Msh1
Xu Y-Z, Arrieta-Montiel MP, Virdi KS, de Paula WBM, Widhalm JR, Basset GJ, Davila JI, Elthon TE, Elowsky CG, Sato SJ, Clemente TE & Mackenzie SA 2011 MutS HOMOLOG1 is a nucleoid protein that alters mitochondrial and plastid properties and plant response to high light. Plant Cell 23:3428-3441.
- it is unlikely that msh1 mutations are prevalent in nature
- MSH1 transcriptional downregulation can occur naturally in stress environments
- exposure to stress during flowering, when MSH1 transcripts are at highest levels, could result in sufficient suppression of MSH1 to influence the status of organelle populations in the forming embryo
- the why1 why3 double mutations led to only low (~4%) frequency variegation
- we presume a similar phenomenon is involved in the high frequency (80 to 100%) variegation observed in msh1
- small (20 to 60 bp) repeats within the chloroplast genome participate in the repair of double-strand breaks
- MSH1 functions in both mitochondria and chloroplasts to influence the frequency or fate of double-strand breaks within each genome
- depletion of MSH1 in the mitochondrion results in high frequency asymmetric recombination at 50- to 550-bp repeats
- in the chloroplast, loss of MSH1 apparently leads to similar asymmetric exchange at much smaller repeats
- whether MSH1 stabilizes each genome to prevent double-strand breaks, or facilitates strand invasion once breaks occur, is not clear
