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As a magnoliid angiosperm, the Liriodendron chinense (Hamsl) Sarg in the Magnoliaceae family is susceptible to external environmental factors. The TEOSINTE BRANCHED 1/CYCLOIDEA/PROLIFERATING CELL FACTORS (TCP) proteins known for their growth and developmental biological roles have been identified in various plant species but not in the Liriodendron chinense. In this study, 15 TCP genes were identified in the L. chinense genome, and categorized into two classes, termed class I (PCF) and class II (CIN and CYC/TB1). A total of 14 TCP genes were located on the 10 chromosomes, and the remaining one, on a contig. Multispecies phylogenetic tree analysis supported the classification of identified LcTCP genes and exhibited that the expansion of the LcTCP gene family was before the angiosperm evolutionary divergence times. Additional gene duplication investigations revealed a purifying selection pressure during evolution history. Moreover, the LcTCP genes were also observed to have various cis-acting elements related to plant growth and development, phytohormone regulations, and abiotic stress responses. Gene expression pattern analysis also paraded that LcTCP genes play a crucial role in abiotic stress regulations. In particular, LcTCP1 in all stresses investigated. Overall, our findings suggest a pivotal role for the TCP gene family during external environmental stresses in L. chinense. This study will provide valuable information on the identification and function of the LcTCPs during abiotic stresses, paving the way for further research on the functional verification of L. chinense TCPs.

bHLH transcription factors play an animated role in the plant kingdom during growth and development, and responses to various abiotic stress. In this current study, we conducted, the genome-wide survey of bHLH transcription factors in Liriodendron chinense (Hemsl) Sarg., 91 LcbHLH family members were identified. Identified LcbHLH gene family members were grouped into 19 different subfamilies based on the conserved motifs and phylogenetic analysis. Our results showed that LcbHLH genes clustered in the same subfamily exhibited a similar conservative exon-intron pattern. Hydrophilicity value analysis showed that all LcbHLH proteins were hydrophilic. The Molecular weight (Mw) of LcbHLH proteins ranged from 10.19 kD (LcbHLH15) to 88.40 kD (LcbHLH50). A greater proportion, ~63%, of LcbHLH proteins had a theoretical isoelectric point (pI) less than seven. Additional analysis on the collinear relationships within species and among dissimilar species illustrated that tandem and fragment duplication are the foremost factors of amplification of this family in the evolution process, and they are all purified and selected. RNA-seq and real-time quantitative PCR analysis of LcbHLH members showed that the expression of LcbHLH35, 55, and 86 are up-regulated, and the expression of LcbHLH9, 20, 39, 54, 56, and 69 is down-regulated during cold stress treatments while the expression of LcbHLH24 was up-regulated in the short term and then later down-regulated. From our results, we concluded that LcbHLH genes might participate in cold-responsive processes of L. chinense. These findings provide the basic information of bHLH gene in L. chinense and their regulatory roles in plant development and cold stress response.

Background The sucrose non-fermenting 1 (SNF1)-related protein kinases (SnRKs) play a vivid role in regulating plant metabolism and stress response, providing a pathway for regulation between metabolism and stress signals. Conducting identification and stress response studies on SnRKs in plants contributes to the development of strategies for tree species that are more tolerant to stress conditions. Results In the present study, a total of 30 LcSnRKs were identified in Liriodendron chinense (L. chinense) genome, which was distributed across 15 chromosomes and 4 scaffolds. It could be divided into three subfamilies: SnRK1, SnRK2, and SnRK3 based on phylogenetic analysis and domain types. The LcSnRK of the three subfamilies shared the same Ser/Thr kinase structure in gene structure and motif composition, while the functional domains, except for the kinase domain, showed significant differences. A total of 13 collinear gene pairs were detected in L. chinense and Arabidopsis thaliana (A. thaliana), and 18 pairs were detected in L. chinense and rice, suggesting that the LcSnRK family genes may be evolutionarily more closely related to rice. Cis-regulation element analysis showed that LcSnRKs were LTR and TC-rich, which could respond to different environmental stresses. Furthermore, the expression patterns of LcSnRKs are different at different times under low-temperature stress. LcSnRK1s expression tended to be down-regulated under low-temperature stress. The expression of LcSnRK2s tended to be up-regulated under low-temperature stress. The expression trend of LcSnRK3s under low-temperature stress was mainly up-or down-regulated. Conclusion The results of this study will provide valuable information for the functional identification of the LcSnRK gene in the future.