The MIEL1‐ABI5/MYB30 regulatory module fine tunes abscisic acid signaling during seed germination

Abstract

The transcription factor ABSCISIC ACID IN-SENSITIVE5 (ABI5) plays a crucial role in abscisic acid (ABA) signaling during seed germination. However, how ABI5 is regulated during this process is poorly understood. Here, we report that the ubiquitin E3 ligase MIEL1 and its target transcription factor MYB30 modulate ABA responses in Arabidopsis thaliana during seed germination and seedling establishment via the precise regulation of ABI5. MIEL1 interacts with and ubiquitinates ABI5 to facilitate its degradation during germination. The transcription factor MYB30, whose turnover is mediated by MIEL1 during seed germination, also interacts with ABI5 to interfere with its transcriptional activity. MYB30 functions downstream of MIEL1 in the ABA response, and both are epistatic to ABI5 in ABA-mediated inhibition of seed germination and postgerminative growth. ABA treatment induces the degradation of MIEL1 and represses the interaction between MIEL1 and ABI5/MYB30, thus releasing both ABI5 and MYB30. Our results demonstrate that MIEL1 directly mediates the proteasomal degradation of ABI5 and inhibits its activity via the release of its target protein MYB30, thus ensuring precise ABA signaling during seed germination and seedling establishment.

An R2R3‐MYB network modulates stem strength by regulating lignin biosynthesis and secondary cell wall thickening in herbaceous peony

“…Based on the conservation of the DNA‐binding domain and the specific motifs in the C‐terminal domain, R2R3‐MYB members are divided into at least 25 subgroups in A. thaliana (Dubos et al., 2010) and 45 in P. trichocarpa (Yang et al., 2021), of which the members of each subgroup usually have similar or identical functions due to similar structures. For example, members of subgroup 5 (S5) and subgroup 6 (S6) AtMYB75, AtMYB90, AtMYB113 and AtMYB114 are related to anthocyanin biosynthesis (Yan et al., 2021), subgroup 1 (S1) and subgroup 23 (S23) members AtMYB30, AtMYB1, AtMYB25 and AtMYB109 participate in responses to biotic and abiotic stress (Beathard et al., 2021; Nie et al., 2022), while subgroup 9 (S9) and subgroup 9 (S23) members AtMYB16, AtMYB73 and AtMYB77 are associated with control cell fate and identity such as cutin biosynthesis and auxin signaling transduction (Yang et al., 2020; Yang, Tran, et al., 2022). Here, evolutionary analysis indicated that PlMYB43, PlMYB83 and PlMYB103 clustered into the MYB20/43 clade, MYB46/83 clade and MYB103 clade, respectively.…”

Integration of ABA, GA, and light signaling in seed germination through the regulation of ABI5

“…In addition to its function in photomorphogenesis, MYB30 is also a critical repressor of ABA-mediated seed germination ( Zheng et al, 2012 ). MYB30 interacts with ABI5 and interferes with its transcriptional activity to restrict the function of ABI5 during seed germination ( Nie et al, 2022 ). The ubiquitin E3 ligase MIEL1 interacts with and ubiquitinates MYB30 and ABI5, thus mediating the turnover of MYB30 and ABI5 during seed germination.…”

“…ABA represses the function of MIEL1 by inducing its degradation and repressing its interaction with MYB30 and ABI5. The MIEL1-MYB30 repression module precisely regulates ABI5, thus ensuring the restriction of ABA signaling during seed germination ( Nie et al, 2022 ).…”

MYB30 integrates light signals with antioxidant biosynthesis to regulate plant responses during postsubmergence recovery

“…The MYB transcription factor family is characterized by conserved MYB repeats and participates in multiple biotic and abiotic stress responses (Dubos et al ., 2010). Among them, MYB30 is a well‐studied member of the Arabidopsis ( Arabidopsis thaliana ) MYB family and acts in regulating the hypersensitive response (Daniel et al ., 1999; Raffaele et al ., 2008; Serrano et al ., 2016), seed germination (Zheng et al ., 2018; Nie et al ., 2022), root growth (Mabuchi et al ., 2018), photomorphogenic development (Yan et al ., 2020), oxidative and heat stresses (Liao et al ., 2017), and salt tolerance (Gong et al ., 2020). A recent study revealed that ethylene enhances the interaction between MYB30 and ETHYLENE INSENSITIVE3, thus antagonistically regulating downstream root hair‐related genes (Xiao et al ., 2021).…”