Label-Free Quantitative Proteomic Analysis of <i>Puccinia psidii</i> Uredospores Reveals Differences of Fungal Populations Infecting Eucalyptus and Guava

Puccinia psidii sensu lato (s.l.) is the causal agent of eucalyptus and guava rust, but it also attacks a wide range of plant species from the myrtle family, resulting in a significant genetic and physiological variability among populations accessed from different hosts. The uredospores are crucial to P. psidii dissemination in the field. Although they are important for the fungal pathogenesis, their molecular characterization has been poorly studied. In this work, we report the first in-depth proteomic analysis of P. psidii s.l. uredospores from two contrasting populations: guava fruits (PpGuava) and eucalyptus leaves (PpEucalyptus). NanoUPLC-MSE was used to generate peptide spectra that were matched to the UniProt Puccinia genera sequences (UniProt database) resulting in the first proteomic analysis of the phytopathogenic fungus P. psidii. Three hundred and fourty proteins were detected and quantified using Label free proteomics. A significant number of unique proteins were found for each sample, others were significantly more or less abundant, according to the fungal populations. In PpGuava population, many proteins correlated with fungal virulence, such as malate dehydrogenase, proteossomes subunits, enolases and others were increased. On the other hand, PpEucalyptus proteins involved in biogenesis, protein folding and translocation were increased, supporting the physiological variability of the fungal populations according to their protein reservoirs and specific host interaction strategies.蒲桃柄锈菌广义种（Puccinia psidii sensu lato, s.l.）是桉树锈病与番石榴锈病的致病原，同时可侵染桃金娘科的多种植物类群，不同寄主来源的种群间存在显著的遗传与生理变异。夏孢子（uredospore）是该菌在田间传播的核心媒介；尽管夏孢子在真菌致病过程中发挥关键作用，但针对其分子特征的研究仍相对匮乏。本研究首次针对两个差异显著的蒲桃柄锈菌广义种群的夏孢子开展深度蛋白质组学分析，所涉种群分别为取自番石榴果实的PpGuava种群与取自桉树叶的PpEucalyptus种群。本研究采用纳米超高效液相色谱-质谱联用法（NanoUPLC-MSE）获取肽段谱图，将谱图比对至UniProt数据库中的柄锈菌属序列，由此完成了该植物病原真菌的首次蛋白质组学分析。通过无标记蛋白质组学技术，共检测并定量到340种蛋白质。两个种群均检测到大量特有蛋白质，且不同种群间部分蛋白质的丰度存在显著差异。在PpGuava种群中，诸多与真菌毒力相关的蛋白质丰度显著上调，包括苹果酸脱氢酶、蛋白酶体亚基、烯醇化酶等；而在PpEucalyptus种群中，参与生物发生、蛋白质折叠与转运过程的蛋白质丰度更高，这一结果印证了该真菌种群可通过自身蛋白质储备与特定寄主互作策略，形成差异化的生理特征。