The transcription factor BBX family is associated with plant responses to abiotic stress. Among the 31 SlBBXs genes in tomato, SlBBX20 is the most strongly induced by saline-alkali stress. However, ...the response mechanism of the SlBBX20 transcription factor under saline-alkali stress remains unclear. In this study, we investigated the effect of the SlBBX20 transcription factor on saline-alkali tolerance in tomato using wild-type (WT), SlBBX20 overexpression lines, SlBBX20-silenced materials (TRV2-SlBBX20) and their controls (TRV2-empty). Under normal conditions, overexpression of SlBBX20 increased tomato photosynthetic capacity (contents of chlorophyll a, chlorophyll b and carotenoids, net photosynthetic rate), leaf palisade and spongy tissue thickness, and total antioxidant capacity. In contrast, the photosynthetic capacity and total antioxidant capacity of SlBBX20 silenced material did not change significantly relative to the control. Under saline-alkali stress, overexpression of SlBBX20 significantly reduced the relative conductivity, malondialdehyde content, reactive oxygen species levels (O2•−, H2O2), and increased the relative water content, photosynthetic capacity, total antioxidant capacity, antioxidant enzyme activities (peroxidase, superoxide dismutase, and catalase) and proline content in tomato leaves. And silencing SlBBX20 showed the opposite trend. Furthermore, through transcriptome sequencing of WT and SlBBX20-OE lines grown in saline-alkali stress condition at 0 h and 12 h, three differentially expressed genes related to saline-alkali stress (SlP5CR, SlHsp21.6A, SlHsp26.2) were identified. Yeast one-hybrid and dual-luciferase assays confirmed that SlBBX20 might bind to the G-box cis-acting elements in the promoter regions of SlP5CR, SlHsp21.6A, and SlHsp26.2 genes, exerting transcriptional regulatory functions. In conclusion, overexpression of SlBBX20 enhances saline-alkali tolerance in tomatoes by sustaining leaf photosynthetic capacity, reducing ROS accumulation, and elevating antioxidant enzyme activity and proline content.
•Expression of SlBBX20 in tomato significantly was induced by saline-alkali stress.•SlBBX20 play a positive role for tomato to resistance saline-alkali stress.•SlBBX20 could preserve leaf photosynthetic capacity, reduce ROS accumulation under saline-alkali stress.•SlBBX20 could interact with the genes SlP5CR, SlHsp21.6 A, and SlHsp26.2 under saline-alkali stress.
•Melatonin promotes photosynthetic carbon fixation in cold-stressed tomato plants.•Melatonin improves antioxidant potential in cold-stressed tomato plants.•Melatonin induces expressions of ...cold-responsive genes in tomato plants.•Melatonin increases accumulation of metabolites in cold-stressed plants.•Melatonin ameliorates cold-induced damage in tomato plants.
Low temperature is an adverse environmental factor posing damage to tomato plants and causing huge loss of yields. Thus, seeking an effective way of ameliorating cold damage is important for sustainable tomato production. Melatonin is a crucial molecule involved in plant abiotic stress responses. In this study, we investigated the role of exogenous melatonin in amelioration of cold damage in tomato plants. Lower malondialdehyde (MDA) content and electrolyte leakage, greater activities of antioxidant enzymes, and higher levels of non-enzymatic antioxidants were observed in melatonin-pretreated plants than in non-melatonin-pretreated plants under cold stress. Gene expression analyses showed that exogenous melatonin substantially promoted expression of cold-responsive genes, including SlICE, SlCBF and SlP5CS, under cold condition. Notably, SlSBP, a gene encoding a Calvin cycle enzyme sedoheptulose-1,7-bisphosphatase (SBPase), was considerably induced in melatonin-treated plants under cold stress, consistent with the observed increase in photosynthetic carbon assimilation. Analyses of metabolites revealed that levels of polyamines, sucrose, and proline were significantly enhanced following cold treatment in melatonin-pretreated plants. Collectively, our data provide evidence for the ameliorative effects of melatonin on cold-induced damage to tomato plants. Our work also provides a case study that exogenous application of melatonin may be potentially employed as a strategy to improve cold tolerance in tomato production.
In order to study the effect of foliar application of sodium selenate on fragrant rice performance at the heading stage, the present study was conducted with two fragrant rice cultivars, ...'Meixiangzhan-2' and 'Xiangyaxiangzhan'. At the heading stage, six concentrations of sodium selenate solution (0, 10, 20, 30, 40, and 50 μmol L-1) were sprinkled to plants. Our results showed that foliar application of sodium selenate increased chlorophyll contents in rice leaves and upregulated net photosynthetic rate at the grain-filling stage. The enhancement was observed in grain yield, seed-setting rate, and in 1,000-grain mass. The highest yield and net photosynthetic rate were both recorded at 40 μmol L-1 treatment for both cultivars. Furthermore, foliar application of sodium selenate also improved some grain quality attributes, such as head rice rate and crude protein content. The Se concentration in fragrant rice grain also increased due to sodium selenate application. In conclusion, sodium selenate has potential to be the exogenous plant growth regulator in fragrant rice production to increase yield and quality.
