The miR319/TaGAMYB3 module regulates plant architecture and improves grain yield in common wheat (Triticum aestivum)

Unveiling novel anti-viral mechanisms of ε-poly-l-lysine on tobacco mosaic virus-infected Nicotiana tabacum through microRNA and transcriptome sequencing

MicroRNAs (miRNAs) play important roles in plant defense against various pathogens. ε-poly-l-lysine (ε-PL), a natural anti-microbial peptide produced by microorganisms, effectively suppresses tobacco mosaic virus (TMV) infection. To investigate the anti-viral mechanism of ε-PL, the expression profiles of miRNAs in TMV-infected Nicotiana tabacum after ε-PL treatment were analyzed. The results showed that the expression levels of 328 miRNAs were significantly altered by ε-PL. Degradome sequencing was used to identify their target genes. Integrative analysis of miRNAs target genes and gene-enriched GO/KEGG pathways indicated that ε-PL regulates the expression of miRNAs involved in critical pathways of plant hormone signal transduction, host defense response, and plant pathogen interaction. Subsequently, virus induced gene silencing combined with the short tandem targets mimic technology was used to analyze the function of these miRNAs and their target genes. The results indicated that silencing miR319 and miR164 reduced TMV accumulation in N. benthamiana, indicating the essential roles of these miRNAs and their target genes during ε-PL-mediated anti-viral responses. Collectively, this study reveals that microbial source metabolites can inhibit plant viruses by regulating crucial host miRNAs and further elucidate anti-viral mechanisms of ε-PL.

OsmiR319-OsPCF5 modulate resistance to brown planthopper in rice through association with MYB proteins

BACKGROUND

The brown planthopper (BPH) is a kind of piercing-sucking insect specific to rice, with the damage tops the list of pathogens and insects in recent years. microRNAs (miRNAs) are pivotal regulators of plant-environment interactions, while the mechanism underlying their function against insects is largely unknown.

RESULTS

Here, we confirmed that OsmiR319, an ancient and conserved miRNA, negatively regulated resistance to BPHs, with overexpression of OsmiR319 susceptible to BPH, while suppression of OsmiR319 resistant to BPH in comparison with wild type. Meanwhile, we identified several targets of OsmiR319 that may mediate BPH resistance. Among them, OsPCF5 was the most obviously induced by BPH feeding, and over expression of OsPCF5 was resistance to BPH. In addition, various biochemical assays verified that OsPCF5 interacted with several MYB proteins, such as OsMYB22, OsMYB30, and OsMYB30C.Genetically, we revealed that both OsMYB22 and OsMYB30C positively regulated BPH resistance. Genetic interaction analyses confirmed that OsMYB22 and OsMYB30C both function in the same genetic pathway with OsmiR319b to mediate BPH resistance.

CONCLUSIONS

Altogether, we revealed that OsPCF5 regulates BPH resistance via association with several MYB proteins downstream of OsmiR319, these MYB proteins might function as regulators of BPH resistance through regulating the phenylpropane synthesis.

Synergistic optimization of crops by combining early maturation with other agronomic traits

Many newly created early maturing varieties exhibit poor stress resistance and low yield, whereas stress-resistant varieties are typically late maturing. For this reason, the polymerization of early maturity and other desired agronomic qualities requires overcoming the negative connection between early maturity, multi-resistance, and yield, which presents a formidable challenge in current breeding techniques. We review the most salient constraints of early maturity breeding in current crop planting practices and the molecular mechanisms of different maturation timeframes in diverse crops from their origin center to production areas. We explore current breeding tactics and the future direction of crop breeding and the issues that must be resolved to accomplish the polymerization of desirable traits in light of the current obstacles and limitations.

The cotton MYB33 gene is a hub gene regulating the trade-off between plant growth and defense in Verticillium dahliae infection

INTRODUCTION

Sessile plants engage in trade-offs between growth and defense capacity in response to fluctuating environmental cues. MYB is an important transcription factor that plays many important roles in controlling plant growth and defense. However, the mechanism behind how it keeps a balance between these two physiological processes is still largely unknown.

OBJECTIVES

Our work focuses on the dissection of the molecular mechanism by which GhMYB33 regulates plant growth and defense.

METHODS

The CRISPR/Cas9 technique was used to generate mutants for deciphering GhMYB33 functions. Yeast two-hybrid, luciferase complementary imaging, and co-immunoprecipitation assays were used to prove that proteins interact with each other. We used the electrophoretic mobility shift assay, yeast one-hybrid, and luciferase activity assays to analyze GhMYB33 acting as a promoter. A β-glucuronidase fusion reporter and 5' RNA ligase mediated amplification of cDNA ends analysis showed that ghr-miR319c directedly cleaved the GhMYB33 mRNA.

