ZmNAC17 Regulates Mesocotyl Elongation by Mediating Auxin and ROS Biosynthetic Pathways in Maize.

The mesocotyl is of great significance in seedling emergence and in responding to biotic and abiotic stress in maize. The NAM, ATAF, and CUC2 (NAC) transcription factor family plays an important role in maize growth and development; however, its function in the elongation of the maize mesocotyl is still unclear. In this study, we found that the mesocotyl length in zmnac17 loss-of-function mutants was lower than that in the B73 wild type. By using transcriptomic sequencing technology, we identified 444 differentially expressed genes (DEGs) between zmnac17-1 and B73, which were mainly enriched in the "tryptophan metabolism" and "antioxidant activity" pathways. Compared with the control, the zmnac17-1 mutants exhibited a decrease in the content of indole acetic acid (IAA) and an increase in the content of reactive oxygen species (ROS). Our results provide preliminary evidence that ZmNAC17 regulates the elongation of the maize mesocotyl.

Multiomics comparative analysis of the maize large grain mutant tc19 identified pathways related to kernel development.

BACKGROUND: The mechanism of grain development in elite maize breeding lines has not been fully elucidated. Grain length, grain width and grain weight are key components of maize grain yield. Previously, using the Chinese elite maize breeding line Chang7-2 and its large grain mutant tc19, we characterized the grain size developmental difference between Chang7-2 and tc19 and performed transcriptomic analysis. RESULTS: In this paper, using Chang7-2 and tc19, we performed comparative transcriptomic, proteomic and metabolomic analyses at different grain development stages. Through proteomics analyses, we found 2884, 505 and 126 differentially expressed proteins (DEPs) at 14, 21 and 28 days after pollination, respectively. Through metabolomics analysis, we identified 51, 32 and 36 differentially accumulated metabolites (DAMs) at 14, 21 and 28 days after pollination, respectively. Through multiomics comparative analysis, we showed that the phenylpropanoid pathways are influenced at transcriptomic, proteomic and metabolomic levels in all the three grain developmental stages. CONCLUSION: We identified several genes in phenylpropanoid biosynthesis, which may be related to the large grain phenotype of tc19. In summary, our results provided new insights into maize grain development.

ZmCOP1 Regulates Maize Mesocotyl Length and Plant Height through the Phytohormone Pathways.

The morphogenesis of crops is critical to their yield performance. COP1 (constitutively photomorphogenic1) is one of the core regulators in plant morphogenesis and has been deeply studied in Arabidopsis thaliana. However, the function of COP1 in maize is still unclear. Here, we found that the mesocotyl lengths of zmcop1 loss-of-function mutants were shorter than those of wild-type B73 in darkness, while the mesocotyl lengths of lines with ZmCOP1 overexpression were longer than those of wild-type B104. The plant height with zmcop1 was shorter than that of B73 in both short- and long-day photoperiods. Using transcriptome RNA sequencing technology, we identified 33 DEGs (differentially expressed genes) between B73's etiolated seedlings and those featuring zmcop1, both in darkness. The DEGs were mainly enriched in the plant phytohormone pathways. Our results provide direct evidence that ZmCOP1 functions in the elongation of etiolated seedlings in darkness and affects plant height in light. Our data can be applied in the improvement of maize plant architecture.

Research Progress on the Mechanism of Salt Tolerance in Maize: A Classic Field That Needs New Efforts.

Maize is the most important cereal crop globally. However, in recent years, maize production faced numerous challenges from environmental factors due to the changing climate. Salt stress is among the major environmental factors that negatively impact crop productivity worldwide. To cope with salt stress, plants developed various strategies, such as producing osmolytes, increasing antioxidant enzyme activity, maintaining reactive oxygen species homeostasis, and regulating ion transport. This review provides an overview of the intricate relationships between salt stress and several plant defense mechanisms, including osmolytes, antioxidant enzymes, reactive oxygen species, plant hormones, and ions (Na+, K+, Cl-), which are critical for salt tolerance in maize. It addresses the regulatory strategies and key factors involved in salt tolerance, aiming to foster a comprehensive understanding of the salt tolerance regulatory networks in maize. These new insights will also pave the way for further investigations into the significance of these regulations in elucidating how maize coordinates its defense system to resist salt stress.

