Yan Zhao

Background: Sulfur (S) is a vital element for the normal growth and development of plants, performing crucial biological functions in various life processes. Methods: This study investigated thirteen S utilization efficiency (SUE)-related traits at the seedling stage of wheat using a recombinant inbred line (RIL) population. The quantitative trait loci (QTLs) were mapped by genetic mapping. Thirteen S utilization efficiency-related traits were investigated under two hydroponic culture trials with low S (0.1S, T1), moderate S (0.5S, T2), and high S (1.5S, T3) levels, using the wheat RILs. Results: A total of 170 QTLs for the thirteen traits in different treatment environments were identified. Among them, 89, 103, and 101 QTLs were found in T1, T2, and T3, respectively. A total of 63 QTLs were found in the multiple treatment environments, the other 107 QTLs only being detected in a single treatment environment. Among them, thirteen relatively high-frequency QTLs (RHF-QTLs) and eleven QTL clusters were found. Five (QSh-1D, QRn-1D, QSdw-1D, QTdw-1D, and QTsc-1D) and six (QRdw-6A, QSdw-6A, QTdw-6A, QRsc-6A, QSsc-6A, and QTsc-6A) RHF-QTLs were identified in QTL clusters C3 and C10, respectively. Conclusion: These thirteen RHF-QTLs and eleven QTL clusters are expected to apply to the molecular marker-assisted selection (MAS) of wheat.

In wheat, a series of dwarf and semi-dwarf plant varieties have been developed and utilized worldwide since the 1960s and caused the ‘Green Revolution’. To date, 25 reduced-height (Rht) genes have been identified, but only several genes for plant height (PH) have been isolated previously. In this study, we identified a candidate gene, ATP-dependent DNA helicase (TaDHL-7B), for PH via QTL mapping and genome-wide association study (GWAS) methods. We knocked out this gene using the CRISPR/Cas9 system in variety ‘Fielder’. Two homozygous mutant genotypes, AAbbDD (−5 bp) and AAbbDD (−1 bp), were obtained in the T₂ generation. The PH values of AAbbDD (−5 bp) and AAbbDD (−1 bp) were significantly reduced compared with the wild-type (WT, ‘Fielder’), indicating that TaDHL-7B is a novel Rht gene that controls the PH. This is the first time that a PH gene of wheat has been isolated with a non-hormone pathway, providing a new insight into the genetic control of PH. The TaDHL gene reduced the PH without a yield penalty. It could be used to improve the lodging resistance and yield in wheat breeding programs.

Potassium (K) is one of the most important mineral nutrients for wheat. In this study, the effects of low K (LK) treatments and the quantitative trait loci (QTLs) for K, calcium (Ca), and magnesium (Mg) use efficiency traits, both at the seedling and maturity stages of wheat, were investigated. The set of “Tainong 18 × Linmai 6” recombinant inbred lines (RILs) were used to identify the QTLs under different K treatments using hydroponic culture and field trials. The majority of K concentrations and content-related traits at seedling and maturity stages decreased with reduced K supply, but the K use efficiency-related traits increased. In contrast, with reduced K supply, the contents of Ca and Mg increased, while the Ca and Mg use efficiency decreased. A total of 217 QTLs for seedling traits and 89 QTLs for adult traits were detected. Four relatively high-frequency QTLs (RHF-QTLs) and 18 QTL clusters (colocation of QTLs for more than two traits) were detected. Eight clusters were detected for K-, Ca-, and Mg-related traits simultaneously. This means that these traits might be controlled by the same QTL. In addition, we highlight that 4B might be an important chromosome regulating the nutrition of K, Ca, and Mg in wheat. The 4B chromosome and four hot QTL clusters, which located 45 QTLs, might be important potential targets for further investigation.