Development and identification of an elite wheat-Hordeum californicum T6HcS/6BL translocation line ND646 containing several desirable traits

Abstract

Hordeum californicum (H. californicum, 2n=2X=14, HcHc), one of the wild relatives of wheat (Triticum aestivum L.), harbors many desirable genes and is a potential genetic resource for wheat improvement. In this study, an elite line ND646 was selected from a BC4F5 population, which was developed using 60Co-γ irradiated wheat-H. californicum disomic addition line WJ28-1 (DA6Hc) as the donor parent and Ningchun 4 as the recurrent parent. ND646 was identified as a novel wheat-H. californicum 6HcS/6BL translocation line using genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), and H. californicum-specific expressed sequence tag (EST) markers. Further evaluation revealed that ND646 had excellent performance in several traits, such as a higher sedimentation value (SV), higher water absorption rate (WAR), and higher hardness index (HI). More importantly, it had more kernels per spike (KPS), a higher grain yields (GY), and good resistance to powdery mildew, leaf rust, and 2,4-D butylate (2,4-D). Its excellent phenotypic performance laid the foundation for further investigation of its genetic architecture and makes ND646 a useful germplasm resource for wheat breeding.

Figure 1 -. Scheme of the development of whea-tH.californicum translocation line ND646.

Figure 2 -. Sequential GISH/FISH analysis of the wheat- H.californicum translocation line ND646. a. GISH of ND646, the genome DNA of H.californicum was visualized in bright green; b. FISH of ND646 using pSc119.2 (shown in red) and pAs1 (shown in green) repetitive DNA as probes, white arrows show the translocation chromosome; c. GISH and FISH diagram of translocation chromosomes in DN646, respectively; d. There were 21 bivalents containing one translocation bivalent (shown in green) at the metaphase I (MI) stage in pollen mother cells (PMCs) of ND646 (Scale bar = 20µm).

Figure 3 -. Amplification of EST-PCR primer pairs in the parents and ND646. a-d. Markers CINAU 91, CINAU 502, CINAU 506 and CINAU 511, respectively. 1-4 were CS, WJ28-1, ND646 and Ningchun 4, respectively; 5-20 were the amplification of marker CINAU 91 in 16 individual plants of ND646; M was a DNA marker with a molecular weight of 100, 250, 500, 750, 1000 and 2000 bp. Arrows showed specific banding of 6H^cS and 6H^cL chromosomes.

Figure 4 -. Responses to diseases and herbicides of Ningchun 4 and ND646. 1 and 2 represent Ningchun 4 and ND646, respectively. a. Powdery mildew on flag leaves; b. Leaf rust on flag leaves; c. Effects of 2,4-D on spikes and whole plants, respectively.

Figure 5 -. Dynamics of grain volume (GV), fresh grain weight (FGW), dry grain weight (DGW), and grain moisture (GM) of Ningchun 4 and ND646 during grain filling.

Figure 6 -. Dynamics of grain filling rate of Ningchun 4 and ND646.