Maize Genetics Cooperation Newsletter

maize gene review

Author: DOI/

Review: pending

Pub date: May 2009

Name: tha1--thylakoid assembly1

Synonyms: SecA homolog

Chromosome 3S bin 3.04
BAC Genome Browser, via cDNA U71123 | 1575789

Function: thylakoid protein targeting.

image of corn mutant

Summary: Chloroplast SecA homolog: required for thylakoid protein targeting via the ATP-dependent "sec" pathway. A tha1 mutant allele is pale green, with high leaf chlorophyll fluorescence, and is seedling lethal due to decreased levels of many thylakoid proteins.

Image: mutant leaf color indicated on a seedling leaf color scale

First reported: Voelker and Barkan 1995.

Key Alleles

tha1-ref::Mu1 (or tha1-m1) Mu1 insertion in an intron, 19 bp away from 5'splice junction. Pale green, high leaf chlorphyll fluorescence, seedling lethal phenotype, with occasional green sectors.

Map Location

RFLP mapping to chromosome 3 (Voelker et al 1997; Davis et al. 1999).

Gene Product

Chloroplast SecA homolog; cp-SecA. Confirmation based on sequence similiarity and mutant protein accumulation.


Functions in etioplasts and chloroplasts (Voelker et al. 1997).


Davis GL, McMullen MD, Baysdorfer C, Musket T, Grant D, Staebell M, Xu G, Polacco M, Koster L, Melia-Hancock S, Houchins K, Chao S, Coe EH Jr. (1999) A maize map standard with sequenced core markers, grass genome reference points and 932 expressed sequence tagged sites (ESTs) in a 1736-locus map. Genetics 152(3):1137-1172. PUBMED

Settles AM, Baron A, Barkan A, Martienssen RA (2001) Duplication and suppression of chloroplast protein translocation genes in maize. Genetics 157(1):349-360. PUBMED

Voelker R, Barkan, A (1995) Two nuclear mutations disrupt distinct pathways for targeting proteins to the chloroplast thylakoid. EMBO J 14: 3905-3914. PUBMED

Voelker R, Mendel-Hartvig J, Barkan A (1997) Transposon-disruption of a maize nuclear gene, tha1, encoding a chloroplast SecA homologue: in vivo role of cp-SecA in thylakoid protein targeting. Genetics 145: 467-478. PUBMED

Links: MGDB tha1 NCBI: tha1 UniProt: O24589