Hormonal and Nutritional Features in Contrasting Rootstock-mediated Tomato Growth under Low-phosphorus Nutrition

Abstract

Grafting provides a tool aimed to increase low-P stress tolerance of crops, however, little is known about the mechanism (s) by which rootstocks can confer resistance to P deprivation. In this study, 4 contrasting groups of rootstocks from different genetic backgrounds (Solanum lycopersicum var. cerasiforme and introgression and recombinant inbred lines derived from the wild relatives S. pennellii and S. pimpinellifolium) were grafted to a commercial F1 hybrid scion and cultivated under control (1 mM, c) and P deficient (0.1 mM, p) conditions for 30 days, to analyze rootstocks-mediated traits that impart low (L, low shoot dry weight, SDW) or high (H, high SDW) vigor. Xylem sap ionic and hormonal anlyses leaf nutritional status suggested that some physiological traits can explain rootstocks impacts on shoot growth. Although xylem P concentration increased with root biomass under both growing conditions, shoot biomass under low-P was explained by neither changes in root growth nor P transport and assimilation. Indeed, decreased root P export only explained the sensitivity of the HcLp rootstocks, while leaf P status was similarly affected in all graft combinations. Interestingly, most of the nutrients analyzed in the xylem sap correlated with root biomass under standard fertilization but only Ca was consistently related to shoot biomass under both control and low-P, suggesting an important role for this nutrient in rootstock-mediated vigor. Moreover, foliar Ca, S, and Mn concentrations were (i) specifically correlated with shoot growth under low-P and (ii) positively and negatively associated to the root-to-shoot transport of the cytokinin trans-zeatin (t-Z) and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), respectively. Indeed, those hormones seem to play an antagonistic positive (t-Z) and negative (ACC) role in the rootstock-mediated regulation of shoot growth in response to P nutrition. The use of Hp-type rootstocks seems to enhance P use efficiency of a commercial scion variety, therefore could potentially be used for increasing yield and agronomic stability under low P availability.

Cadmium (Cd) chloride affects the nutrient uptake and Cd-resistant bacterium reduces the adsorption of Cd in muskmelon plants

“…However, the absorption of N, P, and K increased when the grafted plants were exposed to Cd, suggesting that Cd stimulates rootstock growth, especially root development. Many studies have reported that using rootstock can increase the nutrient uptake or tolerant abiotic stress in grafted plants [13,[36][37][38]. The present work illustrates that the rootstock growth can also be triggered by abiotic stress factors, such as heavy metal Cd.…”

“…Regardless of the treatment (50 or 100 µM), the scion, shoot, root, and total dry weights of the grafted plants significantly increased, whereas the root dry weight increased by nearly onefold (Figure 2b), suggesting that grafted plants grow remarkably when exposed to Cd. Various rootstocks have been used to increase the nutrient uptake in grafted vegetables; thus, grafting improves the plant growth [11,13,30].…”

“…Plants must absorb enough nutrients to grow; for instance, rhizobial inoculants may induce high nutrient uptake in plants [12]. Grafting is a normal way of increasing the nutrient uptake in various horticultural plants [13]. Grafted plants exhibit better nutrient uptake because of the strong ability of the rootstock's roots to absorb nutrients from the soil.…”

Silicon Compensates Phosphorus Deficit-Induced Growth Inhibition by Improving Photosynthetic Capacity, Antioxidant Potential, and Nutrient Homeostasis in Tomato

“…Phosphorus is an essential macroelement that not only stimulates plant growth but also affects plant responses due to its direct involvement in energy production (ATP) and signaling cascades by mediating phosphorylation of various proteins [4,6,38]. Thus, P deficiency impairs nutrient homeostasis, leading to massive physiological and metabolic changes in plants [37,46]. Despite a large number of studies in Si-mediated tolerance to abiotic stresses, the underlying mechanisms remain largely unknown [12].…”

Genome Wide Transcriptome Analysis Reveals Complex Regulatory Mechanisms Underlying Phosphate Homeostasis in Soybean Nodules

“…Additionally, plant phytohormones are suggested to regulate plant responses to Pi starvation, such as auxin, abscisic acid, ethylene, cytokinin [ 9 , 46 , 47 ]. Furthermore, cross-regulation also occurs between Pi and nitrogen (N) starvation in both legume and non-legume plants [ 48 , 49 ].…”