Auxin plays a crucial role throughout the entire life cycle of plants. The auxin/indole-3-acetic acid (Aux/IAA) gene family serves as a negative regulator of auxin response and is one of the earliest auxin-responsive gene families. It regulates the expression of auxin-responsive genes by specifically binding to auxin response factors. This review summarizes the protein structural characteristics of the Aux/IAA gene family and its typical and atypical transduction mechanisms in auxin signaling. Additionally, it examines the role of Aux/IAA in regulating plant growth and development, as well as its function in modulating plant resistance to abiotic stress through hormonal signaling pathways. Our findings indicate that the Aux/IAA gene family plays a significant role in plant growth and development, as well as in abiotic stress resistance. However, research on the functional roles of the Aux/IAA gene family in crops such as rice, wheat, and maize remains relatively scarce. Furthermore, we identified key questions and proposed new research directions regarding the Aux/IAA gene family, aiming to provide insights for future research on plant hormone signaling and molecular breeding in crop design.

The quality of corn kernels is crucial for their nutritional value, making the enhancement of kernel quality a primary objective of contemporary corn breeding efforts. This study utilized 260 corn inbred lines as research materials and assessed three traits associated with grain quality. A genome-wide association study (GWAS) was conducted using the best linear unbiased estimator (BLUE) for quality traits, resulting in the identification of 23 significant single nucleotide polymorphisms (SNPs). Additionally, nine genes associated with grain quality traits were identified through gene function annotation and prediction. Furthermore, a total of 697 quantitative trait loci (QTL) related to quality traits were compiled from 27 documents, followed by a meta-QTL analysis that revealed 40 meta-QTL associated with these traits. Among these, 19 functional genes and reported candidate genes related to quality traits were detected. Three significant SNPs identified by GWAS were located within the intervals of these QTL, while the remaining eight significant SNPs were situated within 2 Mb of the QTL. In summary, the findings of this study provide a theoretical framework for analyzing the genetic basis of corn grain quality-related traits and for enhancing corn quality.

Phosphorus is an essential nutrient for maize growth and development, and its deficiency can significantly inhibit plant growth, leading to reduced yield and quality. To elucidate the genetic mechanisms underlying low phosphorus tolerance in maize, this study utilized a panel of 257 maize inbred lines and conducted controlled experiments under low phosphorus (LP) and normal phosphorus (CK) conditions in artificial climate chambers. Through genome-wide association study (GWAS), a total of 46 SNP loci significantly associated with low phosphorus tolerance were detected, and 74 candidate genes were predicted. To further investigate, the low-phosphorus tolerant material CML422 and the phosphorus-sensitive material CIMBL90 were selected for transcriptome sequencing, which identified a total of 7232 differentially expressed genes (DEGs). KEGG enrichment analysis revealed that these genes were significantly enriched in key pathways such as plant hormone signal transduction, MAPK signaling pathway, and starch and sucrose metabolism, suggesting that maize responds to low phosphorus stress through the coordinated regulation of multiple pathways. By integrating GWAS and transcriptome data, 18 co-localized genes were screened, ultimately identifying 10 candidate genes closely associated with low phosphorus tolerance during the maize seedling stage, which are potentially involved in regulating growth and development under phosphorus stress. This study preliminarily elucidates the molecular mechanisms underlying low phosphorus tolerance in maize through multi-omics analysis, providing both a theoretical basis and genetic resources for breeding new maize varieties with high phosphorus use efficiency.

Maize kernel traits represent crucial agronomic characteristics that significantly determine yield potential. Analyzing the genetic basis of these traits is essential for yield improvement. In this study, we utilized 1283 maize inbred lines to investigate three kernel-related characteristics: kernel length (KL), kernel width (KW), and 100-kernel weight (HKW). We conducted a genome-wide association study (GWAS) on three kernel-related traits, resulting in the identification of 29 significantly associated SNPs and six candidate genes. Additionally, we compiled quantitative trait loci (QTL) information for 765 maize kernel-related traits from 56 studies, conducted a meta-analysis of QTL, and identified 65 meta-QTLs (MQTLs). Among the 23 MQTLs, we found 25 functional genes and reported candidate genes related to kernel traits. We identified 26 maize homologs across 19 MQTLs by utilizing 25 genes that affect rice grain traits. We compared the 29 significant SNPs detected with the physical locations of 65 MQTLs and found that 3 significant SNPs were located within these MQTL intervals, and another 10 significant SNPs were in proximity to these intervals, being less than 2 Mb away, although they were not included within the MQTL intervals. The results of this study provide a theoretical foundation for elucidating the genetic basis of maize kernel-related traits and advancing molecular marker-assisted breeding selection.

Exogenous abscisic acid (ABA) and brassinosteroid (BR) play important roles in alleviating cold stress in maize. In this study, two maize inbred lines with differing cold tolerance were treated with exogenous ABA, BR, and their combined solution under cold stress conditions at 10 °C to investigate the effects of these treatments on the physiological characteristics of maize seedlings. The results indicated that cold stress significantly inhibited the growth of maize seedlings. Exogenous hormone treatments enhanced antioxidant enzyme activities and promoted the synthesis of osmolytes, thereby alleviating cold stress; however, the combined treatment (AR) did not significantly improve maize cold tolerance. Transcriptomic analysis revealed that pathways including plant hormone signal transduction, fatty acid elongation, and phenylpropanoid biosynthesis were involved in the interaction between ABA and BR. Weighted gene co-expression network analysis (WGCNA) identified four key candidate genes responsive to exogenous ABA and BR under cold stress, namely Zm00001eb343270, Zm00001eb401890, Zm00001eb206790, and Zm00001eb199820. Based on the gene annotation results, we speculate that ubiquitin-conjugating enzyme E2 O, tubulin–tyrosine ligase-like protein 12, the negative regulator of systemic acquired resistance SNI1, and mRNA stability regulators in response to DNA damage may be involved in regulating maize cold tolerance. These findings provide further evidence for the regulatory mechanisms by which exogenous ABA and BR affect maize cold tolerance and elucidate their interaction under cold stress.

Salt stress represents a significant abiotic factor that constrains maize growth. Epigenetic modifications play a crucial role in enabling plants to respond effectively to such stresses. Among these alterations, m⁶A methylation, which is the most common post-transcriptional modification of eukaryotic mRNA, shows dynamic variations that are closely linked to stress responses. In this study, we conducted a transcriptome-wide m⁶A methylation analysis on maize roots from the inbred line PH4CV, following treatment with 180 mM NaCl. The results identified 1309 differentially m⁶A methylated peaks (DMPs) and 2761 differentially expressed genes (DEGs) under salt stress conditions. Association analysis revealed that 179 DEGs contain DMPs. Key pathways involved in stress responses, including Ca²⁺ signaling transduction and ABA signaling, as well as ion homeostasis regulation (involving AKT, HKT, and other families) and the reactive oxygen species scavenging system (including POD, SOD, and CAT), play crucial roles in coping with salt stress. Furthermore, we identified a total of 26 m⁶A-related genes, comprising 7 eraser genes, 10 reader genes, and 9 writer genes. Notably, several key salt-responsive genes, such as RBOHB, AKT1, HKT1, and POD12, are correlated with m⁶A modification. This study provides a comprehensive map of m⁶A methylation dynamics in maize roots under salt stress, laying a foundational resource for future investigations into the epigenetic regulation of salt tolerance in maize.