Overexpression of maize GOLDEN2 in rice and maize calli improves regeneration by activating chloroplast development

• Published in: Science China. Life sciences Vol. 66; no. 2; pp. 340 - 349
• Main Authors: Luo, Wanni, Tan, Jiantao, Li, Tie, Feng, Ziting, Ding, Zhi, Xie, Xianrong, Chen, Yuanling, Chen, Letian, Liu, Yao-Guang, Zhu, Qinlong, Guo, Jinxing
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01-02-2023; Springer Nature B.V
• Subjects: Anti-Bacterial Agents - pharmacology; Biomedical and Life Sciences; Biotechnology; Callus; Chloroplasts; Chloroplasts - genetics; Corn; Cultivars; G2 gene; Genetic transformation; Life Sciences; Oryza; Phytohormones; Plant Growth Regulators; Plants, Genetically Modified - genetics; Research Paper; Rice; Transcriptomes; Transformation, Genetic; Transgenic plants; Zea mays - genetics; callus regeneration; genetic transformation; chloroplast; rice; ZmG2
• ISSN: 1674-7305; 1869-1889
• DOI: 10.1007/s11427-022-2149-2

Golden2 (G2), a member of the GARP transcription factor superfamily, regulates several biological processes and phytohormone signaling pathways in plants. In this study, we used a rice codon-optimized maize
G2
gene (
rZmG2
) to improve the regeneration efficiency of rice and maize calli for genetic transformation. We isolated a promoter driving strong and callus-specific expression from rice to drive
rZmG2
transcription from a transgene after transformation of two
indica
and two
japonica
rice cultivars. The resulting
rZmG2
transgenic calli turned green in advance at the differentiation stage, thus significantly raising the regeneration rates of the transgenic
indica
and
japonica
rice plants relative to control transformations. Similar effect of this gene on improving maize transformation was also observed. Transcriptome sequencing and RT-qPCR analyses showed that many rice genes related to chloroplast development and phytohormones are upregulated in
rZmG2
-transgenic calli. These results demonstrate that rZmG2 can promote embryogenic callus differentiation and improve regeneration efficiency by activating chloroplast development and phytohormone pathways. We also established a heat-inducible Cre/
loxP
-based gene-excision system to remove
rZmG2
and the antibiotic selectable gene after obtaining the transgenic plants. This study provides a useful tool for functional genomics work and biotechnology in plants.