The stay green mutations d1 and d2 increase water stress susceptibility in soybeans

• Published in: Journal of experimental botany Vol. 53; no. 373; pp. 1421 - 1428
• Main Authors: Luquez, Virginia M., Guiamét, Juan J.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01-06-2002; OXFORD UNIVERSITY PRESS; Oxford Publishing Limited (England)
• Subjects: Abscisic Acid - pharmacology; Adaptation, Physiological - drug effects; Adaptation, Physiological - genetics; Agronomy. Soil science and plant productions; Apoptosis - drug effects; Apoptosis - genetics; Apoptosis - physiology; Biological and medical sciences; Cellular senescence; Chlorophyll - metabolism; Chloroplasts; Chloroplasts - drug effects; Chloroplasts - genetics; Chloroplasts - physiology; Dehydration; Drought; Economic plant physiology; Fundamental and applied biological sciences. Psychology; Genotype; Genotypes; Glycine max - drug effects; Glycine max - genetics; Glycine max - physiology; Growth and development; Heat-Shock Proteins - metabolism; Leaves; Moisture content; Morphogenesis, differentiation, rhizogenesis, tuberization. Senescence; Mutation; Osmotic Pressure; Photosynthesis - physiology; Plant physiology and development; Plant Proteins - metabolism; Plant Structures - physiology; Plant Transpiration - physiology; Plants; Regulation of Growth, Development and Whole Organism Physiology; senescence; Senescence and abscission; Soil water deficit; soybean; Soybeans; stay green; Stomatal conductance; stress tolerance; Vegetative apparatus, growth and morphogenesis. Senescence; Water - pharmacology; Water - physiology; Chlorophyll; Senescence; Genetic variant; Stomatal conductance; Plant leaf; Glycine max; Water stress; Grain legume; Sensitivity resistance; Leguminosae; Photosynthetic pigment; Water regime; Drought resistance; Dicotyledones; Sesquiterpenes; Angiospermae; Abscisic acid; Plant growth substance; Spermatophyta; Intraspecific comparison; Mutation; Photosynthesis; Chloroplast
• ISSN: 0022-0957; 1460-2431; 1460-2431
• DOI: 10.1093/jexbot/53.373.1421

The stay green mutant genotype d1d1d2d2 inhibits the breakdown of chloroplast components in senescing leaves of soybean (Glycine max L. Merr.). Together with G (a gene that preserves chlorophyll in the seed coat) they may extend photosynthetic activity in some conditions. While wild‐type soybeans maintain high leaf water potentials right up to abscission, leaves of (GG)d1d1d2d2 dehydrate late in senescence, which suggests that water relations may be altered in the mutant. Three‐week‐old plants were subjected to a moderate water deficit (soil water potential=−0.7 MPa) for 7–10 d. Leaf water potential and relative water content decreased significantly more in response to water deficit in unifoliate leaves of GGd1d1d2d2 than in a near‐isogenic wild‐type line. Down‐regulation of stomatal conductance in response to drought was similar in mutant and wild‐type leaves. Likewise, exogenously applied ABA reduced stomatal conductance to a similar extent in the mutant and the wild type, and applied ABA failed to restore water deficit tolerance in GGd1d1d2d2. Experiments with explants lacking roots indicate that the accelerated dehydration of GGd1d1d2d2 is probably not due to alterations in the roots. In a comparison of near‐isogenic lines carrying different combinations of d1, d2 and G, only d1d1d2d2 and GGd1d1d2d2 (i.e. the genotypes that cause the stay green phenotype) were more suscept ible to water deficit than the wild type. These data suggest that pathways involved in chloroplast disassembly and in the regulation of stress responses may be intertwined and controlled by the same factors.