BMC Plant Biology最新文献

The availability and quality of irrigation water in Egypt have become major challenges for the agricultural sector. Thus, increasing water productivity and improving irrigation efficiency are critical goals. A field experiment was conducted under Upper Egypt conditions at the El-Mattana Agricultural Research Station, Luxor governorate, Egypt, to evaluate the effects of different irrigation methods traditional furrow irrigation (Ti), surge furrow irrigation (Si), and alternate furrow irrigation (Ai), on water productivity, growth, and yield of wheat in clay loam soil. The wheat cultivar MISR2 (Triticum aestivum L.) was cultivated during the 20/21 and 21/22 growing seasons, using irrigation scheduled after 50% depletion of the soil available water. The results indicated that the treatment of Si produced the greatest plant height (115.0 and 117.7 cm) and grain yield (7.99 and 8.16 t ha⁻¹) for both seasons, respectively. In contrast, the treatment of Ai resulted in the lowest values for these traits (106.4 and 107.2 cm in plant height and 6.94 and 6.24 t ha⁻¹ in grain yield, respectively). The total annual rainfall during the two growing seasons were recorded as 0 mm. The highest amount of irrigation water applied (6522, 6427.2 m³ ha^-1) was recorded with the treatment of Ti; while the lowest amount (5493.6, 5175.1 m³ ha^-1) was recorded with Ai treatments in 20/21, and 21/22 growing seasons, respectively. The highest irrigation water productivity (1.75 kg m^-3 and 1.35 kg m^-3 in the first season and 1.44 kg m^-3 and 1.20 kg m^-3 in the second season under the treatment of Ai and Si, respectively. The treatment of Ai was most effective for saving water, by 15.8% and 19.48% over the two seasons. These results suggesting that an extra irrigation water amount may be saved without any significant loss in yield of wheat when applying Si irrigation method. This research contributes to developing evidence-based irrigation management strategies for improving wheat production in arid regions.

Background: Global climate change significantly affects photosynthesis in spring wheat. However, the successive dynamic effects of multiple environmental interactions on photosynthesis in spring wheat have been inadequately investigated. This study conducted pot control experiments to determine photosynthesis characteristics, namely light and CO₂ response curves, in spring wheat under progressive drought stress.

Results: Progressive drought stress caused all parameters of the light response curve to decrease logistically and all parameters of the CO₂ response curve to change exponentially. There were noticeable thresholds for these parameter changes. The ability of spring wheat to utilize light was weakened by progressive drought stress. Under all drought levels, the reduction in photosynthetic capacity was greater under strong light than under weak light. The effects on CO₂ utilization and the corresponding photosynthetic capacity depended on the drought level and CO₂ concentration. The optimal light intensity (I_opt) for spring wheat showed a logistic decreasing trend under progressive drought stress. Unexpectedly, the optimal atmospheric CO₂ concentration (CO_2opt) remained at 800 µmol·mol^- 1 under drought stress, which was less severe than extreme drought.

Conclusions: Our results showed that progressive drought stress, combined with different environmental factors, had distinct impacts on the photosynthetic efficiency and carbon assimilation capacity of spring wheat, providing a basis for rational carbon and water resource utilization in spring wheat under climate change.

Background: Phosphorus (P) is an essential macronutrient for Brassica napus L. growth and development, and is mainly acquired from the soil as phosphate (Pi). However, there is no research on the system analysis of Pi utilization related genes (PURs) in B. napus yet.

