Molecular Characterization of Atlas 66-Derived Wheat Near-lsogenic Lines Contrasting in Aluminum (Al) Tolerance

Aluminum (Al) toxicity is the major limiting factor for wheat growth in acidic soils. Genetic improvement of A1 tolerance is one of the most cost-effective solutions to improve wheat productivity. The objective of this study was to characterize near isogenic lines (NILs) contrasting in A1 tolerance derived from Atlas 66 in the backgrounds of Al-sensitive cultivars Chisholm and Century using amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR). A total of 200 AFLP and 88 SSR primer pairs were screened and 12 markers (11 AFLPs and one SSR) were associated with Al-tolerance in NILs of at least one recurrent parental background. Among them, nine were linked to A1 tolerance in the Chisholm-derived NILs, seven were associated with Al-tolerance in the Century-derived NILs, and three AFLPs derived from the primer combinations of pAG/mGCAG, pCAG/mAGC and pGTG/mGCG, and one SSR, Xwmc331 on chromosome 4D, associated with A1 tolerance in NILs of both recurrent parental backgrounds. Those common markers across two backgrounds may be the major marker loci associated with Al-tolerance in Atlas 66 and could be useful for marker-assisted breeding to improve A1 tolerance in wheat. In addition, evaluation of A1 tolerance among different genotypes using hematoxylin stain and relative root growth revealed that Atlas 66 was more tolerant to A1 stress than the NILs, therefore suggested that the Al-tolerant NILs might not carry all Al-tolerance loci from Atlas 66 and inheritance of A1 tolerance in Atlas 66 is more likely multigenic.