Abstract
The connection between soil nitrogen availability, leaf nitrogen, and photosynthetic capacity is not perfectly understood. Because these three components tend to be positively related over ...large spatial scales, some posit that soil nitrogen positively drives leaf nitrogen, which positively drives photosynthetic capacity. Alternatively, others posit that photosynthetic capacity is primarily driven by above-ground conditions. Here, we examined the physiological responses of a non-nitrogen-fixing plant (Gossypium hirsutum) and a nitrogen-fixing plant (Glycine max) in a fully factorial combination of light by soil nitrogen availability to help reconcile these competing hypotheses. Soil nitrogen stimulated leaf nitrogen in both species, but the relative proportion of leaf nitrogen used for photosynthetic processes was reduced under elevated soil nitrogen in all light availability treatments due to greater increases in leaf nitrogen content than chlorophyll and leaf biochemical process rates. Leaf nitrogen content and biochemical process rates in G. hirsutum were more responsive to changes in soil nitrogen than those in G. max, probably due to strong G. max investments in root nodulation under low soil nitrogen. Nonetheless, whole-plant growth was significantly enhanced by increased soil nitrogen in both species. Light availability consistently increased relative leaf nitrogen allocation to leaf photosynthesis and whole-plant growth, a pattern that was similar between species. These results suggest that the leaf nitrogen–photosynthesis relationship varies under different soil nitrogen levels and that these species preferentially allocated more nitrogen to plant growth and non-photosynthetic leaf processes, rather than photosynthesis, as soil nitrogen increased.
We found that increased soil nitrogen fertilization reduced relative leaf nitrogen allocation to photosynthetic processes, driven by reductions in relative nitrogen allocation to Rubisco and bioenergetic processes.
Light, as the energy and signal sources for plant growth and development, is one of the most important environment factors in recently developed plant factories with artificial light (PFALs). To find ...the optimal combination of light wavelengths for lettuce ( Lactuca sativa cv. ‘Tiberius’) plant growth in a PFAL, four treatments, each using red (R; 662 nm) and blue light (B; 447 nm) with a ratio of 4:1 and photon flux density (PFD) of 150 μmol·m −2 ·s −1 , and mixing, respectively, with 50 μmol·m −2 ·s −1 of green light (G; 525 nm; RBG), yellow light (Y; 592 nm; RBY), orange light (O; 605 nm; RBO) and far-red light (FR; 742 nm; RBFR), were set up during this experiment. A combination of R and B with a ratio of 4:1 and PFD of 200 μmol·m −2 ·s −1 was set as the control (RB). The responses of lettuce growth, morphology, anatomical structure of the lettuce leaf, photosynthetic performance, lettuce nutritional quality, and energy use efficiency were investigated. The results showed that RBG, RBO, and RBFR increased the shoot fresh weight of lettuce by 20.5%, 19.6%, and 40.4%, and they increased the shoot dry weight of lettuce by 24.2%, 13.4%, and 45.2%, respectively, compared with those under RB. The P n under RBY was significantly lower than that under RB, although no significant differences in chlorophyll or carotenoid content were found between RBY and RB. RBG increased the lettuce leaf area, the thickness of the leaf palisade tissue, P n , and light use efficiency compared with those under RB. Plants grown under RBO showed better photosynthetic capacity, such as higher P n , Φ PSII , and other photosynthetic parameters. RBFR caused an increase in lettuce leaf area and energy use efficiency, but a decrease in leaf thickness and P n of the single leaf. Moreover, tipburn injury was observed under RBFR. Therefore, these results demonstrate that RBG and RBO can be considered optimal combinations of light wavelengths for lettuce growth in a PFAL in this experiment, although plant growth can also be improved by using RBFR.
Plants respond to resource stress by changing multiple aspects of their biomass allocation, morphology, physiology and architecture. To date, we lack an integrated view of the relative importance of ...these plastic responses in alleviating resource stress and of the consistency/variability of these responses among species.
We subjected nine species (legumes, forbs and graminoids) to nitrogen and/or light shortages and measured 11 above-ground and below-ground trait adjustments critical in the alleviation of these stresses (plus several underlying traits).
Nine traits out of 11 showed adjustments that improved plants’ potential capacity to acquire the limiting resource at a given time. Above ground, aspects of plasticity in allocation, morphology, physiology and architecture all appeared important in improving light capture, whereas below ground, plasticity in allocation and physiology were most critical to improving nitrogen acquisition. Six traits out of 11 showed substantial heterogeneity in species plasticity, with little structuration of these differences within trait covariation syndromes.
Such comprehensive assessment of the complex nature of phenotypic responses of plants to multiple stress factors, and the comparison of plant responses across multiple species, makes a clear case for the high (but largely overlooked) diversity of potential plastic responses of plants, and for the need to explore the potential rules structuring them.
