Morphophysiological adaptation aspects of different Haloxylon aphyllum (Chenopodiaceae) genotypes along a salinity gradient

The seedlings of Haloxylon aphyllum from seeds with different genetic characteristics, which were collected in three natural subpopulations along a soil salinity gradient, were investigated. The plants grown under various levels of NaCl (0–300 mM) differed in the shoot length, the relative growth rate (calculated for fresh and dry biomass), as well as ions and proline contents. The heterozygous genotypes of xerohalophytic H. aphyllum have shown significant advantages in their productivity and sustainability under moderate and high salinity.     

Genetic differentiation of black saxaul, Haloxylon aphyllum (Chenopodiaceae), along a soil salinity gradient in the Kyzylkum Desert

Populations of Haloxylon àphyllum in the Kyzylkum Desert have been found to be markedly deficient in heterozygotes at a medium level of genetic diversity (P ₉₅ = 0.56, A = 1.67, H _o = 0.14, H _e = 0.28). Spatial genetic differentiation of these populations have been revealed along a soil salinity gradient (from 0 to 0.5 mmol Na⁺/g), with their genetic diversity reaching a maximum (H _o = 0.21?C0.25, H _e = 0.25?C0.27) in areas with a moderate salinity level (0.05?C0.1 mmol Na⁺/g). Locus Got-2 can serve as a marker of this differentiation (Fst_Got-2 = 0.4).     

Genetic Diversity in Annual Xerohalophytes of the Family Chenopodiaceae along Soil Moisture and Salinity Gradients

Genetic polymorphism has been studied in populations of two annual xerohalophyte species of the family Chenopodiaceae, Atriplex tatarica and Sedobassia sedoides, growing on soils with different levels of soil moisture and sodium and potassium ion contents. A tendency toward decrease in the percentage of polymorphic loci in A. tatarica at higher soil salinity and increase in the observed heterozygosity of S. sedoides populations at higher levels of soil potassium has been revealed, with parameters of genetic variation in either species showing no dependence on soil moisture. Soil potassium deficiency is a stress factor for S. sedoides at both physiological and population-genetic levels. Mechanisms controlling sodium absorption and maintaining ion homeostasis and also a high level of homozygosity in S. sedoides indicate the improvement of stress tolerance in this annual species.