Reduced Chlorophyll Content Research Articles

The Effect of Biochar on Tomato (Solanum lycopersicum) Cultivar Micro-Tom Grown under Continuous Light

AbstractContinuous lighting (CL) has the potential to increase crop yield in greenhouse production. Tomato plants, however, when exposed to CL develop inter-vascular chlorosis, a leaf injury which causes a reduction in chlorophyll content and necrosis. The application of biochar can reduce physiological stress in plants, we examine if biochar also reduces necrosis in tomatoes when grown under CL. Faecal sludge biochar was applied to an acidic soil to examine plant growth and yield in Micro-Tom tomato plants grown under continuous light. We examined soil and plant growth properties of three soil application treatments: a control soil, biochar treatment (4%w/w) (Biochar), and a combined biochar (2% w/w) and fertilizer (2% w/w) treatment (Biochar + Fert). Faecal sludge biochar addition produced plant heights 216% greater than control and above ground biomass 583% greater than control. The biochar and fertilizer treatment group produced a 487% increase in leaf number compared to biochar. The combined biochar and fertilizer treatment produced a 398% increase in dried above ground biomass and a 177% increase in dried fruit yield compared with biochar. Plants in the biochar and fertilizer treatment group showed less visual evidence of continuous light induced leaf injury.Biochar addition did not limit continuous light induced leaf chlorosis whereas combined biochar and fertilizer treatment resulted in a significant reduction in leaf injury and death. Overall, the application of biochar and biochar and fertilizer combined increased crop yield.

Effects of 910 MHz Solid-State Microwave Cooking on the Quality Properties of Broccoli (Brassica olearacea L. var. Italica Plenck), Carrots (Daucus carota subsp. Sativus), and Red Peppers (Capsicum annuum L. cv. Kapya)

Domestic microwave ovens offer rapid cooking but face challenges such as non-uniform temperature distribution and hot spots. A novel solid-state heating system, which precisely controls microwave frequency and power, provides a promising alternative to traditional microwave ovens utilizing magnetron systems. This study compared the effects of solid-state microwave cooking on the quality of broccoli, red peppers, and carrots with those of traditional microwave and conventional cooking. The traditional microwave cooking used in this study operated at 2450 MHz, while the solid-state system functioned between 902 and 928 MHz. Weight loss was highest for conventional cooking, reaching a maximum of 34%, whereas microwave cooking resulted in a maximum of 11.65% and solid-state microwave cooking in 17.04%. The total phenolic content obtained through conventional cooking ranged between 61.58 and 116.51 mg GAE (gallic acid equivalents)/100 g dry basis, while microwave cooking resulted in a range of 88.04–110.92 mg, and solid-state microwave cooking achieved values between 76.14 and 122.91 mg. Furthermore, reductions in chlorophyll content were observed to be 68.2%, 25.6%, and 35.7% for conventional, microwave, and solid-state microwave cooking, respectively. Lycopene content after conventional cooking decreased to 224.73 mg/100 g dry basis, compared to 289.55 mg after microwave cooking and 242.94 mg after solid-state microwave cooking. β-carotene content showed a decrease of 14.5% in conventional cooking, while both microwave methods showed an increase of 14.7%. These results suggest that solid-state microwave cooking may have promising positive effects on food quality.

Heredity and fine mapping of a yellow leaf and less tillering mutant yllt10 in rice

