Slowing development restores the fertility of thermo-sensitive male-sterile plant lines.

Temperature-sensitive genic male sterility (TGMS) lines are widely used in the breeding of hybrid crops ^1,2 , but by what means temperature as a general environmental factor reverses the fertility of different TGMS lines remains unknown. Here, we identified an Arabidopsis TGMS line named reversible male sterile (rvms) that is fertile at low temperature (17 °C) and encodes a GDSL lipase. Cytological observations and statistical analysis showed that low temperature slows pollen development. Further screening of restorers of rvms, as well as crossing with a slow-growth line at normal temperature (24 °C), demonstrate that slowing of development overcomes the defects of rvms microspores and allows them to develop into functional pollen. Several other Arabidopsis TGMS lines were identified, and their fertility was also restored by slowing of development. Given that male reproductive development is conserved ³ , we propose that slowing of development is a general mechanism applicable to the sterility-fertility conversion of TGMS lines from different plant species.