Identification of quantitative trait loci for related traits of stalk lodging resistance using genome-wide association studies in maize (Zea mays L.).

BACKGROUND: Stalk lodging is one of the main factors affecting maize (Zea mays L.) yield and limiting mechanized harvesting. Developing maize varieties with high stalk lodging resistance requires exploring the genetic basis of lodging resistance-associated agronomic traits. Stalk strength is an important indicator to evaluate maize lodging and can be evaluated by measuring stalk rind penetrometer resistance (RPR) and stalk buckling strength (SBS). Along with morphological traits of the stalk for the third internodes length (TIL), fourth internode length (FIL), third internode diameter (TID), and the fourth internode diameter (FID) traits are associated with stalk lodging resistance. RESULTS: In this study, a natural population containing 248 diverse maize inbred lines genotyped with 83,057 single nucleotide polymorphism (SNP) markers was used for genome-wide association study (GWAS) for six stalk lodging resistance-related traits. The heritability of all traits ranged from 0.59 to 0.72 in the association mapping panel. A total of 85 significant SNPs were identified for the association mapping panel using best linear unbiased prediction (BLUP) values of all traits. Additionally, five candidate genes were associated with stalk strength traits, which were either directly or indirectly associated with cell wall components. CONCLUSIONS: These findings contribute to our understanding of the genetic basis of maize stalk lodging and provide valuable theoretical guidance for lodging resistance in maize breeding in the future.

Transcriptomic analysis of the maize inbred line Chang7-2 and a large-grain mutant tc19.

BACKGROUNDS: Grain size is a key factor in crop yield that gradually develops after pollination. However, few studies have reported gene expression patterns in maize grain development using large-grain mutants. To investigate the developmental mechanisms of grain size, we analyzed a large-grain mutant, named tc19, at the morphological and transcriptome level at five stages corresponding to days after pollination (DAP). RESULTS: After maturation, the grain length, width, and thickness in tc19 were greater than that in Chang7-2 (control) and increased by 3.57, 8.80, and 3.88%, respectively. Further analysis showed that grain width and 100-kernel weight in tc19 was lower than in Chang7-2 at 14 and 21 DAP, but greater than that in Chang7-2 at 28 DAP, indicating that 21 to 28 DAP was the critical stage for kernel width and weight development. For all five stages, the concentrations of auxin and brassinosteroids were significantly higher in tc19 than in Chang7-2. Gibberellin was higher at 7, 14, and 21 DAP, and cytokinin was higher at 21 and 35 DAP, in tc19 than in Chang7-2. Through transcriptome analysis at 14, 21, and 28 DAP, we identified 2987, 2647 and 3209 differentially expressed genes (DEGs) between tc19 and Chang7-2. By using KEGG analysis, 556, 500 and 633 DEGs at 14, 21 and 28 DAP were pathway annotated, respectively, 77 of them are related to plant hormone signal transduction pathway. ARF3, AO2, DWF4 and XTH are higher expressed in tc19 than that in Chang7-2. CONCLUSIONS: We found some DEGs in maize grain development by using Chang7-2 and a large-grain mutant tc19. These DEGs have potential application value in improving maize performance.

ZmACY-1 Antagonistically Regulates Growth and Stress Responses in Nicotiana benthamiana.

Aminoacylase-1 is a zinc-binding enzyme that is important in urea cycling, ammonia scavenging, and oxidative stress responses in animals. Aminoacylase-1 (ACY-1) has been reported to play a role in resistance to pathogen infection in the model plant Nicotiana benthamiana. However, little is known about its function in plant growth and abiotic stress responses. In this study, we cloned and analyzed expression patterns of ZmACY-1 in Zea mays under different conditions. We also functionally characterized ZmACY-1 in N. benthamiana. We found that ZmACY-1 is expressed specifically in mature shoots compared with other tissues. ZmACY-1 is repressed by salt, drought, jasmonic acid, and salicylic acid, but is induced by abscisic acid and ethylene, indicating a potential role in stress responses and plant growth. The overexpression of ZmACY-1 in N. benthamiana promoted growth rate by promoting growth-related genes, such as NbEXPA1 and NbEIN2. At the same time, the overexpression of ZmACY-1 in N. benthamiana reduced tolerance to drought and salt stress. With drought and salt stress, the activity of protective enzymes, such as peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) from micrococcus lysodeikticus was lower; while the content of malondialdehyde (MDA) and relative electrolytic leakage was higher in ZmACY-1 overexpression lines than that in wild-type lines. The results indicate that ZmACY-1 plays an important role in the balance of plant growth and defense and can be used to assist plant breeding under abiotic stress conditions.

