Cytoplasmic male sterility ( CMS , English Cytoplasmic male sterility , CMS) is the phenomenon of the full or partial sterility of androecium of higher plants, the cause of which is the presence of a special mutation in mitochondrion , i.e. in the mitochondrial genome , plant fertility is restored fully or partially in the presence of a dominant allele of the nuclear fertility reducing gene. First described by Marcus M. Rhodes in corn , also described in petunia , cabbage , sunflower and other plants. CMS is characterized by the so-called maternal type of inheritance .
General CMS mechanism
Cytoplasmic male sterility is manifested in the interaction of the nuclear genome with mitochondrion. Mitochondria and plastids as organelles, originating from endosymbiont prokaryotic microorganisms , have their own unique genome, and although during the evolution of eukaryotic cells they lost most of their autonomy and lost most of the genes, some important proteins are still encoded under the control of mitochondrial and plastid genes. Mitochondria and plastids also have a working protein synthesizing apparatus. Cytoplasmic male sterility occurs as a result of a certain mutation in the mitochondrion, resulting in the degeneration of the androecium of the plant, manifested either in the degeneration of the anthers, or in the non-opening of the anthers, or in the formation of non-viable pollen. Genotypes with wild type mitochondria are designated N or Cyt N (i.e., normal cytoplasm type), genotypes with mutant mitochondria are designated S or Cyt S (i.e. sterile cytoplasm). In the nuclear genome of plant cells, there are also special fertility restoring genes ( English restorer of fertility or Rf genes), the dominant alleles of which fully or partially restore the androecium fertility. Only genotypes that have mutant mitochondrion and are recessive homozygotes for Rf genes are sterile (Cyt S rfrf ), all other genotypes are fertile. [one]
CMS in corn
In corn ( Zea mays L. ) several types of CMS are known, the most studied are the so-called T-type CMS [2] (also called Texas), C-type CMS [3] (the so-called charrua type, also called Paraguayan and Colombian) and S-type CMS [4] (also called Moldavian or M-type CMS). Each type of CMS is determined by its specific mutation in the mitochondrion and is restored by its fertility reducing genes. Thus, the T-type of CMS is caused by a mutation in the T-urf region of the mitochondrion [5] , as a result of which mitochondria begin to produce the mutant toxic protein Urf 13 , which in turn leads to the degeneration of tapetum cells, which leads to the formation of a male sterile maize phenotype , the Rf1 gene located in the near-centromeric region of the short arm of chromosome 3, produces mtALDH mitochondrial aldehyde dehydrogenase , which removes the toxic effect of the chimeric protein and leads to the restoration of fertility. The Rf2 gene, located in the pericentromeric region of chromosome 9, complementary interacts with the Rf1 gene , and to restore fertility in maize lines with T-type cytoplasm, both genes must be in a dominant state. The S-type of CMS is caused by a mutation in the open reading frames of orf355 and orf77; a chimeric nucleotide sequence R orf355-orf77 is formed [5] . The fertility reducing gene is Rf3 , because of the postmeiotic fertility recovery, the Rf3rf3 genotypes form 50% of fertile pollen. It has been shown that Rf3 affects the expression levels of mitochondrial and nuclear genes and has a pleiotropic effect at the transcription level. A possible S-type mechanism of CMS in maize is a change in the level of gene expression in orf355-orf77 plants and the inclusion of the programmed cell death mechanism, the restoration of fertility is due to normalization of the level of transcripts in mitochondria and inhibition of apoptotic mechanisms. [6] The Rf3 gene expression product alters the expression level of the orf355-orf77 chimeric sequence. [7] The C-type CMS is caused by a mutation in the ATP synthase genes [5] and the formation of the chimeric ATP synthase of the atp6-atp9 type [8] , the C-type CMS is restored by the Rf4, Rf5 and Rf6 genes .
Notes
- ↑ Totsky V.M. Genetics. - Odessa: Astroprint, 2002. - T. friend vidannya. - S. 273 - 275. - ISBN 966-549-785-5 .
- ↑ Cao J., Schnable P. Global gene expression profiling of maize cms-T tapetal cells (Eng.) // Maize Genetics Conference Abstracts. - 2006. - Vol. 48 . - P. 173 .
- ↑ Meyer LJ, Newton KJ . Expression of chimeric ATP synthase genes in maize CMS-C mitochondria (Eng.) // Maize Genetics Conference Abstracts. - 2008. - Vol. 50 . - P. 82 .
- ↑ Gabay-Laughnan S., Chase CD, Ortega VM, Zhao L. Molecular-genetic characterization of CMS-S restorer-of-fertility alleles identified in Mexican maize and teosinte (Eng.) // Genetics. - 2004. - No. 166 . - P. 959 - 970 .
- ↑ 1 2 3 ALLEN, JO, CM FAURON, P. MINX, L. ROARK, S. ODDIRAJU et al.,. Comparisons among two fertile and three male-sterile mitochondrial genomes of maize (Eng.) // Genetics. - 2007. - No. 177 . - P. 1173 - 1192 .
- ↑ ZUXIN ZHANG ,, WANHU TANG, FANGDONG ZHANG, YONGLIAN ZHENG ,. Fertility Restoration Mechanisms in S-Type Cytoplasmic Male Sterility of Maize (Zea mays L.) Revealed Through Expression Differences Identified by cDNA Microarray and Suppression Subtractive Hybridization // Plant Molecular Biology Reporter. - 2005. - No. 23 . - P. 17 - 38 .
- ↑ Zabala G., Gabay-Laughnan S., Laughnan JR The Nuclear Gene Rf3 Affects the Expression of the Mitochondrial Chimeric Sequence R Implicated in S-Type Male Sterility in Maize (Eng.) // Genetics. - 1997. - No. 147 . - P. 847-861 .
- ↑ Meyer LJ, Newton KJ Expression of chimeric ATP synthase genes in maize CMS-C mitochondria (Eng.) // Maize Genetics Conference Abstracts. - 2008 .-- Vol. 50 . - P. 82 .