IAA Content Research Articles

The contribution of Ca and Mg to the accumulation of amino acids in maize: from the response of physiological and biochemical processes

BackgroundThe quality of maize kernels is significantly enhanced by amino acids, which are the fundamental building blocks of proteins. Meanwhile, calcium (Ca) and magnesium (Mg), as important nutrients for maize growth, are vital in regulating the metabolic pathways and enzyme activities of amino acid synthesis. Therefore, our study analyzed the response process and changes of amino acid content, endogenous hormone content, and antioxidant enzyme activity in kernels to the coupling addition of sugar alcohol-chelated Ca and Mg fertilizers with spraying on maize.Result(1) The coupled addition of Ca and Mg fertilizers increased the Ca and Mg content, endogenous hormone components (indole-3-acetic acid, IAA; gibberellin, GA; zeatin riboside, ZR) content, antioxidant enzyme activity, and amino acid content of maize kernels. The content of Ca and Mg in kernels increased with the increasing levels of Ca and Mg fertilizers within a certain range from the filling to the wax ripening stage, and significantly positively correlated with antioxidant enzyme activities. (2) The contents of IAA, GA, and ZR continued to rise, and the activities of superoxide dismutase (SOD) and catalase (CAT) were elevated, which effectively enhanced the ability of cells to resist oxidative damage, promoted cell elongation and division, and facilitated the growth and development of maize. However, the malondialdehyde (MDA) content increased consistently, which would attack the defense system of the cell membrane plasma to some extent. (3) Leucine (LEU) exhibited the highest percentage of essential amino acid components and a gradual decline from the filling to the wax ripening stage, with the most substantial beneficial effect on essential amino acids. (4) CAT and SOD favorably governed essential amino acids, while IAA and MDA negatively regulated them. The dominant physiological driving pathway for the synthesis of essential amino acids was “IAA-CAT-LEU”, in which IAA first negatively drove CAT activity, and CAT then advantageously controlled LEU synthesis.ConclusionThese findings provide a potential approach to the physiological and biochemical metabolism of amino acid synthesis, and the nutritional quality enhancement of maize kernel.

Microbiological characterization and functional evaluation in formulation made on farm at different times of production

Microbial formulations are routinely produced in several rural areas in Brazil. Its production is made using agricultural remnants, easily accessible products and soil microorganisms captured using cooked rice. However, studies on the microbial population and its functions in these products are still very scarce. The aim of this work was to evaluate the microbial diversity and dynamics, its functions and capacity to produce auxins (IAA). Microorganisms were isolated of the formulation with different times of production, quantified by serial dilution and then identified by DNA sequencing. The IAA production was evaluated by high performance liquid chromatography. The results showed a high variability of microorganisms and was extremely variable over production time. The formulation with 10 days of production showed the highest density of microorganisms and IAA concentration. There was no presence of Salmonella spp. and the mean number of thermotolerant coliforms is within sanitary limits. In conclusion, the formulation with 10 days of production is the most suitable for use.

Different Phenotypic, Photosynthetic, and Physiological Responses to Flooding between Q. nuttallii and Q. palustris.

Flooding stress is an increasingly serious problem in wetlands, often affecting large areas of crops and timber production areas. The current study aimed to explore the species differences in responses to flooding stress between Q. nuttallii and Q. palustris in an outdoor environment. All the tested plants survived after a 60-day flooding treatment that left 5 cm of water above the soil surface. This suggests that the two species are flood-tolerant, so they can be applied in the construction of riparian protection forests and wetland restoration. Compared with control conditions, flooding treatment significantly decreased seedling height and diameter and the Pn, Gs, Tr, Fv/Fm, ABS/CSm, TR0/CSm, ET0/CSm, RE0/CSm, IAA, and GA3 content and significantly increased the content of MDA, H2O2, soluble sugars, SOD, POD, ADH, ABA, and JA. Under control conditions, Q. nuttallii showed significantly greater growth and photosynthetic capability than Q. palustris. In contrast, Q. palustris exhibited less inhibition of growth and photosynthesis, oxidative stress levels, and antioxidant enzyme activities than Q. nuttallii under flooding conditions. The findings indicate that Q. palustris has better defense mechanisms against the damage caused by flooding stress than Q. nuttallii. Q. nuttallii was more sensitive and responsive to flooding than Q. palustris.

Transcriptome Analysis of Early Lateral Root Formation in Tomato.

