Plant Growth Regulation最新文献

Plants, unlike animals, cannot move from one place to another and have to face different climatic disturbances wherever they are growing. So, they have innumerable built-in mechanisms to adapt to various abiotic stressful conditions like drought, heat, cold, and salinity. The changing environmental conditions influence the expression patterns of genes. Epigenetics involves heritable changes in DNA bases or histone proteins, which ultimately create different conformational states of chromatin. The regulatory enzymes of epigenetic modifications are grouped as writers, readers and erasers, which add, recognize and remove the epigenetic marks, respectively. Here, we provide a comprehensive overview of the mechanism of DNA methylation by the RdDM pathway, its maintenance and removal, and different histone modification categories like acetylation, methylation, phosphorylation and ubiquitination. This review further discusses in detail the crucial role these modifications play in adapting to major abiotic stresses and how plants preserve these experiences as stress memory to respond to recurring stresses. It emphasizes the role of epigenetic modifications as a crucial mechanism for building plant’s tolerance and how it can be an important research priority to improve plant growth and development under abiotic stress conditions.

TIFY protein is a plant-specific transcription factor widely found in land plants and plays an important role in plant growth and development, signal transduction and stress response. Although many TIFY gene families have been identified and studied in plants, they have not been well described in octaploid strawberry. In this study, 54 TIFY family genes in strawberry were identified and their biological information was analyzed. The phylogenetic tree showed that FaTIFY genes were divided into four subfamilies: TIFY, JAZ, ZML and PPD. The JAZ subfamily was the largest and can be further divided into five groups. These genes are located on six chromosomes and exhibit a motif range of 3 to 8. Promoter cis-element analysis showed that most FaTIFY genes contain cis-elements associated with plant hormones responses. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis showed that FaTIFY genes had different expression patterns under methyl jasmonate (MeJA), and salicylic acid (SA) treatments. At the same time, we also examined the expression pattern of TIFY gene after boea mold infection and predicted the binding of TIFY protein to WRKY transcription factor, providing a theoretical basis for exploring the role of TIFY gene in hormone delivery and plant defense in strawberry.

Plant lodging severely reduced crop yield and quality. Different plant growth regulators (PGRs) have been applied to improve lodging resistance through the regulation of physiological changes, especially on the increase of stem thickness and strength. Melatonin is a pleiotropic PGR for the regulation of plant growth and development. In this study, we demonstrated that the exogenous treatment of melatonin to Glycine max significantly enhanced plant lateral growth by increasing stem diameter. In addition to the stem thickness, secondary cell wall (SCW) deposition acts as another critical factor for stem rigidity for lodging resistance. To understand whether exogenous treatment of melatonin would regulate SCW biosynthesis genes, we performed transcriptomic analyses on the stems of Glycine max with or without melatonin treatment. Through the differentially-expressed-genes (DEGs) analyses, many SCW biosynthesis genes were found to be regulated by melatonin, including the cellulose, hemicellulose and lignin biosynthesis enzymes. We also found that the two known master regulators, NAC and MYB, of SCW biosynthesis genes were induced under melatonin treatment, which further supported our observation on the differential expression of SCW biosynthesis genes. Our study highlighted the improvement of lodging resistance by the exogenous treatment of melatonin through the increase of plant stem thickness and the regulation of SCW biosynthesis genes and their upstream TFs in Glycine max.

Forsythia suspensa (Thunb.) Vahl is a self-incompatible, heterostylous plant with style-length dimorphism. Heterostyly is a unique flower polymorphism in dioecious angiosperms. Previous research has demonstrated that in heterostylous species like Primula and Turnera, brassinosteroids (BRs) regulate style length. However, the regulatory mechanism of F. suspensa heterostyly remains poorly understood. In this study, we investigated the morphological and cytological differences between the long (L) and short (S) morphs of F. suspensa. We measured the amounts of Teasterone (TE), Typhasterol (TY), Castasterone (CS), and Brassinolide (BL) in the styles. Furthermore, we used topical treatment of the BR inhibitor propiconazole (PPZ) to investigate its impact on style elongation. To clarify the function of BRs in controlling style length, we identified key genes and evaluated their expression levels by analyzing the transcriptome data of F. suspensa. Our findings show that, in contrast to the S-morph, the L-morph shows significant elongation from the flower bud scale abscission phase to the dew corolla phase. L-morph styles have a much higher castasterone level than S-morph styles, and treatment with propiconazole, an inhibitor of BR production, prevents style elongation in the L-morph. Furthermore, transcriptome analysis revealed that the putative orthologous gene of TCH4, a BR-responsive gene, exhibits higher expression in the L-morph compared to S-morph. These findings support the role of BRs as regulators of distinct style lengths in F. suspensa. Additionally, we found that EVM0011396 gene (annotated as FsCYP749A22), encoding a putative BR-degrading enzyme, shows increased expression during S-morph style development, with significantly higher expression in S-morph styles compared to L-morph styles. In contrast, the expression level of EVM0028947 (annotated as FsCYP90D1) coding for a BR biosynthesis gene, is higher in L-morph styles compared to S-morph styles. The expression patterns of EVM0028947 and EVM0011396 suggest their involvement in BR homeostasis in F. suspensa styles. This study provides insight into the molecular mechanism underlying the heterostyly of F. suspensa and lays the foundation for further exploration of this phenomenon.

