Some salt-stress responsive DEGs, mainly involved in ion transmembrane transport,
hormone regulation,
antioxidant system, osmotic regulation, and some
miRNA jointly regulated the
salt response process in allotriploid Populus cathayana. The molecular mechanism of plant
polyploid stress resistance has been a hot topic in biological research. In this study, Populus diploids and first division restitution (FDR) and second division restitution (SDR)
triploids were selected as research materials. All materials were treated with 70 mM NaCl solutions for 30 days in the same pot environment. We observed the growth state of
triploids and diploids and determined the ratio of
potassium and
sodium ions,
peroxidase (POD) activity,
proline content, and ABA and
jasmonic acid (JA)
hormone content in leaves in the same culture environment with the same concentration of NaCl
solution treatment. In addition,
RNA-seq technology was used to study the differential expression of
mRNA and
miRNA. The results showed that
triploid Populus grew well and the K+ content and the K+/Na+ ratio in the
salt treatment were significantly lower than those in the control. The contents of ABA, JA, POD, and
proline were increased compared with contents in diploid under salt stress. The salt-stress responsive DEGs were mainly involved in ion transport, cell homeostasis, the MAPK signaling pathway, peroxisome, citric acid cycle, and other
salt response and growth pathways. The
transcription factors mainly included NAC, MYB, MYB_related and AP2/ERF. Moreover, the differentially expressed
miRNAs involved 32 families, including 743
miRNAs related to predicted target genes, among which 22
miRNAs were significantly correlated with salt-stress response genes and related to the regulation of
hormones, ion transport,
reactive oxygen species (ROS) and other biological processes. Our results provided insights into the physiological and molecular aspects for further research into the response mechanisms of allotriploid Populus cathayana to salt stress. This study provided valuable information for the salt tolerance mechanism of allopolyploids.