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An accurate gas utilization model is essential for precisely detecting plant photosynthetic capacity. Existing equipment for measuring the plant photosynthetic rate typically considers the key parameters of mesophyll cell conductance and a photosynthetic model based on the carbon reaction process under direct light conditions. However, the light environment signals received by the plant canopy not only vary significantly in incidence angles, but the effective light intensity also differs greatly from the measured values under vertical incidence conditions. To reduce the deviation between existing photosynthetic models and the actual photosynthetic efficiency of leaves, this study employs the gas diffusion method from engineering, using the finite element approach. Based on elastic mechanics and seepage mechanics, the internal stress field control equation of tomato leaves and the two-phase flow equation under a CO2 porous medium were derived. A mathematical model of porous gas–liquid two-phase fluid-solid coupling was established, solved, and analyzed. Preliminary verification was conducted through tests. The results show that in the initial stage of CO2 entering the leaf, the gas flow velocity is higher because of the larger pressure gradient between the pore and the leaf. In this stage, the gas diffusion rate is higher. As the intake time increases, the pressure gradient gradually decreases, and the inlet velocity slows down. Consequently, the diffusion rate gradually reduces. Because of the coupling of light quantity and light direction, the gas diffusion rate significantly increases compared with the uncoupled model. Additionally, a diffusion model that does not consider fluid–solid coupling will overestimate the gas flow rate as the depth of gas entry increases. Therefore, the internal gas diffusion model must account for the effect of coupling on the diffusion rate. [ABSTRACT FROM AUTHOR]

This study evaluated the salt tolerance in 40 celery germplasm resources to clarify the different salt tolerances of celery germplasm. A gradient treatment with different concentrations of NaCl solutions (100, 200, and 300 mmol·L−1) was used to simulate salt stress. After 15 days of salt treatment, 14 indicators related to plant growth, physiology, and biochemistry were determined. The results showed that different celery varieties responded differently to salt stress. Notably, there were significant variations in below-ground dry weight, root–crown ratio, antioxidant enzyme activity, and soluble protein content among the accessions under salt stress. Principal component analysis was used to identify important indices for evaluating salt tolerance, including plant height, spread, content of soluble protein, and so on. A comprehensive evaluation was conducted utilizing the salt damage index, principal component analysis, affiliation function analysis, and cluster analysis. The 40 celery germplasms were classified into five highly salt-tolerant, seven salt-tolerant, fifteen moderately salt-tolerant, nine salt-sensitive, and four highly salt-sensitive germplasms. SHHXQ, MXKQ, XBQC, XQ, and TGCXBQ were highly salt-tolerant germplasms, and BFMSGQ, HNXQ, ZQ, and MGXQW were highly salt-sensitive germplasms. The results of this study provide a reference for the variety of celery cultivation in saline areas and lay a foundation for the selection and breeding of salt-tolerant varieties of celery. [ABSTRACT FROM AUTHOR]

The genus Apium, belonging to the family Apiaceae, comprises roughly 20 species. Only two species, Apium graveolens and Apium leptophyllum, are available in China and are both rich in nutrients and have favorable medicinal properties. However, the lack of genomic data has severely constrained the study of genetics and evolution in Apium plants. In this study, Illumina NovaSeq 6000 and Nanopore sequencing platforms were employed to identify the mitochondrial genomes of A. graveolens and A. leptophyllum. The complete lengths of the mitochondrial genomes of A. graveolens and A. leptophyllum were 263,017 bp and 260,164 bp, respectively, and contained 39 and 36 protein-coding genes, five and six rRNA genes, and 19 and 20 tRNA genes. Consistent with most angiosperms, both A. graveolens and A. leptophyllum showed a preference for codons encoding leucine (Leu). In the mitochondrial genome of A. graveolens, 335 SSRs were detected, which is higher than the 196 SSRs found in the mitochondrial genome of A. leptophyllum. Studies have shown that the most common RNA editing type is C-to-U, but, in our study, both A. graveolens and A. leptophyllum exhibited the U-C editing type. Furthermore, the transfer of the mitochondrial genomes of A. graveolens and A. leptophyllum into the chloroplast genomes revealed homologous sequences, accounting for 8.14% and 4.89% of the mitochondrial genome, respectively. Lastly, in comparing the mitochondrial genomes of 29 species, it was found that A. graveolens, A. leptophyllum, and Daucus carota form a sister group with a support rate of 100%. Overall, this investigation furnishes extensive insights into the mitochondrial genomes of A. graveolens and A. leptophyllum, thereby enhancing comprehension of the traits and evolutionary patterns within the Apium genus. Additionally, it offers supplementary data for evolutionary and comparative genomic analyses of other species within the Apiaceae family. [ABSTRACT FROM AUTHOR]

