Effective Categorization of Tolerance to Salt Stress through Clustering Prunus Rootstocks According to Their Physiological Performances

Abstract

The effects of climate change on traditional stone fruit producing areas, together with the generation of new varieties with lower chilling requirements that allow the cultivation of previously unexplored areas, are setting up a challenging scenario for the establishment of productive orchards that must be more efficient in their capacity to adapt to new edaphoclimatic conditions. In this context, the rootstock breeding programs are a key piece in the agronomic strategy to achieve this adaptation through the development of rootstocks compatible with the new varieties and capable of transferring their tolerance to stress. An effective categorization of phenotypes within the germplasm involved in a plant breeding program is of utmost importance. Through the measurement of physiological parameters in both roots and leaves, tolerance to saline stress (120 mM NaCl) was evaluated in seven Prunus rootstocks whose genetic background included representatives of the subgenera Prunus, Cerasus, and Amygdalus. To group the genotypes according to their physiological performance under salt stress, an agglomerative hierarchical clustering was applied. The genotypes were grouped into three clusters containing rootstocks very sensitive (‘Mazzard F12/1’), moderately tolerant (‘Maxma 60’, ‘Cab6P’ and ‘AGAF 0204-09’), and tolerant (‘Mariana 2624’, ‘Garnem’ and ‘Colt’) to salt stress. ‘Mariana 2624’, a plum-based rootstock, was identified as the most tolerant Prunus rootstock. The information reported is valuable both in the productive context, for the selection of the most appropriate rootstocks to establish an orchard, and in the context of plant breeding programs, when choosing parents with outstanding traits to obtain progenies tolerant to salt stress.

Genome-Wide Identification and Gene Expression Analysis of Sweet Cherry Aquaporins (Prunus avium L.) under Abiotic Stresses

“…For root hypoxia treatment, plastic containers were filled with water to approximately 4 cm above the pot substrate level, according to Pimentel et al, 2014 [ 34 ]. For salt treatment, plants were watered three times per week with a solution of 120 mM NaCl, according to Toro et al, 2021 [ 35 ]. For cold treatment, plants were exposed to 4 °C for 72 h. For heat treatment, plants were exposed to 40 °C for 72 h. Drought stress treatment was achieved by progressive substrate drying by applying irrigation with a volume of water equivalent to 90% of the weight of the substrate recorded the previous day until the early appearance of epinasty, which marked the reference point for the start of this treatment.…”

Perspective Chapter: Rootstock-Scion Interaction Effect on Improving Salt Tolerance in Fruit Trees

“…At 4 dm/S, plum vegetative development appeared more sensitive, and the same treatment caused significant leaf damage [35]. Excessive doses of salt in soil reduce significantly the performance of fast-growing plants of Prunus species [40]. Salt load control systems at the whole plant level strongly integrate growth rates and plant shape [41].…”

The Role of Plant Growth-Promoting Rhizobacteria (PGPR) in Mitigating Plant’s Environmental Stresses

“…Salt stress can cause a drastic reduction in the productivity of various crops and mainly fruit crops, such as the species of the genus Prunus, which are considered very sensitive to salt. To prevent, at least in part, these conditions that may limit the normal development of these fruit trees, one of the agronomic strategies successfully adopted is that which uses rootstocks tolerant to biotic and abiotic factors [109]. The phenomenon of salinization concerns all the salts which, if in excess, can cause severe damage, but they are mainly sodium chloride (NaCl), sodium sulphate (Na 2 SO 4 ), magnesium sulphate (MgSO 4 ), and magnesium chloride (MgCl 2 ); however, NaCl is certainly the most critical one.…”