A nuclear mutation affects the synthesis of the chloroplast psbA gene production Chlamydomonas reinhardtii

1992 ◽  
Vol 22 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Jacqueline Girard-Bascou ◽  
Yves Pierre ◽  
Dominique Drapier
Genetics ◽  
1992 ◽  
Vol 132 (2) ◽  
pp. 413-429
Author(s):  
S M Newman ◽  
E H Harris ◽  
A M Johnson ◽  
J E Boynton ◽  
N W Gillham

Abstract Intermolecular recombination of Chlamydomonas chloroplast genes has been analyzed in sexual crosses and following biolistic transformation. The pattern and position of specific exchange events within 15 kb of the 22-kb inverted repeat have been mapped with respect to known restriction fragment length polymorphism markers that distinguish the chloroplast genomes of the interfertile species Chlamydomonas reinhardtii and Chlamydomonas smithii. Recombinant progeny were selected from two- and three-factor crosses involving point mutations conferring herbicide (dr) and antibiotic resistance (er and spr) in the psbA, 23S and 16S ribosomal RNA genes, respectively. Exchange events were not randomly distributed over the 15-kb region, but were found to occur preferentially in a 0.7-kb sequence spanning the 3' end of the psbA gene and were much less common in an adjacent region of ca. 2.0 kb. These findings are corroborated by data showing that the dr mutation is unlinked genetically (3% recombination/kb) to the er and spr rRNA mutations, which are themselves linked and show ca. 1% recombination/kb. This discrepancy is significant since the dr-er and er-spr intervals are about the same length (ca. 7 kb). During chloroplast transformation, the 0.7-kb recombination hotspot also functions as a preferential site for exchange events leading to the integration of donor psbA gene sequences. The 0.7-kb hotspot region contains four classes of 18-37-bp direct repeats also found in other intergenic regions, but no open reading frame. Using deletion constructs in a chloroplast transformation assay, the hotspot was localized to a 500-bp region that lacks most of these repeats, which suggests that the repeats themselves are not responsible for the increased recombination frequency. Within this region, a 400-bp sequence is highly conserved between the chloroplast genomes of C. reinhardtii and C. smithii and includes several structural motifs characteristic of recombination hotspots in other systems.


1993 ◽  
Vol 22 (1) ◽  
pp. 91-99 ◽  
Author(s):  
Udo Johanningmeier ◽  
Silvia Heiss

Author(s):  
Yuichiro Takahashi ◽  
Keiichiro Utsumi ◽  
Aya Hatano ◽  
Yumiko Yamamoto ◽  
Kimiyuki Satoh

Genetics ◽  
1987 ◽  
Vol 115 (4) ◽  
pp. 677-684
Author(s):  
Nicholas W Gillham ◽  
John E Boynton ◽  
Anita M Johnson ◽  
Bryce D Burkhart

ABSTRACT In Chlamydomonas reinhardtii, chloroplast genomes are normally transmitted by the mating type plus (mt  +) parent and mitochondrial genomes by the mating type minus (mt  -) parent. In this paper we describe three new nuclear mutations, designated mat-3-1 to -3, which are tightly linked to the mt  + allele and permit high transmission of chloroplast genomes from the mt  - parent, but have no effect on transmission of mitochondrial genomes. We also show that mat-1, reported by others to be a nuclear mutation linked to mt  - which promotes transmission of chloroplast genomes by the mt  - parent, is probably a vegetative diploid since it contains both mt  + and mt  - alleles. Vegetative diploids behave as if they are mt  - with respect to mating, but posses a level of chloroplast gene transmission intermediate between that of haploid mt  - and mt  + stocks.


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