Salt tolerance at germination and vegetative growth involves different mechanisms in barnyard grass (Echinochloa crusgalli L.) mutants

• Published in: Plant growth regulation 2010, Vol.60 (1), p.1-12
• Main Authors: Abogadallah, Gaber M, Serag, Mamdouh M, El-Katouny, Taha M, Quick, W. Paul
• Format: Article
• Language: English
• Subjects: Agriculture; Biomedical and Life Sciences; Grasses; Life Sciences; Mutants; Original Paper; Plant Anatomy/Development; Plant Physiology; Plant Sciences; Salt tolerance; Seeds; Sodium chloride
• ISSN: 0167-6903; 1573-5087
• DOI: 10.1007/s10725-009-9413-9

In this study we describe the selection and characterization of barnyard grass (Echinochloa crusgalli L.) mutants (fows B) with vegetative salt tolerance as compared to a previously described mutant with salt tolerant germination (fows A3). Salt tolerance of both types of mutants was characterized in two distinctive stages of plant development, germination and vegetative growth. About 46% of fows A3 seeds germinated in 300 mM NaCl but none of the seeds of the wild type or fows B mutants were able to germinate in this salt concentration. However, fows B mutants showed significantly higher fresh weights compared to the wild type and the fows A3 mutant when grown in the presence of 200 mM NaCl for 25 days. This indicated that fows B mutants are more salt tolerant than fows A3 mutant as well the wild type. The vegetative salt tolerance of the fows B mutants depended mainly on maintaining more efficient photosynthetic machinery, by keeping significantly higher chlorophyll and Rubisco contents and accumulating soluble sugars particularly sucrose. In addition, fows B mutants had significantly lower malondialdehyde (MDA) contents than did fows A3 and the wild type. This was apparently the result of higher activities of catalase (CAT) and peroxidase (POD) in fows B mutants compared to the wild type and fows A3, indicating that more efficient control of reactive oxygen species correlates with salt tolerance. However, proline accumulation and K⁺/Na⁺ ratio did seem to be essential to vegetative salt tolerance. The vegetative salt tolerance mechanisms in fows B mutants were weakly expressed in the wild type and fows A3 mutant. The results provide evidence that salt tolerance during germination and vegetative growth could involve different mechanisms.