Lateral roots (LRs) receive signals from the inter-root environment and absorb water and nutrients from the soil. Auxin regulates LR formation, but the mechanism in tomato remains largely unknown. In this study, 'Ailsa Craig' tomato LRs appeared on the third day and were unevenly distributed in primary roots. According to the location of LR occurrence, roots were divided into three equal parts: the shootward part of the root (RB), the middle part of the root (RM), and the tip part of the root (RT). Transverse sections of roots from days 1 to 6 revealed that the number of RB cells and the root diameter were significantly increased compared with RM and RT. Using roots from days 1 to 3, we carried out transcriptome sequencing analysis. Identified genes were classified into 16 co-expression clusters based on K-means, and genes in four associated clusters were highly expressed in RB. These four clusters (3, 5, 8, and 16) were enriched in cellulose metabolism, microtubule, and peptide metabolism pathways, all closely related to LR development. The four clusters contain numerous transcription factors linked to LR development including transcription factors of LATERAL ORGAN BOUNDRIES (LOB) and MADS-box families. Additionally, auxin-related genes GATA23, ARF7, LBD16, EXP, IAA4, IAA7, PIN1, PIN2, YUC3, and YUC4 were highly expressed in RB tissue. Free IAA content in 3 d RB was notably higher, reaching 3.3-5.5 ng/g, relative to RB in 1 d and 2 d. The LR number was promoted by 0.1 μM of exogenous IAA and inhibited by exogenous NPA. We analyzed the root cell state and auxin signaling module during LR formation. At a certain stage of pericycle cell development, LR initiation is regulated by auxin signaling modules IAA14-ARF7/ARF19-LBD16-CDKA1 and IAA14-ARF7/ARF19-MUS/MUL-XTR6/EXP. Furthermore, as a key regulatory factor, auxin regulates the process of LR initiation and LR primordia (LRP) through different auxin signaling pathway modules.

Effects of Different Doses of sUV-B Exposure on Taxane Compounds' Metabolism in Taxus wallichiana var. Mairei.

UV-B is an important environmental factor that differentially affects plant growth and secondary metabolites. The effects of supplemental ultraviolet-B (sUV-B) exposure (T1, 1.40 kJ·m-2·day-1; T2, 2.81 kJ·m-2·day-1; and T3, 5.62 kJ·m-2·day-1) on the growth biomass, physiological characteristics, and secondary metabolites were studied. Our results indicated that leaf thickness was significantly (p < 0.05) reduced under T3 relative to the control (natural light exposure, CK); The contents of 6-BA and IAA were significantly reduced (p < 0.05); and the contents of ABA, 10-deacetylbaccatin III, and baccatin III were significantly (p < 0.05) increased under T1 and T2. The paclitaxel content was the highest (0.036 ± 0.0018 mg·g-1) under T3. The cephalomannine content was significantly increased under T1. Hmgr gene expression was upregulated under T1 and T3. The gene expressions of Bapt and Dbtnbt were significantly (p < 0.05) upregulated under sUV-B exposure, and the gene expressions of CoA, Ts, and Dbat were significantly (p < 0.05) downregulated. A correlation analysis showed that the 6-BA content had a significantly (p < 0.05) positive correlation with Dbat gene expression. The IAA content had a significantly (p < 0.05) positive correlation with the gene expression of Hmgr, CoA, Ts, and Dbtnbt. The ABA content had a significantly (p < 0.05) positive correlation with Bapt gene expression. Dbat gene expression had a significantly (p < 0.05) positive correlation with the 10-deacetylbaccatin content. Hmgr gene expression was positively correlated with the contents of baccatin III and cephalomannine. Bapt gene expression had a significantly (p < 0.01) positive correlation with the paclitaxel content. A factor analysis showed that the accumulation of paclitaxel content was promoted under T2, which was helpful in clarifying the accumulation of taxane compounds after sUV-B exposure.

EFEKTIVITAS AUKSIN DAN GIBERELIN TERHADAP UMUR BERBUNGA DAN PANEN TANAMAN KORO PEDANG (Cannavalia ensiformis)

The aim of this research was to determine the effect of the growth regulator substances auxin and gibberellin as chemical mutagens on flowering time and harvest time of jack bean. This research was carried out in the Greenhouse of the Faculty of Agriculture, Bachelorwiyata Tamansiswa University, Yogyakarta City. This research was carried out from August to December 2023. The research was carried out using the Completely Randomized Design (CRD) method. Consisting of 4 replications, each replication contained 3 treatments. So 12 experimental units were obtained, namely: P1 = IAA 2 ppm + GA 10 ppm, P2 = IAA 4 ppm + GA 10 ppm, P3 = IAA 6 ppm + GA 10 ppm. The collected data was analyzed using 5% ANOVA and further tested using 5% Duncan Multiple Range Test (DMRT). The influence of the growth regulators auxin and gibberellin as chemical mutagens showed varying results at concentrations of IAA 4 ppm and GA 10 ppm which affected the day of harvest. However, there was no difference in flowering age between all treatments.

