Over-expression of a barley aquaporin increased the shoot/root ratio and raised salt sensitivity in transgenic rice plants.
Barley HvPIP2;1 is a plasma membrane aquaporin and its expression was down-regulated after salt stress in barley [Katsuhara et al. (2002) Plant Cell Physiol. 43: 885]. We produced and analyzed transgenic rice plants over-expressing barley HvPIP2;1 in the present study. Over-expression of HvPIP2;1 increased (1) radial hydraulic conductivity of roots (Lp(r)) to 140%, and (2) the mass ratio of shoot to root up to 150%. In these transgenic rice plants under salt stress of 100 mM NaCl, growth reduction was greater than in non-transgenic plants. A decrease in shoot water content (from 79% to 61%) and reduction of root mass or shoot mass (both less than 40% of non-stressed plants) were observed in transgenic plants under salt stress for 2 weeks. These results indicated that over-expression of HvPIP2;1 makes rice plants sensitive to 100 mM NaCl. The possible involvement of aquaporins in salt tolerance is discussed.
Katsuhara
Maki
M
Research Institute for Bioresources, Okayama University, Kurashiki, 710-0046 Japan. kmaki@rib.okayama-u.ac.jp
Koshio
Kazuki
K
Shibasaka
Mineo
M
Hayashi
Yasuyuki
Y
Hayakawa
Takahiko
T
Kasamo
Kunihiro
K
D000222:Adaptation, Physiological / Q000235:genetics / Q000502:physiology; D020346:Aquaporins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D001467:Hordeum / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D008969:Molecular Sequence Data; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D009997:Osmotic Pressure / Q000187:drug effects; D010940:Plant Proteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D018520:Plant Shoots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D030821:Plants, Genetically Modified; D012965:Sodium Chloride / Q000494:pharmacology*
D020346:Aquaporins; D010940:Plant Proteins; C110065:major intrinsic protein, plant; D012965:Sodium Chloride