Defoliation is a type of mechanical stress, and few studies have investigated this process in the early stages of maize development. Pest attacks, hail and machinery traffic have increased in recent decades, thus increasing this stress and potentially leading to losses. Furthermore, there are corn production systems in Brazil where early defoliation naturally occurs. Thus, the objective of this study was to determine the morphophysiological and biochemical changes in maize subjected to early defoliation and their effects on recovery from this stress. The experiment was performed in pots, and the plants were subjected to two treatments at the four fully expanded leaf stage: without defoliation (control) and with defoliation. Morphometric parameters, such as gas exchange, leaf pigment and biomolecule content, phytohormone content, root morphology and leaf anatomy, were evaluated at seven and fourteen days after defoliation. Compared with the control plants, the defoliated corn plants were shorter in height, stem diameter, length, surface area, root diameter and volume, dry biomass and leaf anatomy. However, photosynthesis, chlorophyll content and nutrient content were similar in both treatments. After seven days of treatment, the amino acid content increased in the defoliated plants, and after fourteen days, the reducing sugars, amino acids and proteins decreased in these plants. The levels of gibberellins and salicylic acid were greater in plants subjected to defoliation. The reestablishment of corn plants after defoliation occurred through the action of gibberellins and salicylic acid, which promoted the growth of aboveground biomass, maintenance of chlorophylls and gas exchange. The reallocation of amino acids and reducing sugars also contributes to the formation of new leaf primordia in defoliated plants.

Main Conclusion: The major QTL qATS1 for rice seedling alkali tolerance was identified by QTL-seq and QTL mapping, and further confirmed that OsMYB305 regulates plant alkali tolerance by affecting the transport of Na⁺ and K⁺ in roots and seedlings through qRT-PCR and functional characterization. Rice is a crop sensitive to saline and alkaline stress. However, the scarcity of alkali tolerance genes in rice has resulted in a large number of cultivated rice or germplasm resources that are difficult to cultivate in saline fields. To clone new alkali tolerance genes, we systematically characterized the number of days of seedling survival and sodium and potassium ion concentrations under alkali stress using 840 F_2:3 individuals generated from a cross between Hajingdao8 and Tengxi144. Using QTL-seq technology and QTL mapping based on KASP markers, qATS1 was localized to the 77.15 Kb interval on chromosome 1. A MYB gene, OsMYB305, was identified to strongly respond to alkali stress by gene function annotation, mutation detection, and qRT-PCR analysis of this interval. Knockdown of OsMYB305 in HJD8 resulted in a massive transfer of Na⁺ and K⁺ from the mutant roots to the leaves, leading to the death of osmyb305 leaves after 18 days of alkali stress. In conclusion, this study identified OsMYB305 as an alkali tolerance gene, and the variation of 19 SNPs in the promoter region of OsMYB305 and 4 SNPs on exons can provide a theoretical basis for future search of molecular mechanisms upstream and downstream of OsMYB305 to regulate alkali tolerance and molecular design breeding.

Hypoxis hemerocallidea is a medicinal plant containing hypoxoside (a pharmacologically active phytosterol diglucoside). This study evaluated the elemental composition in leaves of H. hemerocallidea treated with cadmium (Cd) and aluminium (Al) using scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDX). The impact of Cd and Al on photosynthetic pigments and performance, antioxidant activities and ultrastructure were also assessed. Corms of H. hemerocallidea were micropropagated, rooted and then exposed to varying concentrations of Cd, Al, and Cd + Al for six weeks. The SEM/EDX analysis indicated a two-fold increase in carbon content across all treated plants compared to the control. No/little Cd was detected in the leaves compared to a progressive increase in Al concentration with increasing Al treatment levels. This indicted that Al is more readily translocated to the shoots compared to Cd. Plants treated with Cd exhibited a significant decrease in total chlorophyll content accompanied by reduced photosynthetic performance and lower relative electron transport rates. Cd and Al exposure led to higher carotenoid, superoxide dismutase and malondialdehyde levels, indicating oxidative stress. Cd-treated plants displayed increased amylase activity and decreased carbohydrates content. Ultrastructural alterations occurred with exposure to Cd and Al, including abnormal swelling or disintegration of chloroplasts and thylakoid degeneration. An increase in starch grains and a decrease in plastoglobuli were also noted. In conclusion, this investigation provides evidence that both Cd and higher concentrations of Al exert detrimental effects on the ultrastructure, metabolism and photosynthetic performance of H. hemerocallidea, contributing to reduced growth and biological activity when stressed.

