Reversible or irreversible change of molecular dynamics of water in pea seedlings exposed to heat stress

Mari Iwaya-Inoue, Kei Motooka, Hiroaki Nakamoto, Masataka Fukuyama

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Influences of heat stress on epicotyls of pea (Pisum sativum L.) plants were investigated by using non-destructive method. NMR spin-lattice relaxation time (T 1), indicating molecular dynamics of water, was determined in tall type, cv. Alaska and dwarf type, cv. Progress No. 9 seedlings grown under light condition. In no-elongation zone for both fresh cultivars a rapid decrease in T 1 occurred in the tissues exposed to 20-30°C while rapid increase followed by gradual decrease occurred in T 1 for the tissues exposed to 20-40°C during a heat-cool cycle. On the other hand, in heat-denatured dead tissues, T 1 linearly corresponded. Further, when pea plants were heated for 5 h at 20-30°C or 20-40°C thermal hysteresis changes in T 1 corresponding temperature in the subsequent heat-cool cycles was notably different. Epicotyls exposed to 30°C treatments did not show temperature dependency while those of the tissues exposed to 40°C indicated temperature dependency. After the subsequent heat-cool cycles, the former was alive, the latter indicated tissue necrosis. Therefore, the change in T 1 of epicotyls observed within 1 h was considered a fast adaptation or mortality in cells to heat stress, and a temperature dependency of T 1 in the subsequent heat-cool cycles clearly reflected tissue viability in pea epicotyls. In conclusion, T 1 on thermal response can be used as an indicator of reversible or irreversible injury in an intact plant.

Original languageEnglish
Pages (from-to)39-47
Number of pages9
JournalJournal of the Faculty of Agriculture, Kyushu University
Issue number1
Publication statusPublished - Feb 2004

All Science Journal Classification (ASJC) codes

  • Agricultural and Biological Sciences (miscellaneous)


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