Breeding of Vegetable, Spice and Tuber Crops

4.Environmental Genic Male Sterility (EGMS)

Environmental Genic Male Sterility (EGMS)

• EGMS is more popularly termed as “Two line Hybrid Breeding” as against “Three Line Hybrid Breeding” in case of CMS system. Certain GMS lines are conditional mutants, meaning thereby, in particular environment male sterile mutant plants turn into male fertile.
• After determination of critical environment (Usually temperature or photoperiod) for sterility and fertility expression, such GMS mutants are classified under Environmental Genic Male Sterility (EGMS) lines. EGMS lines have been reported in several vegetable crops.
• However, from practical view point, it is necessary to identify critical temperature or photoperiod for the fertility/sterility expression in temperature and photoperiod sensitive genetic male sterility, respectively and may not be hundred per cent.
• Seeds of EGMS line can be multiplied in an environment where it expresses male fertility trait, while hybrid seed can be produced in other environment, where it expresses male sterility trait.
• Initially EGMS lines were thought to be very less practical value, as they were unstable. But now they are considered to represent most efficient system for hybrid seed production.