The role of RNA-binding protein, microRNA and alternative splicing in seed germination: a field need to be discovered.

Seed germination is the process through which a quiescent organ reactivates its metabolism culminating with the resumption cell divisions. It is usually the growth of a plant contained within a seed and results in the formation of a seedling. Post-transcriptional regulation plays an important role in gene expression. In cells, post-transcriptional regulation is mediated by many factors, such as RNA-binding proteins, microRNAs, and the spliceosome. This review provides an overview of the relationship between seed germination and post-transcriptional regulation. It addresses the relationship between seed germination and RNA-binding proteins, microRNAs and alternative splicing. This presentation of the current state of the knowledge will promote new investigations into the relevance of the interactions between seed germination and post-transcriptional regulation in plants.

Diurnal rhythm disruptions induced by chronic unpredictable stress relate to depression-like behaviors in rats.

The relationship between circadian rhythms and mood disorders has been established. Circadian dysregulations are believed to exacerbate the severity of mood disorders and vice versa. Although many studies on diurnal changes of clock genes in animal model of depression have been performed from the RNA level, only a few studies have been carried out from the protein level. In this study, we investigated the diurnal changes induced by chronic unpredictable stress (CUS) using free-running wheel test and Western Blotting (WB). Besides, we examined the depression-like behaviors of rats by sucrose preference test (SPT) and forced swim test (FST). We found that CUS induced significant reductions in the quantity of free-running wheel activity and rhythmic disruptions of clock proteins in hippocampus. Furthermore, we found that the amplitude of PER1 in CA1 was positively related to the severity of depression-like behaviors. These results suggest that CUS results in both changes in diurnal rhythms and in depression-like behaviors and that it is suggested that these changes are related.

Retraction notice to "Diurnal rhythm disruptions induced by chronic unpredictable stress relate to depression-like behaviors in rats" [Pharmacol. Biochem. Behav. 194 (2020) 172939].

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor because of serious doubts regarding the data on melatonin levels. The authors used a melatonin ELISA kit that was not fit for purpose, resulting in data showing peak secretion of this hormone occurring in the middle of the light period, which does not make any physiological sense since melatonin is only produced during darkness.

Convergence and Divergence of Sugar and Cytokinin Signaling in Plant Development.

Plants adjust their growth and development through a sophisticated regulatory system integrating endogenous and exogenous cues. Many of them rely on intricate crosstalk between nutrients and hormones, an effective way of coupling nutritional and developmental information and ensuring plant survival. Sugars in their different forms such as sucrose, glucose, fructose and trehalose-6-P and the hormone family of cytokinins (CKs) are major regulators of the shoot and root functioning throughout the plant life cycle. While their individual roles have been extensively investigated, their combined effects have unexpectedly received little attention, resulting in many gaps in current knowledge. The present review provides an overview of the relationship between sugars and CKs signaling in the main developmental transition during the plant lifecycle, including seed development, germination, seedling establishment, root and shoot branching, leaf senescence, and flowering. These new insights highlight the diversity and the complexity of the crosstalk between sugars and CKs and raise several questions that will open onto further investigations of these regulation networks orchestrating plant growth and development.

Sugar Signaling and Post-transcriptional Regulation in Plants: An Overlooked or an Emerging Topic?

Plants are autotrophic organisms that self-produce sugars through photosynthesis. These sugars serve as an energy source, carbon skeletons, and signaling entities throughout plants' life. Post-transcriptional regulation of gene expression plays an important role in various sugar-related processes. In cells, it is regulated by many factors, such as RNA-binding proteins (RBPs), microRNAs, the spliceosome, etc. To date, most of the investigations into sugar-related gene expression have been focused on the transcriptional level in plants, while only a few studies have been conducted on post-transcriptional mechanisms. The present review provides an overview of the relationships between sugar and post-transcriptional regulation in plants. It addresses the relationships between sugar signaling and RBPs, microRNAs, and mRNA stability. These new items insights will help to reach a comprehensive understanding of the diversity of sugar signaling regulatory networks, and open onto new investigations into the relevance of these regulations for plant growth and development.

