Nitrate sensing by the maize root apex transition zone: a merged transcriptomic and proteomic survey

Abstract

HighlightA combined untargeted approach was adopted to achieve a picture of the transcriptional and proteomic profiles typifying the maize root transition zone in response to nitrate.

Nitrate affects transcriptional regulation of UPBEAT1 and ROS localisation in roots of Zea mays L.

“…The expression of two genes encoding key components of MAPK signalling (MPK7 and MKK2) in N‐depleted roots showed accumulation of transcripts prevalently in the meristem (zone 1), which was significantly reduced in response to nitrate supply, which in turn led to a notable increase in mRNAs in the other three portions, in particular the TZ (zone 2), a trend similar to that observed with ZmPRX112 . This result lends support to the hypothesis that TZ cells function as a specialised centre for NO 3 − sensing (Trevisan et al ) and, in general, for interpreting environmental stimuli and translating them into plastic responses. The idea that normal root morphogenesis could, at least in part, depend on ROS homeostasis in the root apex has been already put forward and discussed (Tsukagoshi , , Kagenishi et al ).…”

“…Based on previous findings (Trevisan et al ), a preliminary staining was performed to compare N‐deprived roots with roots supplied with nitrate for 2 h. We found no evident differences in the relative distributions of H 2 O 2 and O 2 •− (data not shown), leading us to hypothesise that a more prolonged nitrate treatment is needed to induce appreciable effects on ROS distribution. In fact, a significant difference in the staining distribution did appear 24 h after nitrate provision (Fig.…”

“…Q‐PCR analyses were carried out to establish whether nitrate affects ROS distribution by differentially regulating the expression of key genes involved in controlling ROS homeostasis. According to previous RNAseq data (Trevisan et al ), nitrate induces moderate regulation of a large set of genes that are involved in ROS metabolism (Fig. ).…”

“…Identification of a maize orthologue of AtUPB1 (AT2G47270.1). An RNA‐seq experiment (Trevisan et al ) revealed a cluster of genes that are strongly downregulated by short‐term nitrate exposure. Zm00001d037569 was identified among the negatively regulated DEGs (A).…”

“…In maize, NO 3 − seems to be perceived by a specialised portion of the root apex, namely the transition zone (TZ) (Manoli et al , , Trevisan et al , ). When the TZ perceives external environmental stimuli, it translates them into motoric responses and releases cells into the elongation region, thereby providing the growing root apices with an effective mechanism for reprogramming root growth in response to environmental stimuli (Baluska et al ).…”