پاسخ مولکولی، متابولیکی و فیزیولوژیکی زعفران به تنش زیستی ناشی از ویروس موزاییک شلغم

Saffron (Crocus sativus L.) is an herbaceous and perennial plant belonging to the Iridaceae family, well-known for its varied medicinal features. Khorasan region, Iran stands out as the principal global hub for saffron cultivation and produces almost 90% of the world’s saffron. The profitable and precious segment of saffron is its stigmas, which are considered the most costly spices worldwide and encompass three crucial apocarotenoids including crocin, picrocrocin, and safranal. These chemical components have caused saffron to be considered in various industries such as culinary, pharmaceuticals, textiles, cosmetics and perfumery. Plant viruses, as one of the most important biotic stressors, can potentially alter the effective compounds of the saffron plant leading to a reduction or loss of their medicinal properties. Turnip mosaic virus (Potyvirus rapae) is one of the most prevalent plant viruses in the world. To study the effect of P. rapae biotic stress on the saffron quality, different morphological, physiological, metabolic and molecular indices of the saffron medicinal plant were assessed using a completely randomized design. At first, the saffron plant was mechanically inoculated with P. rapae at the beginning of the leaf stage and various indices were investigated. Morphological traits of saffron decreased under virus stress and viral symptoms appeared. P. rapae also caused a decrease in the amount of leaf pigments, petal anthocyanin, flowering performance, greenness and photosynthetic indices. The results of high-performance liquid chromatography (HPLC) analysis revealed that P. rapae treatment led to a statistically notable reduction at a significance level of 5% in crocin and safranal content and picrocrocin induction compared to the mock treatment. The analysis of gene expression involved in the biosynthesis of vital secondary metabolites of saffron showed a high correlation with the content of each metabolite. Inoculation of P. rapae to saffron plant decreased the level of CsALDH31l gene expression in the crocin synthesis pathway while no significant difference was observed in the level of CsUGT709G1 gene expression in the picrocrocin synthesis pathway compared to the mock treatment. Taken together, our findings exhibited the correlation between the biotic stress caused by the virus and the change in the metabolism of the saffron medicinal plant.