Genome-Wide Identification and Expression Analysis of Bx Involved in Benzoxazinoids Biosynthesis Revealed the Roles of DIMBOA during Early Somatic Embryogenesis in Dimocarpus longan Lour.

Benzoxazinoids (BXs) are tryptophan-derived indole metabolites and play a role in various physiological processes, such as auxin metabolism. Auxin is essential in the process of somatic embryogenesis (SE) in plants. In this study, we used bioinformatics, transcriptome data, exogenous treatment experiments, and qPCR analysis to study the evolutionary pattern of Bx genes in green plants, the regulatory mechanism of DlBx genes during early SE, and the effect of 2,4-dihydroxy-7-methoxy-1,4-benzoxazine-3-one (DIMBOA) on the early SE in Dimocarpus longan Lour. The results showed that 27 putative DlBxs were identified in the longan genome; the Bx genes evolved independently in monocots and dicots, and the main way of gene duplication for the DlBx was tandem duplication (TD) and the DlBx were strongly constrained by purification selection during evolution. The transcriptome data indicated varying expression levels of DlBx during longan early SE, and most DlBxs responded to light, temperature, drought stress, and 2,4-dichlorophenoxyacetic acid (2,4-D) treatment; qRT-PCR results showed DlBx1, DlBx6g and DlBx6h were responsive to auxin, and treatment with 0.1mg/L DIMBOA for 9 days significantly upregulated the expression levels of DlBx1, DlBx3g, DlBx6c, DlBx6f, DlB6h, DlBx7d, DlBx8, and DlBx9b. The correlation analysis showed a significantly negative correlation between the expression level of DlBx1 and the endogenous IAA contents; DIMBOA significantly promoted the early SE and significantly changed the endogenous IAA content, and the IAA content increased significantly at the 9th day and decreased significantly at the 13th day. Therefore, the results suggested that DIMBOA indirectly promote the early SE by changing the endogenous IAA content via affecting the expression level of DlBx1 and hydrogen peroxide (H2O2) content in longan.

Restoration of the soil fertility under Cr(VI) and artificial drought condition by the utilization of plant growth-promoting Bacillus spp. SSAU2.

The study explores the potential of an indigenous halo-tolerant microbe identified as Bacillus spp. SSAU-2 in enhancing soil fertility and promoting plant growth for sustainable agricultural practices under the influence of multiple abiotic stresses such as Cr(VI), high salinity, and artificial drought condition. The study investigated various factors influencing IAA synthesis by SSAU-2, such as pH (5 to 11), salinity (10 to 50g/L), tryptophan concentration (0.5 to 1%), carbon (mannitol mand lactose), and nitrogen sources (peptone and tryptone). The highest IAA concentration was observed at pH 10 (1.695mg/ml) and pH 11 (0.782mg/ml). IAA synthesis was optimized at a salinity level of 30g/l, with lower and higher salinity levels resulting in decreased IAA concentrations. Notably, the presence of mannitol and lactose significantly augmented IAA synthesis, while glucose and sucrose had inhibitory effects. Furthermore, peptone and tryptone played a pivotal role in enhancing IAA synthesis, while ammonium chloride exerted an inhibitory influence. SSAU-2 showed a diverse array of capabilities, including the synthesis of gibberellins, extracellular polymeric substances, siderophores, and hydrogen cyanide along with nitrogen fixation and ammonia production. The microbe could efficiently tolerate 45% PEG-6000 concentration and effectively produce IAA in 15% PEG concentration. It could also tolerate high concentration of Cr(VI) and synthesize IAA even in 50ppm Cr(VI). The findings of this study provide valuable insights into harnessing the potential of indigenous microorganisms to promote plant growth, enhance soil fertility, and establish sustainable agricultural practices essential for restoring the health of ecosystems.

