SUPPRESSIVE EFFECT OF SI ON THE DEVELOPMENT OF FUSARIUM HEAD BLIGHT IN YOUNG BARLEY ORGANS UNDER IN VITRO CONDITIONS

Abstract

Although barley is a high silicon (Si) absorber and accumulator monocot; few reports have shown an enhanced adult host resistance to destructive fungal diseases including Fusarium head blight (FHB). However, no study has ever conducted to demonstrate Si ability to suppress FHB development in young barley organs under in vitro environment. To elucidate this, the effect of Si uptake at 1.7 mM on the susceptibility of two barley cultivars, Arabi Aswad (AS, moderately resistant) and Arabi Abiad (AB, moderately susceptible) to four Fusarium species with diverse aggressiveness was investigated in three in vitro experiments. Development of FHB pathogens was expressed by latent period (LP) of detached leaf inoculation, area under disease progress curve (AUDPC) of Petri-dish inoculation as well as coleoptile length reduction (CLR) of a coleoptile infection. At the early development stage, differences in LP, AUDPC and CLR were observed on barley detached leaves and seedlings of Si-Fusarium-inoculated treatments relative to fungal-inoculated-controls, showing the beneficial role played by this element in decreasing head blight disease symptoms on young plant parts under in vitro conditions. Si absorption at 1.7 mM did significantly result in significantly higher LP and lesser AUDPC and CLR compared with controls in AS and AB. Si increased resistance measured by LP, AUDPC and CLR on AB to level comparable to AS not amended with Si, suggesting that Si feeding increase host resistance to FHB development. To our best knowledge, this in vitro study presented the first pathogenic evidence associated with the positive effect of Si on enhancing barley resistance against Fusarium infection in the young host parts, showing that the three components evaluated in this study, i.e., LP, AUDPC and CLR, were negatively impacted by Si. Thus, Si supply at 1.7 mM could be a valuable tool in integrated pathogen management by suppressing pathogen development on barley.