Introgression of Wild Alleles for Improving Abiotic Stress Resistance in Crop Plants

The genetic diversity in wild ancestors of crop plants has been eroded throughout plant domestication and selection in man-made agroecosystems, thus making modern crops vulnerable to environmental stresses. Therefore, introgression of wild alleles into domesticated forms is a major objective of modern breeding.

In wheat (Triticum spp.), QTLs conferring drought resistance were introgressed from wild emmer wheat (T. turgidum ssp. dicoccoides) into durum (T. turgidum ssp. durum) and bread wheat (T. aestivum) cultivars.  The resultant near isogenic lines (NILs) were compared with their recurrent parents under well-watered and water-limited treatments. NIL-U-2B-3, a durum wheat cultivar introgressed with QTL on chromosome 2B, exhibited under both treatments higher grain yield. NIL-B-7A-2, a bread wheat cultivar introgressed with QTL on chromosome 7A, exhibited under water-limited conditions greater grain yield, osmotic adjustment and photosynthetic capacity. In both cases comparisons were made under similar phenology.

In tomato (Solanum spp.), 76 introgression lines (ILs) each containing a single introgression from wild tomato (S. pennellii) in the background of domesticated tomato (S. licopersicon, cv. M82) and their F1 (ILs x M82) progenies were studied under fresh and saline water irrigation.  While none of the ILs exhibited a significant advantage in responses to salinity compared to the parental genotype, F1 hybrids carrying heterozygous introgressions in chromosomes 2, 7 & 9 exhibited heterotic effects and superior performance under salinity.

The results obtained for both crops provide evidences that introgression of major wild QTLs alleles, in a homo- or heretozygote state, can improve crop resilience to various abiotic stress conditions.