Transcriptome and Low-Affinity Sodium Transport Analysis Reveals Salt Tolerance Variations between Two Poplar Trees

Abstract

Salinity stress severely hampers plant growth and productivity. How to improve plants’ salt tolerance is an urgent issue. However, the molecular basis of plant resistance to salinity still remains unclear. In this study, we used two poplar species with different salt sensitivities to conduct RNA-sequencing and physiological and pharmacological analyses; the aim is to study the transcriptional profiles and ionic transport characteristics in the roots of the two Populus subjected to salt stress under hydroponic culture conditions. Our results show that numerous genes related to energy metabolism were highly expressed in Populus alba relative to Populus russkii, which activates vigorous metabolic processes and energy reserves for initiating a set of defense responses when suffering from salinity stress. Moreover, we found the capacity of Na+ transportation by the P. alba high-affinity K+ transporter1;2 (HKT1;2) was superior to that of P. russkii under salt stress, which enables P. alba to efficiently recycle xylem-loaded Na+ and to maintain shoot K+/Na+ homeostasis. Furthermore, the genes involved in the synthesis of ethylene and abscisic acid were up-regulated in P. alba but downregulated in P. russkii under salt stress. In P. alba, the gibberellin inactivation and auxin signaling genes with steady high transcriptions, several antioxidant enzymes activities (such as peroxidase [POD], ascorbate peroxidase [APX], and glutathione reductase [GR]), and glycine-betaine content were significantly increased under salt stress. These factors altogether confer P. alba a higher resistance to salinity, achieving a more efficient coordination between growth modulation and defense response. Our research provides significant evidence to improve the salt tolerance of crops or woody plants.

Microbial community assembly and functional profiles along the soil-root continuum of salt-tolerant Suaeda glauca and Suaeda salsa

“…Excessive Na + was found to trigger overproduction of ROS and damage plant organelles (Ma et al, 2023). Betacyanin is a secondary metabolite produced by plants under stress (Li et al, 2023), and its production and changes have a stronger correspondence and correlation with the environment than primary metabolites.…”

“…Therefore, root-related microorganisms can protect the host from high Na + concentrations, which is consistent with previous studies showing that poplar salt tolerance is closely related to reduced Na + uptake. Furthermore, maintaining K + /Na + homeostasis is also important for plants to resist salt stress (Ma et al, 2023). Maintaining K + /Na + ratios is a key pathway for tolerating salt-induced osmotic stress when Na + enters plant cells (van Zelm et al, 2020).…”

Integration of mRNA and miRNA analysis reveals the molecular mechanisms of sugar beet (Beta vulgaris L.) response to salt stress

“…Evidence exists reporting that an increase in osmotic adjustment compounds, including soluble sugars, alters the osmotic pressure under salt stress 5 . Furthermore, several other response mechanisms have also been widely explored, which includes the activated reactive oxygen species (ROS) scavenging activity to attenuate oxidative damage induced by rising salinity 6 and the increased activity of Na + and K + transporters and channels to sustain the balance of cytosolic Na + /K + ratio 7 .…”