The physiological mechanisms of drought-stress response in Quercus acutissima were explored with the aim to develop potentially valuable drought-resistant species that are adapted to arid regions and barren mountains. Potting experiments of Q. acutissima that simulated drought-stress conditions, and morphological, physiological, photosynthetic, and ultrastructural changes were investigated at different stages of drought stress, including after rehydration and recovery. During drought stress and rewatering, the leaves exhibited yellowing and abscission, followed by the sprouting of new leaf buds. The relative water content (RWC) changed under the drought-rewatering treatment, with a decreasing and then increasing trend, while the relative electrical conductivity (REC) had a more gradual increasing and then decreasing trend. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and the proline (Pro) and soluble sugar (SS) contents increased and then decreased. The change in soluble protein (SP) content showed an N-shaped trend of increasing, decreasing, and then increasing again. The malondialdehyde (MDA) content decreased and then slowly increased. From the drought to recovery phase of the experiment, the net photosynthesis (Pn), stomatal conductance (Gs), and transpiration rate (Tr) decreased gradually at first, and then the Pn increased significantly, while the Gs and Tr increased slowly. During this period, the internal CO₂ concentration (Ci) did not decrease significantly until the last stage of the drought treatment, and then it increased slowly thereafter. The open stomata count in the Q. acutissima leaves was reduced significantly as drought stress increased, but after rewatering, the stomata recovered rapidly, with their opening size increasing. The number of leaf epidermal trichomes gradually declined to a low count in response to drought stress, but it rapidly recovered and increased within a short period of time after rehydration. Q. acutissima was found to have a strong drought tolerance and recovery ability after exposure to drought stress, and it may be an effective pioneer species for reforestation in barren lands.

The calmodulin-binding transcription activator (CAMTA) family plays crucial roles in calcium-mediated abiotic stress responses in plants. This study isolated and functionally characterized FvCAMTA1 , a CAMTA gene from the salt-tolerant woody species Fraxinus velutina . Promoter analysis identified salt-responsive cis-elements, with a 157-bp core region sufficient for basal promoter activity and upstream sequences enhancing transcriptional activation under salt stress. FvCAMTA1 was predominantly expressed in leaves and rapidly induced by NaCl treatment. The heterologous overexpression of FvCAMTA1 in Arabidopsis significantly enhanced salt tolerance, resulting in higher germination rates, improved root elongation, and increased fresh weight, whereas the camta5 mutant exhibited heightened sensitivity. Yeast two-hybrid screening identified 46 proteins interacting with FvCAMTA1 , including FvWRKY7 and FvPP2C60 , interactions subsequently confirmed by bimolecular fluorescence complementation and luciferase complementation assays. Our findings demonstrate that FvCAMTA1 acts as a positive regulator in the salt stress adaptation of woody plants through calcium signaling and transcriptional networks, providing a valuable candidate gene for molecular breeding of stress-resistant trees.

The CCCH zinc finger proteins play critical roles in a wide variety of growth, development, and stress responses. Currently, limited reports are available about the roles of animal CCCH proteins in plants. In this study, we report the identification of human TTP (hTTP) with functional similarity to PdC3H17 in a hybrid poplar. hTTP and PdC3H17 shared highly similar tandem CCCH zinc-finger RNA-binding domains. The fragments excluding the CCCH domain of both hTTP and PdC3H17 possessed transcriptional activation activities in yeast cells. Compared to the controls, ectopic expression of hTTP in poplar caused dwarfism, and resulted in significant increases in stem xylem vessel number and photosynthetic and ROS-scavenging abilities, thereby enhancing plant tolerance to drought stress. Our results suggest that hTTP may perform a function in poplar through the PdC3H17-mediated system, and provide an example for the application of animal genes in plants.

Fraxinus spp. is one of the most important salt-alkali resistant tree species in the Yellow River region of China. However, the limited number of superior families and individuals, as well as the lack of a well-established parent selection system for hybrid breeding, have seriously constrained the improvement of seed orchards and the construction of advanced breeding populations. To address these issues, this study investigated 22 full-sib families of Fraxinus spp., using SSR molecular markers to calculate the genetic distance (GD) between parents. Combined with combining ability analysis, the study aimed to predict heterosis in offspring growth traits and select superior families and individuals through multi-trait comprehensive evaluation. The results showed the following: (1) Tree height (TH), diameter at breast height (DBH), and volume index (VI) exhibited extremely significant differences among families, indicating rich variation and strong selection potential. (2) The phenotypic and genotypic coefficients of variation for TH, DBH, and VI ranged from 4.34% to 16.04% and 5.10% to 17.73%, respectively. Family heritability was relatively high, ranging from 0.724 to 0.818, suggesting that growth is under strong genetic control. (3) The observed and expected heterozygosity of 15 parents were 0.557 and 0.410, respectively, indicating a moderate level of heterozygosity. Nei’s genetic diversity index and Shannon’s information index were 0.488 and 0.670, respectively, indicating relatively high genetic diversity. GD between parents ranged from 0.155 to 0.723. (4) Correlation analysis revealed significant or highly significant positive correlations between family heterosis and growth traits, combining ability, and GD, with specific combining ability (SCA) showing the strongest predictive power. Regression analysis further demonstrated significant linear correlations between GD and heterosis of TH and VI, and between SCA and heterosis of TH, DBH, and VI, establishing a GD threshold (≤0.723) and SCA-based co-selection strategy. In addition, four superior Fraxinus families and 11 elite individuals were selected. Their genetic gains for TH, DBH, and VI reached 2.28%, 3.30%, and 9.96% (family selection), and 1.98%, 2.11%, and 4.00% (individual selection), respectively. By integrating genetic distance (GD) and quantitative genetic combining ability (SCA), this study established a quantifiable prediction model and proposed the “GD–SCA dual-index parent selection method”, offering a new paradigm for genetic improvement in tree breeding.

In order to screen out the high-oil Acer truncatum germplasm resources so as to improve the yield and value of seed oil, this experiment was carried out by analyzing and evaluating a total of 70 samples from natural populations of A. truncatum in nine Central Plains of China, the results were subjected to nested ANOVA and correlation analyses, as well as a comprehensive evaluation of the various groups using principal component analysis and the affiliation function method. The findings demonstrated that the 70 samples ranged in seed kernel oil content from 14.43% to 50.11% (average 33.11%), and that the major fatty acid fractions had coefficients of variation that ranged from 24.13% to 33.40%, with differences between them being significant. According to correlation analysis, latitude, temperature, and precipitation had a greater impact on the seed kernel oil content than they did on the relative content of fatty acid fractions. Altitude, temperature, and precipitation were the primary causes of changes in the content of fatty acid fractions. The principal component analysis reduced the nine indexes to two principal components with a cumulative contribution rate of 84.29%, and ranked them according to the comprehensive evaluation value obtained from the principal component analysis and the transformation of the affiliation function. The analysis screened out the ten germplasm samples with the highest comprehensive quality and the three samples with the highest comprehensive evaluation value.