Jihua Tang’s research while affiliated with Henan Agricultural University and other places

Fusarium ear rot (FER) is a global disease caused by the fungal pathogen Fusarium verticillioides. Maize FER resistance is a quantitative trait controlled by polygenes. In this study, a doubled haploid (DH) population involving 159 lines, developed from the inbred lines B73 (susceptible) and CXS161 (highly resistant), was inoculated with Fusarium verticillioides across 4-year–location environment combinations in China during 2021 and 2022. The lines were genotyped using target sequencing with a 10 K SNP array. The results showed that the estimated broad-sense heritability (H2) in each environment ranged from 0.659 to 0.871, with an overall H2 of 0.805. The average genetic length between adjacent markers in the genetic map constructed using multiple single-nucleotide polymorphisms (mSNP) was smaller than that constructed using SNP, whereas the maximal genetic length was almost the same. Using a genetic map constructed with a SNP, two quantitative trait loci (QTL) were identified on chromosomes 2 and 5, which explained 7.65% and 9.58% of the phenotypic variation, respectively. Using the genetic map constructed by mSNP, four QTL were identified, explaining 6.04–12.60% of the phenotypic variation. Moreover, two kompetitive allele-specific PCR (KASP) markers were developed using single-marker analysis methods, with one KASP marker validated across a backcross population that can be effectively used to identify FER resistance. In conclusion, using mSNP for genetic map construction does not confer advantages when the population size is limited and the marker density is high. However, the mSNP-constructed map identified more minor-effect QTL despite possessing a lower likelihood of the odds (LOD) values.

The optimal plant architecture, characterized by short stature, helps mitigate lodging, enables high‐density planting, and facilitates mechanized harvesting. Internode length (IL), a crucial component of plant height in maize, plays a significant role in these processes. However, the genetic mechanisms underlying internode elongation remain poorly understood. In this study, we conducted a genome‐wide association study to dissect the genetic architecture of IL in maize. The lengths of five internodes above and below the ear (referred as IL‐related traits) were collected across multiple environments, revealing substantial variation. A total of 108 quantitative trait loci (QTL) were associated with 11 IL‐related traits, with 17 QTL co‐detected by different traits. Notably, three QTL have been selected in maize breeding progress. Three hundred and three genes associated with IL were found to operate through plant hormone signal transduction, receptor activity, and carbon metabolism pathways, influencing internode elongation. ZmIL1 , which encodes alcohol dehydrogenase, exhibited a high expression level in internodes during the vegetative stage and has been selected in Chinese modern maize breeding. Additionally, ZmIL2 and ZmIL3 emerged as other crucial regulators of IL. Importantly, ZmIL1 has potential applications in maize varieties in the Huang‐Huai‐Hai region. This study represents the first comprehensive report on the genetic architecture of nearly all ILs in maize, providing profound insights into internode elongation mechanisms and genetic resources. These findings hold significant implications for dwarf breeding programs aimed at optimizing plant architecture for enhancing agronomic performance.

The rigid hull encasing Tartary buckwheat seeds necessitates a laborious dehulling process before flour milling, resulting in considerable nutrient loss. Investigation of lignin composition is pivotal in understanding the structural properties of tartary buckwheat seeds hulls, as lignin is key determinant of rigidity in plant cell walls, thus directly impacting the dehulling process. Here, the lignin composition of seed hulls from 274 Tartary buckwheat accessions is analyzed, unveiling a unique lignin chemotype primarily consisting of G lignin, a common feature in gymnosperms. Furthermore, the hardness of the seed hull showed a strong negative correlation with the S lignin content. Genome-wide detection of selective sweeps uncovered that genes governing the biosynthesis of S lignin, specifically two caffeic acid O-methyltransferases (COMTs) and one ferulate 5-hydroxylases, are selected during domestication. This likely contributed to the increased S lignin content and decreased hardness of seed hulls from more domesticated varieties. Genome-wide association studies identified robust associations between FtCOMT1 and the accumulation of S lignin in seed hull. Transgenic Arabidopsis comt1 plants expressing FtCOMT1 successfully reinstated S lignin content, confirming its conserved function across plant species. These findings provide valuable metabolic and genetic insights for the potential redesign of Tartary buckwheat seed hulls.

