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Ultraviolet-B (UV-B) radiation affects leaf growth in a wide range of species. In this work, we demonstrate that UV-B levels present in solar radiation inhibit maize (Zea mays) leaf growth without causing any other visible stress symptoms, including the accumulation of DNA damage. We conducted kinematic analyses of cell division and expansion to understand the impact of UV-B radiation on these cellular processes. Our results demonstrate that the decrease in leaf growth in UV-B-irradiated leaves is a consequence of a reduction in cell production and a shortened growth zone (GZ). To determine the molecular pathways involved in UV-B inhibition of leaf growth, we performed RNA sequencing on isolated GZ tissues of control and UV-B-exposed plants. Our results show a link between the observed leaf growth inhibition and the expression of specific cell cycle and developmental genes, including growth-regulating factors (GRFs) and transcripts for proteins participating in different hormone pathways. Interestingly, the decrease in the GZ size correlates with a decrease in the concentration of GA19, the immediate precursor of the active gibberellin, GA1, by UV-B in this zone, which is regulated, at least in part, by the expression of GRF1 and possibly other transcription factors of the GRF family.

Interspecific differences in functional traits are a key factor for explaining the positive diversity–productivity relationship in plant communities. However, the role of intraspecific variation attributable to phenotypic plasticity in diversity–productivity relationships has largely been overlooked. By taking a wheat (Triticum aestivum)–maize (Zea mays) intercrop as an elementary example of mixed vegetation, we show that plasticity in plant traits is an important factor contributing to complementary light capture in species mixtures. We conceptually separated net biodiversity effect into the effect attributable to interspecific trait differences and species distribution (community structure effect), and the effect attributable to phenotypic plasticity. Using a novel plant architectural modelling approach, wholevegetation light capture was simulated for scenarios with and without plasticity based on empirical plant trait data. Light capture was 23% higher in the intercrop with plasticity than the expected value from monocultures, of which 36% was attributable to community structure and 64% was attributable to plasticity. For wheat, plasticity in tillering was the main reason for increased light capture, whereas for intercropped maize, plasticity induced a major reduction in light capture. The results illustrate the potential of plasticity for enhancing resource acquisition in mixed stands, and indicate the importance of plasticity in the performance of species-diverse plant communities.

Matching of maize growth with solar radiation is of great importance for achieving high yield. We conducted experiments using different maize cultivars and planting densities under different solar radiations during grain filling to quantitatively analyze the relationships among these factors. We found that a decrease in solar radiation after silking caused a drop in maize grain yield and biomass, with lower solar radiation intensities leading to worse grain yields and biomass. Cultivar ZD958 was more sensitive to solar radiation changes than cultivar XY335; slight decreases in solar radiation (i.e., 15% shading) caused significant declines in ZD958 grain yield. When total solar radiation during grain filling was less than 486.9 MJ m −2 for XY335 and less than 510.9 MJ m −2 for ZD958, the two cultivars demonstrated high yields at lower planting density of 7.5 × 10 4 plants ha −1 ; average yields were 13.36 and 11.09 Mg ha −1 , respectively. When radiation intensities were higher than 549.5 MJ m −2 for XY335 and higher than 605.8 MJ m −2 for ZD958, yields were higher at a higher planting density of 12 × 10 4 plants ha −1 , with average yields of 20.58 Mg ha −1 for XY335 and 19.65 Mg ha −1 for ZD958.

In the first side-by-side large-scale trials of these two C₄ crops in the U.S. Corn Belt, Miscanthus (Miscanthus x giganteus) was 59% more productive than grain maize (Zea mays). Total productivity is the product of the total solar radiation incident per unit land area and the efficiencies of light interception (εi) and its conversion into aboveground biomass (εca). Averaged over two growing seasons, εca did not differ, but εi was 61% higher for Miscanthus, which developed a leaf canopy earlier and maintained it later. The diurnal course of photosynthesis was measured on sunlit and shaded leaves of each species on 26 dates. The daily integral of leaf-level photosynthetic CO₂ uptake differed slightly when integrated across two growing seasons but was up to 60% higher in maize in mid-summer. The average leaf area of Miscanthus was double that of maize, with the result that calculated canopy photosynthesis was 44% higher in Miscanthus, corresponding closely to the biomass differences. To determine the basis of differences in mid-season leaf photosynthesis, light and CO₂ responses were analyzed to determine in vivo biochemical limitations. Maize had a higher maximum velocity of phosphoenolpyruvate carboxylation, velocity of phosphoenolpyruvate regeneration, light saturated rate of photosynthesis, and higher maximum quantum efficiency of CO₂ assimilation. These biochemical differences, however, were more than offset by the larger leaf area and its longer duration in Miscanthus. The results indicate that the full potential of C₄ photosynthetic productivity is not achieved by modern temperate maize cultivars.

