Salt acclimation in sorghum plants by exogenous proline: physiological and biochemical changes and regulation of proline metabolism

  • Paulo André Ferreira de Freitas
  • Humberto Henrique de Carvalho
  • José Hélio Costa
  • Rafael de Souza Miranda
  • Kátia Daniella da Cruz Saraiva
  • Francisco Dalton Barreto de Oliveira
  • Daniel Gomes Coelho
  • José Tarquinio Prisco
  • Enéas Gomes-FilhoEmail author
Original Article


Key message

Mitigation of deleterious effects of salinity promoted by exogenous proline can be partially explained by changes in proline enzymatic metabolism and expression of specific proline-related genes.


Proline accumulation is a usual response to salinity. We studied the ability of exogenous proline to mitigate the salt harmful effects in sorghum (Sorghum bicolor) leaves. Ten-day-old plants were cultivated in Hoagland’s nutrient solution in either the absence or presence of salinity (NaCl at 75 mM) and sprayed with distilled water or 30 mM proline solution. Salinity deleterious effects were alleviated by exogenous proline 14 days after treatment, with a return in growth and recovery of leaf area and photosynthetic parameters. Part of the salinity response reflected an improvement in ionic homeostasis, provided by reduction in Na+ and Cl ions and increases in K+ and Ca2+ ions as well as increases of compatible solutes. In addition, the application of proline decreased membrane damage and did not increase relative water content. Proline-treated salt-stressed plants displayed increase in proline content, a response counterbalanced by punctual modulation in proline synthesis (down-regulation of Δ1-pyrroline-5-carboxylate synthetase activity) and degradation (up-regulation of proline dehydrogenase activity) enzymes. These responses were correlated with expression of specific proline-related genes (p5cs1 and prodh). Our findings clearly show that proline treatment results in favorable changes, reducing salt-induced damage and improving salt acclimation in sorghum plants.


Gene expression Salinity tolerance Sorghum bicolor Proline treatment 



Control treatment


Days after treatments




High-affinity K+ transporter


Na+/H+ antiporter exchanger




Proline treatment




Pyrroline-5-carboxylate dehydrogenase


Δ1-pyrroline-5-carboxylate reductase


P5C synthetase


Proline dehydrogenase/proline oxidase


Saline treatment


Salt overly sensitive 1 Na+/H+ antiporter


Saline/proline treatment



We thank Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for financial support and scholarships.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Supplementary material

299_2019_2382_MOESM1_ESM.doc (594 kb)
Supplementary material 1 (DOC 593 KB)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Departamento de Bioquímica e Biologia Molecular, Instituto Nacional de Ciência e Tecnologia em Salinidade (INCTSal/CNPq)Universidade Federal do CearáFortalezaBrazil
  2. 2.Universidade Federal do PiauíBom JesusBrazil
  3. 3.Instituto Federal de Educação, Ciência e Tecnologia da ParaíbaPrincesa IsabelBrazil

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