Proteomic analysis reveals distinct germination strategies in polymorphic fruits of Haloxylon ammodendron

Abstract

Fruit polymorphism, the production of multiple fruit morphotypes within a species, is an adaptive bet-hedging strategy in variable environments. However, researches about perennial plant and the adaptive mechanisms are not well understood. Haloxylon ammodendron, a constructive desert shrub, exhibits three fruit morphotypes: YY (yellow wings with yellow pericarp), YP (yellow wings with pink pericarp), and PP (pink wings with pink pericarp). We investigated their ecophysiological and molecular mechanisms through germination assays under salt and drought stress, combined with proteomic analysis. YP consistently showed the highest germination percentage (GP) and germination rate index (GRI) under stress, while PP displayed well germination success under low salinity and well-watered conditions (GP=32.7%, 36.7%; GRI=0.018, 0.020), but significantly impaired viability under stress (GP=12.7%, 12.0%; GRI=0.006, 0.006). Proteomics identified 721 differentially expressed proteins (DEPs), with the most (662) between YP and PP, linked to stress response and germination. YPs high abundance of stress-resistant proteins enabled rapid germination, whereas PPs delayed germination aligns with a persistent seed bank strategy. This polymorphism promotes niche differentiation: YP ensures quick colonization, PP enhances long-term resilience, and YY offers an intermediate strategy. Our findings reveal molecular-ecological adaptations in H. ammodendron, aiding targeted germplasm use for desert restoration.