Cryptochromes (CRYs) are photolyase-like blue-light/ultraviolet-A (UV-A) receptors that regulate diverse aspects of plant growth and development. Maize ( Zea mays ), a major crop often grown under high UV-B radiation, harbors four copies of CRY. However, whether CRYs in maize have evolved to improve UV tolerance or acquire novel functions remains unclear. In this study, CRISPR-Cas9-engineered Zmcry mutants are used to investigate the functions of ZmCRYs in maize. The findings reveal that ZmCRYs act redundantly in mediating blue light signaling and inhibiting mesocotyl elongation. Furthermore, we demonstrate that ZmCRYs mediate blue light-enhanced UV-B stress tolerance in maize by upregulating the expression of genes involved in the biosynthesis of UV-B stress tolerance-related metabolites, including phenylpropanoids, flavonoids, and fatty acids. Further analyses show that blue light modulates both the accumulation and composition of epidermal waxes, suggesting that blue light enhances epidermal wax accumulation for UV-B stress tolerance. Notably, we identify that ZmCRY1 directly interacts with GLOSSY2 (GL2), a key acyltransferase in very-long-chain fatty acid metabolism, in a blue light-strengthened manner to mediate blue light-promoted C32 aldehyde accumulation, shedding new light on the enigma of the aldehyde-forming pathway in plants. These results highlight the critical roles of ZmCRY1s in mediating blue light-regulated epidermal wax biosynthesis and UV-B tolerance in Zea mays . Zhao et al. demonstrate that ZmCRY1s, blue-light receptors in maize, interact with GL2 in blue light to promote C32 aldehyde accumulation thereby modulating epidermal wax composition and enhancing UV-B tolerance, revealing a light-regulated wax biosynthetic mechanism critical for maize stress adaptation.

Maize is the third most important grain crop worldwide after wheat and rice; it is a vital global crop, serving as a key source of food, animal feed, and industrial products, making it essential for food security and economic stability in many countries. Drought stress adversely affects water uptake and can stunt growth, reducing the overall productivity of maize. So, this study was carried out to investigate the cytogenetic effects of gamma radiation and drought stress on maize SC131 genotype, focusing on chromosomal aberrations in seedling root meristems induced by varying doses of gamma irradiation (50, 100, 150, 200, and 250 Gray) and drought stress imposed by 10% polyethylene glycol (PEG). The present study also aims to evaluate the impact of these treatments on growth parameters under a controlled pot experiment. Additionally, molecular polymorphism induced by both gamma irradiation and drought stress was analyzed using Real-Time quantitative PCR techniques for DREB2 , ERF , and EF transcription factors. Also, under a field condition experiment, maize plants were subjected to the same gamma irradiation doses and drought stress by reducing the number of irrigations, with subsequent evaluations of yield attributes to assess the overall impact of treatments on plant performance. The study also investigates the sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) banding patterns of proteins in grains yielded under the influence of gamma radiation and drought treatments. Findings of the current investigation indicate that the low dose of gamma radiation (50 Gray) not only induces cytogenetic changes but also enhances drought tolerance and improves yield characteristics, suggesting that targeted gamma irradiation could serve as a viable strategy to bolster maize resilience in challenging environmental conditions.

