Causes of Cytoplasmic Male Sterility

• Cytoplasmic male sterility, or CMS, is an inherited trait. The gene that causes sterile pollen is passed from the female plant to the male plant. The trait may be passed from the female plant via the mitochondria to the nucleus of the cell. Environmental factors, such as pollution and radiation, may contribute to CMS and decreased plant populations. Hybridization often results in CMS in commercially grown agricultural plants.
  
  

Affected Plants

• CMS is not limited to specific species of plants, but hybrid plants are most often affected. Male sterility is common in hybrid corn, rice, wheat and flowering plants. Plants that carry the genetic mutation for male sterility cannot successfully self-pollinate, but may produce viable seed through cross-pollination. The seeds from self-pollinated hybrid plants are usually male sterile.
  
  

Impact on Food Production

• Hybrid crops with the mitochondrial defect causing cytoplasmic male sterility will produce sterile seeds if self-pollinated. Hybrid crops usually produce higher yields per acre of land, but because most crops are self-pollinated, the resulting seeds are sterile. This problem may be overcome by introducing genetic material into the male hybrid line that will restore male fertility in hybrid seeds. This method has been used for commercially grown radishes, rice and sunflowers.
  
  

Research

• Research into the causes of and genetic remedies for cytoplasmic male sterility in plants has helped scientists to develop hybrid plants that are not sterile. Advances in CMS research have led to genetic modifications of food crops that mature rapidly and produce greater yields than non-hybrid plants. Research to produce a gene sequence to restore fertility to hybrid plants may help to increase global food production.