Diurnal rhythm disruptions induced by chronic unpredictable stress relate to depression-like behaviors in rats.

The relationship between circadian rhythms and mood disorders has been established, circadian dysregulations are believed to exacerbate the severity of mood disorders and vice versa. Although many studies on diurnal changes of clock genes in animal model of depression have been performed from the RNA level, only a few studies have been carried out from the protein level. In this study, we investigated the diurnal changes induced by chronic unpredictable stress (CUS) using various methods, including free-running wheel test, enzyme-linked immunosorbent assay (ELISA) and Western Blotting (WB). Besides, we examined the depression-like behaviors of rats by sucrose preference test (SPT) and forced swim test (FST). We found that CUS induced significant reductions in the quantity of free-running wheel activity and the amplitude of melatonin secretion rhythm. We also found that CUS induced rhythmic disruptions of clock proteins in hippocampus. Furthermore, we found that the amplitude of PER1 in CA1 was positively related to the severity of depression-like behaviors. These results suggest that stress results in both changes in circadian rhythms and in depression-like behaviors and that it is suggested that these changes are related.

Cold Induced Antisense Transcription of FLOWERING LOCUS C in Distant Grasses.

Functional conservation of RNAs between different species is a key argument for their importance. While few long non-coding RNAs are conserved at the sequence level, many long non-coding RNAs have been identified that only share a position relative to other genes. It remains largely unknown whether and how these lncRNAs are conserved beyond their position. In Arabidopsis thaliana, the lncRNA COOLAIR is transcribed antisense from FLOWERING LOCUS C (FLC) in response to cold. Despite relatively low sequence similarity, the COOLAIR expression pattern and in vitro RNA secondary structure are highly conserved across the family Brassicaceae, which originated some 50 mya. It is unclear, however, whether COOLAIR functions in distantly related species such as monocots, which diverged some 150 mya. Here, we identified antisense lncRNAs from FLC homologs in various monocot species that share no sequence similarity with A. thaliana COOLAIR. Yet similar to COOLAIR, we found that BdODDSOC1 antisense (BdCOOLAIR1) and BdODDSOC2 antisense (BdCOOLAIR2) are induced by cold in a Brachypodium distachyon winter accession. Across B. distachyon accessions, the sequences of BdCOOLAIR1 and BdCOOLAIR2 are less conserved than exons but more conserved than flanking regions, suggesting a function for the transcript itself. Knock down of the BdODDSOC2 non-overlapping BdCOOLAIR2 transcript did not show a morphological phenotype, but did result in significantly higher BdODDSOC2 expression during cold, indicating that BdCOOLAIR2 performs a role in cis in the rate of BdODDSOC2 silencing. This functional similarity between eudicot and monocot species reveals ancient conservation or convergent evolution of FLC antisense transcription. Either scenario supports its functional importance.

Fine-mapping of qGW4.05, a major QTL for kernel weight and size in maize.

BACKGROUND: Kernel weight and size are important components of grain yield in cereals. Although some information is available concerning the map positions of quantitative trait loci (QTL) for kernel weight and size in maize, little is known about the molecular mechanisms of these QTLs. qGW4.05 is a major QTL that is associated with kernel weight and size in maize. We combined linkage analysis and association mapping to fine-map and identify candidate gene(s) at qGW4.05. RESULTS: QTL qGW4.05 was fine-mapped to a 279.6-kb interval in a segregating population derived from a cross of Huangzaosi with LV28. By combining the results of regional association mapping and linkage analysis, we identified GRMZM2G039934 as a candidate gene responsible for qGW4.05. Candidate gene-based association mapping was conducted using a panel of 184 inbred lines with variable kernel weights and kernel sizes. Six polymorphic sites in the gene GRMZM2G039934 were significantly associated with kernel weight and kernel size. CONCLUSION: The results of linkage analysis and association mapping revealed that GRMZM2G039934 is the most likely candidate gene for qGW4.05. These results will improve our understanding of the genetic architecture and molecular mechanisms underlying kernel development in maize.