Cytoplasmic-Nuclear Male Sterility: Origin, Evaluation and Utilization uri icon

abstract

  • Cytoplasmic-nuclear male sterility (CMS), a potential system for economicalhybrid seeds production, results from disharmonious interaction between thecytoplasmic and nuclear genetic factors. Evaluation of CMS system for its utilityis determined by many factors. Unstable male sterility increases cost and affectsquality of hybrid seed production. Cooler weather during panicle developmentpromotes instability in maize and pigeonpea, high humidity in pearl millet andhot temperature of 42 °C and above in sorghum. Effect of genetic background ofB-lines on male sterility has been found in case of Al CMS system in pearlmillet and sorghum, and fertility restorer gene expressivity in rice. Maintainergene frequency in germplasm is another factor to be considered which hasbearing on genetic diversification of A-lines. In case of Al CMS system insorghum and pearl millet landraces have greater proportion as restorers.Character association influences the commercial viability of a CMS system.Approaches to estimate the diversity of CMS systems to enhance the exploitationof outstanding inbred lines and also to overcome the risk of disease and pestepidemics, include both traditional field evaluation of hybrids for differentialpatterns of male fertility restoration and RFLP analysis of mitochondFial DNA.Steps involved in CMS utilization in hybrid cultivar breeding including (i)identification of potential CMS sources, (ii) development of seed parents (Alines) exhibiting complete sterility, (iii) maintenance of seed parents by takingappropriate steps to prevent contamination with foreign pollen, (iv) developmentof restorer parents through identification of promising restorers, geneticimprovement of existing restorers and transfer of restorer genes into highyielding inbred lines and (v) hybrid seed production keeping in view the four keyelements - isolation distance, off type removal, flowering synchrony between AandR-lines, and A:R lines ratio are discussed

publication date

  • 2004
  • 2004