The growth of Arabidopsis primary root is repressed by several and diverse amino acids through auxin-dependent and independent mechanisms and MPK6 kinase activity

• Published in: Plant science (Limerick) Vol. 302; p. 110717
• Main Authors: Ravelo-Ortega, Gustavo, López-Bucio, Jesús Salvador, Ruiz-Herrera, León Francisco, Pelagio-Flores, Ramón, Ayala-Rodríguez, Juan Ángel, de la Cruz, Homero Reyes, Guevara-García, Ángel Arturo, López-Bucio, José
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.01.2021
• Subjects: Amino acids; Amino Acids - metabolism; Amino Acids - physiology; Arabidopsis - enzymology; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - metabolism; Arabidopsis Proteins - physiology; Auxin; Biostimulants; Glutamic Acid - metabolism; Indoleacetic Acids - metabolism; Leucine - metabolism; Lysine - metabolism; Mitogen-Activated Protein Kinases - metabolism; Mitogen-Activated Protein Kinases - physiology; MPK6; Plant Growth Regulators - metabolism; Plant Growth Regulators - physiology; Plant Root Cap - metabolism; Plant Root Cap - physiology; Plant Roots - enzymology; Plant Roots - growth & development; Plant Roots - metabolism; Root development; Seedlings - enzymology; Seedlings - growth & development; Seedlings - metabolism; Tryptophan - metabolism; Amino acids; MPK6; Auxin; Root development; Biostimulants
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2020.110717

•The growth of the Arabidopsis primary root is affected by various amino acids.•Bioactive amino acids are sensed at the root apex and affect both cell division and elongation.•l-Glu, l-Leu, l-Lys and l-Trp show gene-dependent, specific changes in auxin response.•MPK6 activity is induced by several amino acids and mediates their growth repressing effects in roots. Amino acids serve as structural monomers for protein synthesis and are considered important biostimulants for plants. In this report, the effects of all 20-L amino acids in Arabidopsis primary root growth were evaluated. 15 amino acids inhibited growth, being l-leucine (l-Leu), l-lysine (l-Lys), l-tryptophan (l-Trp), and l-glutamate (l-Glu) the most active, which repressed both cell division and elongation in primary roots. Comparisons of DR5:GFP expression and growth of WT Arabidopsis seedlings and several auxin response mutants including slr, axr1 and axr2 single mutants, arf7/arf19 double mutant and tir1/afb2/afb3 triple mutant, treated with inhibitory concentrations of l-Glu, l-Leu, l-Lys and l-Trp revealed gene-dependent, specific changes in auxin response. In addition, l- isomers of Glu, Leu and Lys, but not l-Trp diminished the GFP fluorescence of pPIN1::PIN1:GFP, pPIN2::PIN2:GFP, pPIN3::PIN3:GFP and pPIN7::PIN7:GFP constructs in root tips. MPK6 activity in roots was enhanced by amino acid treatment, being greater in response to l-Trp while mpk6 mutants supported cell division and elongation at high doses of l-Glu, l-Leu, l-Lys and l-Trp. We conclude that independently of their auxin modulating properties, amino acids signals converge in MPK6 to alter the Arabidopsis primary root growth.