Heimia myrtifolia is an important medicinal plant with several pharmacologically active alkaloids and is also used as an ornamental landscape plant. The purpose of this study is to complete and characterize the chloroplast (cp) genome of H. myrtifolia and compare genomic features to other Myrtales species’ cp genomes. The analysis showed that H. myrtifolia has a total length of 159,219 bp with a typical quadripartite structure containing two identical inverted repeats (IRs) of 25,643 bp isolated by one large single copy (LSC) of 88,571 bp and one small single copy (SSC) of 18,822 bp. The H. myrtifolia cp genome contains 129 genes with eight ribosomal RNAs, 30 transfer RNAs, and 78 protein coding genes, in which 17 genes are duplicated in two IR regions. The genome organization including gene type and number and guanine-cytosine (GC) content is analyzed among the 12 cp genomes in this study. Approximately 255 simple sequence repeats (SSRs) and 16 forward, two reverses, and two palindromic repeats were identified in the H. myrtifolia cp genome. By comparing the whole H. myrtifolia cp genome with 11 other Myrtales species, the results showed that the sequence similarity was high between coding regions while sequence divergence was high between intergenic regions. By employing the full cp genomes for phylogenetic analysis, structural and sequence differences were characterized between H. myrtifolia and 11 Myrtales species illustrating what patterns are common in the evolution of cp genomes within the Myrtales. The first entire cp genome in the genus Heimia provides a valuable resource for further studies in these medicinally and ornamentally important taxa.

Target seedling cultivation pursues high quality and nutrient utilization instead of increasing growth and size. Exposure to light-emitting diode (LED) spectra is a well-known approach that can accelerate growing speed in tree seedlings, but it is still unknown whether seedling quality and nutrient utilization would be further improved with exogeneous polymer additives. Luohan pine (Podocarpus macrophyllus) seedlings were exposed to red (red-green-blue lights, 71.7%-13.7%-14.6%), green (26.2%-56.4%-17.4%), and blue (17.8%-33.7%-48.5%) LED-light spectra with half receiving leaf spray by chitosan oligosaccharides (Cos) at a rate of 2 ppm (w/w) and the other half receiving only water. The red-light spectrum promoted height, biomass, nutrient utilization, and quality assessment (DQI) in water-sprayed seedlings. The Cos spray enhanced fine-root growth, protein, and chlorophyll-b contents with elevated nutrient utilization and quality in seedlings in the green-light spectrum. DQI was found to have a positive relationship with phosphorus utilization. In conclusion, although the red-light LED spectrum can promote seedling growth, green light combined with Cos spray is recommended with the aim of maintaining seedling quality and increasing P utilization in Luohan pine seedlings.

Leaf color mutants serve as excellent models for investigating the metabolic pathways involved in chlorophyll biosynthesis, chloroplast development, and photosynthesis in plants. This study aimed to elucidate the mechanisms underlying color formation in the yellow–green leaf mutant (YL) of Magnolia sinostellata by employing physiological, cytological and transcriptomic analyses to compare the mutant with control plants (wild type Magnolia sinostellata, WT). Physiological assessments revealed a reduction in chlorophyll content, particularly chlorophyll b, alongside an increase in the flavonoid level in YL relative to WT. Cytological examinations indicated the presence of defective chloroplasts within the mesophyll cells of the mutants. Transcriptomic analysis identified 8205 differentially expressed genes, with 4159 upregulated and 4046 downregulated. Genes associated with chlorophyll metabolism, flavonoid metabolism, photosynthesis, and signaling pathways were found to play crucial roles in leaf yellowing. In conclusion, this study delineated the phenotypic, physiological, cytological, and transcriptomic differences between YL and WT leaves, offering novel insights into the mechanisms driving leaf yellowing in Magnolia sinostellata.

Liquidambar formosana Hance is renowned for its rich leaf color and possesses notable advantages, such as robust adaptability, strong resistance to diseases and pests, and rapid growth, making it a preferred choice for urban greening and carbon sequestration forest initiatives. The completion of whole-genome sequencing of L. formosana has spurred an increased interest in exploring the molecular mechanisms underlying seasonal changes in leaf color, marking a significant focus in L. formosana breeding research. However, there is currently a lack of stable reference genes suitable for analyzing the expression patterns of functional genes in L. formosana exhibiting varying leaf colors. This study selected five L. formosana varieties with significant differences in leaf colors. Through the RT-qPCR analysis, and evaluation using BestKeeper, geNorm, NormFinder, Delta Ct, and RefFinder, the expression stability of 14 candidate reference genes was examined. Consequently, two reference genes (LifEF1-α and LifACT) with stable expression, suitable for RT-qPCR of L. formosana with diverse leaf colors, were identified. The stability of these selected reference genes was further validated by examining the LifbHLH137 gene, which promoted the biosynthesis of anthocyanins. This advancement facilitated molecular biology and genetic breeding investigations of L. formosana, providing essential data for the precise quantification of functional genes associated with leaf color variation.