Pokkah Boeng disease caused by Fusarium sacchari seriously threatens the yield and quality of sugarcane worldwide. Effectors play a crucial role in the infection and colonization of pathogens. However, there were few reports on the virulence functions of F. sacchari effectors. To characterize effector functions and unravel the pathogenic mechanisms of F. sacchari, we identified an effector FsSCR6, which was vital for the virulence of F. sacchari. Gene knockout mutants showed no difference in growth rates and colony morphology from wild-type. However, the virulence of knockout mutants was severely impaired. Agrobacterium-mediated transient expression assays in Nicotiana benthamiana showed that FsSCR6 and FsSCR6Δsp (without signal peptide) performed cell death-suppressive activity inside plant cells. 3'3-diaminobenzidine staining and aniline blue staining assays showed that FsSCR6 significantly reduced the accumulation of reactive oxygen species and callose deposition triggered by BCL-2-Associated X protein (BAX) in N. benthamiana leaves. FsSCR6 significantly suppressed the relative expression of the marker genes of the hypersensitive responses and salicylic acid (SA)-, jasmonic acid (JA)-, and ethylene-dependent immunity in N. benthamiana. Overall, FsSCR6 is required for F. sacchari virulence; it performs a function inside plant cells and suppresses the plant immune responses by regulating the SA-, JA- and ethylene-mediated defense pathways. These results clarify the function of this effector from F. sacchari and assist in dissecting the interaction between sugarcane and F. sacchari, ultimately contributing to sugarcane production.
Minyan Lu, Lixiang Zhu, Liuyu Yin et al.· Plant physiology and biochem...· 0 citations
Fusarium sacchari is one of the major pathogenic fungi that cause sugarcane Pokkah Boeng disease (PBD). Effectors play pivotal roles in F. sacchari–sugarcane interaction; thus, characterizing these effectors is essential for elucidating the molecular mechanisms underlying F. sacchari pathogenicity and for developing effective strategies to control PBD. However, only a limited number of effectors have been functionally validated to date. Here, we report FsRGAE1, a candidate effector protein from F. sacchari predicted to encode a rhamnogalacturonan acetylesterase (RGAE). FsRGAE1 exhibits high expression during the early stages of infection and maintains relatively elevated expression levels throughout the F. sacchari–sugarcane interaction. Targeted deletion of the FsRGAE1 gene in F. sacchari had no discernible impact on mycelial growth, conidiation, or carbon-source utilization, yet it significantly attenuated fungal virulence. FsRGAE1 possesses both a signal peptide conferring secretory capacity and a transit peptide enabling its translocation into the host cytoplasm and nucleus. Using the Agrobacterium tumefaciens-mediated transient expression system in Nicotiana benthamiana, FsRGAE1 was confirmed to suppress cell death induced by Bcl-2-associated X protein (BAX), as well as ROS accumulation and callose deposition, and its nuclear localization is indispensable for this immunosuppressive activity. Collectively, these findings indicate that FsRGAE1 promotes F. sacchari virulence by suppressing host immune responses in a nuclear localization-dependent manner, providing new insights into effector-mediated F. sacchari pathogenesis and potential target for resistance breeding in sugarcane.
Huifang Li, Shuai Xu, Ying Chen et al.· Journal of Fungi· 0 citations
First comprehensive characterization of the RLCK gene family in sugarcane is presented, elucidating its evolutionary features, expression dynamics and functional roles, and providing compelling evidence that ScRLCK53 modulates salt tolerance through activation of the JA signaling pathway.
Shichao Wang, Pingping Lin, Deng Wu et al.· Plant physiology and biochem...· 0 citations