Fertile revertants from S-type male-sterile maize grown in vitro

Abstract

Plants were regenerated from callus cultures of maize inbred W182BN with the S(USDA) type of cytoplasmic male sterility (cms). Some regenerates from 16 of 18 separate cultures had fertile tassels. Many other regenerates, whose fertility could not be scored accurately because of abnormal plant morphology, produced fertile progeny after pollination with N cytoplasm W182BN. Revertant plants and/or progeny were obtained from all 18 cultures, which included the CA, D, LBN, and S sources of cmsS. More revertants were recovered from cultures maintained as callus for 12 months than from 3-4 month old cultures. Several types of evidence (absence of segregation for fertility after selfing or pollination of revertants with standard W182BN, pollen viability counts, failure of revertants to restore sterile cmsS lines to fertility, mitochondrial DNA analyses) indicated that the reversion to fertility involved cytoplasmic rather than nuclear alterations. All revertants examined lacked the S1 and S2 plasmid-like DNAs characteristic of the mitochondrial genome of sterile cmsS lines. Most callus cultures lost S1 and S2 after 13-20 months in vitro. No revertants were seen among thousands of W182BN cmsS plants grown from seed in the field or among plants from tissue cultures of W182BN with the C or T types of cms. The cytoplasmic revertants recovered from culture may be useful for the molecular analysis of cmsS.

Patterns of mitochondrial DNA instability in Brassica campestris cultured cells

“…4B). Therefore, based on these observations and similar reports [32,6,12], it appears that in most but not all cases [20,50] 33 the duration of in vitro growth has a continuing impact on the level of changes of the plant mitochondrial genome. At present, there is little evidence for the effect of culture systems (e.g.…”

“…The instability of the mitochondrial genome has been investigated in somatic hybrids [ 15,38,60,41,21 ] as well as in vitro cultures of various plant systems [8,39,18,58,50,4]. An often cited example of culture-induced somaclonal variation associated with mtDNA is the reversion to fertility of different cytoplasmic malesterile types in maize [16,5,12,48]. In several reports, the nature of mitochondrial genome alteration in vitro has been attributed to the culture system, such as the age [34], culture type [7], or the in vitro technique employed [23].…”

Inheritance of male sterility mutations induced in haploid sorghum tissue culture

“…It is well-known that the mitochondrial genome, that controls CMS together with the nuclear genome, is sometimes highly unstable in tissue culture conditions (Kemble & Shepard, 1984;Wilson et al, 1985;Hartmann et al, 1989). Male fertile revertants have been obtained from calli derived from CMS maize plants (Gengenbach et al, 1977;Brettell et al, 1980;Earle et al, 1987). The revertants had cytoplasmic inheritance of induced fertility and considerable rearrangements in their mitochondrial genomes (Schardle et al, 1985;Small et al, 1988;Fauron et al, 1990).…”

Analysis of genic male sterility in Brassica oleracea

“…The consequence of these findings is that mslms I and ms6ms 6 cannot be used as starting material in tissue culture experiments with the aim to induce cytoplasmic revertants, to be used as maintainers in F 1 hybrid breeding programs, on the basis of CMS. Cytoplasmic revertants have been obtained in tissue culture for maize CMS-S (Earle et al, 1987), maize CMS-T (Rottmann et al, 1987) and Brassica napus (Bonhomme et al, 1991). The unexpected segregation of sex phenotypes in the F 2 progenies 5.2.10 and 5.2.11 cannot be explained by classification errors, as the deviations observed in both progenies are far more larger than the deviation found in the F, progeny 5.2.28, where only four individuals were misclassified (Table 2).…”