Chlorogenic acid facilitates root hair formation in lettuce seedlings.

Root hairs, which arise from root epidermal cells, are tubular structures that increase the efficiency of water absorption and nutrient uptake. A low pH (pH 4) medium induced root hair formation in lettuce (Lactuca sativa L.) seedlings, and the decapitation of shoots inhibited root hair formation. The addition of shoot extract to the medium restored root hair formation in the decapitated lettuce seedlings. These results suggest that factors essential to the formation of root hairs may be present in the shoot. We purified one factor from the shoot that facilitates root hair formation. This factor was identified as chlorogenic acid (CGA), a common polyphenol in higher plants. The presence of exogenous CGA in the medium induced root hair formation in decapitated lettuce seedlings at pH 4.0 and in intact lettuce seedlings at pH 6.0. The optimum concentration of CGA for root hair formation was identified as 10(-5) M. Decapitation of the shoots reduced the CGA content in the roots to approximately one-third that in intact plants. Application of the CGA biosynthesis inhibitor L-alpha-aminooxy-beta-phenylpropionic acid (AOPP, 10(-6) M) to intact seedlings grown at pH 4.0 reduced both the CGA content of the roots and the total amount of root hairs. The addition of exogenous CGA restored root hair formation in intact seedlings treated with AOPP. These results suggest that CGA is essential for root hair formation in lettuce seedlings.

[1]  D. E. Koeppe,et al.  The relationship of tissue chlorogenic acid concentrations and leaching of phenolics from sunflowers grown under varying phosphate nutrient conditions , 1976 .

[2]  E. Tsuzuki,et al.  Interactions oftrans-cinnamic acid, its related phenolic allelochemicals, and abscisic acid in seedling growth and seed germination of lettuce , 1993, Journal of Chemical Ecology.

[3]  I. Galis,et al.  Resistance of transgenic tobacco seedlings expressing the Agrobacterium tumefaciens C58-6b gene, to growth-inhibitory levels of cytokinin is associated with elevated IAA levels and activation of phenylpropanoid metabolism. , 2002, Plant & cell physiology.

[4]  Cathie Martin,et al.  Engineering plants with increased levels of the antioxidant chlorogenic acid , 2004, Nature Biotechnology.

[5]  L. Herrera-Estrella,et al.  The role of nutrient availability in regulating root architecture. , 2003, Current opinion in plant biology.

[6]  U. Takahama Ascorbic Acid-Dependent Regulation of Redox Levels of Chlorogenic Acid and its Isomers in the Apoplast of Leaves of Nicotiana tabacum L. , 1998 .

[7]  L. Dolan,et al.  The role of reactive oxygen species in cell growth: lessons from root hairs. , 2006, Journal of experimental botany.

[8]  Y. Inoue,et al.  Randomization of cortical microtubules in root epidermal cells induces root hair initiation in lettuce (Lactuca sativa L.) seedlings. , 2003, Plant & cell physiology.

[9]  Masae Konno,et al.  Role of manganese in low-pH-induced root hair formation in Lactuca sativa cv. Grand Rapids seedlings , 2003, Journal of Plant Research.

[10]  Jonathan D. G. Jones,et al.  Reactive oxygen species produced by NADPH oxidase regulate plant cell growth , 2003, Nature.

[11]  D. Inzé,et al.  Cell proliferation and hair tip growth in the Arabidopsis root are under mechanistically different forms of redox control. , 1997, Proceedings of the National Academy of Sciences of the United States of America.

[12]  Y. Inoue,et al.  Ethylene promotes the induction by auxin of the cortical microtubule randomization required for low-pH-induced root hair initiation in lettuce (Lactuca sativa L.) seedlings. , 2003, Plant & cell physiology.

[13]  J. Lynch,et al.  Stimulation of root hair elongation in Arabidopsis thaliana by low phosphorus availability , 1996 .

[14]  R. J. Pitts,et al.  Auxin and ethylene promote root hair elongation in Arabidopsis. , 1998, The Plant journal : for cell and molecular biology.

[15]  B. Logan,et al.  Energy dissipation and radical scavenging by the plant phenylpropanoid pathway. , 2000, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[16]  Y. Inoue,et al.  Isolation and characterization of the ACC synthase genes from lettuce (Lactuca sativa L.), and the involvement in low pH-induced root hair initiation. , 2003, Plant & cell physiology.

[17]  N. Amrhein,et al.  Novel inhibitors of ethylene production in higher plants , 1979 .

[18]  Y. Inoue,et al.  Effects of Low pH on the Induction of Root Hair Formation in Young Lettuce (Lactuca sativa L. cv. Grand Rapids) Seedlings , 2000, Journal of Plant Research.

[19]  Y. Inoue,et al.  Effect of Light on Root Hair Formation in Arabidopsis thaliana Phytochrome-Deficient Mutants , 2000, Journal of Plant Research.

[20]  S. Gilroy,et al.  Oscillations in extracellular pH and reactive oxygen species modulate tip growth of Arabidopsis root hairs , 2007, Proceedings of the National Academy of Sciences.

[21]  Y. Inoue,et al.  Evidence of Phytochrome Mediation in the Low-pH-Induced Root Hair Formation Process in Lettuce (Lactuca sativa L. cv. Grand Rapids) Seedlings , 2000, Journal of Plant Research.

[22]  L. Dolan Positional information and mobile transcriptional regulators determine cell pattern in the Arabidopsis root epidermis. , 2006, Journal of experimental botany.

[23]  M. Ishimaru,et al.  Correlation of Flowering Induced by Low Temperature and Endogenous Levels of Phenylpropanoids inPharbitis nil: A Study with a Secondary-metabolism Mutant , 1996 .

[24]  Y. Inoue,et al.  Image Processing-Aided Simple Analysis Method for Root Hair Formation in Plants , 1995 .

[25]  Yuejin Wu,et al.  Targeted Irradiation of Shoot Apical Meristem of Arabidopsis Embryos Induces Long-Distance Bystander/Abscopal Effects , 2007, Radiation research.

[26]  J. Esseling,et al.  Microtubules guide root hair tip growth. , 2005, The New phytologist.

[27]  L. Mondolot,et al.  Evolution in caffeoylquinic acid content and histolocalization during Coffea canephora leaf development. , 2006, Annals of botany.

[28]  L. Dolan,et al.  Cell expansion in roots. , 2004, Current opinion in plant biology.

[29]  M. Zucker The Influence of Light on Synthesis of Protein and of Chlorogenic Acid in Potato Tuber Tissue. , 1963, Plant physiology.

[30]  L. Dolan,et al.  Ethylene is a positive regulator of root hair development in Arabidopsis thaliana. , 1995, The Plant journal : for cell and molecular biology.