Acidic soils, which account for over 50% of the world's potential cultivable land and serve as the core substrate for agricultural production in southern China, release soluble aluminum ions (Al³⁺) that damage plant roots and constrain crop growth. Notably, Rhodomyrtus tomentosa (rose myrtle) not only tolerates high-aluminum environments but also uses low aluminum concentrations to enhance its growth—a "harm-to-benefit" trait whose molecular basis has long intrigued researchers.

Recently, a research team led by Prof. DENG Shulin from the South China Botanical Garden of the Chinese Academy of Sciences, has systematically deciphered the dual molecular mechanisms that enable R. tomentosa to adapt to aluminum stress and achieve aluminum-promoted growth. Their findings were published recently in Plant Physiology.

By focusing on the plant's aluminum-responsive pathways, the team identified significant functional divergence between two key genes—RtALMT11 and RtALMT18—from the aluminum-activated malate transporter (ALMT) family.

At the systems biology level, this divergence underpins the precise regulation of aluminum responses: RtALMT11 mediates a canonical passive defense mechanism by secreting malic acid to chelate rhizosphere Al³⁺ and mitigate toxicity; in contrast, RtALMT18 has evolved constitutive expression to regulate cell wall callose synthesis and growth signaling pathways, fulfilling dual functions of aluminum tolerance and growth promotion as an active adaptive strategy. This differentiation allows R. tomentosa to thrive in both low- and high-aluminum acidic soils by switching between growth promotion and stress defense modes.

The findings enrich the molecular framework of plant aluminum tolerance and provide new insights for evolutionary biology studies on plant stress adaptation.

This work was supported by the National Natural Science Foundation of China, the Guangdong Forestry Science and Technology Innovation Project, and other funding sources.