Rice (Oryza sativa L.) is a major food crop and increasing rice yield is the primary objective of rice research. Photosynthesis and nitrogen utilization efficiency directly affect the tiller number of rice, which affects the yield of rice. In this study, a stable yellow leaf and less tillering rice mutant yllt10 (yellow leaf and less tillering 10) was obtained by heavy-ion beam mutagenesis of rice variety 'Ke-fu-geng 7'. Compared with the wild type, yllt10 showed reduced chlorophyll content, decreased photosynthesis rate, and abnormal chloroplast structure. The genetic analysis indicated that the phenotype of yllt10 was controlled by a single recessive nuclear gene. Map-based cloning localized YLLT10 between two molecular markers J4 and J5 on chromosome 10. The sequencing of candidate genes within this interval revealed that YLLT10 was an allelic mutation of CAO1/PGL with a single base deletion in the first exon resulting in the frame shift mutation of CAO1/PGL, and YLLT10 was a new allelic variation of CAO1/PGL. The mutant yllt10 was insensitive to changes in nitrogen concentration when being incubated with different nitrogen concentrations. YLLT10 controls leaf color and tiller number and affects photosynthesis and yield of rice. The study of this gene provides a theoretical basis for molecular breeding of rice.

Integrated proteome and pangenome analysis revealed the variation of microalga Isochrysis galbana and associated bacterial community to 2,6-Di-tert-butyl-p-cresol (BHT) stress.

The phenolic antioxidant 2,6-Di-tert-butyl-p-cresol (BHT) has been detected in various environments and is considered a potential threat to aquatic organisms. Algal-bacterial interactions are crucial for maintaining ecosystem balance and elemental cycling, but their response to BHT remains to be investigated. This study analyzed the physiological and biochemical responses of the microalga Isochrysis galbana and the changes of associated bacterial communities under different concentrations of BHT stress. Results showed that the biomass of I. galbana exhibited a decreasing trend with increasing BHT concentrations up to 40mg/L. The reduction in chlorophyll, carotenoid, and soluble protein content of microalgal cells was also observed under BHT stress. The production of malondialdehyde and the activities of superoxide dismutase, peroxidase, and catalase were further determined. Scanning electron microscopy analysis revealed that BHT caused surface rupture of the algal cells and loss of intracellular nutrients. Proteomic analysis demonstrated the upregulation of photosynthesis and citric acid cycle pathways as a response to BHT stress. Additionally, BHT significantly increased the relative abundance of specific bacteria in the phycosphere, including Marivita, Halomonas, Marinobacter, and Alteromonas. Further experiments confirmed that these bacteria had the ability to utilize BHT as the sole carbon resource for growth, and genes related to the degradation of phenolic compounds were detected through pangenome analysis.

Drought tolerance and recovery capacity of two ornamental shrubs: Combining physiological and biochemical analyses with online leaf water status monitoring for the application in urban settings

When plants are transferred from nursery to urban environments, they often face drought stress due to inadequate maintenance, such as insufficient irrigation. Using drought tolerant species may help mitigate the adverse impact of drought stress in urban settings. Additionally, utilizing novel technologies for water status monitoring may help optimize irrigation schedules to prevent transplanting failures. This study investigated the physiological and biochemical responses of two ornamental shrubs, Photinia x fraseri and Viburnum tinus, subjected to water stress of increasing severity and rewatering. Water relations, gas exchanges, chlorophyll fluorescence and biochemical analyses were conducted alongside real-time monitoring of water status using leaf-water-meter sensors (LWM).The progression of water stress had a notable negative impact on leaf gas exchanges and water relations in both species. Notably, P. fraseri avoided photoinhibition by reducing chlorophyll content and actual efficiency of PSII. Adjustments in leaf phenolic compounds played a significant role in enhancing drought tolerance of both species due to their antioxidant and photoprotective properties.Upon rewatering, both species exhibited complete recovery in their physiological functions, underscoring their remarkable tolerance and resilience to drought stress. Additionally, LWM sensors efficiently tracked the dehydration levels, exhibiting a rising trend during the water stress progression and a subsequent decline after rewatering for both species. These findings confirm the reliability of LWM sensors in monitoring physiological status of plants in outdoor contexts, making them a suitable tool for use in urban settings.

Impact of Various Extraction Technologies on Protein and Chlorophyll Yield from Stinging Nettle.