Exogenous dopamine mitigates the effects of salinity stress in tomato seedlings by alleviating the oxidative stress and regulating phytohormones

Salt stress is a worldwide major threat to agricultural production. The aim was to investigate the effects of exogenous dopamine (DA) treatments on physiological, morphological and biochemical characteristics of tomato seedlings under salinity stress. Salt stress was created using a 100 mM NaCl solution. Dopamine solutions (0, 50, 100 and 200 µM) were applied with 7-day intervals. Salt stress significantly suppressed plant growth and DA treatments alleviated the negative effects of salt stress on the growth of tomato seedlings. 100 µM DA treatment increased plant and root dry weights, plant stem diameter, plant height and, leaf area by 286.84%, 150.00%, 108.37%, 160.89%, and 158.28%, respectively, compared to the control. Under salinity LRWC, SPAD, chl-a, chl-b, and total chlorophyll contents decreased; membrane permeability (MP), H2O2, MDA, proline and sucrose contents, CAT, POD and SOD activities increased. Under salt stress, when 100 µM DA was applied, LRWC, SPAD, chl-a, chl-b, and total chlorophyll contents of plants increased by 13.64%, 18.62%, 43.08%, 64.90%, and 50.00%, while MP reduced by 21.08% compared to the control. When 200 µM DA was applied under salt stress, H2O2, MDA, proline and sucrose contents, and CAT, POD and SOD activities were reduced by 31.86%, 18.66%, 56.00%, 38.24%, 11.16%, 17.81% and 10.80%, respectively, compared to non-DA-treated plants. Exogenous application of DA increased IAA content, decreased ABA content and increased ratio of K+/Na+ and Ca2+/Na+ under salt stress as well. In conclusion, exogenous dopamine treatments effectively prevent cellular damage in tomato seedlings and improve plant tolerance to salt stress.

Potato (Solanum tuberosum L.) Planlet Acclimatization on Various Auxin Concentrations and Growing Media

The provision of quality potato seeds is a problem faced by farmers. Tissue culture propagation is an effort to increase the availability of quality seeds. The success of tissue culture is influenced by the ability to control environmental conditions, growth regulators, and growing media at the acclimatization stage. The research aims to determine the interaction between the use of auxin concentrations and the planting medium and to obtain the appropriate concentration of auxin and planting medium for potato acclimatization. The research used a split-plot design with 2 factors and 3 replications. The main plot is the auxin concentration consisting of 3 levels; 1 ppm, 2 ppm, and 3 ppm. Subplots are planting media consisting of 3 levels; husk charcoal:vermicompost, cocopeat:vermicompost, and husk charcoal:cocopeat:vermicompost. Data were analyzed using ANOVA and followed by DMRT at a 5% level. The results showed that there was an interaction between the treatment of 3 ppm IAA concentration and the planting medium of husk charcoal:cocopeat:vermicompost on the plant height parameter 4 WAP. The IAA concentration of 3 ppm was better than the concentration of 1 ppm in the parameter number of leaves 8 WAP. The growing media of husk charcoal:cocopeat:vermicompost was better than the growing medium of charcoal husk:vermicompost on the parameters of plant height 8 WAP, number of leaves 8 WAP, leaf length and leaf width 8 WAP.

Comparative metabolome profiling of two contrasting wheat cultivars in late-season water deficit

Abiotic stresses, including water deficit, cause myriad changes in plant metabolism. Metabolomics is a powerful tool for understanding plant resistance to such stresses. Therefore, this research was conducted to evaluate the effects of after anthesis water deficit (WD: from anthesis to maturity), i.e., maintaining moisture at field capacity (well-watered: WW) and 50% field capacity, on metabolome profiling (amino acids, hormones, nucleotides, soluble and insoluble sugars, sugar alcohols, and enzymes) in grains of two contrasting wheat cultivars grown in a greenhouse at Razi University as a factorial experiment. Based on the results, WD decreased grain yield (57%), 1000 grain weight (50%), and grain plant-1 (9%) in the sensitive cultivar (SC), while it had no significant effect on the tolerant cultivar (TC). In WW, the concentration of IAA, glucose, and fructose, as well as the activity of three invertase isoforms (vacuolic, cytosolic, and cell wall bound), were significantly higher at 10 days after anthesis compared to 17 and 31 days. In WD, these traits were significantly reduced in SC. ABA and sucrose concentration and sucrose synthase activity were significantly higher 17 days after anthesis than 10 days after anthesis. WD. In contrast to ABA, sucrose concentration decreased significantly in growing grains of SC in WD. The ATP/ADP ratio, inositol, glycerol and erythritol contents of TC were significantly higher in WD than in SC. Among the different amino acids, asparagine, glutamine and lysine were the highest, while ACC and methionine were the lowest. Contrary to SC, WD significantly increased the sum of the amino acid concentrations determined in the grains of TC, i.e. asparagine (22%), aspartic acid (48%), glycine (48%), ACC (79%) and valine (133%). These findings could help us to understand the resistance mechanisms to late season water deficit, which can increase sink strength (sink size and sink activity) and achieve higher yield quantity and quality in wheat.

