Journal of Plant Growth Regulation最新文献

The straightness of Paeonia lactiflora stems is pivotal for their use in cut flowers, often influenced by cellulose and other cell wall materials. Variances in auxin (IAA) content between straight and bending cultivars have been noted, yet the underlying mechanism remains elusive. Here, we treated the bending cultivar ‘Qi Hualushuang’ with 150 mg·L⁻¹ IAA across five developmental stages, examining morphological, anatomical, and cellulose metabolism-related changes. The results showed that exogenous IAA significantly improved stem straightness, plant height, and stem diameter. This improvement coincided with the early development of vascular tissue at the early and mid-stage of stem growth. IAA application down-regulated the expression of cellulose synthase genes, altering sucrose synthase and cellulase activities, ultimately resulting in higher cellulose content during the bud-breeding stage. Notably, an early accumulation of cellulose in vascular tissue was observed, characterized by earlier and more orderly arranged cellulose microfibrils, oriented at a smaller angle to the growth direction. This observation suggests that early cellulose development is advantageous for achieving stem straightness. Our study also found that the promotional effect of IAA on stem growth was mainly in the early stages, and other phytohormones may be jointly involved in the regulation. In summary, our study suggests that IAA enhances stem straightness by modulating the development of cell wall cellulose and vascular tissue. These findings provide a theoretical basis for the cultivation and trait improvement of P. lactiflora cut flower cultivars.

Gamma-aminobutyric acid (GABA) is a non-protein amino acid and has been thoroughly studied in animals, where it works as a neurotransmitter. In plants, GABA was found to be a signaling molecule after the discovery of its binding sites. GABA metabolism takes place through the GABA shunt. It occurs in mitochondria and bypasses two steps of the tricarboxylic acid (TCA) cycle. It is also produced via proline and polyamine metabolic pathways. Both abiotic and biotic stress conditions affect plant’s growth and development. These stresses impact respiration and energy production in mitochondria, resulting in the elevated production of reactive oxygen species (ROS), which ultimately leads to cell death. The synthesis of GABA aids in the restoration of respiratory processes and energy production. Its accumulation is observed during plant stress conditions. In stress conditions, GABA concentration increases which raises the tolerance level of plants. It mitigates ROS formation, improves photosynthetic machinery, regulates the opening of stomata, and activates antioxidant enzymes. The transport of GABA is crucial for its functioning throughout plants, making it important to understand its cell and organelle transport. This review describes the biosynthesis, distribution, transport, and signaling roles of GABA, and also highlights the management aspects of the GABA shunt pathway for ROS production and in the defense mechanism of plants.

The GATA-binding factor (GATA) plays a major role in regulating plant development and response to distinct environmental stresses. At present, GATAs are characterized in various model plant species, including Arabidopsis thaliana and Oryza sativa. However, the GATA gene family in Platycodon grandiflorum is not yet fully understood. The study aimed to develop a comprehensive understanding of the GATA TFs and explore the regulatory mechanism of methyl jasmonate (MeJA) on the GATA members in P. grandiflorum. A total of 22 PgGATAs were identified based on publicly available genome data of P. grandiflorum, and each member was analyzed in detail. The 22 identified genes were distributed across nine chromosomes. Their phylogenetic tree and domain structures showed that the GATAs could be clustered into four subfamilies (A–D). The structural protein domains and conserved motifs of the PgGATA family members were relatively conserved across different subfamilies. Light and hormone response elements were found in abundance in the promoter sequences. In addition, quantitative real-time polymerase chain reaction (qRT-PCR) indicated that PgGATA4, 6, 7, 8, and 11 were sensitive to MeJA treatment in P. grandiflorum roots. Nevertheless, co-expression network analysis revealed that the activities of the genes in the family remained significantly correlated, suggesting possible synergy in their functions. Two (PgGATA5 and PgGATA9) and three (PgGATA8, PgGATA11, and PgGATA22) hub PgGATAs were identified that might have central functions in P. grandiflorum tissues and MeJA-treated roots, respectively. This study provided detailed information about the PgGATA gene family and facilitated a functional characterization of the candidate genes.