Stinging nettle (Urtica dioica L.) has gained attention as a sustainable protein source due to its rich bioactive compound profile and medicinal properties, but research on optimizing its protein extraction remains limited. This research explores various cell disruption methods, including pulsed electric fields and high-pressure homogenization, combined with extraction techniques like isoelectric precipitation, ultrafiltration, and salting-out, to enhance protein yield and assess its impact on chlorophyll content. The findings indicate that high-pressure homogenization combined with isoelectric precipitation achieved the highest protein yield of 11.60%, while pulsed electric fields with ultrafiltration significantly reduced chlorophyll content from 4781.41 µg/g in raw leaves to 15.07 µg/g in the processed sample. Additionally, the findings suggest that innovative extraction technologies can improve the efficiency and sustainability of protein isolation from stinging nettle, offering a valuable addition to the repertoire of alternative protein sources. These advancements could pave the way for broader applications of stinging nettle in food fortification and functional ingredient development.

An assessment of in vitro lead (Pb) bioaccumulation of Dianthus chinensis L. (Chinese pink).

Heavy metals (HM) also known as potentially toxic elements (PTEs), are well-known environmental pollutants, among which lead (Pb) is a widespread and hazardous soil contaminant. Its removal from soil sediments is often difficult to achieve. In this study, in vitro experiments were conducted to investigate the bioaccumulation capability of Dianthus chinensis L. in solid and liquid Murashige and Skoog (MS) medium supplemented with varying concentrations (0, 10, 100, and 200µM) of Pb as lead nitrate [Pb(NO3)2] for 30days. The objectives of the study were to assess the efficiency of the selected plant as a bio-accumulator in the in vitro system and to obtain data on morphological, biochemical, and molecular changes during Pb salt-induced stress. Significant growth patterns of initial growth promotion up to 100µM lead nitrate supplemented medium were observed, with maximum shoot length and biomass production along with remarkable lead bioaccumulation. Molecular studies on in vitro raised plantlets confirm the high degree of genetic uniformity (98.3%) of the selected plants after a considerable duration (30days) of Pb exposure. Biochemical parameters revealed significant stress effects, including a 284% reduction in total chlorophyll content, altered carotenoid, and proline level during the study. The experiment revealed the high tolerance capacity of D. chinensis to Pb salt and its bioaccumulation potential (397.33mg/kg). This increases the possible use of such an ornamental and floriculture plant as a prospective candidate for the efficient removal of soil Pb pollutants, as they can remediate soils, coupled with aesthetic and profitable outcomes for the growers.

Characterization of Low-Temperature Sensitivity and Chlorophyll Fluorescence in Yellow Leaf Mutants of Tomato

Leaf color mutants serve as valuable models for studying the regulation of plant photosynthesis, alternations in chloroplast structure and function, and the analysis of associated gene functions. A yellow leaf mutant, ylm, was separated from the wild tomato M82, with its yellowing intensity influenced by low temperature. To assess the low-temperature sensitivity of this mutant, the photosynthetic and chlorophyll fluorescence responses of ylm and M82 were examined under different temperature conditions. In this study, the ylm mutant and its wild type, M82, were exposed to three temperature levels, 16, 25, and 30 °C, for 48 h. The impact of these temperature treatments on leaf color change, chlorophyll content, photosynthetic performance, and chlorophyll fluorescence characteristics of mutant ylm was investigated. The results revealed the following: (1) After exposure to 16 °C, the ylm mutant exhibited significant yellowing, a marked reduction in chlorophyll content, and a notable increase in carotenoid content. At 25 °C, the differences were less pronounced, and at 30 °C, the differences between ylm and M82 were minimal. (2) The photosynthetic rate of the ylm mutant was lower than that of M82 at 16 °C, with the gap narrowing as temperature increased, eventually converging at higher temperatures. (3) The fluorescence transient curve (OJIP) of the ylm mutant differed significantly from that of M82 at 16 °C, with higher fluorescence intensity at the O point and lower intensity at the J, I, and P points. This difference was decreased at 25 °C and nearly disappeared at 30 °C. Additionally, the Fv/Fm, Fv/Fo, PIabs, PItotal, ABS/CSm, TRo/CSm, and ETo/CSm values of ylm were lower than those of M82 at 16 °C, while the ABS/RC and DIo/RC values were higher, with no significant differences observed at 30 °C. These findings suggest that the ylm mutant is highly sensitive to low temperature, with pronounced yellowing, reduced light energy absorption and capture efficiency, and impaired electron transport at lower temperature.

