title: Effects of exogenous 5-aminolevulinic acid on photosynthesis, stomatal conductance, transpiration rate, and PIP gene expression of tomato seedlings subject to salinity stress.
abstract: The effects of exogenous 5-aminolevulinic acid (ALA) on photosynthesis, plant growth, and the expression of two aquaporin genes in tomato seedlings under control and salinity conditions were investigated. Exogenous ALA application significantly improved net photosynthetic rate (Pn), total chlorophyll content, and plant biomass accumulation of tomato seedlings under salinity stress. As revealed by real-time PCR analyses, after treatment with ALA alone, expression of both LePIP1 and LePIP2 in the two tomato cultivars was up-regulated at 2 h and subsequently decreased to normal levels. Under salinity stress, transcript levels of LePIP1 in both leaves and roots of salt-sensitive cultivars (cv. Zhongza No.9) increased significantly and were considerably higher than in cultivars exposed to ALA alone. In contrast, the expression levels of LePIP1 and LePIP2 in cvs. Jinpeng No.1 cultivars were slightly lower under salinity stress than under ALA treatment. In addition, transcript levels of both LePIP1 and LePIP2 in the roots of Jinpeng No. 1 cultivars were considerably lower than those in the roots of Zhongza No. 9 cultivars under salinity stress, regardless of ALA supplementation, implying that Jinpeng No. 1 cultivars had a better capacity to maintain membrane intrinsic protein stability. Further, ALA application distinctly counteracted the up- or down-regulation of LePIP1 and LePIP2 in both cultivars under salinity stress, in accordance with the improvements instomatal conductance, transpiration rate, and Pn of tomato leaves. The results presented here indicate that ALA controls aquaporin expression, thus, presumably ALA regulates water homeostasis and enhances salt tolerance of tomato seedlings.
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: Y Y
authors.initials: YY
authors.lastname: Zhao
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: F
authors.initials: F
authors.lastname: Yan
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: L P
authors.initials: LP
authors.lastname: Hu
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: X T
authors.initials: XT
authors.lastname: Zhou
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China zouzhirong2005@hotmail.com.
authors.forename: Z R
authors.initials: ZR
authors.lastname: Zou
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: L R
authors.initials: LR
authors.lastname: Cui
mesh_terms: D000622:Aminolevulinic Acid / Q000494:pharmacology; D002734:Chlorophyll / Q000378:metabolism; D018551:Solanum lycopersicum / Q000187:drug effects / Q000254:growth & development*; D010788:Photosynthesis / Q000187:drug effects* / Q000235:genetics; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D054712:Salinity; D055049:Salt Tolerance / Q000187:drug effects*; D036226:Seedlings / Q000187:drug effects / Q000235:genetics*; D013312:Stress, Physiological / Q000187:drug effects
chemical_list: D002734:Chlorophyll; D000622:Aminolevulinic Acid