Research Institute of Subtropical Foresty

Calcium-dependent protein kinases (CDPKs/CPKs) represent a specialized class of Ca²⁺ sensor proteins that decode intracellular calcium fluctuations and translate these signals into phosphorylation cascades, ultimately modulating downstream gene expression. Despite their established roles in model plant species, the functional characterization of CDPKs in moso bamboo ( Phyllostachys edulis ) - particularly their involvement in the lignification process of this economically important non-timber forest species - remains largely unexplored. In this study, we identified 50 PeCDPK genes through genome-wide analysis and conducted comprehensive characterization of their phylogenetic relationships, conserved domain architectures, gene structure organization, syntenic conservation patterns, and cis -regulatory element composition. Expression profiling demonstrated both tissue-specific patterns and a striking correlation between PeCDPK32 expression and lignification progression in developing bamboo shoots, as confirmed by integrated transcriptomic and qRT-PCR analyses. Through yeast two-hybrid screening, 50 proteins interacting with PeCDPK32 were identified, including the calmodulin-binding protein PeCML4 and the lignin-biosynthetic peroxidase PePRX2. Subcellular localization analysis demonstrated that both PeCDPK32 and PePRX2 localized to the endoplasmic reticulum (ER). Transient overexpression of PeCDPK32 in Nicotiana benthamiana significantly enhanced PePRX2 enzymatic activity, while stable transformation in P. edulis calli promoted lignin biosynthesis. Two autophosphorylation sites on PeCDPK32 were identified by IP-MS analysis. This study presents a systematic genomic and functional characterization of the CDPK gene family in P. edulis , identifying PeCDPK32 as a central regulator of lignin biosynthesis that modulates the lignification pathway through its interaction with key enzymes in the lignification pathway. • Identification of 50 PeCDPK genes in moso bamboo resolves their evolution, structure and syntenic conservation. • Functional validation of PeCDPK32 demonstrates its positive correlation with lignin deposition in bamboo shoots. • PeCDPK32 interacts with PeCML4 and PePRX2 to sense calcium signals and enhance lignin biosynthesis. • Discovery of autophosphorylation sites (Ser-85/Ser-104) on PeCDPK32 provides insights into kinase activation.

Abstract Density dependence, both conspecific and heterospecific, is widely recognized as a crucial driver of plant species diversity. However, treating multiple heterospecific species as a homogeneous group obviously overlooks the variability in the impacts of different heterospecific neighbors on the survival or growth of focal species. In this study, we developed the Static-Dynamic Coupled Interspecific Association Classification Framework (SDIACF), which categorizes heterospecific neighbors based on their positive/negative interspecific associations and dynamic changes with focal species. We further used generalized linear mixed-effect models to analyze how conspecific and various heterospecific neighbors classified by the above framework influenced the survival and growth rates of the focal species. Our results revealed that heterospecific neighbors, deconstructed using SDIACF, exerted distinct effects on the focal species. Specifically, regardless of their initial interspecific association with the focal species, heterospecific neighbors with more negative associations showed a negative impact on the focal species, while those with more positive associations showed a positive effect. However, among heterospecific neighbors exhibiting identical dynamic interspecific associations, positively associated neighbors were slightly more conducive to the survival of the focal species than negatively associated ones, but slightly detrimental to its growth. In summary, our results demonstrate that heterospecific neighbors are not a homogeneous entity but play important and complex roles in species coexistence. The development of SDIACF not only constitutes a significant supplement to traditional density dependence research but also offers a novel perspective for further exploring species coexistence.

Abstract Background In angiosperm, Self-incompatibility (SI) is a common and widespread mechanism for plant preventing inbreeding risk and late-acting self-incompatibility (LSI) is even more ancestral conserved. In this work, we worked on Schima superba, one species in Theaceae, commercially important timer and fire-resistant tree species and revealed its LSI mechanism. Results The self-pollen tubes grew to the bottom of the stylus and enter ovary until 48h, but failed to penetrate the ovule. Meanwhile, the hormone and peroxidase levels were dramatically changed. Transcriptome and proteome analysis explored the molecular mechanisms of LSI and candidate genes related to LSI in S.superba. Overall 586.71 million reads were obtained and 79,642 (39.08%) unigenes were annotated. KEGG and GO showed that 4531 differentially expressed genes (DEGs) and 82 differentially expressed proteins (DEPs) were at 48h in self- (SP) vs outcross-pollination (OP). Among these, 160 DEGs and 33 DEPs involved in pollen-pistil interaction. The “pollen-pistil interaction”, “signal recognition” and “component of membrane” were downregulated in SP whereas the “cell wall and membrane biosynthetic process”, “oxidoreductase activity” were upregulated. The DEGs involved with S-RNases and SCF during SP suggested that the LSI was happened at 48h ovary, and the LSI in S.superba was under gametophyte control. The calcium ion increase-releasement and F-actin depolymerization initiated metacaspases-1 activity and lead to PCD progress. Also, mitochondrial function loss and ROS disruption further aggravated the PCD progress and cell death. Cell wall biosynthetic progress upregulated and cellulose synthase downregulated could lead to ovary xylification and withering. Conclusions The LSI of S.superba which happened at 48h after pollination was key time point. The incompatibility PT ceased growth in ovary because of the S-RNase recognition and PCD happened in this organ. This study highlight the LSI molecular mechanism in S.superba and also gave a reference to other species in Theaceae.

