The MdABI5 transcription factor interacts with the MdNRT1.5/MdNPF7.3 promoter to fine-tune nitrate transport from roots to shoots in apple

Abstract

Nitrate is a major nitrogen resource for plant growth and development and acts as both a crucial nutrient and a signaling molecule for plants; hence, understanding nitrate signaling is important for crop production. Abscisic acid (ABA) has been demonstrated to be involved in nitrate signaling, but the underlying mechanism is largely unknown in apple. In this study, we found that exogenous ABA inhibited the transport of nitrate from roots to shoots in apple, and the transcription of the nitrate transporter MdNRT1.5/MdNPF7.3 was noticeably reduced at the transcriptional level by ABA, which inhibited the transport of nitrate from roots to shoots. Then, it was found that the ABA-responsive transcription factor MdABI5 bound directly to the ABRE recognition site of the MdNRT1.5 promoter and suppressed its expression. Overexpression of MdABI5 inhibited ABA-mediated transport of nitrate from roots to shoots. Overall, these results demonstrate that MdABI5 regulates the transport of nitrate from roots to shoots partially by mediating the expression of MdNRT1.5, illuminating the molecular mechanism by which ABA regulates nitrate transport in apple.

SnRK2.4‐mediated phosphorylation of ABF2 regulates ARGININE DECARBOXYLASE expression and putrescine accumulation under drought stress

“…For example, in a very recent study, two bZIP TFs, including bZIP29 and Opaque2, were phosphorylated by SnRK2.2 to transactivate downstream target genes for endosperm filling in maize (Yang et al, 2022). In addition, either SnRK2s or ABFs have been separately shown to act as the pivotal regulators of various physiological and biological processes, such as root growth (Liu et al, 2021), stomatal development (Ding et al, 2020), sugar metabolism (Ma et al, 2017a), flower senescence (J. Z.…”

“…For example, in a very recent study, two bZIP TFs, including bZIP29 and Opaque2, were phosphorylated by SnRK2.2 to transactivate downstream target genes for endosperm filling in maize (Yang et al ., 2022). In addition, either SnRK2s or ABFs have been separately shown to act as the pivotal regulators of various physiological and biological processes, such as root growth (Liu et al ., 2021), stomatal development (Ding et al ., 2020), sugar metabolism (Ma et al ., 2017a), flower senescence (J. Liu et al ., 2017; Z. Liu et al ., 2017), and abiotic stress response (Chen et al ., 2020; Takahashi et al ., 2020; Li et al ., 2021), among others. As increasing evidence showed that activation of ABFs requires SnRK2‐mediated phosphorylation (Kobayashi et al ., 2005; Wang et al ., 2012; Umezawa et al ., 2013; W. Wang et al ., 2019; X. Wang et al ., 2019), it is reasonable to assume that SnRK2s and ABFs in various combinations might function in synergy to play crucial roles in the regulation of plant development and responses to environmental stresses.…”

MdMKK9-Mediated the Regulation of Anthocyanin Synthesis in Red-Fleshed Apple in Response to Different Nitrogen Signals

“…AtNRT2.7 is induced by nitrate and hormones, enhances the growth of the root system, and improves the absorption and utilization of nitrogen [ 47 ]. In apples, the expression of MdNRT1.5 / MdNPF7.3 inhibits the transport of nitrate from root to branch [ 48 ]. Nitrate has been reported to mediate phosphorus absorption and starvation signals by activating the NIGT1-SPX-PHR cascade signaling pathway [ 49 ].…”

Functional characterization of MdERF113 in apple

“…The apple calli was transiently transformed by Agrobacterium carrying ProMdERF113::GUS as previously described (Hu et al, 2017; Y. J. Liu et al, 2021). They were cultured on a solid medium containing NaCl (120 mM), PEG 6000 (4%), temperature (4°C), and ABA (100 μM) for 24 h, respectively.…”