Establishment of Effective Callus Induction in the Economically Important Brown Seaweed Ecklonia cava

The edible brown seaweed, Ecklonia cava, is highly valued for its bioactive compounds, and is widely used in food supplements and functional foods. The increasing demand for this seaweed in the food industry emphasizes the necessity for sustainable cultivation practices. This study focused on inducing callus in the meristem and stipe of E. cava using different culture media: Provasoli’s enriched seawater medium (PESI), enriched artificial seawater medium (ESAW), artificial enriched seawater medium (ASP2), or Von Stosch’s enriched seawater medium (VS). Various abiotic stress factors (photoperiod, agar concentration, and temperature), growth regulators, carbon sources, polyamines, and plasma treatments were explored for their impact on callus induction. Both stipe and meristem explants developed callus within three to six weeks across all media except ASP2. Callus development was favored at temperatures between 8 to 13 °C and in the absence of light. Stipe explants showed a higher callus induction rate (up to 65.59 ± 6.24%) compared to meristem (up to 57.53 ± 8.32%). Meristem explants showed optimal callus induction in PESI medium with a low concentration of indole-3-acetic acid (IAA; 40.93 ± 8.65%). However, higher concentrations of IAA and 1-naphthaleneacetic acid (NAA) reduced meristem callus induction. Stipe showed high induced-callus (up to 50.37 ± 5.17%) in PESI medium with low concentrations of IAA, NAA, and 6-benzylaminopurine (BAP). Both stipe and meristem explants induced largest callus at 2% sucrose, but higher carbon source concentrations reduced callus induction. Spermine (Spm) at 1 µM resulted in high induced calluses; however, increasing Spm concentrations decreased callus induction. This tissue culture technique not only supports mass cultivation of E. cava, but also holds potential for extending to other seaweed species, contributing to the sustainability of seaweed stocks for the food industry.

Morphological, cytological, physiological, and molecular evidence to explain how underground fleshy roots expand in herbaceous peony (Paeonia lactiflora Pall.)

The fleshy roots of herbaceous peonies serve as vital storage organs and are the primary source material for Chinese herbal medicine. Moreover, in certain cultivars, these roots can be propagated by root cuttings. However, the specific mechanisms governing the expansion and development of fleshy roots in herbaceous peonies currently remain unclear. To elucidate patterns of changes during the enlargement and development of herbaceous peony fleshy roots, this study assessed fleshy roots in six growth and development periods (P1–P6). By integrating environmental monitoring data, morphological, cytological, physiological and biochemical, as well as molecular characteristics across these developmental periods were compared. Both precipitation and temperature influenced the development of fleshy roots. The fastest enlargement of fleshy roots occurred under the following growth conditions: daily average precipitation = 5.6 mm; monthly average air temperature = 25.6°C; monthly average soil temperature = 26.3°C. Phloem and xylem, produced by the activity of vascular cambium, are important components of fleshy roots. Secondary xylem thickness consistently increased across the six developmental periods, resulting in the radial expansion of fleshy roots. When average monthly air and soil temperatures were about 26°C, starch accumulated gradually in fleshy roots, and carbohydrates were mostly starch-based. However, when the average monthly air and soil temperatures decreased to about 11.0°C, soluble sugar content increased. Endogenous hormones such as IAA, ZR, GA3, MeJA, and ABA played regulatory roles throughout the development of fleshy roots, and their levels and dynamic equilibrium were correlated with expansion rate. Elevated IAA and ZR content, and stabilized IAA/ABA and MeJA/ABA ratios, favored fleshy root expansion. Trends in the expression of three genes that play key roles in the expansion of fleshy roots (PlEXLB3, PlAUX1 and PlWRKY13) were consistent with morphological and physiological data, but PlHXK1 and PlIPT3 also play important roles. These findings lay a foundation for studying, in greater depth, the regulatory mechanisms governing the enlargement of herbaceous peony fleshy roots, and offer practical advice pertaining to field cultivation and management practices of this ornamental plant.

