Pinus massoniana is an important timber tree species in southern China, and acid aluminum stress seriously endangers its growth. This study focuses on physiology, gene regulation and root exudates. Aluminum stress increased the activity of malondialdehyde (MDA), proline (PRO), peroxidase (POD), soluble proteins (SP), soluble sugars (SS) and superoxide dismutase (SOD) in P. massoniana seedlings, and led to changes in growth. We identified hub genes (UCHL3, TCP1, SEC27, GluRS and ACTF) responding to aluminum stress of low concentration and hub genes (RGP, MPT, RPL24, RPL7A and EC3.2.1.58) responding to aluminum stress of high concentration. Aluminum stress mainly affected phenylpropanoid biosynthesis and flavonoid biosynthesis, and it may alleviate aluminum toxicity by inducing the upregulation of genes such as CHS, COMT, DFR and LAR to enhance root exudation of catechin. These results lay the foundation for in-depth studying the molecular mechanism of P. massoniana aluminum stress.

Pinus massoniana, a conifer of significant economic and ecological value in China, is renowned for its wide adaptability and oleoresin production. We sequenced and assembled the chromosomal-level P. massoniana genome, revealing 80,366 protein-coding genes and significant gene family expansions associated with stress response and plant–pathogen interactions. Long-intron genes, which are predominantly presented in low-copy gene families, are strongly linked to the recent long terminal repeat burst in the Pinus genome. By reanalyzing population transcriptomic data, we identified genetic markers linked to oleoresin synthesis, including those within the CYP450 and TPS gene families. The results suggest that the genes of the resin terpene biosynthesis pathway can be activated in several cell types, and the oleoresin yield may depend on the rate-limiting enzymes. Using a multiomics algorithm, we identified several regulatory factors, including PmMYB4 and PmbZIP2, that interact with TPS and CYP450 genes, potentially playing a role in oleoresin production. This was further validated through molecular genetics analyses. We observed signatures of adaptive evolution in dispersed duplicates and horizontal gene transfer events that have contributed to the species adaptation. This study provides insights for further research into the evolutionary biology of conifers and lays the groundwork for genomic-assisted breeding and sustainable management of Masson pine.

Pinus massoniana Lamb. is found in 17 Chinese provinces and is an important timber tree species in southern China. The current seasonal drought climate is becoming increasingly severe, threatening P. massoniana growth and limiting the development of the P. massoniana industry. Plant growth, development, and stress were all regulated by AP2/ERF. We identified 124 AP2/ERF transcription factor family members in this study and discovered that all the genes had their own conserved structural domains and that PmAP2/ERFs were divided into 12 subfamilies with high conservation and similarity in gene structure and evolutionary level. Nine PmAP2/ERF genes were constitutively expressed under drought treatment, and it was hypothesized that the PmAP2/ERF96 gene negatively regulated drought stress, PmAP2/ERF46 and PmAP2/ERF49 genes showed a positive or negative response to drought in different tissues, while the remaining six genes were positively regulated. The PmAP2/ERF genes responded to drought stress following treatment with the exogenous hormones SA, ABA, and MeJA, but the expression patterns differed, with each gene responding to at least one exogenous hormone to induce up-regulation of expression under drought stress, with PmAP2/ERF11, PmAP2/ERF44, PmAP2/ERF77, and PmAP2/ERF80 genes significantly induced by three hormones. The genes mentioned above may be involved in hormone signaling pathways in response to drought stress. The results indicate that the PmAP2/ERF genes may positively or negatively regulate the corresponding signaling pathways in P. massoniana to improve drought resistance.

Pinus massoniana is a vital kind of coniferous species rich in rosin. Aluminum stress is a severe problem for P. massoniana growth in acidic soil causing root poisoning. However, the molecular mechanisms of aluminum-responsive are still unclear. We performed a transcriptome analysis of the P. massoniana root in response to aluminum stress. Through WGCNA analysis, we identified 338 early and 743 late response genes to aluminum stress. Gene Ontology analysis found many critical functional pathways, such as carbohydrate binding, cellulase activity, and phenylalanine ammonia-lyase activity. In addition, KEGG analysis revealed a significant enrichment of phenylpropanoid biosynthesis pathways. Further analysis showed that the expression of lignin synthesis genes 4CL, CAD, and COMT were up-regulated, indicating that they may play a crucial role in the process of aluminum tolerance in P. massoniana roots. These results provide method support for studying the regulation mechanism of P. massoniana aluminum stress.

Pinus massoniana L. is one of the most important conifer species in southern China and is the mainstay of the forest ecosystem and timber production, yet low temperatures limit its growth and geographical distribution. This study used 30-day-old seedlings from families of varying cold-tolerance to examine the morphological traits of needles and stems, chlorophyll fluorescence characteristics, protective enzymes, and changes in starch and lignin under different low-temperature stresses in an artificial climate chamber. The results showed that the seedlings of Pinus massoniana exhibited changes in phenotypic morphology and tissue structure under low-temperature stress. Physiological and biochemical indexes such as protective enzymes, osmoregulatory substances, starch, and lignin responded to low-temperature stress. The cold-tolerant family increased soluble sugars, starch grain, and lignin content as well as peroxidase activity, and decreased malondialdehyde content by increasing the levels of actual photochemical efficiency (ΦPSII), electron transport rate (ETR), and photochemical quenching (qP) to improve the cold tolerance ability. This study provides a reference for the selection and breeding of cold-tolerant genetic resources of Pinus massoniana and the mechanism of cold-tolerance, as well as the analysis of the mechanism of adaptation of Pinus massoniana in different climatic regions of China.