Plant Growth Regulation最新文献

Abstract

The membranes of plants are where temperature sensing begins and where freezing injury typically occurs. Barley’s adaptation to and survival after freezing stress is aided by remodelling of its membrane lipid composition. The modifications of individual lipid molecular species in different stress-treated plant species and cultivars can indicate the functions of genes regulating lipid metabolism or signaling. In this study, we employed a membrane lipidomic approach to investigate the response of barley of two cold-tolerant and two cold-sensitive cultivars to freezing temperatures during the barley trefoil stage. A total of 56 predominant lipid compounds changed significantly under freezing stress were identified. Phosphatidic acid (PA), lysophosphatidic acid (LPA) and monogalactosyldiacylglycerol (MGDG) in freezing-tolerant varieties were significantly upregulated under freezing stress, while there was a decrease in freezing-sensitive cultivars. Freezing-tolerant varieties experienced greater changes in lipid composition compared to freezing-sensitive cultivars, which had proportionally smaller changes. In addition, when exposed to short-term cold stress, varieties A and B had lower levels of monoglyceride lipase (MGLL) than varieties C and D. However, under long-term cold stress, the opposite was observed. Additionally, the freezing-tolerant variety A showed a notable increase in the expression of diacylglycerol acyltransferase 1 (DGAT1) after being exposed to 4 °C. Furthermore, SENSITIVE TO FREEZING 2 (SFR2) reached its highest level in all four varieties after being exposed to cold treatment for 48 h. This study indicates that freezing injury in barley leaves is correlated with extensive changes in lipid metabolism and that freezing-tolerant varieties can alleviate freezing injury by membrane lipid remodelling. The study’s outcomes may improve our understanding of barley’s freezing adaptation mechanisms and contribute to breeding for better tolerance.

Seredipita indica (formerly Piriformospora indica) is an endophytic fungus that establishes the symbiosis within the roots of various plants, exhibiting analogous functions to arbuscular mycorrhizal fungi. S. indica can proliferate in vitro in synthetic media, without the need of a host. Due to its isolation from desert environments, S. indica is particularly prominent in enhancing the host plant’s tolerance to abiotic stresses. This review briefly analyzes the role of S. indica in plants exposed to abiotic stresses (e.g., drought, waterlogging, salt stress, low temperatures, and heavy metal stress). This review also elucidates the underlying mechanism regarding S. indica-enhanced tolerance of host plants in response to abiotic stress by regulating nutrient acquisition, osmoregulation (proline, soluble sugars, betaine, and K⁺), phytohormone (auxins, abscisic acid, ethylene, and gibberellins) balance, antioxidant enzyme defense systems, polyamines (e.g., putrescine), and functional genes (e.g., aquaporins and phosphate transporter). Some of the fungus’ own genes, such as transporters of polyamines, also respond to abiotic stresses, thereby assisting the host in co-resistance to abiotic stresses. The review further examines the application potential of S. indica to enhance stress tolerance in the field as well as proposes future prospects (e.g., omics, fungal self-response, reactive oxygen species signalling transduction, and its association with other microorganisms).

Melatonin (MT) is a tryptophan derivative with multiple functions in both animals and plants. Exogenously-provided MT such as through seed priming has emerged as an effective way to improve stress tolerance of plants. However, little is known about MT priming in improving salinity tolerance of halophytes particularly during their early life-cycle stages. We therefore examined roles of MT priming in enhancing salinity tolerance of seeds and nascent seedlings of five warm subtropical halophytes. Priming with different MT concentrations alleviated primary dormancy of the seeds of annual halophytes Z. simplex and P. oleracea. Seed priming with MT also reduced the inhibitory effects of salinity on germination of halophytes by improving mean final and rate of germination under saline conditions. MT priming also improved germination recovery, when un-germinated seeds were transferred from saline solutions to water. Furthermore, MT priming also improved growth parameters such as total length, leaf area and photosynthetic pigments of the seedlings of test species under both non-saline and saline conditions. In general, low (5 and 100 µM) concentrations of MT were found most effective in improving seed dormancy, germination and early seedling growth of halophytes particularly under saline conditions.

