The physiology and proteomics of drought tolerance in maize: early stomatal closure as a cause of lower tolerance to short-term dehydration?
Understanding the response of a crop to drought is the first step in the breeding of tolerant genotypes. In our study, two maize (Zea mays L.) genotypes with contrasting sensitivity to dehydration were subjected to moderate drought conditions. The subsequent analysis of their physiological parameters revealed a decreased stomatal conductance accompanied by a slighter decrease in the relative water content in the sensitive genotype. In contrast, the tolerant genotype maintained open stomata and active photosynthesis, even under dehydration conditions. Drought-induced changes in the leaf proteome were analyzed by two independent approaches, 2D gel electrophoresis and iTRAQ analysis, which provided compatible but only partially overlapping results. Drought caused the up-regulation of protective and stress-related proteins (mainly chaperones and dehydrins) in both genotypes. The differences in the levels of various detoxification proteins corresponded well with the observed changes in the activities of antioxidant enzymes. The number and levels of up-regulated protective proteins were generally lower in the sensitive genotype, implying a reduced level of proteosynthesis, which was also indicated by specific changes in the components of the translation machinery. Based on these results, we propose that the hypersensitive early stomatal closure in the sensitive genotype leads to the inhibition of photosynthesis and, subsequently, to a less efficient synthesis of the protective/detoxification proteins that are associated with drought tolerance.
Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Prague, Czech Republic.
Monika
M
Benešová
Dana
D
Holá
Lukáš
L
Fischer
Petr L
PL
Jedelský
František
F
Hnilička
Naďa
N
Wilhelmová
Olga
O
Rothová
Marie
M
Kočová
Dagmar
D
Procházková
Jana
J
Honnerová
Lenka
L
Fridrichová
Helena
H
Hniličková
D000222:Adaptation, Physiological; D000975:Antioxidants / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D003681:Dehydration; D055864:Droughts; D015180:Electrophoresis, Gel, Two-Dimensional; D005838:Genotype; D005980:Glutathione Reductase / Q000378:metabolism; D054046:Plant Stomata / Q000502:physiology*; D040901:Proteomics; D013482:Superoxide Dismutase / Q000378:metabolism; D003313:Zea mays / Q000201:enzymology / Q000235:genetics / Q000502:physiology*
D000975:Antioxidants; D002374:Catalase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase