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Embryo defective 14 encodes a plastid‐targeted cGTP ase essential for embryogenesis in maize
Author(s) -
Li Cuiling,
Shen Yun,
Meeley Robert,
McCarty Donald R.,
Tan BaoCai
Publication year - 2015
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13045
Subject(s) - plastid , embryo , biology , embryogenesis , genetics , microbiology and biotechnology , gene , chloroplast
Summary The embryo defective ( emb ) mutants in maize genetically define a unique class of loci that is required for embryogenesis but not endosperm development, allowing dissection of two developmental processes of seed formation. Through characterization of the emb14 mutant, we report here that Emb14 gene encodes a circular permuted, YqeH class GTP ase protein that likely functions in 30S ribosome formation in plastids. Loss of Emb14 function in the null mutant arrests embryogenesis at the early transition stage. Emb14 was cloned by transposon tagging and was confirmed by analysis of four alleles. Subcellular localization indicated that the EMB 14 is targeted to chloroplasts. Recombinant EMB 14 is shown to hydrolyze GTP in vitro ( K m = 2.42 ± 0.3 μ m ). Emb14 was constitutively expressed in all tissues examined and high level of expression was found in transition stage embryos. Comparison of emb14 and WT indicated that loss of EMB 14 function severely impairs accumulation of 16S rRNA and several plastid encoded ribosomal genes. We show that an EMB 14 transgene complements the pale green, slow growth phenotype conditioned by mutations in At NOA 1, a closely related YqeH GTP ase of Arabidopsis. Taken together, we propose that the EMB 14/At NOA 1/YqeH class GTP ases function in assembly of the 30S subunit of the chloroplast ribosome, and that this function is essential to embryogenesis in plants.