Abstract

The traditional approaches for utilizing straw as a growth support for plants in their initial growth phases may not be optimal owing to its protracted decomposition rate. We aim to address this problem by improving the degradation rate of straw through mechanochemical crushing, which can significantly expedite the process. Moreover, there remains a lack of clarity regarding the mechanisms responsible for the positive impact of mechanochemically crushed straw on rice growth. To gain a better understanding of the differences between using whole straw and mechanically crushed straw, this study investigates how mechanical crushing affects the structure of straw. Additionally, this study has examined the effects of incorporating mechanochemically crushed straw into paddy soil on bacterial communities, soil properties, and the growth of rice plants. In this investigation, whole straw was employed and two distinct methodologies for straw crushing were implemented, involving one instance of straw subjected to a 10 min crushing duration and another subjected to a 20 min crushing duration (SC20), while a control group was maintained devoid of any treatment. Our results demonstrated that the SC20 treatment significantly improved plant height (25.1%) and fresh (74.6%) and dry weight (76.3%) and increased soil nutrients, such as soil organic carbon (31.6%), total nitrogen (20.0%), available potassium (53.5%), available phosphorus (50.8%), microbial biomass carbon (48.4%) and microbial biomass nitrogen (52.2%), but significantly decreased soil pH (from 7.22 to 7.07) compared to the control group. The relative distribution of several specific bacteria, including WCHBI-32, Anaeromyxobacter and Anaerolinea, was significantly increased in both treatments, but the structure of the soil bacterial community was modulated by mechanochemically crushed straw, which were found to enhance carbon-related functional groups, but simultaneously reduce nitrogen-related functional groups in the soil. Overall, these findings suggest that incorporating crushed straw in paddy soil can alter soil properties, influence the microbial community and promote the growth of rice crop.

Symbiotic microorganisms are essential for promoting plant growth and establishment from the early stages of plant development. However, the diversity of seed-associated endophytes in native Andean trees and their role in growth promotion and seedling establishment have scarcely been studied. This study aimed to characterize the microbial diversity associated with seeds of Nothofagus obliqua (Mirb.) Oerst. Viable seeds were collected from healthy young trees in a section of the Nahuelbuta Mountains, south-central Chile. Then, they were processed to characterize total microbial diversity using a 16S rRNA gene and an internal transcribed spacer (ITS) region metabarcoding approach. The diversity of culturable bacteria was determined and tested for plant growth-promoting effects. Effects on seed germination, seedling development, and plantlet establishment were evaluated by in vivo inoculations. Seed-associated microbial diversity was dominated by Ascomycota and Proteobacteria, with Diaphorte and Pantoea being the most abundant genera. Five different strains of culturable bacteria were identified, with Rahnella aquatilis being the strain with the most traits that promote plant growth. Bioaugmentation with R. aquatilis improved seed germination, plantlet growth, and establishment of N. obliqua plantlets in the field. Specifically, bioaugmentation with R. aquatilis stimulated height (+ 52%), stem cross-sectional area (+ 89%), stomatal conductance to water vapor (+ 25%), and leaf mass area (+ 29%). These results provide evidence for the beneficial properties of seed-associated bacteria that can support the establishment of native forest tree species in the southern Andes.