Drought stress may be mitigated by the high electron transfer capability of carbon quantum dots, effectively improving the growth and physiological efficiency of plants under stress. Accordingly, a two-year field experiment was conducted to examine the effects of carbon quantum dots on physiological efficiency of soybean plants under drought stress. The carbon quantum dots were applied as a foliar treatment at a concentration of 5 mg L⁻¹ on soybean plants under normal and water-stress conditions. The results showed that the application of carbon quantum dots did not have a noticeable impact on the physiological performance of plants under regular irrigation. However, under drought stress, carbon quantum dots significantly improved various parameters, including soybean ground green cover (about 14%), leaf area (21%), chlorophyll content (18%), maximum efficiency of photosystem II (19%), relative photosynthetic electron transport rate (23%), leaf water content, osmolyte production, antioxidative activities, and grain yield (25%). Additionally, carbon quantum dots reduced the generation of reactive oxygen species, lipid peroxidation, and osmotic stress during drought conditions. These findings suggest that carbon quantum dots can protect plant cells from oxidative and osmotic damage, thereby enhancing physiological performance during periods of drought stress. These results reveal the potential of CQDs as a promising tool for enhancing drought tolerance in soybean plants, with implications extending beyond this crop. The mechanistic insights highlighted the broader applicability of CQD treatments in agriculture, offering a novel strategy to mitigate drought stress across diverse crop species. Our study also offers tangible benefits for farmers and researchers, paving the way for sustainable crop management practices in the face of climate change-induced challenges.

Ammodendron bifolium is an endangered plant in the Takeermohuer Desert. Its population has gradually decreased due to human activities and the harsh climate, and this decrease was exacerbated by low germination rates in the natural environment. However, the cause and classification of seed dormancy are not entirely clear. We investigated the contributions of seed coats, embryos, and endogenous hormones to seed dormancy and explored methods for breaking dormancy. Studies have shown that A. bifolium seeds exhibit high vitality and impermeability and seed coats and embryos contain germination inhibitors; thus, dormancy of A. bifolium seeds can be classified as exhibiting combinational dormancy based on Baskin’s category system. The authors hypothesized that endogenous abscisic acid (ABA) might be critical for inducing seed dormancy. In addition, this study indicated that ethylene (ETH), 1-aminocyclopropane carboxylic acid (ACC), trans-zeatin-riboside (tZR), fluridone (FL), and thiourea (CH₄N₂S) could be used to break dormancy after scarification treatment. The findings of this study provide a better understanding of the dormancy mechanism of A. bifolium seeds and lay the foundation for the revegetation of desert A. bifolium.

Hormones are the key mediators of plant growth, development, and adaptive responses to diverse environmental growth conditions. However, the knowledge of how the endogenous concentration of a hormone affects those of other hormones in plants during their growth is not completely comprehended. JA (jasmonic acid) is a key hormone having multifaceted roles in shaping plant growth and development and driving plant responses to abiotic and biotic stressors. Here, we studied how the disruption in the JA biosynthetic pathway in Arabidopsis thaliana affects the homeostasis of other hormones by measuring the concentrations of various hormones, including ABA (abscisic acid), AUX [auxin, specifically IAA (indole-3-acetic acid)], CKs (cytokinins), GAs (gibberellins), and SA (salicylic acid) in 10 days old Arabidopsis JA-deficient aos (allene oxide synthase) knock-out mutant seedlings. We noted increased levels of trans-zeatin class of CKs but reduced levels of cis-zeatin and isopentenyladenine class of CKs, as well as reduced levels of IAA, GAs, and SA in the aos mutant seedlings, compared with WT (wild-type) seedlings. We also noted reduced expression levels of the genes associated with AUX biosynthesis but increased expression levels of the genes associated with the catabolism of SA and GAs in aos mutant plants compared with those of corresponding genes in WT plants. These results indicate that the levels of these hormones are positively correlated with that of JA in plants during their growth, at least at the seedling stage.

Tobacco black shank (TBS) disease, caused by Phytophthora nicotianae (P. nicotianae), poses a severe threat to tobacco productivity, necessitating the identification of effective control methods. Sulfur dioxide (SO₂) has emerged as a signaling molecule involved in modulating plant stress responses, yet its role in inducing resistance to TBS in tobacco remains unclear. This study investigated the potential of enhancing TBS resistance through root irrigation with SO₂ derivatives and elucidates the underlying mechanisms. Our findings revealed that SO₂ derivative root irrigation significantly enhanced tobacco resistance to TBS. This was evidenced by reduced malondialdehyde levels, increased hydrogen peroxide accumulation, and elevated activities of antioxidant enzymes such as superoxide dismutase and peroxidase. Moreover, analyses of phytohormones—jasmonic acid (JA), salicylic acid, abscisic acid, and ethylene—indicated a notable increase in endogenous JA levels in SO₂-pretreated plants. The application of the JA biosynthesis inhibitor diethyldithiocarbamate acid (DIECA) significantly decreased JA levels and attenuated the SO₂-induced TBS resistance. Furthermore, transcription of several JA-responsive defense genes was significantly upregulated in SO₂-pretreated plants during P. nicotianae infection. These results demonstrate that SO₂ application elevates endogenous JA levels, thereby activating the antioxidant defense system and enhancing TBS resistance in tobacco plants. This study advances our understanding of SO₂-induced resistance mechanisms and offers an effective, economical, and environmentally friendly strategy for managing soil-borne fungal diseases in crop production.