Results: In this study, 285 PURs were identified in B. napus genome, including 4 transcription factor (TF) gene families (83 genes) and 17 structural gene families (202 genes). Subcellular localization analysis showed that the proteins encoded by B. napus PURs were mainly located in the nucleus (~ 46.0%) and cell membrane (~ 36.5%). Chromosome localization analysis suggested that B. napus PURs were distributed on An (131) and Cn (149) subgenomes without bias. Analysis of 35 representative species confirmed that PURs were widely present in plants ranging from Chlorophyta to angiosperms with a rapid expansion trend. Collinearity analysis revealed that allopolyploidization and small-scale duplication events resulted in the large expansion of B. napus PURs. For each gene pair of B. napus PURs, the sequence identity of promoter was significantly lower than that of CDS, proving the significant difference in promoter region that might be related to the divergence of PURs expression and function. Transcription factor (TF) binding site prediction, cis-element analysis, and microRNA prediction suggested that the expressions of B. napus PURs are regulated by multiple factors including 32 TF gene families (362), 108 types of CRE (29,770) and 25 types of miRNAs (66). Spatiotemporal expression analysis demonstrated that B. napus PURs were widely expressed during the whole developmental stages, and most synteny-gene pairs (76.42%) shared conserved expression patterns. RNA-seq analyses revealed that most B. napus PURs were induced by low Pi stress, and the hub genes were generally the Pi transporter (PHT) family members. qRT-PCR analysis proved that the expression levels of four B. napus PURs were positively correlated with the root system architecture of three B. napus varieties under low Pi supply at the seedling stage.

Conclusion: The 285 PURs were identified from B. napus with strong LP inducible expression profile. Our findings regarding the evolution, transcriptional regulation, and expression of B. napus PURs provide valuable information for further functional research.

Background: This study investigated the effects of inoculating Lactobacillus parafarraginis alone or in combination with citric acid on the silage quality, microbial community structure, and metabolic characteristics of hybrid Pennisetum. The experiment included three treatments: (1) addition of 10 ml distilled water (CON); (2) addition of 1 × 10⁶ cfu/g L. parafarraginis (LP); (3) addition of 1 × 10⁶ cfu/g L. parafarraginis and 1% citric acid (LCA). The fermentation was maintained at 25 ℃ for 60 days.

Results: The addition of L. parafarraginis increased the dry matter, water-soluble carbohydrates, and crude protein content of the silage and decreased the fiber contents. Moreover, lactic acid content was notably higher, and pH values were lower in the L. parafarraginis group, with higher lactic acid bacteria (LAB) compared with the CON. The microbial community analysis indicated that adding L. parafarraginis promoted the proliferation of beneficial LAB and inhibited spoilage bacteria, such as Clostridium. In the LCA, amino acid metabolism was improved, particularly with an increase in L-tyrosine concentration, along with significant enrichment of pathways related to tryptophan metabolism.

Conclusions: The addition of L. parafarraginis improved the fermentation quality of the silage, reduced undesirable microorganisms, and increased the content of organic acids, indicating its potential to enhance the flavor of the silage. Compared with individual treatments, the combination of L. parafarraginis and citric acid improved amino acid metabolism and enriched pathways related to tryptophan metabolism, further enhancing the quality of the silage. These findings highlight the potential of L. parafarraginis, especially in combination with citric acid, as an effective additive for producing high-quality, nutritious hybrid Pennisetum silage.

Aims: Fertilizers can significantly influence leaf senescence and hormonal regulation, which in turn impacts crop yield. Despite significant advancements in understanding fertilizer effects on plant growth, the specific molecular mechanisms through which fertilizers influence hormonal regulation and leaf senescence, and subsequent impact on yield, remain underexplored. This study addresses this critical gap by examining transcriptional, physiological, and molecular mechanisms in the semiarid regions of rainfed spring maize under long-term fertilizers.

Methods: Fertilizer treatments include no amendment (NA), inorganic fertilizer (CF), combined inorganic and organic fertilizer (SC), organic fertilizer (SM), and maize straw (MS) replicated three times.

