Functional Plant Biology最新文献

Plant stems grow towards the incident light in response to unilateral blue light to optimize photosynthesis. However, our findings reveal that unilateral high-intensity blue light (HBL) triggers backlit lodging in etiolated cotton (Gossypium hirsutum ) hypocotyls when they are pulled approximately 1.5cm from the soil. Phenotypic analysis indicated that stomata on the lit side were open, while those on the shaded side were closed under unilateral HBL. To investigate the relationship between stomatal movement and backlit lodging, we applied abscisic acid (ABA), hydrogen peroxide (H2 O2 ), and lanthanum chloride (LaCl3 ) to the lit side, and cytokinins (6-BA) and ascorbic acid (ASA) to the shaded side. Results showed that all these treatments inhibited the backlit lodging phenomenon, specifically, ABA, H2 O2 , and LaCl3 reduced stomatal opening on the lit side, while 6-BA and ASA enhanced stomatal opening on the shade side. These results demonstrate that HBL-induced asymmetrical stomatal opening on the lit and shade side of hypocotyl supports the backlit lodging phenomenon. Notably, maize (Zea mays ), which lack stomata in the hypocotyl did not exhibit HBL-induced backlit lodging, whereas soybean (Glycine max ), which has stomata in its etiolated hypocotyl, displayed a similar phenotype to that of cotton. Additionally, while both red light and low-intensity blue light (LBL) can induce stomatal opening, they do not trigger the backlit lodging phenomenon. These findings suggest that backlit lodging is a unique HBL-dependent response, but the mechanism need further investigation.

The NHX1 gene encodes a Na+ /H+ antiporter located in the tonoplast membrane, which plays critical role in regulating plant salt tolerance. It is also involved in the uptake and accumulation of K in plants; however, its precise mechanism is unknown. In this research, we elucidated the physiological basis underlying the increases in K content induced by NHX1 . We evaluated main agronomic traits, leaf K content, K+ uptake kinetics, and root morphological and physiological characteristics from field-planted and hydroponic plants. We included a wild-type tobacco (Nicotiana tabacum ) variety (K326) and three transgenic tobacco lines (NK7, NK9, NK10) that overexpress AtNHX1 from Arabidopsis thaliana . Results demonstrated that the agronomic performance of the AtNHX1 -overexpressing tobacco lines was similar to K326 in field and hydroponic settings. The three AtNHX1 -overexpressing tobacco lines had significantly higher leaf K contents than K326. Under hydroponic condition, enhanced K uptake capacity and a larger maximum K uptake rate were seen in AtNHX1 -overexpressing tobacco lines. AtNHX1 -overexpressing lines also exhibited significantly superior root morphological and physiological traits relative to K326, including root biomass, root volume, absorption area, root activity, cation exchange capacity, soluble protein content, and H+ -ATPase activity. Overexpression of AtNHX1 in tobacco significantly improves the K uptake and accumulation. Therefore, leaf K content greatly increased in these transgenic lines in the end. Our findings strongly suggest that AtNHX1 overexpression increased leaf K content by boosting the capacity of enriching K in tobacco roots, thereby advancing the understanding of the function of AtNHX1 .

Plants often experience variations in light intensity, referred to as light stress, that negatively impact important aspects of plant growth and development, including photosynthesis and antioxidant system. The photosynthetic machinery is susceptible to these disturbances, especially photosystem II and its reaction centers. We aimed to evaluate the role of brassinosteriod in plants under both high and low light conditions by examining various physiological parameters such as photosynthetic efficiency, pigment levels, and enzymatic activity of various antioxidant enzymes in one month old tomato plants. We investigated various chlorophyll fluorescence parameters under low light (LL) and high light (HL) conditions and the associated gene expression related to photosynthesis, including plastocyanin, ferredoxin, and photosystem II oxygen-evolving enhancer protein 3 (PsbQ). Our results indicate that exogenous brassinosteroid application considerably increased tolerance to both high and low light stress in 4-week-old tomato as treated plants displayed enhanced photosynthesis, reduced oxidative damage, and increased antioxidant enzyme activity in comparison to control plants. Furthermore, brassinosteroid treatment enhanced the expression of genes associated with antioxidant pathways, which significantly contributed to the recovery of chlorophyll fluorescence parameters crucial for plant growth and development. Our results provide valuable insights into how brassinosteroid reduces light-induced stress in tomato plants.