Biopriming can be considered as a sustainable method that involves the application of beneficial plant growth-promoting microorganisms to seeds or seedlings, enhancing their growth, vigour, and ultimately the yield of the crop plants. The microbial symbionts of epiphytic orchids may function as efficient plant growth promoters as they are particularly beneficial in environments where contact with the soil is limited. The present study is an attempt to explore the biopriming effects of microbial consortium, prepared from the bacterial and fungal associates of the epiphytic endemic orchid Dendrobium ovatum, on the growth of Amaranthus tricolor (Red Amaranth) and Oryza sativa (Uma MO16). The bacterial and fungal isolates that displayed beneficial plant growth-promoting capabilities like extracellular enzyme production, Indole-3-Acetic Acid (IAA), hydrogen cyanide, phosphate solubilisation, and ammonia production were selected for the preparation of bacterial, fungal, and bacterial-fungal consortium. The various growth parameters like shoot and root length, plant biomass, Chlorophyll a fluorescence parameters, pigment composition, metabolite production (total soluble sugars, amino acids, and total phenolics), and yield parameters were analysed and compared in bioprimed and non-primed A. tricolor and O. sativa seedlings. The results demonstrate increased biomass, enhanced accumulation of photosynthetic pigments and photochemistry, metabolite production, and yield in all the bioprimed plantlets, compared to the control. The results demonstrate the enhanced seedling vigour and health, culminating in enhanced yield of crop plants. The findings from the present study point towards the growth- and yield-enhancing effect of biopriming using the microbial consortium prepared from the native aerial epiphytic microorganisms on the crop plants that can contribute towards sustainable agriculture practices and ecosystem preservation.

Soil salinization and freshwater scarcity are the major challenges threatening conventional agriculture development due to their negative impacts on plant growth and productivity. Fungal infections accentuate these challenges and pose a threat to global food security. Thermo-halotolerant bacteria exhibit a great ability to eradicate phytopathogen proliferation, enhance agricultural yields, and enable the use of saline water for irrigation in arid and semi-arid regions characterized by increasing temperatures and harsh climates. Ten novel halotolerant bacteria isolated from Qatar desert environment and coastline were screened in vitro for their halotolerance, thermotolerance, and plant-growth-promoting potential. Among these, five strains showed significant ability to produce cell-wall degrading enzymes, ACC-deaminase, siderophores, solubilize phosphorous, fix nitrogen, inhibit fungal proliferation, and form biofilms. Particularly, Bacillus cabrialesii strain HB7 displayed interesting potential to eradicate gray mold disease on post-harvested tomato fruits Solanum lycopersicum var. cerasiforme and promote seeds germination and seedlings growth under saline conditions. Scanning electron microscopy evidenced that HB7 is an endophytic strain, capable of forming protective biofilm around tomato seedling roots. This biofilm may play an important role in protecting internal plant tissues and preventing salt infiltration. These findings support the use of Bacillus cabrialesii strain HB7 as an efficient biofertilizer, offering a pathway to sustainable agricultural practices that leverage saline water resources for irrigation.

Tea plants exposed to temperature stress conditions exhibit reduced quality and yield. Long non-coding RNAs (lncRNAs) are key regulators in temperature stress responses. A genome-wide lncRNA analysis using RNA sequencing data from tea plants under varying temperature stresses was carried out in this study. The analysis identified a total of 23589 putative lncRNAs, with 2483 being differentially expressed (DE). Weighted gene co-expression network analysis (WGCNA) showed 445 DE lncRNAs co-expressed with 544 genes associated to temperature stress responses. Functional annotation indicated that these genes are involved in processes like protein folding, cellular response to decreased oxygen level, response to hypoxia, unfolded protein binding, and response to heat during high temperature stresses; and response to cold, water transport, and water channel activity during low temperature stresses. Additionally, competing endogenous RNA (ceRNA) network analysis revealed 230 temperature-responsive lncRNAs regulating 400 DE genes via 106 microRNAs (miRNAs). To validate high-throughput sequencing data, primers were designed for eight DE lncRNAs, and their expression levels were confirmed. This study enhances understanding of lncRNAs in temperature stress responses, providing a foundation for further research in tea plants.