Integrating amino acid metabolic pathways into plant defense and immune systems provides the building block for stress acclimation and host-pathogen interactions. Recent progress in L-aspartate (Asp) and its deployed metabolic pathways highlighted profound roles in plant growth and defense modulation. Nevertheless, much remains unknown concerning the multiple isoenzyme families involved in Asp metabolic pathways in Populus trichocarpa, a model tree species. Here, we present comprehensive features of 11 critical isoenzyme families, representing biological significance in plant development and stress adaptation. The in silico prediction of the molecular and genetic patterns, including phylogenies, genomic structures, and chromosomal distribution, identify 44 putative isoenzymes in the Populus genome. Inspection of the tissue-specific expression demonstrated that approximately 26 isogenes were expressed, predominantly in roots. Based on the transcriptomic atlas in time-course experiments, the dynamic changes of the genes transcript were explored in Populus roots challenged with soil-borne pathogenic Fusarium solani (Fs). Quantitative expression evaluation prompted 12 isoenzyme genes (PtGS2/6, PtGOGAT2/3, PtAspAT2/5/10, PtAS2, PtAspg2, PtAlaAT1, PtAK1, and PtAlaAT4) to show significant induction responding to the Fs infection. Using high-performance liquid chromatography (HPLC) and non-target metabolomics assay, the concurrent perturbation on levels of Asp-related metabolites led to findings of free amino acids and derivatives (e.g., Glutamate, Asp, Asparagine, Alanine, Proline, and α-/γ-aminobutyric acid), showing marked differences. The multi-omics integration of the responsive isoenzymes and differential amino acids examined facilitates Asp as a cross-talk mediator involved in metabolite biosynthesis and defense regulation. Our research provides theoretical clues for the in-depth unveiling of the defense mechanisms underlying the synergistic effect of fine-tuned Asp pathway enzymes and the linked metabolite flux in Populus.

The Plateau Hongliu (Myricaria elegans Royle.) is a woody shrub halophyte that thrives in arid areas of western Tibet, in the Himalayan Mountains. It is acclaimed as superior in saline stress acclimation and as a critical pharmaceutical resource of the Tibetan traditional herb. Nevertheless, the mitogenome in the genus Myricaria remains unknown. Here, using the Illumina and PacBio sequencing assays, the first complete mitogenome of the M. elegans revealed a multi-branched skeleton with a total length of 416,354 bp and GC content of 44.33%, comprising two circular molecules (M1 and 2). The complete mitogenome annotates 31 unique protein-encoding genes (PEGs), fifteen tRNAs, and three rRNA genes. The UAA exhibits the most prominent codon usage preference as a termination, followed by UUA codons for leucine. The mitogenome contains 99 simple sequence repeats and 353 pairs of dispersed repeats, displaying the most frequent in palindromic repeats. Gene transfer analyses identified 8438 bp of 18 homologous fragments from the plastome, accounting for 2.03% of the total length. Using the PREP suite, 350 C-U RNA editing sites were predicted, of which nad4 and ccmB were on the top frequency. Syntenic and phylogenetic analyses suggested weakly conserved patterns of M. elegans in Caryophyllales owing to the genome rearrangement. In summary, the deciphered unique features and complexities of the mitogenome in M. elegans provide novel insights into understanding the evolution and biological conservation underlying climate resilience in halophytes.