Physiological Characteristics and Proteome of Dalbergia odorifera in Loam and Gravel Substrates

Dalbergia odorifera, a crucial medicinal and commercial plant, shows great potential for ecological restoration in karst rocky desertification (KRD) areas. However, no studies have examined its adaptation mechanism to barren KRD environments. We focused on the physiological and protein variations of D. odorifera grown under loam substrate (LS), composite substrate (CS, 50% gravel), and gravel substrate (GS, 100% gravel). Results showed that volume, surface area, and dry weight of root in CS were the highest. Proteomic analysis revealed 516 and 443 differentially accumulated proteins (DAPs) in CS compared with LS and GS, respectively. Functional analysis showed that epidermal morphogenesis, organic substrate transport, lipid transport, and detection of abiotic stimulus were enriched in the overlapped DAPs. In addition, compared to LS, specific DAPs in CS were enriched to Gene Ontology (GO) terms such as root hair cell differentiation, ATP, carbohydrate metabolism, and also to pathways including carbohydrate digestion and absorption, starch and sucrose metabolism, HIF-1 signaling, mineral absorption, and lysosome. However, specific DAPs in CS relative to GS were clustered to hydrogen peroxide, fatty acid biosynthesis, and lipid metabolism. Furthermore, a series of transcripts encoding crucial DAPs were confirmed by RT-qPCR. In conclusion, the physiological characteristics and proteomic landscape showed that CS substrate was more favorable to the adaptation of D. odorifera to KRD than LS and GS substrates. The protein evaluation related to substrates in this study provides further evidence for ecological management of D. odorifera in KRD areas.