks has been conducted in various species [18,19]. However, the P efficiency of grafted plants is both rootstock and scion dependent.…”

Scions impact biomass allocation and root enzymatic activity of rootstocks in grafted melon and watermelon plants

“…Since, RL : LA ratio reflects the plant's structural expenditures for uptake (Körner and Renhardt, 1987), our data indicate the presence of a useful mechanism in successfully (i.e., compatible) grafted plants to increase the allocation of assimilates to rootstocks under limiting soil resources. In contrast, Gautier et al (2021) reported only minor effects of specific Vitis scion/ rootstock combinations on root-to-shoot fresh biomass ratios. However, previous studies on compatibility aspects among different Solanaceae (Kawaguchi et al, 2008) and also woody perennials such as apple trees (Thomaj et al, 2019) underlined that carbohydrate concentration and C partitioning between graft components are highly diverse and dependent on specific rootstock-scion combinations.…”

“…Increased concentrations of specific nutrients in grafted vs. non-grafted plants were, e.g., reported for leaves and stems of grafted cucumber (Rouphael et al, 2008), melon (Ruiz et al, 1997), and watermelon (Colla et al, 2010a). However, while many previous studies addressed the effects of different rootstocks on vegetative growth (Babaj et al, 2014a;Babaj et al, 2014b), stress tolerance (Savvas et al, 2010;Rouphael et al, 2018), yield (Balliu et al, 2008;Yuan et al, 2016), and fruit quality (Kyriacou et al, 2017) of scions, little is still known about possible influences of scions on the architecture and metabolic activity of the rootstocks (Neumann et al, 2014;Gautier et al, 2021). Furthermore, while a few published reports, to the best of our knowledge, address the effects of a scion cultivar on the rooting pattern of the rootstock (Franco et al, 1995;Harrison et al, 2016;Thomaj et al, 2019), potential eco-physiological alterations affecting the nutrient acquisition capacity and efficiency of rootstocks remain poorly understood (Shu et al, 2017).…”