Yield performance of chromosomally engineered durum wheat-Thinopyrum ponticum recombinant lines in a range of contrasting rain-fed environments across three countries

Introgressions of Thinopyrum ponticum 7AgL chromosome segments spanning 23%, 28% and 40% of the distal end of durum wheat 7AL arm were previously shown to contain multiple beneficial gene(s)/QTL for yield-related traits. In the present study, durum wheat near isogenic recombinant lines (NIRLs) harbouring each of the three introgressions, were included for the first time in multi-location field trials, to evaluate general and environment-specific effects of the alien chromatin on 25 yield-related traits. The results from 11 different trials across contrasting environments of three countries and five years revealed that the presence of 7AgL chromatin had the strongest positive effect on spike (+11%) and grain number (+9%) m -2 , which represented the main contributors to the observed increases in grain yield and biomass (2-6%). In particular, grain yield was significantly increased (+18%) in 7AgL-carrier NIRLs in the water-limited South Australian environment. NIRLs carrying 23% and 28% 7AgL (named R5 and R112, respectively) displayed 2-30% higher grain yield with respect to the site′s mean in most of the tested environments. Thus, also for other positive 7AgL genes they carry ( Lr19 , Sr25 , Yp ), they could be readily moved into site-directed breeding pipelines. Across all environments evaluated, the NIRL with a 40%-long 7AgL segment (named R23) resulted in increasing effects on grain number m -2 and spike -1 (averaging 47% and 14%, respectively) when compared with its control (no-7AgL). From comparison with the other NIRLs, this major gene/QTL can be located within the most proximal 28-40% 7AgL region, exclusive to the R23 recombinant. The present study represents an important validation of the use of chromosomally engineered genetic stocks for targeted durum wheat improvement.