Mutations in RZF1, a zinc-finger protein, reduce magnesium uptake in roots and translocation to shoots in rice

Abstract

Magnesium (Mg) homeostasis is critical for maintaining many biological processes, but little information is available to comprehend the molecular mechanisms regulating Mg concentration in rice (Oryza sativa). To make up for the lack of information, we aimed to identify mutants defective in Mg homeostasis through a forward genetic approach. As a result of the screening of 2,825 M2 seedlings mutated by ion-beam irradiation, we found a rice mutant that showed reduced Mg content in leaves and slightly increased Mg content in roots. Radiotracer 28Mg experiments showed that this mutant, named low magnesium content 1 (LMGC1), has decreased Mg2+ influx in the root and Mg2+ translocation from root to shoot. Consequently, LMGC1 is sensitive to the low Mg condition and prone to develop chlorosis in the young mature leaf. The MutMap method identified a 7.4-kbp deletion in the LMGC1 genome leading to a loss of two genes. Genome editing using CRISPR-Cas9 further revealed that one of the two lost genes, a gene belonging to the RanBP2-type zinc finger family that we named RanBP2-TYPE ZINC FINGER1 (OsRZF1), was the causal gene of the low-Mg phenotype. OsRZF1 is a nuclear protein and may have a fundamental role in maintaining Mg homeostasis in rice plants.

The RING zinc finger protein LbRZF1 promotes salt gland development and salt tolerance in Limonium bicolor

“…In this study, we demonstrated that LbRZF1 also positively regulated the secretion of salt by salt glands. Under salt stress conditions, Na + enters plant cells and eventually disrupts ion homeostasis (Kobayashi et al, 2023). We observed that LbRZF1 improved the salt tolerance of L. bicolor , possibly by affecting Na + and K + homeostasis (Figure 4H).…”

Mitogen‐activated protein kinase MxMPK3‐2 mediated phosphorylation of MxZR3.1 participates in regulating iron homoeostasis in apple rootstocks

“…In addition, zinc finger proteins are responsible for the regulation of nutrient uptake and stress responses. For example, the rice zinc finger protein OsRZF1 is crucial for the absorption of magnesium in the root system and its transport to the stem (Kobayashi et al, 2023). The interaction between SlSZP1 and STOP1 prevents SlRAE1 from degrading STOP1, thereby enhancing aluminium stress in tomato (Zhang, Dong, et al, 2022).…”