Random amplified polymorphic DNA (RAPD) marker associated with salt tolerance during seeds germination and growth of selected Acacia senegal provenances
Seed germination and seedling growth of 20 provenances of Acacia senegal were evaluated under salinity conditions. For germination study, seeds irrigated with NaCl in five concentrations had electrical conductivities (EC) of 0 (only distilled water), 2, 4, 6 and 10 dSm-1. Final germination percentage (FG) and germination rate index (GRI) were recorded during 14 days. The result showed significant effect of salinity and provenance on FG and GRI. Seed germination was significantly reduced in all provenances with the increase in NaCl concentrations. Provenance Al Feel (FE, clay+ high rainfall) from Eastern Sudan was more tolerant than the other provenances at seed emergence stage. Greenhouse experiment examined the growth response of 8 provenances A. senegal chosen as the most tolerant provenances at seeds germination study. Potted seedlings aged 3 weeks were irrigated with 0, 4, 6 and 10 dSm-1. Seedling height, root length, shoot dry weight, root dry weight and root/shoot ratio were measured for 4 weeks. Provenances showed a large variability in growth characteristics. No correlation between seed sources (soil type and rainfall) and growth response was found. However, provenance MH shows tolerance to salt stress at seedling stage. The genetic polymorphism between the provenances was detected by RAPD analysis. Forty four (44) out of 51 bands detected were polymorphic for the provenances of A. senegal and the dissimilarity indices between the studied provenances were less than 39%.
Key words: Acacia Senegal, provenance variation, random amplified polymorphic DNA (RAPD) marker, salt tolerance, seed germination, seedling growth.