Transcriptome analysis and association mapping revealed the genetic regulatory network response to cadmium stress in Populus tomentosa.

Quan, Mingyang; Liu, Xin; Xiao, Liang; Chen, Panfei; Song, Fangyuan; Lu, Wenjie; Song, Yuepeng; Zhang, Deqiang

Long non-coding RNAs (lncRNAs) play essential roles in plant abiotic stress responses, however, the lncRNA-mediated genetic networks response to cadmium (Cd) treatment remain elusive in trees, the promising phytoremediation candidates for Cd contamination. Here, we identified 172 Cd-responsive lncRNAs and 295 differentially expressed target genes in the leaves of Populus tomentosa under Cd treatment. Functional annotation revealed that these lncRNAs involved in various processes, including photosynthesis, hormone regulation, and phenylalanine metabolism. Association studies identified 78 significant associations, representing 14 Cd-responsive lncRNAs and 28 target genes for photosynthetic and leaf physiological traits. Epistasis uncovered 83 pairwise interactions among these traits, unveiling Cd-responsive lncRNA-mediated genetic networks for photosynthesis and leaf physiology in P. tomentosa. We then focused on the roles of two Cd-responsive lncRNA-gene pairs, MSTRG.22608.1-PtoMYB73 and MSTRG.5634.1-PtoMYB27, in Cd tolerance of Populus, and detected insertions/deletions within lncRNAs as polymorphisms driving target gene expression. LncRNAs genotype analysis and heterologous overexpressing PtoMYB73 and PtoMYB27 in Arabidopsis indicated their positive effects on enhancing Cd tolerance, photosynthetic rate, and leaf growth, and the potential interaction mechanisms of PtoMYB73 with abiotic stresses. Our study provides the genetic basis for Populus response to Cd treatment, facilitating genetic improvement of enhancing Cd tolerance in trees.