Development, Chlorophyll Content, and Nutrient Accumulation in In Vitro Shoots of Melaleuca alternifolia under Light Wavelengths and 6-BAP.

In vitro cultivation of Melaleuca could contribute to the cloning of superior genotypes. Studies of factors affecting micropropagation are needed, such as the interaction with light-emitting diodes (LEDs) and plant growth regulators added to the culture media. This study aimed at better understanding the effects of spectra on the development and physiology of melaleuca cultivated in vitro, as well as the interaction of LEDs with the main cytokinin used in micropropagation, N6-Benzylaminopurine (6-BAP). 6-BAP, spectra, and their interaction had a significant effect on most of the variables analyzed, altering the in vitro development and chlorophyll concentrations in the plants, as well as changing different variables in the culture medium, such as pH, EC, and levels of Ca2+, Mg2+, and P, and nutrient accumulation in the shoots. The results demonstrate that the main effects of adding BAP to the in vitro cultivation of melaleuca are an increase in the number of shoots, which resulted in greater fresh and dry masses; a reduction in height and chlorophyll content; complete inhibition of adventitious rooting; higher consumption of Mg, and lower consumption of Ca and P from the culture medium; higher content of Fe, and lower content of P, S, Mn, Cu and B in the in vitro shoot tissues.

Evanescent hormesis effect induced by environmentally relevant PFOS to marine Chlorella sp.

Perfluorooctanesulfonic acid (PFOS) is widely detected in the aquatic environment. More attentions were paid to its acute biotoxicity at high-dose concentrations, whereas the actual long-term effect (hormesis or inhibition of growth) of PFOS with environmental concentrations on marine phytoplankton remains unclear. In this study, marine Chlorella sp. was exposed to PFOS at low concentrations (100 ng/L, 10 μg/L, and 1 mg/L) for 26 days. The hormesis effect disappeared at the population level on Day 18, but persisted at the molecular and cellular levels on Day 24, suggesting that the stimulatory hormetic effect induced by low-level PFOS (approximating environmental concentrations) does not persist throughout algal life cycle at population level. The 100 ng/L and 1 mg/L PFOS treatments caused algal cell to swell and shrink, respectively. The low-level PFOS treatments could accelerate cells apoptosis and induce cell necrosis at 100 ng/L. Specifically, the energy metabolism associated with carbohydrate metabolism and amino acid metabolism was significantly up-regulated as well as the reduced chlorophyll content (related to the down-regulation of porphyrin metabolism) to combat the 100 ng/L PFOS rather than be engaged in divide and growth. Additionally, the decreased biomass in the 100 ng/L treatment was also attributed to certain proteins associated with down-regulations of carotenoid biosynthesis, thiamine metabolism, non-homologous end-joining, and nitrogen metabolism along with the increased oxidative stress. Our findings provide a new insight into the long-term ecological effect of PFOS at environmental concentrations.

Chlorophyll and Carotenoid Metabolism Varies with Growth Temperatures among Tea Genotypes with Different Leaf Colors in Camellia sinensis

