Increased tolerance to salinity in citrus rootstocks

Citrus are species highly sensitive to salinity but are frequently grown in arid and semiarid areas where salinity is a threat.
As a consequence, much effort has been dedicated to obtaining new rootstocks and cultivars able to endure salt stress conditions.
In this study, four mutants (MM3B, MM4A, MM4B and MMN1) of Citrus macrophylla were studied for their tolerance to 100 mM of NaCl.
The salt stress was maintained for 8 weeks, after which, plant growth, leaf damage, and plant and root dry weight were assessed.
The Na, Cl^– and NO₃^– contents were measured to check the levels of toxic ions absorbed, as well as any alteration in the absorption dynamic.
All the mutants showed an improved tolerance to salinity compared with Citrus macrophylla. Also, all the mutants were more efficient than Citrus macrophylla with regard to exclusion of toxic ions. Citrus macrophylla plants had more damaged leaves than the mutant plants.
MM4B and MMN1 plants showed higher growth than Citrus macrophylla and the other two mutants, while the biomass, both of roots and the shoot, of most of the mutants was less reduced than in Citrus macrophylla plants.
The leaf Na (MM4B and MMN1) or Cl^– (MM4A, MM3B) contents were lower in the mutants than in Citrus macrophylla. Furthermore, the greater the extent to which mutant plants were able to exclude Cl^–, the more efficient they were in NO₃^– absorption, which is an advantage for plants that struggle to balance nutrient absorption in stress conditions.

IV International Symposium on Horticulture in Europe – SHE2021

M. Pérez-Jiménez, F. Córdoba, V. Celdrán-Sánchez, R.C. García-Almodóvar, O. Pérez-Tornero

salt stress, sodium, chloride, gamma rays, citrus breeding, mutagenesis

https://doi.org/10.17660/ActaHortic.2021.1327.83