Molecular cytogenetic characterization of an Agropyron cristatum 6PL chromosome segment conferring superior kernel traits in wheat

The wild relative of wheat, Agropyron cristatum (L.) Gaertn. (genome PPPP), acts as an important genetic resource for providing valuable genes for wheat improvement and increasing the diversity of cultivated wheat. In the present study, cytogenetic and molecular tools were used to characterize wheat-A. cristatum 6P derivatives. The novel translocation line Pubing260 exhibiting wider flag leaves and superior spike traits was further characterized and analysed. Cytological studies demonstrated that Pubing260 (2n = 42) contained a T3BL3BS-6PL terminal translocation. We compared molecular markers on chromosomes 6P and 3B and confirmed that the translocated wheat chromosome was 3BS and that the chromosome breakage occurred in bin 3BS9-0.57-0.75. Compared with its recurrent parent Fukuhokomugi, Pubing260 had a wider flag leaf, more spikelets and more grains per spike in two growing seasons. Genetic analysis conducted using BC1F2 and BC2F1 populations suggested that the A. cristatum chromosomal fragment from bin 6PL-0.72-1.00 conferred these potentially valuable agronomic traits. On average, the flag leaf width (FLW), and numbers of grain per spike (GNS), spikelets per spike (SNS) and kernels per spikelet of plants with the translocation were 2 mm wider and 5.1, 0.8 and 0.3 higher, respectively, than those of plants lacking the translocation in segregating populations. Significant and positive correlations were observed among GNS, SNS and FLW. In summary, this study not only reports a novel germplasm that is potentially valuable for wheat improvement but also enriches the genetic resources of wheat.