Pepper fruits are subjected to various postharvest diseases such as black mold caused by Alternaria alternata. The efficacy of exogenous applications of salicylic acid (SA) in bulk and nanoscale forms to control the black mold was studied. In vitro studies revealed that both SA bulk materials and SA nanoparticles (SANPs) at 1.4 mM significantly suppressed the growth of A. alternata, yet SANPs showed a higher suppressive effect compared to SA bulk equivalent. Examinations using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed hyphal and conidial deformations in addition to changes in cellular structure of A. alternata when treated with both forms of SA at 1.4 mM concentration. The preharvest spraying of SANPs at 1.4 mM displayed the highest significant suppression of disease severity under artificial inoculation and natural infection of pepper fruits. The efficiency of SA bulk materials and SANPs as elicitors to stimulate the innate immune responses in pepper plants were also investigated. The basic PR-1 gene (CaBPR1), beta-1, 3-glucanase (CaBGLU) and peroxidase (CaPO1) defense-related genes showed upregulation expression in leaves of pepper plants treated by both forms of SA. The expression of the three studied genes was affected by SA concentrations. Levels of expression of PR-1, β-1, 3-glucanase and peroxidase genes were the highest (8.8, 8.1 and 7.2 fold change, respectively) in pepper tissues treated with SANPs at 1.4 mM. This study contributes to our understanding of the potential use of SA nanoparticles as a safe strategy to inhibit the fungal infection.

胡椒果实易遭受各种收获后的疾病，如链格孢引起的黑霉病。研究了水杨酸（SA）散装和纳米级形式对黑霉病防治的外源功效。体外研究表明，SA填充材料和1.4 mM的SA纳米颗粒（SANP）均显着抑制了链霉菌的生长，但与SA填充等效物相比， SANP表现出更高的抑制作用。使用扫描电子显微镜（SEM）和透射电子显微镜（TEM）进行的检查显示，菌丝状和分生孢子形变以及互生线虫的细胞结构发生了变化。当用两种形式的SA以1.4 mM浓度处理时。在辣椒果实的人工接种和自然感染下，收获前的1.4 mM SANP喷洒显示出对病害严重程度的最大抑制作用。还研究了SA散装材料和SANP作为引发物刺激辣椒植物先天免疫应答的效率。基本PR-1基因（CaBPR1），β-​​1、3-葡聚糖酶（CaBGLU）和过氧化物酶（CaPO1）防御相关基因在两种形式的SA处理后的辣椒植物叶片中均表达上调。三个研究基因的表达受到SA浓度的影响。在以1.4 mM的SANP处理的辣椒组织中，PR-1，β-1、3-葡聚糖酶和过氧化物酶基因的表达水平最高（分别为8.8、8.1和7.2倍变化）。这项研究有助于我们了解SA纳米颗粒作为抑制真菌感染的安全策略的潜在用途。