Liquidambar formosana is important for its ornamental value in China; it is increasingly used for landscaping and gardening trees due to its diverse leaf colors and seasonal changes. Varieties including either a fixed leaf color, the purplish ‘Fuluzifeng’ (ZF), or seasonal changes in leaf color, the reddish ‘Nanlinhong’ (NLH) have been bred and registered as new plant varieties under the International Union for the Protection of New Plant Varieties (UPOV) system. To gain practical insights into the anthocyanin biosynthetic process, transcriptome sequencing (Illumina) was performed to clarify the metabolic pathways present in the three seasonal changes in leaf colors in NLH and in the springtime purple-red color of ZF. qRT-PCR was used to verify the speculation. Based on the differentially expressed genes and flavonoids analyses, the spring, summer, and autumn leaves of NLH were compared to study the seasonal differences. NLH and ZF were compared to study the formation mechanism of the two leaf colors in spring. Transcriptome sequencing produced a total of 121,216 unigenes from all samples, where 48 unigenes were differentially expressed and associated with the anthocyanidin pathway. The expression levels of LfDFR and LfANS genes corresponded to the accumulation of concentrations of cyanidins in spring (NLHC) and autumn leaves (NLHQ), respectively, with different shades of red. Moreover, the LfF3′5′H gene corresponded to the accumulation of flavonols and delphinidins in purple-red leaves (ZFC). Cyanidin and peonidin were the key pigments in red and dark-red leaves, and purple-red leaves were co-pigmented by cyanidins, pelargonidins, and delphinidins.

To understand the origin and evolutionary history, and the geographical and historical causes for the formation of the current distribution pattern of Lquidambar formosana Hance, we investigated the phylogeography by using chloroplasts DNA (cpDNA) non-coding sequences and species distribution models (SDM). Four cpDNA intergenic spacer regions were amplified and sequenced for 251 individuals from 25 populations covering most of its geographical range in China. A total of 20 haplotypes were recovered. The species had a high level of chloroplast genetic variation (Ht = 0.909 ± 0.0192) and a significant phylogeographical structure (genetic differentiation takes into account distances among haplotypes (Nst) = 0.730 > population differentiation that does not consider distances among haplotypes (Gst) = 0.645; p < 0.05), whereas the genetic variation within populations (Hs = 0.323 ± 0.0553) was low. The variation of haplotype mainly occurred among populations (genetic differentiation coefficient (Fst) = 0.73012). The low genetic diversity within populations may be attributed to the restricted gene flow (Nm = 0.18). The time of the most recent common ancestor for clade V mostly distributed in Southwestern China, Central China, Qinling and Dabieshan mountains was 10.30 Ma (95% Highest posterior density (HPD): 9.74–15.28) dating back to the middle Miocene, which revealed the genetic structure of L. formosana was of ancient origin. These results indicated that dramatic changes since the Miocene may have driven the ancestors of L. formosana to retreat from the high latitudes of the Northern Hemisphere to subtropical China in which the establishment and initial intensification of the Asian monsoon provided conditions for their ecological requirements. This scenario was confirmed by the fossil record. SDM results indicated there were no contraction–expansion dynamics, and there was a stable range since the last interglacial period (LIG, 130 kya). Compared with the population expansion detected by Fu’s Fs value and the mismatch distribution, we speculated the expansion time may happen before the interglacial period. Evidence supporting L. formosana was the ancient origin and table range since the last interglacial period.

Introduction: Dryland plants must balance atmospheric water demand with below-ground water and nutrient acquisition, yet it remains unclear whether increasing aridity drives coordinated whole-plant trait shifts or instead promotes modular adjustment of leaf and root functions. Here, we examined leaf–root functional coordination in herbaceous plant communities across a continuous aridity gradient in Xinjiang, northwestern China. Methods: We measured six leaf traits, four root traits and plotlevel environmental variables for 474 matched species-by-plot observations, and combined single-trait models, multivariate trait axes, leaf–root correlation networks, sliding-window coordination analyses and path modeling. Trait responses to aridity were selective rather than uniform. Drier conditions were associated with thicker leaves and higher specific root length, whereas wetter conditions supported greater lateral-root proliferation. By contrast, leaf dry matter content, leaf water content, root length and root diameter showed weak or no direct responses to the aridity gradient. Leaf–root coordination was also trait-specific: leaf size traits were positively linked to root length and root diameter, but negatively associated with specific root length, indicating a separation between below-ground structural support and absorptive efficiency. Environmental models further showed that variation in leaf and root trait axes was associated with aridity through direct and indirect statistical pathways involving soil water availability, microbial carbon processes, SOC–N nutrient status, elevation and life form. Results: Our results suggest that dryland herbaceous plants do not respond to aridity through a single synchronized whole-plant economic axis. Instead, they maintain function through coupled but modular adjustments involving leaf structural protection, absorptive root morphology and lateral-root proliferation. Discussion: This modular leaf–root coordination provides a trait-based framework for understanding how herbaceous plants persist along dryland moisture gradients and may improve predictions of plant functional responses to intensifying drought.