Black point (BP) disease affects wheat ( Triticum aestivum ) production worldwide, and identifying BP resistance genes is essential for developing resistant cultivars. We previously detected QBB.hau-4A , a major QTL for BP resistance, using the fungal pathogen Bipolaris sorokiniana with a recombinant inbred line (RIL) population from a cross between wheat lines Wanyuanbai 1 and SN4143. Here, we fine mapped QBB.hau-4A using secondary F 2 and F 2:3 populations derived from resistant and susceptible RILs. Using 14 dCAPS markers, the QTL was delimited to a 1.36 Mb interval. With gene-specific markers, we narrowed this interval to a 1.06 Mb region between markers BP-100-d1 and BP-4A-d34 (40.87–41.93 Mb), containing six high-confidence genes in the Chinese Spring reference genome. Based on parental expression patterns and sequence polymorphisms, we identified four candidate genes for QBB.hau-4A : TraesCS4A02G050400 , TraesCS4A02G050500 , TraesCS4A02G050700 , and TraesCS4A02G050800 . Of these, TraesCS4A02G050800 is the most likely candidate for QBB.hau-4A . We developed BP-800-d1 , a gene-specific marker for TraesCS4A02G050800 based on a SNP and an InDel distinguishing the resistant and susceptible parents. This marker was subsequently validated in two F 2 populations and a diverse panel of 412 wheat accessions. To our knowledge, this study represents one of the first efforts to identify candidate genes associated with BP resistance. In addition to offering valuable information for understanding the complex genetic basis of BP resistance, it provides molecular markers for breeders.
In rice ( Oryza sativa L.), the vascular bundle tissue in the panicle neck plays a critical role in transporting photosynthetic products, nutrients, and water from the roots and leaves to the panicles, and is positively associated with grain yield. However, the genetic mechanisms regulating vascular bundle number in the panicle neck remain poorly understood. Here, we report the map-based cloning and functional characterization of LVN3 , a quantitative trait locus controlling the number of large vascular bundles in rice ( Oryza sativa L.) panicle neck. LVN3 encodes OsGA20ox1, an enzyme in gibberellin (GA) biosynthesis. It is expressed in developing panicles and vascular bundles, and positively regulates both the number and cross-sectional area of vascular bundles in the panicle neck and the second internode, as well as flag leaf size and grain number per panicle. Compared with the near-isogenic line NIL- LVN3 LT , NIL- LVN3 TQ showed significantly increased vascular bundle number and area, enlarged flag leaves, and improved panicle morphology, ultimately leading to a 6.6% increase in grain yield. RNA-seq analysis revealed that LVN3 affects the expression of auxin-related genes in the shoot apex, suggesting that LVN3 -mediated vascular development is partly driven by crosstalk between GA and auxin signaling. Cultivars carrying the LVN3 -2 haplotype exhibited moderate effective panicle number per plant, grain number, and grain weight, yet achieved the highest grain yield among six haplotypes, identifying LVN3 -2 as a superior haplotype for optimizing grain yield components. Moreover, natural variation at position rs3:36150392 in the LVN3 promoter may represent a functional site associated with vascular bundle development and grain number per panicle in the japonic a ( Geng ) subpopulation. Together, these findings demonstrate that LVN3 regulates source capacity, sink size, and transport efficiency, showing potential for application in rice breeding programs aimed at increasing grain yield.
Rice blast, caused by Magnaporthe oryzae , is one of the most destructive diseases threatening rice production worldwide. This study aimed to characterize the function of the transcription factor OsEREBP109 and its regulatory network in rice immunity against M. oryzae. We generated OsEREBP109 overexpression lines and CRISPR/Cas9-mediated knockout mutants to evaluate blast resistance phenotypes. The direct binding and transcriptional activation of OsEREBP109 on its downstream target were examined using yeast one-hybrid, electrophoretic mobility shift assay, and dual-luciferase reporter assays. Overexpression of OsEREBP109 enhanced blast resistance, whereas its knockout significantly reduced resistance. OsEREBP109 was shown to directly bind the cis -element in the promoter of OsGRP5 (encoding a glycine-rich RNA-binding protein) and activate its transcription. Loss-of-function of OsGRP5 compromised resistance to M. oryzae , confirming it as a critical downstream target. Moreover, OsGRP5 associated with RNA and modulated the expression of multiple defence-related genes, including OsARF2 , OsFBX400 , and OsNAC030 . Together, these results define a hierarchical ERF-RBP regulatory module in which OsEREBP109 directly induces OsGRP5 to maintain the abundance of key immune transcripts, thereby enhancing rice resistance to M. oryzae .
Triticum monococcum ssp. aegilopoides (syn. T. boeoticum ) is a wild diploid species that harbors the A b A b genome containing many disease resistance genes useful for wheat improvement. Genetic analysis conducted on an F 2 population from a cross between T. boeoticum accessions PI 427741 and PI 427560, which are contrasting in powdery mildew responses, indicated that the resistance in PI 427741 was controlled by two dominant genes, PmNCA6 and another unknown gene. Bulked segregant exome capture sequencing (BSE-Seq) analysis of a segregating F 3 family without PmNCA6 demonstrated a new powdery mildew resistance gene, Pm72 , on the long arm of chromosome 6A. Through linkage analysis, Pm72 was mapped to a 1.28-cM genetic interval defined by markers XTb6AL04 and XTb6AL06 . According to the reference genome of T. boeoticum accession TA299, the Pm72 locus corresponded to a 940-kb physical region (Chr6A: 635,963,867–636,888,696), containing 21 nucleotide-binding leucine-rich repeat receptor (NLR)-like disease resistance genes. Phenotyping showed that Pm72 confers effective resistance to powdery mildew at both the seedling and the adult-plant stages in the hexaploid wheat background. The co-segregating marker XTb6AL05 was useful for marker-assisted selection of Pm72 . The identification of the new powdery mildew resistance gene Pm72 will contribute to its positional cloning and breeding application in wheat.