The phenotype of albino tea plants (ATPs) is significantly influenced by temperature regimes and light conditions, which alter certain components of the tea leaves leading to corresponding phenotypic changes. However, the regulatory mechanism of temperature-dependent changes in photosynthetic pigment contents and the resultant leaf colors remain unclear. Here, we examined the chloroplast microstructure, shoot phenotype, photosynthetic pigment content, and the expression of pigment synthesis-related genes in three tea genotypes with different leaf colors under different temperature conditions. The electron microscopy results revealed that all varieties experienced the most severe chloroplast damage at 15 °C, particularly in albino cultivar Baiye 1 (BY), where chloroplast basal lamellae were loosely arranged, and some chloroplasts were even empty. In contrast, the chloroplast basal lamellae at 35 °C and 25 °C were neatly arranged and well-developed, outperforming those observed at 20 °C and 15 °C. Chlorophyll and carotenoid measurements revealed a significant reduction in chlorophyll content under low temperature treatment, peaking at ambient temperature followed by high temperatures. Interestingly, BY showed remarkable tolerance to high temperatures, maintaining relatively high chlorophyll content, indicating its sensitivity primarily to low temperatures. Furthermore, the trends in gene expression related to chlorophyll and carotenoid metabolism were largely consistent with the pigment content. Correlation analysis identified key genes responsible for temperature-induced changes in these pigments, suggesting that changes in their expression likely contribute to temperature-dependent leaf color variations.

An Excessive K/Na Ratio in Soil Solutions Impairs the Seedling Establishment of Sunflower (Helianthus annuus L.) through Reducing the Leaf Mg Concentration and Photosynthesis

In saline conditions, establishing healthy seedlings is crucial for the productivity of sunflowers (Helianthus annuus L.). Excessive potassium (K+) from irrigation water or overfertilization, similar to sodium (Na+), could adversely affect sunflower growth. However, the effects of salt stress caused by varying K/Na ratios on the establishment of sunflower seedlings have not been widely studied. We conducted a pot experiment in a greenhouse, altering the K/Na ratio of a soil solution to grow sunflower seedlings. We tested three saline solutions with K/Na ratios of 0:1 (P0S1), 1:1 (P1S1), and 1:0 (P1S0) at a constant concentration of 4 dS m−1, along with a control (CK, no salt added), with five replicates. The solutions were applied to the pots via capillary rise through small holes at the bottom. The results indicate that different K/Na ratios significantly influenced ion-selective uptake and transport in crop organs. With an increasing K/Na ratio, the K+ concentration in the roots, stems, and leaves increased, while the Na+ concentration decreased in the roots and stems, with no significant differences in the leaves. Furthermore, an excessive K/Na ratio (P1S0) suppressed the absorption and transportation of Mg2+, significantly reducing the Mg2+ concentration in the stems and leaves. A lower leaf Mg2+ concentration reduced chlorophyll concentration, impairing photosynthetic performance. The lowest plant height, leaf area, dry matter, and shoot/root ratio were observed in P1S0, with reductions of 27%, 48%, 48%, and 13% compared to CK, respectively. Compared with CK, light use efficiency and CO2 use efficiency in P1S0 were significantly reduced by 13% and 10%, respectively, while water use efficiency was significantly increased by 9%. Additionally, improved crop morphological and photosynthetic performance was observed in P1S1 and P0S1 compared with P1S0. These findings underscore the critical role of optimizing ion composition in soil solutions, especially during the sensitive seedling stage, to enhance photosynthesis and ultimately to improve the plant’s establishment. We recommend that agricultural practices in saline regions incorporate tailored irrigation and fertilization strategies that prioritize optimal K/Na ratios to maximize crop performance and sustainability.

Transcriptional and genetic characteristic of chimera pea generation via double ethyl methanesulfonate-induced mutation revealed by transcription analysis.