Maize tassel spindle length is closely related to the number of pollen grains and the duration of the flowering stage, ultimately affecting maize yield and adaptations to stress conditions. In this study, 182 maize inbred lines were included in an association population. A genome-wide association study was conducted on maize tassel spindle length using the Q + K model. With p ≤ 1.0 × 10⁻⁴ applied as the significance threshold, 240 SNPs significantly associated with tassel spindle length were detected, which were associated with 99 quantitative trait loci (QTLs), with 21 QTLs detected in two or more environments. Moreover, 51 candidate genes were detected in 21 co-localized QTLs. A KEGG enrichment analysis and candidate gene expression analysis indicated that Zm00001d042312 affects plant hormone signal transduction and is highly expressed in maize tassels. A haplotype analysis of Zm00001d042312 revealed three main haplotypes, with significant differences between Hap1 and Hap2. In conclusion, we propose that Zm00001d042312 is a gene that regulates maize tassel spindle length. This study has further elucidated the genetic basis of maize tassel spindle length, while also providing excellent genetic targets and germplasm resources for the genetic improvement of maize tassel spindle length and yield.

Key message In summary, we characterized a maize semi-dwarf mutant, sdw9, and successfully isolated the responsible gene, which encodes a GRAS protein, through a combination of map-based cloning and Re-sequencing (Re-seq). Our findings demonstrate that the candidate gene ZmGRAS42 regulates BR signaling genes, thereby influencing internode development. This regulatory function likely involves processes such as cell division, cell cycle regulation and cell wall synthesis. Favorable variations of ZmGRAS42 identified in this study may hold promise for the development of lodging-resistant maize cultivars suitable for high-density planting, contributing to the improvement of maize breeding programs. Abstract Plant height and lateral root angle are crucial determinants of plant architecture in maize (Zea mays) which are closely related to lodging resistance at high planting density. These traits are intricately regulated by various phytohormones. Mutations affecting hormone biosynthesis and signaling often lead to reduced yield alongside diminished plant height, posing challenges in breeding dwarf maize varieties. In this study, the maize mutant sdw9 was characterized, which displays shorter stature and altered lateral root angle compared to WT, while showing potential to increase planting density and improve overall yield despite a slight reduction in single-ear yield. Employing positional cloning coupled with Re-seq techniques, we pinpointed a transposon insertion in the candidate gene ZmGRAS42, which encodes a GRAS transcription factor involved in BR signaling in maize. Transcriptome analysis revealed that ZmGRAS42 orchestrates the expression of several known dwarfing genes such as D8, Br2, and Na2, along with genes associated with cell wall organization, cell division, and cell cycle regulation, notably Cesa4, Cesa7, and Cyc11. Furthermore, identification of favorable ZmGRAS42 haplotypes linked to reduced plant height offers novel avenues for maize breeding strategies. These findings not only hold the potential for enhancing maize lodging resistance but also for optimizing land utilization through high-density planting practices.

Disease resistance is often associated with compromised plant growth and yield due to defense‐growth tradeoffs. However, key components and mechanisms underlying the defense‐growth tradeoffs are rarely explored in maize. In this study, we find that ZmSKI3, a putative subunit of the SUPERKILLER (SKI) complex that mediates the 3′‐5′ degradation of RNA, regulates both plant development and disease resistance in maize. The Zmski3 mutants showed retarded plant growth and constitutively activated defense responses, while the ZmSKI3 overexpression lines are more susceptible to Curvularia lunata and Bipolaris maydis. Consistently, the expression of defense‐related genes was generally up‐regulated, while expressions of growth‐related genes were mostly down‐regulated in leaves of the Zmski3‐1 mutant compared to that of wild type. In addition, 223 differentially expressed genes that are up‐regulated in Zmski3‐1 mutant but down‐regulated in the ZmSKI3 overexpression line are identified as potential target genes of ZmSKI3. Moreover, small interfering RNAs targeting the transcripts of the defense‐ and growth‐related genes are differentially accumulated, likely to combat the increase of defense‐related transcripts but decrease of growth‐related transcripts in Zmski3‐1 mutant. Taken together, our study indicates that plant growth and immunity could be regulated by both ZmSKI3‐mediated RNA decay and post‐transcriptional gene silencing in maize.