Investigation of Salt Tolerance Mechanisms Across a Root Developmental Gradient in Almond Rootstocks

Abstract

The intensive use of groundwater in agriculture under the current climate conditions leads to acceleration of soil salinization. Given that almond is a salt-sensitive crop, selection of salt-tolerant rootstocks can help maintain productivity under salinity stress. Selection for tolerant rootstocks at an early growth stage can reduce the investment of time and resources. However, salinity-sensitive markers and salinity tolerance mechanisms of almond species to assist this selection process are largely unknown. We established a microscopy-based approach to investigate mechanisms of stress tolerance in and identified cellular, root anatomical, and molecular traits associated with rootstocks exhibiting salt tolerance. We characterized three almond rootstocks: Empyrean-1 (E1), Controller-5 (C5), and Krymsk-86 (K86). Based on cellular and molecular evidence, our results show that E1 has a higher capacity for salt exclusion by a combination of upregulating ion transporter expression and enhanced deposition of suberin and lignin in the root apoplastic barriers, exodermis, and endodermis, in response to salt stress. Expression analyses revealed differential regulation of cation transporters, stress signaling, and biopolymer synthesis genes in the different rootstocks. This foundational study reveals the mechanisms of salinity tolerance in almond rootstocks from cellular and structural perspectives across a root developmental gradient and provides insights for future screens targeting stress response.

Cellulose synthase‐like protein OsCSLD4 plays an important role in the response of rice to salt stress by mediating abscisic acid biosynthesis to regulate osmotic stress tolerance

“…Salt stress can damage and inhibit the growth of plant roots, therefore, the root growth can represent plant salt stress tolerance (Arsova et al, 2020;Dinneny, 2019;Li et al, 2021;Shao et al, 2021). The results from qPCR assays revealed that OsCSLD4 was expressed in rice roots, stems and leaves (Figure S2; Ding et al, 2015).…”

Morphological, physiological, biochemical, and transcriptome studies reveal the importance of transporters and stress signaling pathways during salinity stress in Prunus

“…However, recycled waters have a higher salt concentration than freshwater, representing a challenge for their use in glycophytic C3 species sensitive to salinity stress, such as almonds 17 . Root anatomical, cellular, and molecular traits have been investigated in three different almond rootstocks to study mechanisms of salinity tolerance at an early growth stage 18 . It has been shown that increasing electrical conductivity (EC) of experimental irrigation waters led to detrimental effects on the productivity of almonds, including decreased chlorophyll fluorescence, root and shoot growth 19 .…”

Effects of Salinity and Abscisic Acid on Lipid Transfer Protein Accumulation, Suberin Deposition and Hydraulic Conductance in Pea Roots

“…Responsiveness of LTP genes to drought and salinity stress [5,6] implies an involvement in stress adaptation. Nevertheless, importance of LTPs for suberin deposition under drought is mentioned only rarely [1,7], whilst no attempt seems to have been made to relate LTP-dependent formation of apoplast barriers to salt stress responses even though enhanced deposition of suberin and lignin in apoplastic root barriers is an important component of salt tolerance [8]. Transgenic tobacco overexpressing an LTP gene has been shown to accumulate low Na + level upon exposure to high salinity [9].…”