Results: The highest number of differentially expressed genes (DEGs) were observed under CF (3972) followed by SC (1949) in comparison to NA, showing a strong effect of inorganic fertilizer on gene expressions. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that numerous genes involved in the biosynthesis of secondary metabolites, plant hormone signaling, photosynthesis pathways, and metabolic pathways showed varied expressions of up- and downregulation. Genes involved in the ethylene, abscisic acid, jasmonic acid, salicylic acid, and brassinosteroid pathways indicated their interaction and promoted leaf senescence, whereas those related to auxin and gibberellin pathways had minimal impact. In the ethylene pathway known to influence senescence, two ethylene receptor (ETR) genes (Zm00001d013486 and Zm00001d021687) were downregulated, whereas, two ethylene-insensitive proteins 3 (EIN2) genes (Zm00001d053594 and Zm00001d033625) showed upregulation in the CF, SC and SM treatments. Furthermore, 86 highly up-regulated genes involved in the photosynthesis pathway encompassing components such as photosynthesis antenna, photosynthesis complexes II, cytochrome complexes, photosynthesis electron transport, and ATP complex in SC and CF compared to SM and MS.

Conclusion: In summary, the study finds that DEGs showed stronger responses to inorganic fertilizers, likely due to organic fertilizers decomposing at a slower rate. Nevertheless, transcriptional and physiological analyses indicate that the SC treatment sustainably enhances maize productivity without causing adverse environmental effects, outperforming the other treatments (NA, CF, SM, MS). These results provide new perspectives on genetic regulation and pathway discovery in rainfed maize cultivation in semiarid areas.

Background: Tocopherols are a class of lipid-soluble compounds that have multiple functional roles in plants and exhibit vitamin E activity, an essential nutrient for human and animal health. The tocopherol biosynthetic pathway is conserved across the plant kingdom, but source of the key tocopherol pathway precursor, phytol, is unclear. Two protochlorophyllide reductases (POR1 and POR2) were previously identified as loci controlling the natural variation of total tocopherols in maize grain, a non-photosynthetic tissue. POR1 and POR2 are key genes in chlorophyll biosynthesis yet the contribution of the chlorophyll biosynthetic pathway to tocopherol biosynthesis is still not understood.

Results: We took two approaches to alter the activity of these two POR genes within kernel tissue, physiological treatments and CRISPR/Cas9-mediated knockouts, to determine the role of chlorophyll biosynthesis for tocopherol content. Since light is required for POR enzymatic activity, we imposed a dark treatment on developing kernels, which reduced chlorophyll a and tocopherols levels in embryo tissue by 92-99% and 87-90%, respectively, compared to the light treatment. In CRISPR/Cas9-mediated knockouts, the levels of chlorophyll a and tocopherols in embryos of the por1 por2 double homozygous mutant were reduced by 98-100% and 76-83%, respectively, compared to WT.

Conclusion: These findings demonstrate that tocopherol synthesis in maize grain depends almost entirely on phytol derived from chlorophyll biosynthesis within the embryo. POR1 and POR2 activity play crucial roles in chlorophyll biosynthesis, underscoring the importance of POR alleles and their activity in the biofortification of vitamin E levels in non-photosynthetic grain of maize.

The thermal conversion of municipal sewage sludge (MSS) offers significant potential for sustainable waste management, particularly through the production of biochar. This study investigates the properties and soil application effects of three biochar types produced via pyrolysis: (i) pure sewage sludge (100%), (ii) sewage sludge blended with sawdust (50%+50%), and (iii) sewage sludge combined with sawdust and zeolite (50%+45%+5%). These biochars were applied at rates of 2.5% and 7.5% (w/w) to arable soil and assessed in an 8-week greenhouse experiment using lettuce (Lactuca sativa L. var. Brilant) as a model crop. The sewage sludge biochar was characterized by high nitrogen, phosphorus, and water-extractable calcium but exhibited low organic matter and organic carbon content. It enhanced soil enzyme activities related to carbon and nitrogen mineralization without affecting microbial respiration. However, at 7.5% application rate, this biochar caused the highest chlorophyll b content in lettuce, despite acidifying the soil. Adding sawdust to the pyrolysis feedstock significantly increased organic matter, organic carbon (with reduced recalcitrance), and the C: N ratio of biochar. This biochar formulation promoted microbial activity (as indicated by changes in soil respiration) and nutrient cycling, particularly through increased glucosidase activity. Conversely, addition of zeolite to the pyrolysis feedstock reduced the organic matter and organic carbon content while increasing biochar recalcitrance and nutrient immobilization, particularly of sulfur, ammonium, phosphorus, and calcium. At the 7.5% dose, the sawdust + zeolite-enriched biochar improved soil pH and potentially enhanced nutrient retention. However, it did not stimulate microbial enzyme activity or respiration, leading to lower photosynthetic pigment levels and reduced biomassin lettuce, especially at higher application rate. For short-term soil applications under the conditions of this pot trial, the sewage sludge-sawdust biochar demonstrated the most beneficial effects, rapidly stimulating microbial activity and nutrient transformation. In contrast, the sewage sludge-sawdust-zeolite biochar limited nutrient availability and plant growth, suggesting it may be less suitable for immediate soil and plant nutrition. Long-term studies are needed to fully assess the implications of these biochar types for sustainable agriculture. This study highlights the importance of feedstock composition and selection in tailoring biochar properties to meet specific soil and crop requirements.

