Unraveling the UV-responsive molecular mechanisms behind high-altitude adaptation in Prunus mira Koehne

Prunus mira Koehne is a significant fruit crop in the Xizang region of China, valued for its economic, ornamental,edible,and research importance. However, the challenging geographic terrain of Xizang, with sample collection altitudes ranging from 2800 to 4498m, poses obstacles to the cultivation of Prunus mira Koehne. Despite its importance, research on Prunus mira Koehne remains limited, particularly regarding its response to ultraviolet radiation at high altitudes. In this study, we investigated the effects of UV-B irradiation on Prunus mira Koehne leaves compared to cultivated peach leaves, aiming to elucidate the mechanisms underlying their response. Our analysis focused on phenotypic traits, physiological parameters, transcriptomic profiles, and metabolic pathways in both species post-irradiation. Additionally, we confirmed the transient expression of the MYB16 transcription factor identified through weighted gene co-expression network analysis (WGCNA). Our findings contribute to understanding the molecular basis of Prunus mira Koehne's adaptation to high-altitude radiation. The findings indicated that leaves of Prunus mira Koehne exhibited reduced yellowing compared to those of cultivated peach, demonstrated higher UV-B stress tolerance, and post-UV-B stress, displayed elevated chlorophyll levels relative to cultivated peach leaves. Following UV-B stress, Prunus mira Koehne manifested 170 differentially expressed genes (DEGs), with 976 up-regulated and 724 down-regulated genes, a higher count compared to the 639 DEGs in cultivated peaches (27 up-regulated and 612 down-regulated). Moreover, Prunus mira Koehne displayed 3761 differentially abundant metabolites (DAMs) post-UV-B stress, with 2313 up-regulated and 1448 down-regulated, surpassing the 2988 DAMs in cultivated peach (1404 up-regulated and 1584 down-regulated). Notably, pathways such as phenylpropanoid biosynthesis, flavonoid biosynthesis, and porphyrin metabolism were identified as pivotal mechanisms enabling Prunus mira Koehne to withstand high-altitude radiation. Furthermore, transient expression verification of the MYB16 transcription factor revealed synchronous up-regulation and down-regulation with changes in chlorophyll, flavonoids, and other UV-B responsive substances.