Abstract

Sulla constitutes an important genetic resource contributing to pastoral production, particularly in semi-arid regions. In Tunisia, seedlings of the southern species Sulla carnosa (Desf.) and the northern species Sulla coronaria (L.) were treated with NaCl (0, 100 and 200 mM) for 27 days. Salt treatments decreased leaf dry matter more in S. carnosa than in S. coronaria. S. coronaria accumulated less Na⁺ and greater amounts of K⁺ and showed greater K/Na selectivity, a trait which could be related to the maintenance of higher net K⁺ uptake and transport in the presence of NaCl. Pigments were severely affected by salt stress in leaves of S. carnosa when compared with leaves of S. coronaria. In addition to these physiological characterisations, genetic diversity was measured between the two accessions using inter simple sequence repeat (ISSR) markers. Three ISSR primers generated a total of 63 DNA amplicons for S. carnosa and 64 DNA amplicons for S. coronaria, all of which were polymorphic between the two accessions. Correlations between the molecular and physiological data revealed statistically significant correlations between the salt response of these two Sulla accessions and two molecular markers B340 and B860, in roots and shoots, respectively. S. coronaria showed greater salt tolerance on the basis of growth and K/Na selectivity, making it a good candidate for inclusion in a future breeding programme.

Key words: Salt constraint, Sulla, growth, ISSR markers.

Abbreviation

AFLP, Amplified fragment length polymorphism; ISSR, inter simple sequence repeat; PCR, polymerase chain reaction; RAPD, random amplified polymorphic DNA; RFLP, restriction fragment length polymorphism; SSR, simplesequence repeat.