TY - JOUR
T1 - Mycorrhizal symbiosis and response of sorghum plants to combined drought and salinity stresses
AU - Cho, Keunho
AU - Toler, Heather
AU - Lee, Jaehoon
AU - Ownley, Bonnie
AU - Stutz, Jean C.
AU - Moore, Jennifer L.
AU - Augé, Robert M.
N1 - Funding Information:
This manuscript is based upon work supported by the US Department of Agriculture under Award no. 00-35100-9238 and by the Tennessee Agricultural Experiment Station.
PY - 2006/3/3
Y1 - 2006/3/3
N2 - Arbuscular mycorrhizal (AM) symbiosis can confer increased host resistance to drought stress, although the effect is unpredictable. Since AM symbiosis also frequently increases host resistance to salinity stress, and since drought and salinity stress are often linked in drying soils, we speculated that the AM influence on plant drought response may be partially the result of AM influence on salinity stress. We tested the hypothesis that AM-induced effects on drought responses would be more pronounced when plants of comparable size are exposed to drought in salinized soils. In two greenhouse experiments, several water relations characteristics were measured in sorghum plants colonized by Glomus intraradices (Gi), Gigaspora margarita (Gm) or a mixture of AM species, during a sustained drought following exposure to salinity treatments (NaCl stress, osmotic stress via concentrated macronutrients, or soil leaching). The presence of excess salt in soils widened the difference in drought responses between AM and nonAM plants in just two instances. Days required for plants to reach stomatal closure were similar for Gi and nonAM plants exposed to drought alone, but with exposure to combined NaCl and drought stress, stomates of Gi plants remained open 17-22% longer than in nonAM plants. Promotion of stomatal conductance by Gm occurred with exposure to NaCl/drought stress but not with drought alone or with soil leaching before drought. In other instances, however, the addition of salt tended to nullify an AM-induced change in drought response. Our findings confirm that AM fungi can alter host response to drought but do not lend much support to the idea that AM-induced salt resistance might help explain why AM plants can be more resilient to drought stress than their nonAM counterparts.
AB - Arbuscular mycorrhizal (AM) symbiosis can confer increased host resistance to drought stress, although the effect is unpredictable. Since AM symbiosis also frequently increases host resistance to salinity stress, and since drought and salinity stress are often linked in drying soils, we speculated that the AM influence on plant drought response may be partially the result of AM influence on salinity stress. We tested the hypothesis that AM-induced effects on drought responses would be more pronounced when plants of comparable size are exposed to drought in salinized soils. In two greenhouse experiments, several water relations characteristics were measured in sorghum plants colonized by Glomus intraradices (Gi), Gigaspora margarita (Gm) or a mixture of AM species, during a sustained drought following exposure to salinity treatments (NaCl stress, osmotic stress via concentrated macronutrients, or soil leaching). The presence of excess salt in soils widened the difference in drought responses between AM and nonAM plants in just two instances. Days required for plants to reach stomatal closure were similar for Gi and nonAM plants exposed to drought alone, but with exposure to combined NaCl and drought stress, stomates of Gi plants remained open 17-22% longer than in nonAM plants. Promotion of stomatal conductance by Gm occurred with exposure to NaCl/drought stress but not with drought alone or with soil leaching before drought. In other instances, however, the addition of salt tended to nullify an AM-induced change in drought response. Our findings confirm that AM fungi can alter host response to drought but do not lend much support to the idea that AM-induced salt resistance might help explain why AM plants can be more resilient to drought stress than their nonAM counterparts.
KW - Arbuscular mycorrhizal symbiosis
KW - Drought stress
KW - Lethal water potential
KW - Salinity stress
KW - Sorghum
KW - Stomatal conductance
UR - http://www.scopus.com/inward/record.url?scp=32344431983&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=32344431983&partnerID=8YFLogxK
U2 - 10.1016/j.jplph.2005.05.003
DO - 10.1016/j.jplph.2005.05.003
M3 - Article
C2 - 16473656
AN - SCOPUS:32344431983
SN - 0176-1617
VL - 163
SP - 517
EP - 528
JO - Journal of Plant Physiology
JF - Journal of Plant Physiology
IS - 5
ER -