Salicylic Acid-Induced syntaxin Gene Expression Coexists with Enhanced Resistance against Colletotrichum gloeosporioides Infection in Cassava

Abstract

The major challenge of cassava cultivation is phytopathogen damage and lack of resistant cultivars. Investigating the defense mechanism in cassava should provide insights into the development of new disease control strategies. Colletotrichum gloeosporioides f. sp. manihotis (CAD) is a fungal pathogen that causes cassava anthracnose disease, which is a serious disease worldwide, affecting cassava production and yield loss. Syntaxins contribute to mediate vesicles fusion in trafficking pathway by specifically forming as ternary SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) complex to transport defense components to site of microbe infection between the plasma membrane and plant cell wall. The function of syntaxins is largely unknown in resistance to Colletotrichum spp. in cassava. To manipulate resistance against Colletotrichum spp., the role of syntaxin genes and plant hormones; salicylic acid (SA) and jasmonic acid (JA) in triggering various responses to biotic stress was studied. All syntaxin genes in cassava genome were identified, and gene expression was investigated in CAD-resistant (HB60) and -susceptible (HN) cultivars of cassava. MePR1 was highly up-regulated in HB60 upon CAD infection. SA-pretreatment induced MeSYP121 expression and coexisted with delayed development of disease symptoms in HB60. In contrast, the different expression patterns of both genes were demonstrated in HN, and JA-pretreatment could not induce CAD-resistance. Altogether, the results suggest the role of SA-induced syntaxin gene expression to mediate vesicle trafficking and trigger defense-associated factors for more disease resistance in cassava. This investigation could be useful for the development of effective crop protection strategies and plant disease management in modern agriculture.