Ethyl methanesulfonate (EMS)-induced mutagenesis is a prominent method for generating plant mutants, often resulting in chimera plants; however, their transcriptional and genetic characteristic remain elusive. In this investigation, chimera pea (Pisum sativum L.) specimens, labeled GY1 and GY2, exhibiting a distinctive phenotype with yellow and green leaves were meticulously cultivated via sequential double EMS mutagenesis. The observed color disparity between the yellow and green leaves was attributed to a significant reduction in chlorophyll content coupled with heightened lutein levels in both chimeric variants. Transcriptome profiling revealed the enrichment of differentially expressed genes in both GY1 and GY2, specifically implicating Kyoto Encyclopedia of Genes and Genomes pathways linked to amino acid biosynthesis and ribosome development, alongside Gene Ontology (GO) biological processes linked with stress response mechanisms. Few structural genes associated with chlorophyll and lutein biosynthesis exhibited discernible differential expression. Despite these functional similarities, distinctive nuances were evident between specimens, with GY1 exhibiting enrichment in GO pathways related to chloroplast development and GY2 showing enrichment for ribosome development pathways. Single-nucleotide polymorphism (SNP) analysis uncovered a shared pool of 599 and 598 polymorphisms in the yellow and green leaves of GY1 and GY2, respectively, likely stemming from the initial EMS mutagenesis step. Further investigation revealed an increased number of unique SNPs in the yellow leaves following the second EMS application, whereas the green leaves exhibited sparse and unique SNP occurrences, suggestive of potential evasion from secondary mutagenesis. This inherent genetic variability underpins the mechanism underlying the formation of chimera plants. Predominant base mutations induced by EMS were characterized by G/A and C/T transitions, constituting 74.1% of the total mutations, aligning with established EMS mutation induction paradigms. Notably, genes encoding the eukaryotic translation initiation factor eIIso4G and the ubiquitin ligase RKP, known to modulate leaf color in model plants, harbored two SNPs in the yellow leaves of both GY1 and GY2, implicating their putative role in the yellow leaf phenotype. Collectively, this study provides novel insights into the transcriptional and genetic characteristics of chimera plants via EMS-induced mutagenesis.

Potential of a novel marine microalgae Dunaliella sp. MASCC-0014 as feed supplements for sustainable aquaculture

Microalgae, as live feed organisms in aquatic ecosystems, play a crucial role in enhancing water quality by providing oxygen and nutrients. The accumulation of heavy metals in microalgae, however, can pose significant threats to environmental sustainability and human health. In this study, we focused on the marine microalgae Dunaliella sp. MASCC-0014, which exhibited resilience to a wide range of salinities from 0.5 to 4.5 M NaCl, with optimal growth at 0.5 M NaCl. Phylogenetic analysis revealed that MASCC-0014 is closely related to Dunaliella salina CCAP 19/25. Biosorption assay indicated that MASCC-0014 had limited capacity to absorb cadmium, cobalt, and nickel from the liquid medium, while Dunaliella salina CCAP 19/18, Dunaliella tertiolecta FACHB-821 and Dunaliella bardawil FACHB-847 showed varied degrees of cadmium biosorption. When exposed to cadmium stress, MASCC-0014 exhibited suppressed growth and increased activities of catalase (CAT) and peroxidase (POD), suggesting cadmium still triggered cellular responses in MASCC-0014. Furthermore, MASCC-0014 displayed reduced chlorophyll content per cell but increased biomass in warmer conditions, indicating its preference of tropical water over temperate water. This unique microalga strain, which is rich in protein but with limited heavy metal biosorption capabilities, shows promise as a sustainable feed source in aquaculture. The findings in this study offer valuable insights into mitigating the risks of heavy metal enrichment in the food chain through algae-based feeds.

A missense mutation in the barley Xan-h gene encoding the Mg-chelatase subunit I leads to a viable pale green line with reduced daily transpiration rate

Key messageThe barley mutant xan-h.chli-1 shows phenotypic features, such as reduced leaf chlorophyll content and daily transpiration rate, typical of wild barley accessions and landraces adapted to arid climatic conditions.The pale green trait, i.e. reduced chlorophyll content, has been shown to increase the efficiency of photosynthesis and biomass accumulation when photosynthetic microorganisms and tobacco plants are cultivated at high densities. Here, we assess the effects of reducing leaf chlorophyll content in barley by altering the chlorophyll biosynthesis pathway (CBP). To this end, we have isolated and characterised the pale green barley mutant xan-h.chli-1, which carries a missense mutation in the Xan-h gene for subunit I of Mg-chelatase (HvCHLI), the first enzyme in the CBP. Intriguingly, xan-h.chli-1 is the only known viable homozygous mutant at the Xan-h locus in barley. The Arg298Lys amino-acid substitution in the ATP-binding cleft causes a slight decrease in HvCHLI protein abundance and a marked reduction in Mg-chelatase activity. Under controlled growth conditions, mutant plants display reduced accumulation of antenna and photosystem core subunits, together with reduced photosystem II yield relative to wild-type under moderate illumination, and consistently higher than wild-type levels at high light intensities. Moreover, the reduced content of leaf chlorophyll is associated with a stable reduction in daily transpiration rate, and slight decreases in total biomass accumulation and water-use efficiency, reminiscent of phenotypic features of wild barley accessions and landraces that thrive under arid climatic conditions.