Abstract Flooding can adversely worsen the metal contaminated soil and plant growth thus, it is crucial to explore the ecophysiological responses of plants upon co-exposure to heavy metals and flooding. Here, the plant growth, photosynthesis, and nutrient elements composition in arbor willow (Salix jiangsuensis ‘J172’) and shrub willow (Salix integra ‘Yizhibi’) were studied using a pot experiment with Cu contaminated soil (239.51 mg∙kg-1) under flooded versus non flooded condition. Salix integra showed larger BCFs than Salix jiangsuensis in both treatments, soil flooding significantly decreased the Cu contents and BCF while obviously increased TF values in both willow species (p < 0.05). Soil flooding markedly enhanced the leaf C:P and N:P ratios, while significantly decreased root C:P and N:P ratios, as compared to non flooded condition. The shrub willow exhibited better tolerance to soil flooding with little alteration in biomass and photosynthetic rate, and showed greater potential of Cu accumulation capacity, even though its total biomass was significantly lower than arbor willow. Our study also helps further understanding the nutrient balance and stoichiometry of willows in Cu contaminated soil and their response to soil flooding, helping the management of Cu-contaminated flooded soils.

The selection of superior lines is extremely important to improve the utilization rate and economic value of bamboo. In this research, 120 anther-regenerated bamboo lines were planted in the field, and the survival rate reached 84.2% one year after planting. During five years of observations, we continuously measured and recorded the number of shoots and the size of the new bamboo of these regenerated lines. The results showed that there were considerable differences in culm size and growth rate among the different lines. After comprehensive evaluation, we found that one of the lines (P82) had obvious advantages in culm size and growth rate compared with the others. The chromosome ploidy of line P82 and the other three lines (P38, P84, and P34) was detected. It was found that P82 was hexaploid, while the other three lines were dodecaploid. Nutritional components of the P82 shoots were further detected. The results showed that the content of soluble sugar was 1.4%, the content of free amino acid was 3.5 g·kg−1 (FW, fresh weight), and the content of protein was 14.8 g·kg−1 (FW), and there were no significant differences compared with the local wild mature bamboo. Anatomical analysis showed that the vascular bundle size of the line P82 (hexaploid) was significantly larger than that of line P38 (dodecaploid), and the length of parenchyma cells in the culm wall of line P82 was similar to that of line P38, however, the cell width of line P82 was significantly wider than that of line P38. In this study, the breeding of superior lines of regenerated bamboo plants from an anther culture was realized, which provided an example for a new method for selecting superior lines from an anther culture, and also enriched the resources of superior lines of D. latiflorus.

BackgroundSpartina alterniflora is an invasive plant on the coast of China that replaces native vegetation and has a serious negative impact on local ecosystems. Monitoring the spatial distribution of S. alterniflora and its changes over time can reveal its expansion mechanism, which is crucial for the management of coastal ecosystems. The purpose of this study was to map the distribution of S. alterniflora in Zhejiang Province from 1985 to 2015 using a time series of Landsat TM/OLI images and analyze the temporal and spatial patterns of expansion of this species.ResultsAfter analyzing the distribution of coastal vegetation, the vegetation index was calculated based on Landsat images for 4 years (1985, 1995, 2005 and 2015). According to a threshold determined based on expert knowledge, the distribution of S. alterniflora in Zhejiang Province was extracted, and the temporal and spatial changes in the distribution of S. alterniflora were analyzed. The classification accuracy was 90.3%. S. alterniflora has expanded rapidly in recent decades after being introduced into southern Zhejiang. Between 1985 and 2015, S. alterniflora increased its area of distribution by 10,000 hm2, and it replaced native vegetation to become the most abundant halophyte in tidal flats. Overall, S. alterniflora expanded from south to north over the decades of the study, and the fastest expansion rate was 463.64 hm2/year, which occurred between 1995 and 2005. S. alterniflora was widely distributed in the tidal flats of bays and estuaries and expanded outward as sediment accumulated.ConclusionsThis study reveals the changes over time in S. alterniflora cover in Zhejiang and can contribute to the control and management of this invasive plant.

Abstract The patterns, components, and controls of soil respiration in an old‐growth subtropical forest were investigated using an automatic chamber system. We measured soil respiration in three treatments (control, trenching, litter removal) over 15 months. The annual total soil respiration (1248 gC m–2 yr–1) showed considerable spatial variation (coefficient of variation = 27.8%) within the forest. Thirty samples were required to obtain results within 10% of the mean value at a 95% confidential level. A distinctive cosine‐like diel pattern of soil respiration was observed; the time lag between gross primary production and soil respiration at this scale was calculated to be 4–5 h. Seasonality of soil respiration was strong (~1 µmol m–2 s–1 near the end of winter; ~6 µmol m–2 s–1 in midsummer). No time lag was discerned between gross primary production and soil respiration at the seasonal scale. Soil temperature at 5 cm below surface can explain most (>91%) of the observed annual variation in soil respiration. The apparent respiration temperature sensitivity index (Q10) was 3.05. The lowest Q10 value was observed in winter, when soil moisture was low. Soil respiration was overestimated by a Q10 function during both dry and wet periods. The relative contributions of soil organic matter (RSOM), litterfall decomposition (RL), and root respiration (RR) to total soil respiration are 65.25%, 18.73%, and 16.01%, respectively; the temperature sensitivity of these components differ: RL (Q10 = 7.22) > RSOM (2.73) > RR (1.65). This relationship between Q10 values for litter respiration, soil organic matter decomposition, and root respiration still holds after minimizing the confounding effect of moisture. A relatively constant substrate supply and/or thermal acclimation could account for the observed low‐temperature sensitivity in root respiration. Given the high carbon stocks and fluxes, the old‐growth subtropical forests of China seem important in the global carbon budget and climate change.