The plant mitochondria play a crucial role in various cellular energy synthesis and conversion processes and are essential for plant growth. Watercress (Oenanthe javanica) is a fast-growing vegetable with strong adaptability and wide cultivation range, and it possesses high nutritional value. In our study, we assembled the O. javanica mitochondrial genome using the Illumina and Nanopore sequencing platforms. The results revealed that the mitochondrial genome map of watercress has a circular structure of 384,074 bp, containing 28 tRNA genes, 3 rRNA genes, and 34 protein-coding genes. A total of 87 SSR (simple sequence repeat) loci were detected, with 99% composed of palindrome repeats and forward repeats, while no complementary repeats were identified. Codon preference analysis indicated that watercress prefers to use codons encoding leucine, isoleucine, and serine with a preference for A/U-ending codons. Phylogenetic analysis showed that watercress is closely related to species of Bupleurum, Apium, Angelica, and Daucus, with the closest evolutionary relationship observed with Saposhnikovia divaricata and Apium graveolens. This study provides a valuable resource for the study of the evolution and molecular breeding of watercress. [ABSTRACT FROM AUTHOR]

Asparagus belongs to the Liliaceae family and has important economic and pharmacological value. Lignin plays a crucial role in cell wall structural integrity, stem strength, water transport, mechanical support and plant resistance to pathogens. In this study, various biological methods were used to study the mechanism of shading on the asparagus lignin accumulation pathway. The physiological results showed that shading significantly reduced stem diameter and cell wall lignin content. Microstructure observation showed that shading reduced the number of vascular bundles and xylem area, resulting in decreased lignin content, and thus reducing the lignification of asparagus. Cinnamic acid, caffeic acid, ferulic acid and sinapyl alcohol are crucial intermediate metabolites in the process of lignin synthesis. Metabolomic profiling showed that shading significantly reduced the contents of cinnamic acid, caffeic acid, ferulic acid and sinapyl alcohol. Transcriptome profiling identified 37 differentially expressed genes related to lignin, including PAL, C4H, 4CL, CAD, CCR, POD, CCoAOMT, and F5H related enzyme activity regulation genes. The expression levels of POD, CCoAOMT, and CCR genes were significantly decreased under shading treatment, while the expression levels of CAD and F5H genes exhibited no significant difference with increased shading. The downregulation of POD, CCoAOMT genes and the decrease in CCR gene expression levels inhibited the activities of the corresponding enzymes under shading treatment, resulting in decreased downstream content of caffeic acid, ferulic acid, sinaperol, chlorogenic acid and coniferin. A significant decrease in upstream cinnamic acid content was observed with shading, which also led to decreased downstream metabolites and reduced asparagus lignin content. In this study, transcriptomic and metabolomic analysis revealed the key regulatory genes and metabolites of asparagus lignin under shading treatment. This study provides a reference for further understanding the mechanism of lignin biosynthesis and the interaction of related genes. [ABSTRACT FROM AUTHOR]

This study sequenced and assembled the chloroplast (cp) genome of Brasenia schreberi cv. 'Mahu Chuncai', a novel variety of B. schreberi rich in nutrients with distinctive characteristics, unlike other varieties in China. The cpDNA genome of 'Mahu Chuncai' has a typical quadripartite structure, with a full length of 158,973 bp, including 88 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The phylogenetic analysis revealed that all species can be divided into three main clades. Results from inverted repeats (IR) boundary analysis revealed substantial differences between Brasenia and Cabomba species. The cpDNA genome of B. schreberi identified was strongly related to Brasenia species but appeared to be a distant relative of Cabomba aquatica more than other species in Cabombaceae. In contrast with the species from Cabombaceae, 'Mahu Chuncai' was a close relative of B. schreberi MN315507.1, which was a distant relative of C. aquatica MG720559.1. Furthermore, we found four potential molecular markers, i.e., ycf1 in the IR region, psbT in the LSC region, and ndhF and rps15 in the SSC region. Collectively, our findings confirm the phylogenetic evolution and cultivation origin of B. schreberi. We identified genetic characteristics and nucleotide diversity hotspots, which provides a theoretical basis for additional research on variety identification, germplasm resources, and molecular breeding of the precious vegetable. [ABSTRACT FROM AUTHOR]

