Huiyong Zhang

Fusarium ear rot (FER), caused by Fusarium verticillioides (F. verticillioides), is a major disease of maize that reduces grain yield and quality globally. However, few major loci for FER have been verified and cloned. Resistance to FER is a quantitative trait influenced by environmental conditions, and maize genotypes completely resistant to the pathogen remain unknown. To gain a comprehensive understanding of the genetic basis of natural variation in FER resistance, a recombinant inbred line (RIL) population consisting of 257 progenies was developed by crossing the resistant line BT with the susceptible line Xi502. This population was genotyped using a set of 6807 high-density single nucleotide polymorphism (SNP) markers developed in this study. As a result, a total of five QTLs were identified by linkage mapping across three years, located on five chromosomes, and explaining 4.38–13.13% of the phenotypic variation. Among these was a major QTL, qFER5-2. Located on chromosome 5 within the interval 185568562–185574073, qFER5-2 explained 13.13% of the total phenotypic variance. The two candidate genes within qFER5-2 exhibited distinct expression profiles between the BT and Xi502 inbred lines, suggesting their potential association with FER resistance. Collectively, these findings provide candidate genetic resources for further investigation and offer potentially useful materials for maize disease resistance breeding.

The escalating global temperatures and intensifying heat stress events pose significant threats to maize productivity worldwide. Uncovering key thermotolerance genes and their functional mechanisms is thus critical for developing climate‐resilient crops. Here, we report that ZmCTU2, a cytoplasmic tRNA thiolation factor, acts as a central regulator of heat tolerance in maize. Expression of ZmCTU2 correlates positively with kernel‐setting under high temperatures. Overexpression of ZmCTU2 confers enhanced thermotolerance at both seedling and adult stages, improving survival and field yield under heat stress, whereas loss‐of‐function mutants of ZmCTU2 or its partner ZmCTU1 display severe seed developmental defects and lethality. Mechanistically, ZmCTU2 translocates to stress granules under thermal stress, where it recruits ZmCTU1 and ROS‐scavenging peroxidases, shielding them from degradation. This dual recruitment facilitates synergistic protective responses: maintenance of tRNA thiolation to ensure translational fidelity, and stabilisation of antioxidative enzymes to bolster redox homeostasis. Our study identifies ZmCTU2 as a scaffold protein within stress granules that coordinates proteostatic and antioxidative pathways under heat stress, providing a valuable genetic resource for engineering thermotolerant maize.

Drought stress is a common abiotic challenge that profoundly impacts plant growth and development. As sessile organisms, plants rely on various physiological and morphological adaptations to cope with drought conditions. The CIPK (calcineurin B‐like protein‐interacting protein kinase) family proteins play a pivotal role in mediating plant responses to abiotic stress through modulation of cellular membrane events via the CBL‐CIPK complex. However, reports documenting the CIPKs’ regulation of non‐membrane events are scant. In this study, we discovered a novel subcellular localisation pattern of the AtCIPK20 protein of Arabidopsis, specifically to cortical microtubules (cMT), which is distinct from previously reported localisation patterns of plant CIPKs. AtCIPK20 regulates ABA‐induced loss of cMT organisation in guard cells, thereby facilitating stomatal closure, mitigating leaf water loss, and protecting plants from drought stress in Arabidopsis. The C‐terminal regulatory domain of AtCIPK20 governs its cMT targeting, whereas the interaction of AtCIPK20 with its CBL partners disrupts this localisation. Notably, the cMT targeting characteristic of AtCIPK20 is not exclusive, as several other CIPK members in Arabidopsis, maize, and rice exhibit similar localisation patterns. These findings broaden our current understanding of the role of plant CIPK members in abiotic stress resistance and suggest that future exploration of CIPK molecular functions should adopt a more comprehensive perspective.

Summary: Fusarium verticillioides (F. verticillioides) is a widely distributed phytopathogen that incites multiple destructive diseases in maize, posing a grave threat to corn yields and quality worldwide. However, there are few reports of resistance genes to F. verticillioides. Here, we reveal that a combination of two single nucleotide polymorphisms (SNPs) corresponding to ZmWAX2 gene associates with quantitative resistance variations to F. verticillioides in maize through a genome‐wide association study. A lack of ZmWAX2 compromises maize resistance to F. verticillioides‐caused seed rot, seedling blight and stalk rot by reducing cuticular wax deposition, while the transgenic plants overexpressing ZmWAX2 show significantly increased immunity to F. verticillioides. A natural occurrence of two 7‐bp deletions within the promoter increases ZmWAX2 transcription, thus enhancing maize resistance to F. verticillioides. Upon Fusarium stalk rot, ZmWAX2 greatly promotes the yield and grain quality of maize. Our studies demonstrate that ZmWAX2 confers multiple disease resistances caused by F. verticillioides and can serve as an important gene target for the development of F. verticillioides‐resistant maize varieties.