Background: The genus Caragana, known for its adaptability and high forage value, is commonly planted to rehabilitate barren land and prevent desertification. Several Caragana species are also used for medicinal purposes. Analysis of synonymous codon usage bias and their primary influencing factors in chloroplast genomes aims to provide insights into molecular research and germplasm innovation for Caragana plants.

Results: The GC content of the five Caragana species ranged from 36.00% to 37.10%, showing a preference for codons ending in A/U, although the codon bias was weak. The screening identified nine to twelve optimal codons, but their frequency of use was low. Correlation analysis, neutrality plots, ENC plots and PR2 plots of the parameters identified two potential groups among the five species: Caragana arborescens and Caragana jubata, and Caragana turkestanica, Caragana opulens and Caragana tibetica. These groups showed a high level of intragroup similarity in the parameter analyses. In the RSCU cluster tree analysis, Caragana turkestanica and Caragana arborescens grouped together, while Caragana tibetica, Caragana jubata and Caragana opulens formed a separate clade in the CDS sequence and complete sequence phylogenetic tree analysis.

Conclusions: The codon usage bias in the chloroplast genomes of the five Caragana species showed high similarity, suggesting that natural selection has a greater influence on codon bias than mutation. Furthermore, the identified optimal codons provide valuable insights for germplasm improvement of Caragana plants.

Background: Camellia reticulata Lindl. (C. reticulata) is the tallest ornamental camellia globally, with wild populations comprising a polyploid complex of diploids (2×), tetraploids (4×), and hexaploids (6×). The type specimen of C. reticulata is a heteroploid hexaploid derived from 2 × ancestors, including C. pitardii, C. saluenensis, and 2 × C. reticulata. Currently, limited information exists regarding the evolutionary characteristics of the chloroplast genomes of C. reticulata at different ploidy levels, and the phylogenetic position of 2 × and 4 × C. reticulata remains unclear.

Results: This study sequenced, assembled, and annotated the chloroplast genomes of 2 × and 4 × C. reticulata, comparing them with those of 6 × C. reticulata and other closely related species. The results indicated that the chloroplast genome sizes of C. reticulata ranged from 156,519 to 156,927 bp, with gene counts, distributions, GC content, and codon usage being similar across different ploidy levels. The ycf1 gene exhibited significant differentiation among species, and was identified as a candidate for adaptive evolution in C. reticulata. Additionally, 11 highly differentiated intergenic regions were identified, with six hotspots of variation that can serve as molecular markers for genetic studies in C. reticulata populations. Analysis of selection pressure indicated that four genes were under positive selection. Phylogenetic analysis revealed that the polyploid complex of C. reticulata, along with C. pitardii, C. saluenensis, and C. mairei, formed a well-supported clade. The genetic distances between 6 × C. reticulata and its three 2 × ancestors were relatively small.

Conclusion: Camellia pitardii, C. saluenensis, and C. mairei may have participated in the allopolyploidization of C. reticulata, with both 2 × and 4 × C. reticulata have the potential for independent classification. These findings provide valuable insights into chloroplast genome alterations following allopolyploidization, establishing a crucial foundation for understanding the systematic evolutionary history of various ploidy levels in C. reticulata.