Mustard is an edible vegetable in the genus Brassica with tender and clean sprouts and short growth cycles that has become a rich source of nutrients required by humans. Here, the effects of dark exposure duration and planting density on the health-promoting phytochemicals and the antioxidant capacity of mustard sprouts were evaluated. The content of soluble sugar, soluble protein, chlorophyll, and carotenoids and the antioxidant capacity of mustard were higher in the two-day dark treatment; the content of indolic glucosinolates was also more affected in the dark day experiment than in the planting density experiment. The soluble sugar, soluble protein, and aliphatic and total glucosinolate levels were higher when sprouts were grown at high densities (6–7 g per tray); however, no significant variation was observed in the content of chlorophyll and carotenoids and the antioxidant capacity. The results of this study show that the optimum cultivation regime for maximizing the concentrations of nutrients of mustard plants is a planting density of 6 g of seeds per tray and a two-day dark treatment. [ABSTRACT FROM AUTHOR]

Drought stress is a key factor limiting the growth and tuber yield of potatoes (Solanum tuberosum L.). Brassinosteroids (BRs) have been shown to alleviate drought stress in several plant species; however, little is known about the physiological and molecular mechanisms by which BRs enhance drought resistance in potatoes. Here, we characterized changes in the physiology and transcriptome of the tetraploid potato variety 'Xuanshu-2′ in response to drought stress after 24-epibrassinolide (EBR) pretreatment. The abscisic acid (ABA) content, photosynthetic capacity, and the activities of antioxidant enzymes were increased; the intercellular CO2 concentration, relative conductivity, reactive oxygen species, malondialdehyde, proline, and soluble sugar content were decreased after EBR pretreatment compared with plants under drought stress. Transcriptome analysis revealed 1330 differently expressed genes (DEGs) involved in the response to drought stress after EBR pretreatment. DEGs were enriched in plant hormone signal transduction, starch and sucrose metabolism, circadian rhythm, flavonoid biosynthesis, and carotenoid biosynthesis. DEGs associated with the BR signaling and biosynthesis pathways, as well as ABA metabolic pathways were identified. Our findings provide new insights into the mechanisms by which BRs enhance the drought resistance of potatoes. [ABSTRACT FROM AUTHOR]

Purple flowering stalks and green flowering stalks of Brassica campestris are widely cultivated in the middle and upper reaches of the Yangtze River. Here, concentrations of the main health-promoting compounds and antioxidant capacity levels were characterized in different parts (leaves, peel, flesh, and inflorescences) of purple and green flowering stalks. There were significant differences in the concentrations of health-promoting compounds between the two variants; the concentrations of pigments, especially anthocyanidins, and gluconapin, were significantly higher in purple flowering stalks than in green flowering stalks, and the progoitrin content was significantly higher in green flowering stalks than in purple flowering stalks. The leaves were judged to be the most nutritional edible part because they had the highest concentrations of pigments, ascorbic acid, proanthocyanidins, flavonoids, and total phenolics. Antioxidant capacity was also highest in the leaves, and it was positively correlated with the concentration of health-promoting compounds. Purple flowering stalks and green flowering stalks were found to be rich in health-promoting compounds, especially glucosinolates. Overall, our findings indicate that consumption of the leaves and peel would provide the most health benefits. Some suggestions are provided regarding the processing and utilization of these edible components. [ABSTRACT FROM AUTHOR]