Melatonin is an important phytohormone influencing plant growth and defense responses. However, the mechanism mediating the regulatory effects of melatonin on the salt tolerance of germinating maize seeds remains unexplored. In this study, the application of exogenous melatonin enhanced the salt tolerance of germinating maize seeds. A transcriptome analysis indicated that complex regulatory pathways may be associated with the melatonin-mediated salt tolerance. Remarkably, antioxidant activities, transcriptional regulation, and phytohormone (e.g., cytokinin and auxin) pathways were induced following the exogenous application of melatonin. The microRNA (miRNA)-seq analysis result indicated that exogenous melatonin obviously altered the expression of a set of miRNAs. Notably, many differentially expressed miRNAs and their target genes, including several transcription factor genes, were revealed to contribute to salt stress responses. According to metabolite profiles, the abundance of diverse metabolites, like secondary metabolites, nucleotides, cofactors, and vitamins, increased significantly after using exogenous melatonin. The combined analysis of the transcriptome and metabolome indicated that several gene–metabolite networks related to amino acid metabolism and secondary metabolite biosynthetic pathways are essential for melatonin-mediated maize tolerance to salt stress. Consistent with these findings, exogenously applied melatonin altered the phytohormone levels and increased the antioxidant enzyme activities and energy supply. Our results reflect the significance of melatonin for enhancing the salt tolerance of germinating maize seeds, which is achieved through the regulation of antioxidant capacity, phytohormone content, and metabolic adaptation.

Currently, in vitro cell, tissue, and organ cultures are used to produce plant secondary metabolites that are used as natural coloring agents, nutraceuticals, and medications. Various strategies have been applied for the hyperaccumulation of biomass and bioactive secondary compounds in vitro. The elicitation of cultured cells and organs with biotic and abiotic elicitors is an excellent strategy that has yielded promising results. Among various abiotic elicitors, light parameters such as light quality, intensity, and photoperiod have evolved as biotechnological tools to elicit cultures. Of the various light sources tested, ultraviolet (UV) lights, particularly UV-B, red, blue, and a mixture of light emitted by fluorescent light or light-emitting diodes, have yielded outstanding results and boosted the accumulation of bioactive compounds in cultured cells and organs. The objective of the current study was to evaluate light as an elicitor source and summarize the advantages and limitations of various light sources as elicitors for the bioaccumulation of secondary metabolites in vitro. The mechanism of the elicitation of secondary metabolism by UV and spectral light is discussed in this review.

To reveal responses of photosynthetic physiological characteristics in Phoebe bournei seedlings to different light qualities and provide a basis for light environment regulation in seedling cultivation and under-canopy regeneration, we analyzed the photosynthetic physiological characteristics of P. bournei seedlings under five types of light qualities (white, red, blue, green, red: blue = 1:1) with the same photosynthetic photon flux density of 100 ± 5 μmol·m⁻²·s⁻¹. The results showed that blue light significantly promoted chlorophyll content, Rubisco, RCA and photosynthetic rate (Pn), but water use efficiency (WUE) was reduced by blue light. The red light treatment exhibited the highest initial fluorescence (Fo), but wasn't conducive to the accumulation of photosynthetic pigments and had the lowest maximum photochemical efficiency (Fv/Fm) and potential photochemical efficiency (Fv/Fo). The seedlings treated by green light showed the lowest Pn, Tr, WUE, rubisco, with the highest Fv/Fm and Fv/Fo. Red-blue light significantly increased WUE, photosynthetic electron transfer rate (ETR), actual photosynthetic efficiency Y(II), and quantum yield of regulated energy dissipation Y(NPQ) in PSII of P. bournei seedlings, with the second highest Pn across treatments. In conclusion, the effects of single light quality on photosynthetic characteristics of P. bournei seedlings exhibited both advantages and disadvantages. The combination of red and blue light, which integrated the advantages of single light quality, enhanced the photosynthetic performance and photoprotective ability of P. bournei seedlings. It promoted the energy conversion and utilization efficiency of PSII, resulting in the best carbon assimilation efficiency. Therefore, red-blue light promoted the growth and development of Phoebe bournei seedlings.