RESULTS

Overexpressing miR319c-resistant GhMYB33 (rGhMYB33) promoted plant growth, accompanied by a significant decline in resistance against Verticillium dahliae. Conversely, its knockout mutant, ghmyb33, demonstrated growth restriction and concomitant augmentation of V. dahliae resistance. GhMYB33 was found to couple with the DELLA protein GhGAI1 and bind to the specific cis-elements of GhSPL9 and GhDFR1 promoters, thereby modulating internode elongation and plant resistance in V. dahliae infection. The ghr-miR319c was discovered to target and suppress GhMYB33 expression. The overexpression of ghr-miR319c led to enhanced plant resistance and a simultaneous reduction in plant height.

CONCLUSION

Our findings demonstrate that GhMYB33 encodes a hub protein and controls the expression of GhSPL9 and GhDFR1, implicating a pivotal role for the miR319c-MYB33 module to regulate the trade-offs between plant growth and defense.

Overview of Repressive miRNA Regulation by Short Tandem Target Mimic (STTM): Applications and Impact on Plant Biology

The application of miRNA mimic technology for silencing mature miRNA began in 2007. This technique originated from the discovery of the INDUCED BY PHOSPHATE STARVATION 1 (IPS1) gene, which was found to be a competitive mimic that prevents the cleavage of the targeted mRNA by miRNA inhibition at the post-transcriptional level. To date, various studies have been conducted to understand the molecular mimic mechanism and to improve the efficiency of this technology. As a result, several mimic tools have been developed: target mimicry (TM), short tandem target mimic (STTM), and molecular sponges (SPs). STTM is the most-developed tool due to its stability and effectiveness in decoying miRNA. This review discusses the application of STTM technology on the loss-of-function studies of miRNA and members from diverse plant species. A modified STTM approach for studying the function of miRNA with spatial-temporal expression under the control of specific promoters is further explored. STTM technology will enhance our understanding of the miRNA activity in plant-tissue-specific development and stress responses for applications in improving plant traits via miRNA regulation.

Recent advances and future perspectives in early-maturing cotton research

Cotton's fundamental requirements for long periods of growth and specific seasonal temperatures limit the global arable areas that can be utilized to cultivate cotton. This constraint can be alleviated by breeding for early-maturing varieties. By delaying the sowing dates without impacting the boll-opening time, early-maturing varieties not only mitigate the yield losses brought on by unfavorable weathers in early spring and late autumn but also help reducing the competition between cotton and other crops for arable land, thereby optimizing the cropping system. This review presents studies and breeding efforts for early-maturing cotton, which efficiently pyramid early maturity, high-quality, multiresistance traits, and suitable plant architecture by leveraging pleiotropic genes. Attempts are also made to summarize our current understanding of the molecular mechanisms underlying early maturation, which involves many pathways such as epigenetic, circadian clock, and hormone signaling pathways. Moreover, new avenues and effective measures are proposed for fine-scale breeding of early-maturing crops to ensure the healthy development of the agricultural industry.

miR319 and its target TCP4 involved in plant architecture regulation in Brassica napus

Plant architecture is a collection of genetically controlled crop productivity and adaptation. MicroRNAs (miRNAs) have been proved to function in various biological processes, but little is known about how miRNA regulates plant architecture in rapeseed (Brassica napus L.). In this study, four small RNA libraries and two degradome libraries from shoot apex of normal and rod-like plants were sequenced. A total of 639 miRNA precursors and 16 differentially expressed miRNAs were identified in this study. In addition, 322 targets were identified through degradome sequencing. Among them, 14 targets were further validated via RNA ligase-mediated 5' rapid amplification of cDNA ends. Transgenic approach showed that increased TCP4 activity in Arabidopsis resulted in premature onset of maturation and reduced plant size along with early flowering and shortened flowering time. miR319-OE lines in Brassica napus exhibited serrated leaves and abnormal development of shoot apical meristem (SAM), which led to the deformed growth of stem and reduced plant height. In conclusion, our study lays the foundation for elucidating miRNA regulate plant architecture and provides new insight into the miR319/TCP4 module regulates plant architecture in rapeseed.

TaSPL14-7A is a conserved regulator controlling plant architecture and yield traits in common wheat (Triticum aestivum L.)

Plant architecture is a crucial influencing factor of wheat yield and adaptation. In this study, we cloned and characterized TaSPL14, a homologous gene of the rice ideal plant architecture gene OsSPL14 in wheat. TaSPL14 homoeologs (TaSPL14-7A, TaSPL14-7B and TaSPL14-7D) exhibited similar expression patterns, and they were all preferentially expressed in stems at the elongation stage and in young spikes. Moreover, the expression level of TaSPL14-7A was higher than that of TaSPL14-7B and TaSPL14-7D. Overexpression of TaSPL14-7A in wheat resulted in significant changes in plant architecture and yield traits, including decreased tiller number and increased kernel size and weight. Three TaSPL14-7A haplotypes were identified in Chinese wheat core collection, and haplotype-based association analysis showed that TaSPL14-7A-Hap1/2 were significantly correlated with fewer tillers, larger kernels and higher kernel weights in modern cultivars. The haplotype effect resulted from a difference in TaSPL14-7A expression levels among genotypes, with TaSPL14-7A-Hap1/2 leading to higher expression levels than TaSPL14-7A-Hap3. As favorable haplotypes, TaSPL14-7A-Hap1/2 underwent positive selection during global wheat breeding over the last century. Together, the findings of our study provide insight into the function and genetic effects of TaSPL14 and provide a useful molecular marker for wheat breeding.