Assessing the impact of turnip yellows virus infection and drought on canola performance: implications under a climate change scenario

IntroductionCanola (Brassica napus L.) is one of the most important crops worldwide. Turnip yellows virus (TuYV), transmitted by aphids, is one of the most damaging viruses affecting canola crops and is challenging to control. With the prediction of more intense and prolonged drought events due to future climate change, an additional factor may extensively impact the epidemiology of plant diseases. This study aimed to understand the impact of drought on canola plants infected with TuYV and to explore the relationship between virus infection and drought.MethodsTwo glasshouse experiments were conducted: 1. Competition: Four plants (two infected, two non-infected) were grown in the same pot. 2. No Competition: One plant was grown per pot. In both experiments, infected and non-infected canola plants were exposed to well-watered conditions, water stress (simulated drought), and terminal drought. Various plant traits were recorded, including biomass, leaf area, height, number of leaves, chlorophyll content, water use efficiency, and virus symptom expression.ResultsBoth virus infection and water stress reduced dry biomass, leaf area, and height. Virus infection alone reduced canola biomass by up to 49% compared to non-infected, well-watered controls. Under water stress or terminal drought, the biomass of TuYV-infected plants was further reduced by up to 71% and 65%, respectively. Virus infection also reduced the number of leaves, although water treatment alone did not. Chlorophyll content was higher in water-stressed and terminal drought plants compared to well-watered ones, while virus infection reduced chlorophyll content. The impact of drought and virus infection was more pronounced when plants were under competition.DiscussionGiven the expected increase in prolonged and frequent droughts in many canola-growing regions due to climate change, a significant detrimental effect on canola production due to the combined influence of drought and TuYV is anticipated. This study underscores the need for developing mitigation strategies to protect canola production in a changing climate.

EMS-induced missense mutation in TaCHLI-7D affects leaf color and yield-related traits in wheat.

Mutations in TaCHLI impact chlorophyll levels and yield-related traits in wheat. Natural variations in TaCHLI-7A/B influence plant productivity, offering potential for molecular breeding. Chlorophyll is essential for plant growth and productivity. The CHLI subunit of the magnesium chelatase protein plays a key role inserting magnesium into protoporphyrin IX during chlorophyll biosynthesis. Here, we identify a novel wheat mutant chlorophyll (chl) that exhibits yellow-green leaves, reduced chlorophyll levels, and increased carotenoid content, leading to an overall decline in yield-related traits. Map-based cloning reveals that the chl phenotype is caused by a point mutation (Asp186Asn) in the TaCHLI-7D gene, which encodes subunit I of magnesium chelatase. Furthermore, the three TaCHLI mutants: chl-7b-1 (Pro82Ser), chl-7b-2 (Ala291Thr), and chl-7d-1 (Gly357Glu), also showed significant reductions in chlorophyll content and yield-related traits. However, TaCHLI-7D overexpression in rice significantly decreased thousand kernel weight, yield per plant, and germination. Additionally, natural variations in TaCHLI-7A/B are significantly associated with flag leaf, spike exsertion length, and yield per plant. Notably, the favorable haplotype, TaCHLI-7B-HapII, which displayed higher thousand kernel weight and yield per plant, is positively selected in wheat breeding. Our study provides insights on the regulatory molecular mechanisms underpinning leaf color and chlorophyll biosynthesis, and highlights TaCHLI functions, which provide useful molecular markers and genetic resources for wheat breeding.

