Transcriptomic efficiency shapes growth-defense trade-offs in alpine desert plants under climate change

Climate change on the Qinghai-Xizang Plateau, characterized by simultaneous warming and increased precipitation during the growing season, will challenge alpine plants to balance resource acquisition with stress defense. However,the governing physiological and molecular mechanisms remain elusive. Here, we conducted a multi-year in-situ experiment manipulating temperature and precipitation on two dominant alpine desert species, Ajania tibetica (Aj) and Ceratoides compacta (Ce), to decipher their divergent acclimation strategies. Aj adopted a conservative strategy in which warming triggered oxidative stress and inhibited growth regardless of water availability. A higher physiological-transcriptomic decoupling index (PTDI) revealed that this response involved a metabolically costly upregulation of ribosome biogenesis with negligible physiological gains. In contrast, Ce employed an opportunistic strategy characterized by a lower PTDI and enhanced growth. This physiological efficiency was underpinned by a molecular network centered on heat shock proteins, which maintained proteostasis with minimal transcriptional volatility. These findings demonstrate that divergent transcriptomic plasticity, specifically the trade-off between a high-cost repair mode and an efficient maintenance mode, determines adaptive success. Our study further suggests that opportunistic species like Ce may outcompete conservative species under future warmer and wetter climate scenarios, potentially driving significant shifts in alpine desert community structures.