Abstract
The effects of a subminimal temperature on germinating Zea mays kernels have been studied at the physiological and ultrastructural levels. After 72 h of germination at 16 °C, kernels were exposed to 4 °C for intervals ranging from 4 to 25 days and then returned to 16 °C. Resumption of growth of all the embryos occurred when the cold exposure was 6 or 8 days. When periods at 4 °C were longer than 8 days, a decrease in the percentage of embryos able to grow was observed; this was proportional to the length of cold exposure. After 26 days or more at 4 °C, all the embryos died. An ultrastructural study of the primary root cells showed that modifications occur in the cytoplasm and in the nucleolus. The nucleolus became predominantly fibrillar and unusual ribonucleoproteinic granules [Formula: see text] were frequently observed in and near the nucleolus organizer region. These changes were related to a strong decrease in transcription.
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Claims 6
Claim · model-written summary
Embryos resumed growth after 6 or 8 days of cold exposure at 4 °C.
Zea maysNot reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Zea mays”
e0“kernels were exposed to 4 °C for intervals ranging from 4 to 25 days”
e1“Resumption of growth of all the embryos occurred when the cold exposure was 6 or 8 days”
Claim · model-written summary
Percentage of embryos able to grow decreased when cold periods were longer than 8 days, in proportion to exposure length.
- Treatment
- periods at 4 °C were longer than 8 dayse2
- Outcome
- percentage of embryos able to growe2
- Direction
- decreasee2
- Qualifier
- proportional to the length of cold exposuree2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Zea mays”
e2“When periods at 4 °C were longer than 8 days, a decrease in the percentage of embryos able to grow was observed; this was proportional to the length of cold exposure”
Claim · model-written summary
All embryos died after 26 days or more at 4 °C.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Zea mays”
e3“After 26 days or more at 4 °C, all the embryos died”
Claim · model-written summary
Cold exposure made the nucleolus of primary root cells predominantly fibrillar.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Zea mays”
e0“kernels were exposed to 4 °C for intervals ranging from 4 to 25 days”
e4“The nucleolus became predominantly fibrillar”
e5“An ultrastructural study of the primary root cells showed that modifications occur in the cytoplasm and in the nucleolus”
Claim · model-written summary
Unusual ribonucleoproteinic granules were frequently observed in and near the nucleolus organizer region after cold exposure.
- Organ / stage
- nucleolus organizer regione6
- Treatment
- 4 °Ce0
- Outcome
- unusual ribonucleoproteinic granulese7
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Zea mays”
e0“kernels were exposed to 4 °C for intervals ranging from 4 to 25 days”
e6“were frequently observed in and near the nucleolus organizer region”
e7“unusual ribonucleoproteinic granules”
Claim · model-written summary
Cold-related nucleolar changes were related to a strong decrease in transcription.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Zea mays”
e5“An ultrastructural study of the primary root cells showed that modifications occur in the cytoplasm and in the nucleolus”
e7“These changes were related to a strong decrease in transcription”