High sensitivity of roots to salt stress as revealed by novel tip bioassay in wheat seedlings

Abstract

Salinity is one of major environmental constraints that adversely affect plant growth and pose a serious threat to crop productivity. One basic concern is related to tissue sensitivity differences to salt stress. It is intriguing that much more research efforts have been directed to shoots/ leaves than roots, although roots are the first tissues directly encountering salt stress and acting as its sensor. We focused on the tissue sensitivity differences to salt stress in wheat seedlings by adopting a novel tip bioassay. The tip bioassay employed a set of 5-mL pipette tips filled with vermiculite placed over racks containing NaCl solution. Using this simple device, after determining the time course of growth inhibition under varying concentrations of NaCl, we compared the salt sensitivity in 19 diverse germplasms from five Triticum species after 7 and 14 days of exposure to 200 mmol/L NaCl. Markedly greater reduction in root length than shoot length was observed in all lines. Both the magnitude and relative rate of inhibition were much greater in roots than shoots and significant differences were observed in tissue, line, stress duration and their interactions. Our tip bioassay demonstrated that roots were more sensitive than shoots to the growth-suppressing effect of salt during the early seedling stage in wheat. These results point out the need of further research targeted on the role of and communication between roots and shoots in salt stress sensing and response.

Integrated metabolomic and transcriptomic analysis reveals the role of phenylpropanoid biosynthesis pathway in tomato roots during salt stress

“…S. lycopersicum is a moderately salt-sensitive plant and seedlings are vulnerable to severe impacts of salt stress during the growth period ( Cuartero et al., 2006 ; Tanveer et al., 2019 ). Roots, as the main organs of plants to perceive salt stress signals, play an essential function in response to salt stress ( Deolu-Ajayi et al., 2019 ; Nakamura et al., 2020 ). Therefore, an integrated metabolomic and transcriptomic analysis to investigate the response of S. lycopersicum seedling roots to salt stress may be meaningful to reveal the mechanism of salt tolerance in S. lycopersicum .…”

“…Since the effective response capacity of plants under salt stress depends on the roots ( Deolu-Ajayi et al., 2019 ; Nakamura et al., 2020 ). A combined metabolome and transcriptome analysis have been carried out in G. max ( Jin et al., 2021 ), S. alopecuroides ( Zhu et al., 2021 ), B. vulgaris ( Liu et al., 2020 ), and B. napus ( Wang et al., 2022b ) roots to reveal the molecular mechanisms underlying their salt tolerance.…”

“…Besides, roots are the main carriers of nutrient and water uptake by plants and are the first organs to be damaged by salinity and the most sensitive against salt stress. This means that the effective response capacity of plants under salt stress depends on the roots ( Yang and Guo, 2018 ; Deolu-Ajayi et al., 2019 ; Nakamura et al., 2020 ). In recent years, the results of studies that integrated physiological, transcriptional, and metabolic analyses to reveal the molecular mechanisms of salt tolerance in soybean ( Glycine max ) roots have demonstrated that salt tolerant varieties have higher rates of nitrogen (N) uptake and assimilation, an increased amino acid accumulation and more rapid tricarboxylic acid cycle activity in response to salt stress, which contributes to their improved adaptation under salt stress ( Jin et al., 2021 ).…”

How Salt (NaCl) stress modulates histidine kinase-based signalling systems

“…). Many researchers agree with the suggestion that the root is the primary organ to carry receptors and primarily responds with the activation/deactivation of corresponding transporters (Nakamura et al 2021). Thus, rst Na + enters the root and then is transported up to the shoot and leaves.…”

Plant Salinity Sensors: Current Understanding and Future Directions

“…Auxin plays a key role in this process ( Gilroy, 2008 ; Galvan-Ampudia and Testerink, 2011 ). Although the identity of primary salt-stress sensors and their detailed mechanisms of action are unclear, it can be inferred that they are located in a certain zone of the root meristem ( Wu et al, 2015 ; Wu, 2018 ; Nakamura et al, 2021 ).…”