CMS - senecio7の日記

Budar F, Touzet P & De Paepe R 2003 The nucleo-mitochondrial conflict in cytoplasmic male sterilities revisited. Genetica 117:3-16.

reallocation of resources from pollen to seeds reduces the transmission of nuclear genes because biparental transmission depends on success through both seeds and pollen

the overproduction of seeds by female individuals in gynodioecious populations is not always observed
this female fertility advantage is a key parameter in evolutionary models of gynodioecy
it can be caused by:
maternal sex effects through resource compensation
inbreeding effects

apart from the necessary gain in female fertility conveyed by the sterile cytoplasm, additional alternative constraints must be invoked to explain the persistence of CMS in populations:
deleterious effects of the restorer alleles in their alien cytoplasm type in panmictic population, causing a restoration cost
population structure in non-equilibrium metapopulations via founder effects and recurrent introduction of cytoplasmic male steriles

in different species of thyme, all the studied populations are gynodioecious but there is a high interpopulation variability in female frequency:
from 5 to 95% in Thymus vulgaris with a approximate mean of 60%
from 41 to 99% in Thymus mastichina
from 17 to 87% in T. zygis
female thyme plants usually produce 1.5-3.5 times as many viable seeds as hermaphrodites
this female advantage may vary among populations and in time
inbreeding depression may partially explain the persistence of gynodioecy as well as the reallocation of resources to seed production and provisioning in females
both of these parameters are variable among populations and with female frequency

a strong linkage disequilibrium is observed between the mitochondrial and chloroplastic haplotypes
migration rather than recurrent mutation might explain the occurrence of mitotypes in populations of wild beets
in beet, no clear female advantage has been documented so far
in a recent study, a cytonuclear disequilibrium might suggest a cost associated with restorer alleles of CMS E