To understand the effect of exogenous PA on the watermelon root system, the watermelon variety 'Zaojia 84–24' was used as experimental material. This study investigated the effects of allelochemicals DIBP and DOP at varying different concentrations (0, 0.05, 0.1, 0.5, 1, and 4 mmol·L−1) on the physiological characteristics and mineral content of watermelon roots. The results revealed that proper PA treatment concentrations (0.05~0.1 mmol·L−1) promoted seed germination, increased the number of RBCs and the survival rate of RBCs, and enhanced the activities of PME and dehydrogenase in watermelon roots. In addition, proper PA treatment concentrations (0.05~0.1 mmol·L−1) promoted the activities of SOD, POD, CAT, and NR in watermelon roots. The contents of MDA and soluble protein were increased at 0.05~4 mmol·L−1 PA. In addition, proper PA treatment concentrations promoted the absorption and accumulation of P, K, Ca, Fe, Cu, and Zn elements in watermelon roots. These results indicate that PA at a concentration of 0.05~0.5 mmol·L−1 can promote watermelon seed germination, improve antioxidant enzyme activity of watermelon roots, and maintain normal physiological activities of watermelon by affecting absorption and accumulation of mineral elements in the root system. [ABSTRACT FROM AUTHOR]

Wasabi (Eutrema japonicum) is a vegetable of Brassicaceae family, currently cultivated in East Asia. It is rich in nutritional and has a spicy flavour. It is regarded as a rare condiment worldwide. Its genetic profile for yield improvement and the development of E. japonicum germplasm resources remains unknown. Cognizant of this, this study sequenced and assembled the chloroplast (cp) genome of E. japonicum to enrich our genomic information of wasabi and further understand genetic relationships within the Eutrema species. The structural characteristics, phylogeny, and evolutionary relationship of cp genomes among other Brassicaceae plants were analyzed and compared to those of Eutrema species. The cp genome of E. japonicum has 153,851 bp with a typical quadripartite structure, including 37 tRNA genes, 8 rRNA genes, and 87 protein-coding genes. It contains 290 simple sequence repeats and prefers to end their codons with an A or T, which is the same as other Brassicaceae species. Moreover, the cp genomes of the Eutrema species had a high degree of collinearity and conservation during the evolution process. Nucleotide diversity analysis revealed that genes in the IR regions had higher Pi values than those in LSC (Large single copy) and SSC (Small single copy) regions, making them potential molecular markers for wasabi diversity studies. The analysis of genetic distance between Eutrema plants and other Brassicacea plants showed that intraspecies variation was found to be low, while large differences were found between genera and species. Phylogenetic analysis based on 29 cp genomes revealed the existence of a close relationship amongst the Eutrema species. Overall, this study provides baseline information for cp genome-based molecular breeding and genetic transformation studies of Eutrema plants. [ABSTRACT FROM AUTHOR]

Excessive aluminum ions (Al3+) in acidic soil can have a toxic effect on watermelons, restricting plant growth and reducing yield and quality. In this study, we found that exogenous application of nitric oxide (NO) could increase the photochemical efficiency of watermelon leaves under aluminum stress by promoting closure of leaf stomata, reducing malondialdehyde and superoxide anion in leaves, and increasing POD and CAT activity. These findings showed that the exogenous application of NO improved the ability of watermelon to withstand aluminum stress. To further reveal the mitigation mechanism of NO on watermelons under aluminum stress, the differences following different types of treatments—normal growth, Al, and Al + NO—were shown using de novo sequencing of transcriptomes. In total, 511 differentially expressed genes (DEGs) were identified between the Al + NO and Al treatment groups. Significantly enriched biological processes included nitrogen metabolism, phenylpropane metabolism, and photosynthesis. We selected 23 genes related to antioxidant enzymes and phenylpropane metabolism for qRT-PCR validation. The results showed that after exogenous application of NO, the expression of genes encoding POD and CAT increased, consistent with the results of the physiological indicators. The expression patterns of genes involved in phenylpropanoid metabolism were consistent with the transcriptome expression abundance. These results indicate that aluminum stress was involved in the inhibition of the photosynthetic pathway, and NO could activate the antioxidant enzyme defense system and phenylpropane metabolism to protect cells and scavenge reactive oxygen species. This study improves our current understanding by comprehensively analyzing the molecular mechanisms underlying NO-induced aluminum stress alleviation in watermelons. [ABSTRACT FROM AUTHOR]