In soybean (Glycine max ), limiting whole-plant transpiration rate (TR) response to increasing vapor pressure deficit (VPD) has been associated with the 'slow-wilting' phenotype and with water-conservation enabling higher yields under terminal drought. Despite the promise of this trait, it is still unknown whether it has a genetic basis in soybean, a challenge limiting the prospects of breeding climate-resilient varieties. Here, we present the results of a first attempt at a high-throughput phenotyping of TR and stomatal conductance response curves to increasing VPD conducted on a soybean mapping population consisting of 140 recombinant inbred lines (RIL). This effort was conducted over two consecutive years, using a controlled-environment, gravimetric phenotyping platform that enabled characterizing 900 plants for these responses, yielding regression parameters (R 2 from 0.92 to 0.99) that were used for genetic mapping. Several quantitative trait loci (QTL) were identified for these parameters on chromosomes (Ch) 4, 6, and 10, including a VPD-conditional QTL on Ch 4 and a 'constitutive' QTL controlling all parameters on Ch 6. This study demonstrated for the first time that canopy water use in response to rising VPD has a genetic basis in soybean, opening novel avenues for identifying alleles enabling water conservation under current and future climate scenarios.

Previous research from our lab demonstrated that hypergravity that can be simulated using tabletop centrifuges, offering significant benefits to crop plants. Hypergravity enhances seedling vigor and growth parameters in bread wheat (Triticum aestivum ) variety UAS 375. This enhanced root growth phenotype is believed to boost abiotic stress tolerance by facilitating deeper access to water and nutrients from the soil. This study investigated whether hypergravity-induced root growth enhancements could offer resilience to induced drought and salt stress, and whether such benefits would extend across other wheat genotypes. Hypergravity (10g for 12h) conferred significant tolerance to simulated drought and salt stress, evidenced by improved seedling growth parameters as well as increased chlorophyll content and proline accumulation in response to hypergravity followed by stress challenge, compared to stress challenge alone. Liquid chromatography with tandem mass spectrometry indicated dynamic phytohormone modulation, and quantitative reverse transcription polymerase chain reaction data revealed significant alterations in the expression of genes associated with antioxidant enzymes and abiotic stresses. Thus, this study further supports the view that hypergravity boosts abiotic stress resilience through genetic and hormonal dynamics. Notably, these effects were consistent across genotypes. In conclusion, this study provides evidence that hypergravity can effectively improve resilience against seedling abiotic stresses in wheat.

Senescence represents a developmentally orchestrated and precisely regulated cascade of events, culminating in the abscission of plant organs and ultimately leading to the demise of the plant or its constituent parts. In this study, we observed that senescence in cut Lilium tigrinum flowers is induced by elevated ABA levels and the hyperactivation of lipoxygenase (LOX) activity. This cascade increased ROS concentrations, heightened oxidative damage, and disrupted cellular redox equilibrium. This was evidenced by elevated lipid peroxidation, attenuated antioxidant machinery, and reduced membrane stability index (MSI). Despite its known role in delaying flower senescence, the specific biochemical and molecular mechanisms by which nitric oxide (NO) regulates senescence in cut L. tigrinum flowers are not fully elucidated. Specifically, the interactions between NO signaling and ABA metabolism, the regulation of protease activity, and the influence of NO-mediated ROS scavenging, senescence-associated gene expression requires further exploration. Exogenous application of sodium nitroprusside (SNP), a source of NO, mitigated senescence in L. tigrinum cut flowers by upregulating the activity of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and reducing the LOX activity, an indicator of lipid peroxidation. SNP treatment also downregulated the relative expression of senescence-associated gene (SAG12 ),lipoxygenase 1 (LOX1 ), and abscisic aldehyde oxidase 3 (AAO3 ). NO also upregulated defender against apoptotic death 1 (DAD1 ) expression correlated with minimized protease activity and reduced α-amino acid content in SNP-treated tepals. This regulation was accompanied by increased contents of sugars, proteins and phenols and reduced abscisic acid content, which collectively delayed the senesecence and enhanced the longevity of L. tigrinum cut flowers. This study demonstrates that exogenous SNP application can effectively mitigate senescence in cut L. tigrinum flowers by modulating antioxidant enzyme activities, reducing oxidative stress, and regulating the expression of key senescence-associated genes. This study unravels the complex molecular networks involved in NO-mediated senescence delay, which may lead to the development of innovative approaches for improving flower longevity.

