Structural and functional features of Triticum aestivum (Poaceae) plants at the initial period of cold adaptation
2008
Venzhik, Yu.V. | Frolova, S.A. | Titov, A.F., Russian Academy of Sciences, Petrozavodsk (Russian Federation). Karelian Research Centre | Koteeva, N.K. | Miroslavov, E.A., Russian Academy of Sciences , Saint-Petersburg (Russian Federation). The V. L. Komarov Botanic Inst.
Wheat seedlings of the frost-resistant variety Moskovskaya 39 grown in filter-paper on Knop nutrient media at the temperature of a climate chamber of 25 deg C are tested. After one week of the growth the seedlings have been treated by cold (at a temperature of 4 deg C). The temperature caused the destruction of 50% leaf parenchyma palisade cells after freezing during 5 min is considered as a measure of plant cold resistance. After 1 hour of hardening the stroma of chloroplasts (CP) and mitochondrions (MD) consolidates, the percentage of grans with a little thylakoid number and the one of big grans decreases in the CP. After 24 h the peroxisoma (PX) and CP size enlarges, the PX and MD number increases and the percentage of small grans transcends the control values nearly in 2 times. After 96 h the gran number decreases, the CP stroma volume expands, the CP and PX are grouped around the CP by 4-5 units. The total content of chlorophyll and its content in light-harvesting complex have lowered during the first 24 h of hardening and then have increased gradually. Carotenoid content has not changed during the first 2 days and then it has risen. Amidase activity has grown up a little after 1 h of cold treatment and then it has fell down. Cysteic proteinase activity has reached the maximum meaning on the second day of hardening after growing up, but then it has gone down being higher in compare with the control plants. A new structural and functional organization of plant cells is formed during the process of hardening is concluded. This organization allows tolerating cold temperatures without disastrous effects.
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