MOS1 Negatively Regulates Sugar Responses and Anthocyanin Biosynthesis in Arabidopsis

Abstract

Sugars, which are important signaling molecules, regulate diverse biological processes in plants. However, the convergent regulatory mechanisms governing these physiological activities have not been fully elucidated. MODIFIER OF snc1-1 (MOS1), a modulator of plant immunity, also regulates floral transition, cell cycle control, and other biological processes. However, there was no evidence of whether this protein was involved in sugar responses. In this study, we found that the loss-of-function mutant mos1-6 (mos1) was hypersensitive to sugar and was characterized by defective germination and shortened roots when grown on high-sugar medium. The expression of MOS1 was enhanced by sucrose. Hexokinase 1, an important gene involved in sugar signaling, was upregulated in the mos1 mutant compared to wild-type Col-0 in response to sugar. Furthermore, the mos1 mutant accumulated more anthocyanin than did wild-type Col-0 when grown on high-sugar concentration medium or under high light. MOS1 was found to regulate the expression of flavonoid and anthocyanin biosynthetic genes in response to exogenous sucrose and high-light stress but with different underlying mechanisms, showing multiple functions in addition to immunity regulation in plant development. Our results suggest that the immune regulator MOS1 serves as a coordinator in the regulatory network, governing immunity and other physiological processes.

An OsPRMT5‐OsAGO2/miR1875‐OsHXK1 module regulates rice immunity to blast disease

“…HXK1 plays versatile roles in plant growth, development, and sugar sensing (Huang et al, 2019; Zheng et al, 2019; Li et al, 2020b; Barbier et al, 2021). HXK1 has been reported to positively regulate plant immunity to pathogens by controlling ROS and anthocyanin accumulation and stomatal closure (Hu et al, 2016; Li et al, 2018; Ye et al, 2020; Zhang et al, 2020; Wang et al, 2021c). Similarly, we found that overexpressing OsHXK1 enhanced resistance to M. oryzae infection by inducing ROS accumulation (Figure 2B–D).…”

Functional Conservation and Divergence of MOS1 That Controls Flowering Time and Seed Size in Rice and Arabidopsis

“…MOS1 performs various regulatory activities in multiple aspects of plant growth, including the flowering time, cell cycle, and stress responses in Arabidopsis [ 27 , 28 , 31 , 32 ]. Here, we focused on the functional characterization of a rice MOS1 , OsMOS1 , which is a close homolog of Arabidopsis MOS1 as it contains the conserved BAT2 domain.…”

“…The defection of endopolyploidization in the mos1 mutant can be suppressed by the mutations of SUF4 , but not FLC , indicating that MOS1 modulates the endopolyploidization and flowering time through different genetic pathways [ 27 ]. In addition, MOS1 negatively regulates sugar responses and anthocyanin biosynthesis in Arabidopsis , possibly at the transcriptional level [ 32 ]. Thus, the existing finding indicates that MOS1 functions as a key coordinator in the regulation of growth and biotic and abiotic stress responses in Arabidopsis .…”