Fusarium ear rot (FER), caused by Fusarium verticillioides, is a destructive fungal disease of maize. FER resistance is a complex, quantitatively inherited trait controlled by multiple minor-effect genes. In this study, we employed two recombinant inbred line (RIL) populations with the common resistant parental line CML304 to identify FER-resistance loci. Initial QTL analysis identified 23 FER-resistance QTL, each explaining 5.21%–30.51% of the total phenotypic variation. Notably, one major QTL, qRfv2, on chromosome 2 was repeatedly detected, accounting for 11.92%–30.51% of the total phenotypic variation. qRfv2 was fine mapped to an interval of 1.01 Mb, flanked by the markers IDP8 and IDP10. qRfv2 is a semi-dominant resistance gene that could reduce the disease severity index (DSI) by 12.4%–20%, suggesting its potential for enhancing FER resistance in maize. Transcriptome analysis showed that 22 of the 28 annotated functional genes in the qRfv2 region displayed differential expression between parental lines in response to FER. One of the candidate genes, ZmLOX6, was validated to presumably provide a positive effect on FER resistance. Our study provides a basis for the potential cloning and application of FER resistance genes in maize breeding.

Grain water content (GWC) is a key determinant for mechanical harvesting of maize (Zea mays). In our previous research, we identified a quantitative trait locus, qGWC1, associated with GWC in maize. Here, we examined near-isogenic lines (NILs) NIL^L and NIL^H that differed at the qGWC1 locus. Lower GWC in NIL^L was primarily attributed to reduced grain water weight (GWW) and smaller fresh grain size, rather than the accumulation of dry matter. The difference in GWC between the NILs became more pronounced approximately 35 d after pollination (DAP), arising from a faster dehydration rate in NIL^L. Through an integrated analysis of the transcriptome, proteome, and metabolome, coupled with an examination of hormones and their derivatives, we detected a marked decrease in JA, along with an increase in cytokinin, storage forms of IAA (IAA-Glu, IAA-ASP), and IAA precursor IPA in immature NIL^L kernels. During kernel development, genes associated with sucrose synthases, starch biosynthesis, and zein production in NIL^L, exhibited an initial up-regulation followed by a gradual down-regulation, compared to those in NIL^H. This discovery highlights the crucial role of phytohormone homeostasis and genes related to kernel development in balancing GWC and dry matter accumulation in maize kernels.

Control of flowering time is crucial for reproductive success of cereal crops, and has a significant impact on grain yield as well as adaptation to diverse environmental conditions. Plants integrate signals from both environmental cues and endogenous regulatory pathways to fine-tune flowering time. The CCT domain originally described to a 43-amino acid sequence at the C-terminus of three Arabidopsis proteins, namely CONSTANS (CO), CO-LIKE, and TIMING OF CAB1 (TOC1). The CCT domain-containing genes (CCT genes), which encode transcription co-factors, are the major genetic determinants that modulate flowering time, and this in turn enables plants to effectively expand their territory to take advantage of favorable habitats. Moreover, certain CCT genes have pleiotropic effects on morphological traits and confer resistance/tolerance to biotic/abiotic stresses. CCT genes can be classified into three families, namely COL (CONSTANS-like), PRR (Pseudo-response regulator), and CMF (CCT motif family), based on their non-CCT domains. During domestication, natural and artificial selection resulted in reduced nucleotide diversity of CCT genes in modern cultivated cereals than their wild types. Here, we review the features and functions of CCT genes in cereal crops and propose future research to focus on CCT genes and their utilization in crop breeding.

Head smut, caused by the fungal pathogen Sporisorium reilianum, poses a grave threat to maize (Zea mays) production worldwide. Here we report cytological and molecular evidence for maize resistance to head smut. During early stages of root infection, S. reilianum mycelium was capable of penetrating the root epidermis of both resistant (Ji1037) and susceptible (HZ4) inbred lines. S. reilianum hyphae were observed in the root–stem junction at 6days after inoculation. In an attempt to monitor hyphal spread within the maize plant, a highly specific and sensitive real-time PCR method was established to estimate the hyphal content in infected maize tissues. During the upward growth of endophytic S. reilianum, the extent of hyphal spread was markedly different between Ji1037 and HZ4. Very little or no pathogen was detected in aerial parts of Ji1037, whereas large amounts of pathogen accumulated in aboveground tissues, particularly inflorescences, of HZ4. Thus, maize resistance to S. reilianum was achieved mainly by inhibition of endophytic hyphal growth rather than by prevention of early-root penetration by the pathogen.