Powdery mildew caused by Blumeria graminis f. sp. tritici (Bgt) is a destructive wheat disease. Although it can be easily overcome by deployment of resistance genes, the resistance is often quickly compromised by pathogen virulence. Thus, exploration and characterization of new resistance genes is always ongoing. Line NJ3946 derived from a cross of einkorn wheat accessions TA2032 and M389 showed resistance to powdery mildew. Inheritance analysis of an F₂ population derived from a cross of NJ3946 and M389 suggested that the resistance was conferred by a dominant allele. With polymorphic markers identified through bulked segregant analysis (BSA), this gene was mapped to a novel locus on chromosome 3A, and was designated as PmNJ3946. Bulked segregant RNA-seq analysis (BSR-seq) was conducted to obtain more closely linked markers, which allowed delimitation of the PMNJ3946 locus to a 0.9 cM interval covering a physical distance of less than 1 Mb. PMNJ3946 was flanked by Xwgrc5153 and SNP-derived marker CHS21_3A008915069, and co-segregated with SNP-derived markers CHS21_3A008939814 and CHS21_3A008943175. The PmNJ3946 discovery expands the diversity of powdery mildew resistance genes and is useful for wheat breeding.

Spike architecture is an indicative trait of grain yield in common wheat (Triticum aestivum). A segregating population was generated for mapping genes contributing to spike morphometric traits by crossing the two common wheat cultivars 'CItr 17600' with branching spikes and 'Yangmai 18' with normal spikes. A major quantitative trait locus for spike length was mapped to the Q5A region of chromosome 5A. Yangmai 18 carried a Q5Ab allele for short spikes, which harbored one SNP in the last intron, and a 1-bp InDel in the 720-bp fragment from the start codon, compared to Q5Aa in Chinese Spring. CItr 17600 harbored a q5Ab allele for long spikes, which has a 6-bp deletion compared to the reported q5Aa allele that was involved in the binding site of microRNA 172 (miR172). This 6-bp deletion in immediately upstream of this binding site was involved in changes of four amino acids. The natural q5A allele appeared to be rare in common wheat but frequent in tetraploid T. turgidum accessions with branching spikes. The CRISPR/Cas9 technology was used to edit the upstream region involving in the miR172 binding site in Yangmai 18 and identified two independent editing events, one with a 1-bp insertion in Q5A and the other with a 2-bp deletion in Q5D, resulting in several shapes of spikes in the transgenic progeny. In addition to the effects of natural q5A allele and the edited Q5A genes, this study indicated the regeneratability and transformability of Yangmai 18 as an elite cultivar. Altogether, this study provides insight into future modification and engineering of spike architecture in common wheat.

Fusarium head blight (FHB) or scab caused by Fusarium graminearum is a major threat to wheat production in China as well as in the world. To combat this disease, multiple efforts have been carried out internationally. In this article, we review our long-time effort in identifying the resistance genes and dissecting the resistance mechanisms by both forward and reverse genetics approaches in the last two decades. We present recent progress in resistance QTL identification, candidate functional gene discovery, marker-assisted improvement of FHB resistant varieties, and findings in investigating association of signal molecules, such as Ca⁺⁺, SA, JA, and ET, with FHB response, with the assistance from rapidly growing genomics platforms. The information will be helpful for designing novel and efficient approaches to curb FHB.