Hosta is commonly acknowledged as a popular and preferred plant for landscaping and gardening. The 'sunburn' caused by prolonged exposure to strong sunlight is reducing the ornamental values of Hosta plants. However, there is a scarcity of research focusing on the genetic components linked to light-induced harm in Hosta . Here, the violaxanthin de-epoxidase (VDE) homolog from Hosta ventricosa was isolated and functionally identified through conducting HvVDE -overexpression tobacco (Nicotiana tabacum ) lines. The results showed that HvVDE encodes a putative protein comprising 481 amino acids with a molecular weight of 54.304kDa. The phylogenetic analysis found that HvVDE exhibited close similarity to JcVDE. Besides, the expression patterns of HvVDE found that HvVDE was expressed differently across tissues, withexpression induced by high light intensities. And overexpression of HvVDE led to the restoration of non-photochemical quenching in tobacco, suggesting that HvVDE plays a role in dissipating excess light energy as thermal energy in H. ventricosa . These findings underscore the significance of HvVDE in mitigating photoinhibition and enhancing photoprotection mechanisms in H. ventricosa .

Artemia is a genus of aquatic microcrustaceans that belong to the class Branchiopoda. Encysted Artemia urmiana embryos are resistant to harsh environmental stressors, including repeated desiccation, prolonged anoxia, extreme temperatures, and high levels of UV radiation. The protein artemin has a chaperone activity and is believed to play a crucial role in protecting the organism against such stresses. To elucidate the potential functional roles of artemin in plants, the cDNA sequence of artemin was cloned into the pZPY122 binary plant expression vector. Agrobacterium -mediated transformation and the floral-dip technique were used to introduce this construct into Arabidopsis thaliana . Three independent transgenic lines (art1 , art2 , art3 ) were generated and subjected to heat stress at 45°C. Results showed a significant interaction between heat stress and genotype for germination rate, germination speed, vigor index, and seedling and root length. The transgenic lines with the artemin transgene (ART ) exhibited remarkable heat stress tolerance compared with wild-type plants. They also had markedly lower levels of electrolyte leakage, hydrogen peroxide content, higher activities of catalase, superoxide dismutase and peroxidase, greater total protien content, and increased accumulation of proline. Under heat stress conditions, the expression of two key abiotic stress-responsive genes, DREB2A and HSFA3 , was significantly upregulated in the ART lines compared to the wild-type . These findings suggest that the ART gene from A. urmiana may act as molecular chaperone when expressed in Arabidopsis , thereby enhancing the plant's tolerance to heat stress.

Oxygenic photosynthesis is characterised by the cooperation of two photo-driven complexes, Photosystem II (PSII) and Photosystem I (PSI), sequentially linked through a series of redox-coupled intermediates. Divergent evolution has resulted in photosystems exhibiting complementary redox potentials, spanning the range necessary to oxidise water and reduce CO2 within a single system. Catalysing nature's most oxidising reaction to extract electrons from water is a highly specialised task that limits PSII's metabolic function. In contrast, potential electron donors in PSI span a range of redox potentials, enabling it to accept electrons from various metabolic processes. This metabolic flexibility of PSI underpins the capacity of photosynthetic organisms to balance energy supply with metabolic demands, which is key for adaptation to environmental changes. Here, we review the phenomenon of 'PSII-less photosynthesis' where PSI functions independently of PSII by operating cyclic electron flow using electrons derived from non-photochemical reactions. PSII-less photosynthesis enables supercharged ATP production and is employed, for example, by cyanobacteria's heterocysts to host nitrogen fixation and by bundle sheath cells of C4 plants to boost CO2 assimilation. We discuss the energetic benefits of this arrangement and the prospects of utilising it to improve the productivity and stress resilience of photosynthetic organisms.

Drought-induced stress represents one of the most economically detrimental natural phenomena impacting grapevine (Vitis vinifera ) development, yield, and fruit characteristics. Also, auxin is one of the most important plant growth regulators that can reduce damage caused by stress in plants. In this study, the impact of exogenously sprayed auxin (0, 50, and 200mgL-1 ) on growth, biochemical, and anatomical parameters was investigated in two grapevine varieties (cvs. 'Rashe' and 'Fakhri') under water deficit. According to our findings, water deficit led to a notable decrease in growth, protein content, and anatomical parameters; but significantly enhanced electrolyte leakage. Grapevines exposed to water deficit exhibited substantial increases in total phenolic compounds and antioxidant activity. Applying 50mgL-1 napthalene acetic acid (NAA) reduced the effects of water deficit in both grapevine cultivars by decreasing electrolyte leakage (15% in 'Rashe' and 20% in 'Fakhri'), and accumulating protein content (22% 'Rashe' and 32% 'Fakhri'), total phenolic compounds (33%'Rashe' and 40% 'Fakhri'), and antioxidant capacity (11% 'Rashe' and 39% 'Fakhri'); anantomical parameters were also improved. However, application of 200mgL-1 NAA had adverse effects on growth and biochemical traits of grapevines, with a more pronounced impact on root growth and anatomical parameters compared to other NAA concentrations. In conclusion, the application of 50mgL-1 NAA enhanced grapevine growth, enabling them to better thrive under water deficit.