Extensive within-canopy light gradients importantly affect the photosynthetic productivity of leaves in different canopy positions and lead to light-dependent increases in foliage photosynthetic ...capacity per area (AA
). However, the controls on AA
variations by changes in underlying traits are poorly known. We constructed an unprecedented worldwide database including 831 within-canopy gradients with standardized light estimates for 304 species belonging to major vascular plant functional types, and analyzed within-canopy variations in 12 key foliage structural, chemical and physiological traits by quantitative separation of the contributions of different traits to photosynthetic acclimation. Although the light-dependent increase in AA
is surprisingly similar in different plant functional types, they differ fundamentally in the share of the controls on AA
by constituent traits. Species with high rates of canopy development and leaf turnover, exhibiting highly dynamic light environments, actively change AA
by nitrogen reallocation among and partitioning within leaves. By contrast, species with slow leaf turnover exhibit a passive AA
acclimation response, primarily determined by the acclimation of leaf structure to growth light. This review emphasizes that different combinations of traits are responsible for within-canopy photosynthetic acclimation in different plant functional types, and solves an old enigma of the role of mass- vs area-based traits in vegetation acclimation.
Soil temperature rise caused by global warming is one of the most serious threats to crop physiology and production. Straw return is considered as a potential strategy to improve soil health and ...agricultural productivity. However, little is known about their interactive effects on wheat growth and production, which limits the development of strategies and technological innovations for future food security. Therefore, in the two wheat seasons from 2018 to 2020, with or without straw return, the heating cable was laid at a depth of 20 cm to increase the soil temperature by 3.8 ℃, and the phenology, photosynthesis, root growth, and grain yield of winter wheat were studied. Soil warming advanced the anthesis date by one week and promoted pre-anthesis wheat growth and dry matter transportation. However, soil warming decreased post-anthesis duration, leaf area index, SPAD, net photosynthesis, and spectral vegetation indexes. Therefore, post-anthesis dry matter accumulation and grain filling were inhibited, lowering the 1000-grain weight and harvest index. Furthermore, the post-anthesis root weight, length, surface area densities and root to shoot ratio were also decreased under soil warming. Finally, soil warming reduced the grain yield by 35.2% in the dry 2018–2019 year. However, the wheat growth characteristics were considerably higher and no difference in grain yield was detected among treatments in the wet 2019–2020 season, indicating that increased precipitation may offset the adverse effect of soil warming on wheat yield. Straw return increased aboveground biomass, but had no effect on wheat yield, probably because the positive effects were limited in the short experimental duration. The findings suggested that soil warming would promote pre-anthesis wheat growth but accelerate post-anthesis wheat senescence, affect dry matter transportation and accumulation, eventually reducing wheat yield in the NCP, especially under dry condition.
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•Warming shortened pre-anthesis duration and promoted pre-anthesis wheat growth.•Warming shortened post-anthesis length, decreased photosynthetic capacity and root growth, eventually reducing wheat yield.•Straw return increased aboveground biomass but had no effect on wheat yield.
•Plant density alters leaf nitrogen allocation to photosynthetic apparatus and nitrogen partitioning among photosynthetic components.•Cotton optimized photosynthetic nitrogen use efficiency and ...photosynthetic capacity by adjusting leaf mass per area.•Appropriate spatial distributions of leaf N allocation to the photosynthetic apparatus and photosynthetic use efficiency of photosynthetic N contribute to efficient utilization of light and nitrogen.
Plant population density (PPD) is an important practice for optimizing canopy structure and improving canopy photosynthetic capacity of field-grown cotton (Gossypium hirsutum L.). A 2-yr field experiment was conducted to determine if and how PPD (7.5, 19.5 or 31.5 plants m−2) affects the light-saturated photosynthetic rate and photosynthetic nitrogen use efficiency in cotton leaves, with a focus on the key canopy characteristics for efficient utilization of light and nitrogen. The results showed that leaf N allocation and partitioning among different components of the photosynthetic apparatus were significantly affected by PPD. As PPD changed, cotton optimized photosynthetic N use efficiency and photosynthetic capacity by adjusting leaf mass per area, which in turn affected leaf N allocation to the photosynthetic apparatus. In the upper canopy layer, leaf N allocation to the photosynthetic apparatus increased as PPD increased, resulting in an increase in leaf photosynthetic N use efficiency. In contrast, in the mid- and lower-canopy layers, leaf N allocation to the photosynthetic apparatus decreased as PPD increased, resulting in declines in leaf light-saturated photosynthetic rate and photosynthetic N use efficiency. The overall results indicated that high photosynthetic capacity of leaves in the upper-canopy layer and high leaf N allocation to the photosynthetic apparatus and photosynthetic use efficiency of photosynthetic nitrogen in the mid- and lower-canopy layers were two key canopy characteristics for efficient utilization of light and nitrogen by cotton. The medium-PPD is the optimum plant density due to high light utilization efficiency, superior spatial distribution of leaf N allocation to the photosynthetic apparatus and photosynthetic use efficiency of photosynthetic N in leaves within the canopy.
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