Pollen is the male gametophyte of higher plants. Its major function is to deliver sperm cells to the ovule to ensure successful fertilization. During this process, many interactions occur among pollen tubes and pistil cells and tissues, and calcium ion (Ca²⁺) dynamics mediate these interactions among cells to ensure that pollen reaches the embryo sac. Although the precise functions of Ca²⁺ dynamics in the cells are unknown, we can speculate about its roles on the basis of its spatial and temporal characteristics during these interactions. The results of many studies indicate that calcium is a critical element that is strongly related to pollen germination and pollen tube growth.

Sapium discolor is a valuable native species in southern China, valued for its rapid growth and vibrant foliage, and widely used in ecological restoration and landscaping. To identify superior propagation materials with fast growth and red leaves, regional open-pollinated progeny trials of 10 elite trees were established in Nanping, Sanming, and Zhangzhou (Fujian Province) in 2015. Growth (tree height and diameter) was monitored from 2015 to 2023, and leaf color (the proportion of red in leaf color) was assessed in 2024. The species showed early fast growth, with mean tree height and diameter at breast height (DBH) reaching 7.98 m and 9.99 cm at six years, then slowing. Family-level phenotypic variation was limited. ANOVA revealed highly significant differences among families for growth traits from 2016 onward and for leaf color in 2024. Broad-sense heritability was moderate for 2023 tree height (0.3839), DBH (0.1879), and 2024 leaf color (0.2102), with low narrow-sense heritability, indicating non-additive genetic effects. Clonal selection based on genotypic values achieved notable genetic gains, especially for growth. One superior clone combined improvements in height (13.1%), diameter (10.1%), and red coloration (8.3%). These results highlight the value of clonal selection and the need to consider genotype × environment interactions in breeding programs.

Pine wilt disease (PWD), caused by the pine wood nematode (PWN) Bursaphelenchus xylophilus , results in significant economic and ecological damage to Pinus forests and plantations worldwide. Pinus massoniana is the primary host of PWD in southern China, but its response to the PWN remains largely unstudied. Previously, we observed PWD in a P. massoniana nursery that contained over 71 commonly used cultivars. Through field phenotyping, we identified two groups of PWN resistant cultivars. Resistant cultivars (RC) exhibited very low PWN carrying amounts (PCA) and had relatively low mortality, and tolerant cultivars (TC) had high PCA but low mortality. In this study, we confirmed via PWN inoculation assays that the resistant and tolerant cultivars had lower mortality rates, 10% and 11%, respectively, than other cultivars (which had a mortality rate of 83.3%). The RC had a PCA that was significantly lower than that of other cultivars, while the TC exhibited a higher PCA. To explore the molecular mechanisms underlying the response of P. massoniana to PWN, the transcriptome and metabolome of the above cultivars were profiled by high throughput sequencing. As no reference genome is available for P. massoniana , we generated a new full-length transcriptome library with iso-seq. Using the transcriptome and metabolome from different P. massoniana cultivars inoculated with PWN, we found three major PWD resistance strategies. 1) The common response strategy involved three important molecular pathways. First, synthesis of indole-3-acetic acid (IAA) and abcisic acid (ABA) were suppressed during PWN invasion, thus suppressing the synthesis of polysaccharides (especially myo-inositol and trehalose) and (-)-riboflavin through ABC transporters. Second, by inhibiting aspartic acid, the synthesis of arginine and proline through APS5 (aspartate aminotransferase 5) were suppressed. Third, by reducing cysteine, GERD (germacrene D synthase) was up-regulated, and sesquiterpenoid and triterpenoid metabolites were accumulated to resist PWN invasion. 2) The most effective resistance strategy involved the accumulation of reactive oxygen species (ROS), which enhanced jasmonic acid (JA) accumulation and highly induced the expression of chitinase, thus improving resistance to PWN. 3) The tolerance strategy involved the induction of phosphatidylcholine, which promoted flavonoid and anthocyanin synthesis via LPIN (phosphatidate phosphatase), LOX2S (lipoxygenase), and LOX1_5 (linoleate 9S-lipoxygenase), thus significantly inhibiting the pathogenicity of the PWN but not the PCA. These results illustrate the molecular mechanisms by which P. massoniana cultivars resist or tolerate PWN and are of great significance in the prevention and control of PWD.

The conservation and genetic improvement of rare and endangered tree species are crucial for sustainable forest management. Liriodendron chinense, a relict species with limited distribution in China, exhibits high cross-compatibility with Liriodendron tulipifera, providing opportunities for interspecific hybrid breeding. In this study, 29 Liriodendron hybrids were established in a progeny trial plantation in Fujian Province, China, and subjected to multi-year evaluation of tree height, diameter at breast height (DBH), and individual stem volume. Significant differences (p < 0.01) among hybrids and hybrid × replicate interactions were detected for all traits across all assessment years, with individual stem volume showing the highest phenotypic coefficient of variation (35.30–40.56%). The mean annual increment in tree height increased during the early years, peaking at 1.50 m in the fourth year. Broad-sense and narrow-sense heritabilities for growth traits were consistently high (0.4073–0.7253 and 0.3410–0.6501, respectively), and the ratio of narrow-sense to broad-sense heritability ranged from 0.64 to 0.99, supporting the feasibility of early hybrid and individual selection. At a 10% selection intensity, hybrids No. 39, No. 59, and No. 74 were identified as elite, with selection based on individual stem volume providing the highest predictive accuracy and genetic gain (26.54–34.69%). Individual selection at a 1% intensity yielded genetic gains of 95.55–107.12% for stem volume. These results demonstrate substantial potential for early and efficient genetic improvement in Liriodendron hybrids, providing a theoretical foundation for the selection and deployment of elite hybrids and individuals in subtropical forest plantations.