The abiotic stress gene (Asg) family member Asg2 as a modulator of plant responses to salt stress

The Abiotic Stress Gene (Asg) family, unique to plants, includes members with the DUF1005 domain of unknown function (DUFs). Although earlier studies have associated members of the Asg gene family and various aspects of plant growth, development, and reactions to abiotic stress, their precise biological roles and underlying mechanisms are not yet well understood. This research found that Asg2 functions not only in regulating root development but also serves as an inhibitor in how the plant responds to salt stress. Overexpression of Asg2 enhances primary root elongation, while gene-edited mutants display the opposite effect. Under salt stress conditions, Arabidopsis lines with increased Asg2 expression exhibit inhibited primary root elongation, reduced seed germination rates, and heightened sensitivity of leaves and seedlings to salt stress. These changes coincide with increased electrolyte leakage, reduced chlorophyll content, decreased antioxidant enzyme activity, and elevated levels of reactive oxygen species (ROS). Transcriptomic analysis revealed that overexpression of Asg2 under salt stress leads to the downregulation of stress resistance genes, thereby increasing sensitivity to salt stress. In conclusion, this research emphasizes the important function of the Asg gene in influencing salt tolerance, providing a foundational framework and genetic resource for comprehending how plants respond to salt stress.

Mechanism of Phloretin Accumulation in Malus hupehensis Grown at High Altitudes: Evidence from Quantitative 4D Proteomics.

Phloretin is a natural dihydrochalcone (DHC) that exhibits various pharmacological and therapeutic activities. Malus hupehensis Rehd. (M. hupehensis) is widely planted in the middle of China and its leaves contain an extremely high content of phloridzin, a glycosylated derivative of phloretin. In the present study, we observed a significant increase in phloretin content in the leaves of M. hupehensis planted at high altitudes. To investigate the mechanisms of phloretin accumulation, we explored changes in the proteome profiles of M. hupehensis plants grown at various altitudes. The results showed that at high altitudes, photosynthesis- and DHC biosynthesis-related proteins were downregulated and upregulated, respectively, leading to reduced chlorophyll content and DHC accumulation in the leaves. Moreover, we identified a novel phloridzin-catalyzing glucosidase whose expression level was significantly increased in high-altitude-cultivated plants. This work provided a better understanding of the mechanism of phloretin accumulation and effective and economic strategies for phloretin production.

Elucidating the Role of SlBBX31 in Plant Growth and Heat-Stress Resistance in Tomato.

Heat stress inhibits plant growth and productivity. Among the main regulators, B-box zinc-finger (BBX) proteins are well-known for their contribution to plant photomorphogenesis and responses to abiotic stress. Our research pinpoints that SlBBX31, a BBX protein harboring a conserved B-box domain, serves as a suppressor of plant growth and heat tolerance in tomato (Solanum lycopersicum L.). Overexpressing (OE) SlBBX31 in tomato exhibited yellowing leaves due to notable reduction in chlorophyll content and net photosynthetic rate (Pn). Furthermore, the pollen viability of OE lines obviously decreased and fruit bearing was delayed. This not only affected the fruit setting rate and the number of plump seeds but also influenced the size of the fruit. These results indicate that SlBBX31 may be involved in the growth process of tomato, specifically in terms of photosynthesis, flowering, and the fruiting process. Conversely, under heat-stress treatment, SlBBX31 knockout (KO) plants displayed superior heat tolerance, evidenced by their improved membrane stability, heightened antioxidant enzyme activities, and reduced accumulation of reactive oxygen species (ROS). Further transcriptome analysis between OE lines and KO lines under heat stress revealed the impact of SlBBX31 on the expression of genes linked to photosynthesis, heat-stress signaling, ROS scavenging, and hormone regulation. These findings underscore the essential role of SlBBX31 in regulating tomato growth and heat-stress resistance and will provide valuable insights for improving heat-tolerant tomato varieties.