OsNAC3 regulates seed germination involving abscisic acid pathway and cell elongation in rice

Chengwei Huang, Jia Zhao, Qianqian Huang, Liling Peng, Zhibo Huang, Wenwen Li, Shan Sun, Yongqi He, Zhoufei Wang

New Phytol.; 2024 Jan; 241(2):650-664. doi: 10.1111/nph.19362.

Abstract

Seed germination is a critical trait for the success of direct seeding in rice cultivation. However, the underlying mechanism determining seed germination is largely unknown in rice. Here, we report that NAC transcription factor OsNAC3 positively regulates seed germination of rice. OsNAC3 regulates seed germination involving abscisic acid (ABA) pathway and cell elongation. OsNAC3 can directly bind to the promoter of ABA catabolic gene OsABA8ox1 and cell expansion gene OsEXP4, which consequently activates their expressions during seed germination. We also find that the expression of OsEXP4 is reduced by ABA during seed germination in rice. OsNAC3 regulates seed germination by influencing cell elongation of the embryo through directly affecting OsEXP4 expression and indirectly ABA-medicated OsEXP4 expression. The OsNAC3 elite haplotype is useful for genetic improvement of seed germination, and overexpression of OsNAC3 can significantly increase seed germination. We therefore propose that OsNAC3 is a potential target in breeding of rice varieties with high seed germination for direct seeding cultivation.

See https://pubmed.ncbi.nlm.nih.gov/37908121/

Figure 1:

Characterization of OsNAC3 regulation on seed germination in rice. (a) The CRISPR targets of OsNAC3. (b) Sequences of mutations of targets in Osnac3 mutants. The gray, yellow, blue, and black lines indicate the nucleotide A, T, C, and G, respectively. (c) Representative images of seed germination for 3 d among Nipponbare wild-type (WT), Osnac3 mutant (Osnac3-1, Osnac3-2, and Osnac3-3), and complemented lines (Com-1 and Com-2). Bars, 10 mm. (d) Dynamic of germination percentage (GP), and comparisons of (e) time for 50% germination percentage (T₅₀), and (f) germination index (GI) among WT, Osnac3 mutant, and complemented lines. Data were presented as mean ± SD, n = 3 biological replicates. In (e, f), different letters indicate significant differences (one-way ANOVA: P = 0.05).