Plant stem growth is important in plant aerial parts and not only affects plant biomass but is also related to plant defense against the external environment. Thus, the regulation of stem growth has attracted increased attention and has been extensively studied. Plant stems require appropriate development to improve their adaptation to various environmental conditions. The stem growth stage can be divided into two parts, stem elongation and stem thickness, which belong to the primary growth and secondary growth of the stem, respectively. The regulatory mechanism is controlled by a sophisticated genetic network including interactions among various molecules, which work individually or coordinate with others. Recently, plant hormones have been reported to be core regulators in stem growth, in combination with other components such as transcription factors and noncoding RNAs. However, few comprehensive overviews of plant stem growth alone have been reported. This review discusses the mechanisms of phytohormones, transcription factors, and noncoding RNAs involved in the regulatory network of main stem growth during the process of primary stem development in vascular plants and provides references for improving plant architecture in the future.

Biochar amendment is a management strategy to alleviate drought stress in plants. However, in-depth assessments are needed to elucidate how biochar amendment affects root growth by modulating various physiological and biochemical changes under drought stress. In this study, we investigated ion fluxes, metabolic levels, and physiological traits of maize roots in biochar-amended soil under drought stress using noninvasive micro-test technology, metabolomics profiling, and ratiometric fluorescence. The results revealed that the biochar treatment increased soil K⁺ supply and root sap K⁺ concentration, but decreased root Ca²⁺ efflux under moderate drought stress, compared to the no biochar treatment. Root apoplastic pH and abscisic acid content increased significantly in the biochar treatment under severe drought stress. Consequently, root osmolality and root malonaldehyde content decreased, whereas root water potential, root ascorbate peroxidase activity, and plant fresh weight increased in the biochar treatment under severe drought stress. In addition, the biochar treatment enhanced the accumulation of trehalose and 3-hydroxyanthranilic acid in response to moderate and severe drought stress while reducing the levels of uridine, cytidine, guanosine, l-tryptophan, and l-glutamine in maize roots. These results indicate that the biochar-mediated improvements in plant drought tolerance were associated with increased K⁺ concentration, less Ca²⁺ efflux, and an increase in apoplastic pH in maize roots.

Abstract

Soil cadmium (Cd), which can occur naturally in the environment or arise from industrial pollution, seriously affects crop quality and threatens human health. Therefore, reducing grain Cd accumulation (GCA) has become an important topic worldwide. To comprehensively assess the research status of GCA, we reviewed the research into physiological and molecular mechanisms of GCA, including the characteristics of Cd uptake, transport, and accumulation from roots to grain; furthermore, literature on GCA-related quantitative trait locus identification and gene functional analysis were reviewed. Based on physiological and molecular mechanisms, two strategies to reduce GCA, namely soil management and genetic improvement, were also critically summarized. It became clear that further research is necessary into the physiological mechanisms of Cd uptake, transportation, and accumulation in grain. It is also important to accelerate the discovery and use of effective functional markers and genes associated with low Cd accumulation and to improve the feasibility and potential value of breeding low Cd grain crops.

Seed germination is a crucial plant-life process whose success depends largely on the seed's ability to germinate under favourable environmental conditions. Through molecular signalling, a seed is able to perceive environmental information, assimilate it, and transmit signals that determine its destiny. Reactive Oxygen and Nitrogen Species (RONS) function as signalling molecules that influence multiple phases of plant development. In the process of seed germination, their presence generally promotes germination completion, though not to the same extent in all species and environments. As signalling molecules, they participate in the sensing of light and temperature fluctuations as favourable germination cues, but they also play a role in inhibiting germination when temperatures exceed the optimal range, preventing seedling exposure to heat. Depending on environmental conditions, RONS set up crosstalk with the major phytohormones involved in germination, ABA, GA, and even auxin, regulating their biosynthesis and signalling. Here, we show relevant studies on how RONS exert seed germination control on multiple levels, such as through protein oxidation, epigenetic control, promotion of phytohormone key-metabolism genes expression, post-translational protein modifications, and redox interactions with DOG1. This review summarises the current understanding of the role of RONS in the seed, from its maturation to the transduction of environmental conditions. Special consideration is given to the RONS-mediated germination response to favourable stimuli, such as light or temperature fluctuations, and to conditions that inhibit germination, such as high temperatures.