Glutamate is an essential amino acid in both the energy and biosynthetic processes in plant cells. The aim of this work was to study changes in glutamate metabolism upon irradiation of maize (Zea mays L.) leaves with light of different spectral compositions, as well as to identify mechanisms regulating the work of enzymes involved in the studied process. A study was conducted of light-induced changes in glutamate metabolism in maize leaves, mediated by redirecting the glutamate flow to the γ-aminobutyric acid (GABA) shunt. Glutamate dehydrogenase (GDH) was more active in darkness, and the irradiation by red light inhibited the expression of both the Gdh1 and Gdh2 genes. EGTA and ruthenium red abolished the effects of light, indicating the participation of Ca2+ ions in phytochrome signal transduction. Contrary to GDH, glutamate decarboxylase (GAD) activity was moderately higher in the light, stimulated by red light, while far-red light reversed the effect. The effect of light on Gad expression was more pronounced than on GAD activity. Irradiation by red light also resulted in the increase in activity of GABA transaminase (GTA), which was abolished by far-red light. The third enzyme of the GABA shunt, succinic semialdehyde dehydrogenase (SSADH), was also activated by light. The effect of light on the expression of Ssadh1, but not on Ssadh2, was phytochrome-dependent. It is concluded that irradiation by light shifts glutamate metabolism from GDH to GAD with the activation of GABA transaminase and SSADH. This suggests that the GABA pathway plays a role in the maintenance of the tricarboxylic acid cycle in the light via bypassing its reactions when the 2-oxoglutarate dehydrogenase complex is inhibited and the cycle switches to the open mode.

This study investigates the potential interrelationship between gene expression and biosynthesis of vitamin C, E and folate in sweet corn sprouts. Germination of sweet corn kernels was conducted in light and dark environments to determine if this relationship was regulated by photo-illumination. Results indicated that light and dark environments affected the DHAR, TMT and GTPCH expression and that these genes were the predominant genes of vitamin C, E and folate biosynthesis pathways respectively during the germination. Levels of vitamin C and folate increased during the germination of sweet corn seeds while vitamin E had a declining manner. Sweet corn sprouts had higher vitamin C and E levels as well as relevant gene expression levels in light environment while illumination had little influence on the folate contents and the gene expression levels during the germination. These results indicate that there might be a collaborative relationship between vitamin C and folate regulation during sweet corn seed germination, while an inhibitive regulation might exist between vitamin C and E.

Plants are constantly facing rapid changes in evaporative demand and soil water content, which affect their water status and growth. In apparent contradiction to a hydraulic hypothesis, leaf elongation rate (LER) declined in the morning and recovered upon soil rehydration considerably quicker than transpiration rate and leaf water potential (typical half-times of 30 min versus 1-2 h). The morning decline of LER began at very low light and transpiration and closely followed the stomatal opening of leaves receiving direct light, which represent a small fraction of leaf area. A simulation model in maize (Zea mays) suggests that these findings are still compatible with a hydraulic hypothesis. The small water flux linked to stomatal aperture would be sufficient to decrease water potentials of the xylem and growing tissues, thereby causing a rapid decline of simulated LER, while the simulated water potential of mature tissues declines more slowly due to a high hydraulic capacitance. The model also captured growth patterns in the evening or upon soil rehydration. Changes in plant hydraulic conductance partly counteracted those of transpiration. Root hydraulic conductivity increased continuously in the morning, consistent with the transcript abundance of Zea maize Plasma Membrane Intrinsic Protein aquaporins. Transgenic lines underproducing abscisic acid, with lower hydraulic conductivity and higher stomatal conductance, had a LER declining more rapidly than wild-type plants. Whole-genome transcriptome and phosphoproteome analyses suggested that the hydraulic processes proposed here might be associated with other rapidly occurring mechanisms. Overall, the mechanisms and model presented here may be an essential component of drought tolerance in naturally fluctuating evaporative demand and soil moisture.

The dynamics between fluorescence (Fs) yield and photochemical (P) yield in a changing environment are essential for understanding the relationship between photosynthesis and fluorescence. The ratio of Fs yield and P yield tends to be constant under high light intensity, but the relationship between these two yields, and its response to environmental conditions, need to be explored further under intermediate and low light. In this study, we performed leaf-scale measurements of fluorescence parameters by pulse-amplitude modulation (PAM) technology in summer maize (Zea mays L.) plants grown under intermediate light conditions in a climate chamber. Plants were treated as moderately water stressed and non-water stressed. Results showed that a decrease in P yield was accompanied by increases in Fs yield and non-photochemical quenching (NPQ) yield in response to moderate water stress under intermediate and low light conditions. Fs yield was negatively correlated with P yield under intermediate and low light conditions when there was sufficient soil water in the root zone. Under water stress, the correlation between Fs yield and P yield was negative in low light, but became positive under higher light levels. Fs yield was negatively related to P yield when NPQ yield was low; however, they were synergistically and positively associated when excessive light dissipation was dominated by NPQ.