Internal fungal contamination in cereal grains may affect plant growth and result in health concerns for humans and animals. Fusarium verticillioides is a seedborne fungus that can systemically infect maize. However, few efforts had been devoted to studying the genetics of maize resistance to seedborne F. verticillioides. In this study, we developed a disease evaluation method to identify resistance to seedborne F. verticillioides in maize, by which a set of 121 diverse maize inbred lines were evaluated. A 160 F₁₀-generation recombinant inbred line (RIL) population derived from a cross of the resistant (BT-1) and susceptible (N6) inbred line was further used to identify major quantitative trait loci (QTLs) for seedborne F. verticillioides resistance. Eighteen inbred lines with a high resistance to seedborne F. verticillioides were characterized and could be used as potential germplasm resources for genetic improvement of maize resistance. Six QTLs with high heritability across multiple environments were detected on chromosomes 3, 4, 6, and 10, among which was a major QTL, qISFR4-1. Located on chromosome 4 at the interval of 12922609-13418025, qISFR4-1 could explain 16.63% of the total phenotypic variance. Distinct expression profiles of eight candidate genes in qISFR4-1 between BT-1 and N6 inbred lines suggested their pivotal regulatory roles in seedborne F. verticillioides resistance. Taken together, these results will improve our understanding of the resistant mechanisms of seedborne F. verticillioides and would provide valuable germplasm resources for disease resistance breeding in maize.

Although microRNAs (miRNAs) regulate the defence response against multiple pathogenic fungi in diverse plant species, few efforts have been devoted to deciphering the involvement of miRNA in resistance to Fusarium verticillioides , a major pathogenic fungus affecting maize production. In this study, we discovered a novel F. verticillioides‐ responsive miRNA designated zma‐unmiR4 in maize kernels. The expression of zma‐unmiR4 was significantly repressed in the resistant maize line but induced in the susceptible lines upon exposure to F. verticillioides exposure, whereas its target gene ZmGA2ox4 exhibited the opposite pattern of expression. Heterologous overexpression of zma‐unmiR4 in Arabidopsis resulted in enhanced growth and compromised resistance to F. verticillioides . By contrast, transgenic plants overexpressing ZmGA2ox4 or the homologue AtGA2ox7 showed impaired growth and enhanced resistance to F. verticillioides . Moreover, zma‐unmiR4‐mediated suppression of AtGA2ox7 disturbed the accumulation of bioactive gibberellin (GA) in transgenic plants and perturbed the expression of a set of defence‐related genes in response to F. verticillioides . Exogenous application of GA or a GA biosynthesis inhibitor modulated F. verticillioides resistance in different plants . Taken together, our results suggest that the zma‐unmiR4– ZmGA2ox4 module might act as a major player in balancing growth and resistance to F. verticillioides in maize.

Development of interactive web applications to deposit, visualize and analyze biological datasets is a major subject of bioinformatics. R is a programming language for data science, which is also one of the most popular languages used in biological data analysis and bioinformatics. However, building interactive web applications was a great challenge for R users before the Shiny package was developed by the RStudio company in 2012. By compiling R code into HTML, CSS and JavaScript code, Shiny has made it incredibly easy to build web applications for the large R community in bioinformatics and for even non-programmers. Over 470 biological web applications have been developed with R/Shiny up to now. To further promote the utilization of R/Shiny, we reviewed the development of biological web applications with R/Shiny, including eminent biological web applications built with R/Shiny, basic steps to build an R/Shiny application, commonly used R packages to build the interface and server of R/Shiny applications, deployment of R/Shiny applications in the cloud and online resources for R/Shiny.

MicroRNAs (miRNAs) play key roles in the post‐transcriptional regulation of gene expression in plants. Many miRNAs are responsive to environmental signals. Light is the first environmental signal perceived by plants after emergence from the soil. However, less is known about the roles and regulatory mechanism of miRNAs in response to light signal. Here, using small RNA sequencing, we determined that miR163 is significantly rapidly induced by light signaling in Arabidopsis thaliana seedlings. The light‐inducible response of miR163 functions genetically downstream of LONG HYPOCOTYL 5 (HY5), a central positive regulator of photomorphogenesis. HY5 directly binds to the two G/C‐hybrid elements in the miR163 promoter with unequal affinity; one of these elements, which is located next to the transcription start site, plays a major role in light‐induced expression of miR163. Overexpression of miR163 rescued the defective primary root elongation of hy5 seedlings without affecting lateral root growth, whereas overexpressing of miR163 target PXMT1 inhibited primary root elongation. These findings provide insight into understanding the post‐transcriptional regulation of root photomorphogenesis mediated by the HY5‐miR163‐PXMT1 network.

Fusarium ear rot (FER) caused by Fusarium verticillioides is one of the most common diseases affecting maize production worldwide. FER results in severe yield losses and grain contamination with health-threatening mycotoxins. Although most studies to date have focused on comprehensive analysis of gene regulation in maize during defense responses against F. verticillioides infection, less is known about the role of microRNAs (miRNAs) in this process. We used deep sequencing to compare small RNA libraries from the maize kernels of susceptible (N6) or resistant (BT-1) inbred lines from uninfected plants and upon F. verticillioides infection. We found that pathogen exposure was accompanied by dynamic alterations in expression levels of multiple miRNAs, including new members of previously annotated miRNA families. A combination of transcriptomic, degradomic, and bioinformatics analyses revealed that F. verticillioides-responsive miRNAs and their potential target genes displayed opposite expression patterns in the susceptible and resistant genotypes. Functional category analysis uncovered preferential enrichment of the pathogen-responsive miRNAs and their targets in the phenylpropanoid metabolic processes, plant–pathogen interactions, and plant phytohormone signal transduction pathways. Furthermore, transgenic maize plants overexpressing miR408b exhibited reduced resistance to F. verticillioides infection in a susceptible maize line. These findings provide new insights into the regulatory roles of miRNAs in maize immunity against FER and new resources for breeding disease resistance into maize.