The presence of apoplastic DAFP-1, even at fairly modest levels of activity,
produced a small, but significant, decrease in the temperature at
which freezing was initiated. (4) The fourth cooling protocol produced freezing that began at much lower temperatures. Stems were
severed at the base, mounted in vacuum grease, and cooled at
5 ◦ C h−1 . These plants were not sprayed with water or Cit7 bacteria. Once again, the transgenics with apoplastic DAFP-1 froze at a
significantly lower (p ≤ 0.05) temperature (−16.6 ◦ C) than the wild-
type (−13.3 ◦ C), an average of 3.3 ◦ C colder.