Genetic dissection of quantitative trait loci for flag leaf size in bread wheat (Triticum aestivum L.)

Flag leaf size is a crucial trait influencing plant architecture and yield potential in wheat. A recombinant inbred line (RIL) population derived from the cross of W7268 and Chuanyu 12 was employed to identify quantitative trait loci (QTL) controlling flag leaf length (FLL), flag leaf width (FLW), and flag leaf area (FLA) in six environments and the best linear unbiased estimator (BLUE) datasets. Using a 55 K SNP-based genetic map, six major and stable QTL were detected with 6.33-53.12% of explained phenotypic variation. Except for QFlw.cib-4B.3, the other five major QTL were co-located within two intervals on chromosomes 2B and 2D, namely QFll/Fla.cib-2B and QFll/Flw/Fla.cib-2D, respectively. Their interactions and effects on the corresponding traits and yield-related traits were also assessed based on flanking markers. QFll/Fla.cib-2B showed pleiotropic effects on spikelet number per spike (SNS). QFlw.cib-4B.3 and QFll/Flw/Fla.cib-2D had effects on grain number per spike (GNS) and thousand-grain weight (TGW). Comparison analysis suggested that QFll/Fla.cib-2B was likely a new locus. Two candidate genes, TraesCS2B03G0222800 and TraesCS2B03G0230000, associated with leaf development within the interval of QFll/Fla.cib-2B were identified based on expression-pattern analysis, gene annotation, ortholog analysis, and sequence variation. The major QTL and markers reported here provide valuable information for understanding the genetic mechanism underlying flag leaf size as well as breeding utilization in wheat.

Evolutionary characterization of miR396s in Poaceae exemplified by their genetic effects in wheat and maize

MiR396s play important roles in regulating plant growth and stress response, and great potential for crop yield promotion was anticipated. For more comprehensive and precise understanding of miR396s in Poaceae, we analyzed the phylogenetic linkage, gene expression, and chromosomal distribution of miR396s in this study. Although the mature miR396s' sequences were mostly conserved, differential expression patterns and chromosomal distribution were found among Poaceae species including the major cereal crops rice, wheat, and maize. Consistently, in comparison with rice, wheat and maize plants transformed with the target mimicry construct of miR396 (MIM396) exhibited differential effects on grain size and disease resistance. While the TaMIM396 plants showed increased grain size, panicle length and sensitivity to B. graminis, the ZmMIM396 plants didn't show obvious changes in grain size and disease resistance. In Addition, several GROWTH-REGULATING FACTOR (GRF) genes in wheat and maize were repressed by miR396s, which could be reversed by MIM396, confirming the conserved regulatory roles of miR396 on GRFs. While providing new solution to enhance grain yield in wheat and revealing potential regulatory variations of miR396s in controlling grain size and disease resistance in different crops, this study gives clues to further explore miR396s' functions in other Poaceae species.

Two alternative splicing variants of a wheat gene TaNAK1, TaNAK1.1 and TaNAK1.2, differentially regulate flowering time and plant architecture leading to differences in seed yield of transgenic Arabidopsis

In wheat production, appropriate flowering time and ideal plant architecture are the prerequisites for high grain yield. Alternative splicing (AS) is a vital process that regulates gene expression at the post-transcriptional level, and AS events in wheat have been found to be closely related to grain-related traits and abiotic stress tolerance. However, AS events and their biological roles in regulating flowering time and plant architecture in wheat remain unclear. In this study, we report that TaNAK1 undergoes AS, producing three splicing variants. Molecular characterization of TaNAK1 and its splicing variants demonstrated that all three protein isoforms have a conserved NB-ARC domain and a protein kinase domain, but the positions of these two domains and the length of the protein kinase domains are different among them, implying that they may have different three-dimensional structures and therefore have different functions. Further investigations showed that the two splicing variants of TaNAK1, TaNAK1.1 and TaNAK1.2, exhibited different expression patterns during wheat growth and development, while the other one, TaNAK1.3, was not detected. Subcellular localization demonstrated that TaNAK1.1 was mainly localized in the cytoplasm, while TaNAK1.2 was localized in the nucleus and cytoplasm. Both TaNAK1.1 and TaNAK1.2 exhibit protein kinase activity in vitro. Ectopic expression of TaNAK1.1 and TaNAK1.2 in Arabidopsis demonstrated that these two splicing variants play opposite roles in regulating flowering time and plant architecture, resulting in different seed yields. TaNAK1.2 positive regulates the transition from vegetative to reproductive growth, plant height, branching number, seed size, and seed yield of Arabidopsis, while TaNAK1.1 negatively regulates these traits. Our findings provide new gene resource for regulating flowering time and plant architecture in crop breeding for high grain yield.