Plants have evolved a lignin-based Casparian strip (CS) in roots that restricts passive diffusion of mineral elements from the soil to the stele. However, the molecular mechanisms underlying CS formation in rice (Oryza sativa), which contains a CS at both the exodermis and endodermis, are poorly understood. Here, we demonstrate that CS formation at the rice endodermis is redundantly regulated by three MYELOBLASTOSIS (MYB) transcription factors, OsMYB36a, OsMYB36b, and OsMYB36c, that are highly expressed in root tips. Knockout of all three genes resulted in a complete absence of CS at the endodermis and retarded plant growth in hydroponic conditions and in soil. Compared with the wild-type, the triple mutants showed higher calcium (Ca) levels and lower Mn, Fe, Zn, Cu, and Cd levels in shoots. High Ca supply further inhibited mutant growth and increased Ca levels in shoots. Transcriptome analysis identified 1,093 downstream genes regulated by OsMYB36a/b/c, including the key CS formation gene OsCASP1 and other genes that function in CS formation at the endodermis. Three OsMYB36s regulate OsCASP1 and OsESB1 expression by directly binding to MYB-binding motifs in their promoters. Our findings thus provide important insights into the mechanism of CS formation at the endodermis and the selective uptake of mineral elements in roots.

Cultural diversity holds an irreplaceable ecological value in biodiversity conservation. Jingxi is a county-level city in Baise City, Guangxi Zhuang Autonomous Region. In Jingxi, where the Zhuang ethnic group accounts for 99.4% of the population, a symbiotic relationship has developed between its unique ethnic culture and ecological environment. According to the 2017 census of old trees (OTs) in Jingxi, a total of 1361 OTs were recorded, of which 63.3% (865 trees) were concentrated in human settlements, including village entrances or exits, and cultivated lands, demonstrating significant spatial differentiation. This distinctive distribution pattern raises two core research questions: (1) What are the spatial distribution patterns of OTs within human settlements? (2) Do cultural factors play a significant role in OTs conservation? Therefore, an ethnobotanical study of OTs in Jingxi is necessary. The objectives of this study are to: (1) conduct a comprehensive ethnobotanical investigation of the OTs among the Zhuang people in the region; (2) summarize the environmental spaces of OTs based on their geographical locations; (3) analyze the symbolic cultural meaning associated with OTs across different environmental spaces. This study also aims to reveal conservation strategies for OTs from a cultural perspective and to integrate cultural values into biodiversity conservation, thereby providing significant insights into the mechanisms underlying cultural–ecological synergy.