To better understand the genetic control of resin yield, growth traits and morphologic traits for Pinus elliottii families, genetic relationships among these traits were examined in three 27-year-old progeny trials located in Jingdezhen, Jian and Ganzhou, Jiangxi Province, China. In total, 3695 trees from 112 families were assessed at the three sites. Significant site, family and family × site effects were found for resin yield, growth traits and morphologic traits. Resin yield and growth traits were found to be under moderate genetic control for the three sites combined, with family heritability and individual narrow-sense heritability ranging from 0.41 to 0.55 and 0.11 to 0.27, respectively. The coefficient of genotypic variation (CV_G) of stem volume (SV) and crown surface area (CSA) were higher than those of other traits at each site. Genetic correlation estimates indicated that selection for growth traits might lead to a large increment in resin yield (RY), and most morphologic traits had moderate to strong correlations with growth traits at each individual site. One possible strategy in tree breeding would be to maximize resin production through selection for growth traits.

Moso bamboo expansion is common across the world. The expansion of moso bamboo into adjacent forests altered plant and soil characteristics. While the community structure of soil fungi and bacteria plays an important role in maintaining the function of forest ecosystems, changes in microbial community compositions remain unclear, limiting our understanding of ecological process changes following moso bamboo expansion. To explore changes in the community structure of soil fungi and bacteria in Japanese cedar plantations experiencing expansion of moso bamboo, Illumina NovaSeq high-throughput sequencing technology was used to elucidate changes in soil microbial communities as well as alteration in litter and soil chemical characteristics. The results showed that moso bamboo expansion decreased content of soil organic carbon, total nitrogen, litter carbon, and the carbon to nitrogen ratio as well as the number of bacterial operational taxonomic units (OTUs) at the genus level, the α-diversity Simple index, and the abundance of Acidobacteria, Chloroflexi, and Gemmatimonadetes. Moso bamboo expansion also increased soil NH₄⁺-N, pH, while it decreased fungi OTUs at the phyla, class, order, family, and genus level. The expansion of moso bamboo into Japanese cedar substantially altered soil fungal and bacterial community structure, which might have implications for changes in the ecosystem element-cycling process. In the forest ecosystem and expansion management of moso bamboo, the types and different expansion stages of moso bamboo should be paid attention to, in the assessment of ecological effects and soil microbial structure.

For capital breeding Lepidoptera, larval food quality is a key determinant of their fitness. A series of studies have suggested that the larval host species or varieties dramatically impact their development and reproductive output. However, few studies have reported the role of foliar age and adult mating success has often been ignored in these studies. In this paper, the influence of host species and needle age on larval performances, adult mating behavior and fitness consequences has been studied using a capital breeding caterpillar, Dendrolimus punctatus Walker (Lepidoptera:Lasiocampidae). In larval performance trial, a strong effect of larval host species and needle age was found on survivorship, developmental duration, body weight, percentage of adult emergence, and growth index, but not on percentage of female progeny. In adult mating trial, larval host species and needle age also significantly affected mating latency and mating duration, but not mating success. In adult fitness trial, female fecundity, longevity and fitness index, but not oviposition duration and fertility, influenced by larval host species and needle age. These results reveal the importance of larval host species and needle age on larval performance and adult reproductive fitness in this capital breeding insect and provide strong evidence that old needles of masson pine P. massoniana is the best host for D. punctatus.

Slash pine (Pinus elliottii Engelmann) is a pine species widely cultivated for its high oleoresin production capacity. However, little is known about the underlying molecular mechanism of oleoresin biosynthesis between high and low oleoresin-yielding slash pines. In this study, the terpenoid compositions of oleoresin harvested from high- and low-yielding slash pines were identified using gas chromatography/mass spectrometry (GC-MS) analysis. The monoterpenes and diterpenes are the major constituents, of which the α- and β-pinenes are the overwhelming majority of turpentines, and abietic acid, levopimaric acid, and neoabietic acid are the most abundant in rosin. The transcriptomic analysis was also performed with secondary xylem tissues of high- and low-yielding slash pines. After functional annotation, the DEGs of RNA-seq data between high- and low-yielding pines in April, July, and October were screened, and many key enzyme genes were found to be implicated in terpenoid backbone biosynthesis. Moreover, weighted gene correlation network analysis (WGCNA) was carried out to uncover the gene modules highly related to α- and β-pinene biosynthesis in slash pine. Twenty-three modules were attained in this study. Focusing on the total oleoresin yield, the MEblue module exhibited the highest positive correlation, while the MEgreen module exhibited the highest negative correlation. A total of 20 TFs were identified in gene modules. Among these genes, the c215396.graph_c0 encoding an MYB TF is the key differentially expressed gene (DEG) between high- and low-yielding pines. The subsequent one-hybrid yeast assay verified that c215396.graph_c0 can activate the transcription of Apetala 2 (AP2) and 1-deoxy-d-xylulose 5-phosphate synthase (dxs), which are also two DEGs between high- and low-yielding pines. Thus, our study identified a set of key enzymes and TFs that are involved in regulating oleoresin and composition between high- and low-yielding slash pines and provided us a deep insight into oleoresin biosynthesis.

A firm understanding of the genetic relationships among wood properties is a prerequisite for breeding for higher wood quality in Pinus elliottii families. To examine and deal with such relationships, increment cores were sampled at breast height from 1260 trees in 42 open-pollinated families in three 27-year-old Slash pine progeny trials in southern China, and genetic variation, genotype-by-environment (G × E) interaction, genetic correlation and correlated response were investigated. The basic density (BD), dynamic modulus of elasticity (MOE_D) and tracheid traits were found to be under moderate to strong genetic control for the three locations combined, with individual narrow-sense and family mean heritability ranging from 0.28 to 0.44 and 0.52 to 0.69, respectively. Type B genetic correlation estimates indicated that the G × E interaction had a small-level influence on wood properties. Strong genetic correlations (r_g) were found between BD and MOE_D at the three sites (r_g = 0.46–0.85), and BD or MOE_D showed moderate to strong correlations with most tracheid traits at specific localities. In tree breeding programs, one possible strategy would be to improve pulpwood quality and the strength of structural wood through selection for different wood quality traits.