Study on the interaction mechanism between Crocus sativus and Fusarium oxysporum based on dual RNA-seq

Abstract

Fusarium oxysporum is a widely distributed soil-borne fungus, which is the most serious pathogen in Crocus sativus production. Due to the lack of resistant cultivars of saffron，and the unclear disease resistance and pathogenic mechanism, there is no really effective control method at present. In this study, the process of F.oxysporum infection of saffron corms and the physiological responses of saffron were analyzed. On this basis, dual RNA-seq was performed on the saffron corms inoculated on the 3th and 6th days of F. oxysporum to analyze the defense-related genes of saffron and the pathogenicity-related genes of F. oxysporum. The results showed that on the third day of infection, it was observed that the hyphae completely entered the corm cells and colonized and spread in the cells; on the sixth day of infection, hyphae have appeared in xylem cells to block vessels. Interacting transcriptome results indicate that in the host saffron, its phenylpropanoid metabolism, plant hormone signal transduction and plant-pathogen interaction pathways were activated during infection process, which were conducive to the enhancement of cell wall, the occurrence of hypersensitivity, and the accumulation of various antibacterial proteins and phytoantitoxins. Meanwhile, in the fungus, the expression levels of cell wall degradationenzyme-related genes, growth and development -related genes and pathogenicity-related genes in F. oxysporum were up-regulated, indicating its strong pathogenicity. The study provides a new insight into the molecular mechanism of the interaction between C. sativus and F. oxysporum, and also provides a theoretical basis for mining saffron disease resistance genes.

Injury and not the pathogen is the primary cause of corm rot in Crocus sativus (saffron)

“…In addition, nematodes and rodents have also been reported to attack the corms and cause injury ( Khan and Sharma, 2020 ). Some researchers have reported the infection without injury and by just dipping the corm or germinated roots in the spore suspension ( Palmero et al., 2014 ; Gupta et al., 2020 ; Mirghasempour et al., 2022b ) but the present study and others have reported the infection after injuring the corm artificially ( Gupta and Vakhlu, 2015 ; Wani et al., 2016 ; Wani et al., 2018 ; Zhang et al., 2020 ; Bhagat et al., 2022 ; Luo et al., 2022 ). There are many reports on other plants wherein the screening for pathogenicity is done by injury such as cork oak ( Luque et al., 2000 ), kiwi fruit ( Di Marco et al., 2004 ), grape vines ( Halleen et al., 2007 ), Dendrobium nobile , and Dendrobium officinale ( Sarsaiya et al., 2020 ), potato ( Azil et al., 2021 ).…”