Interspecific grafting promotes poplar growth and drought resistance via regulating phytohormone signaling and secondary metabolic pathways

Populus cathayana (C) grafted onto P. deltoides (D) (C/D) can promote growth better than self-grafting (C/C and D/D). However, the mechanisms underlying growth and resistance to drought stress are not clear. In this study, we performed physiological and RNA-seq analysis on the different grafted combinations. It was found that C/D plants exhibited higher growth, net photosynthetic rate, IAA content and intrinsic water use efficiency (WUEi) than C/C and D/D plants under both well-watered and drought-stressed conditions. However, most growth, photosynthetic indices, and IAA content were decreased less in C/D, whereas ABA content, WUEi and root characteristics (e.g., root length, volume, surface area and vitality) were increased more in C/D than in other grafting combinations under drought-stressed conditions. Transcriptomic analysis revealed that the number of differentially expressed genes (DEGs) in leaves of C/D vs C/C (control, 181; drought, 121) was much lower than that in the roots of C/D vs D/D (control, 1639; drought, 1706), indicating that the rootstocks were more responsive to drought resistance. KEGG and GO functional enrichment analysis showed that the enhanced growth and drought resistance of C/D were mainly related to DEGs involved in the pathways of ABA and IAA signaling, and secondary metabolite biosynthesis, especially the pathways for lignin and dopamine synthesis and metabolism. Therefore, our results further demonstrated the dominant role of rootstock in drought resistance, and enriched our knowledge on the mechanism of how interspecific grafting enhanced the growth and drought resistance in poplar.

An ARF gene mutation creates flint kernel architecture in dent maize

Dent and flint kernel architectures are important characteristics that affect the physical properties of maize kernels and their grain end uses. The genes controlling these traits are unknown, so it is difficult to combine the advantageous kernel traits of both. We found mutation of ARFTF17 in a dent genetic background reduces IAA content in the seed pericarp, creating a flint-like kernel phenotype. ARFTF17 is highly expressed in the pericarp and encodes a protein that interacts with and inhibits MYB40, a transcription factor with the dual functions of repressing PIN1 expression and transactivating genes for flavonoid biosynthesis. Enhanced flavonoid biosynthesis could reduce the metabolic flux responsible for auxin biosynthesis. The decreased IAA content of the dent pericarp appears to reduce cell division and expansion, creating a shorter, denser kernel. Introgression of the ARFTF17 mutation into dent inbreds and hybrids improved their kernel texture, integrity, and desiccation, without affecting yield.

Morphological, Anatomical, and Physiological Characteristics of Heteroblastic Acacia melanoxylon Grown under Weak Light.

Acacia melanoxylon is a fast-growing macrophanerophyte with strong adaptability whose leaf enables heteromorphic development. Light is one of the essential environmental factors that induces the development of the heteroblastic leaf of A. melanoxylon, but its mechanism is unclear. In this study, the seedlings of A. melanoxylon clones were treated with weak light (shading net with 40% of regular light transmittance) and normal light (control) conditions for 90 d and a follow-up observation. The results show that the seedlings' growth and biomass accumulation were inhibited under weak light. After 60 days of treatment, phyllodes were raised under the control condition while the remaining compound was raised under weak light. The balance of root, stem, and leaf biomass changed to 15:11:74 under weak light, while it was 40:15:45 under control conditions. After comparing the anatomical structures of the compound leaves and phyllode, they were shown to have their own strategies for staying hydrated, while phyllodes were more able to control water loss and adapt to intense light. The compound leaves exhibited elevated levels of K, Cu, Ca, and Mg, increased antioxidant enzyme activity and proline content, and higher concentrations of chlorophyll a, carotenoids, ABA, CTK, and GA. However, they displayed a relatively limited photosynthetic capacity. Phyllodes exhibited higher levels of Fe, cellulose, lignin, IAA content, and high photosynthetic capacity with a higher maximum net photosynthetic rate, light compensation point, dark respiration rate, and water use efficiency. The comparative analysis of compound leaves and phyllodes provides a basis for understanding the diverse survival strategies that heteroblastic plants employ to adapt to environmental changes.

Valorization of treated swine wastewater and generated biomass by microalgae: Their effects and salt tolerance mechanisms on wheat seedling growth

The extensive use of mineral fertilizers has a negative impact on the environment, whereas wastewater and microalgal biomass can provide crops with nutrients such as nitrogen, phosphorus, and potassium, and have the potential to be used as a source of fertilizers in circular agriculture. In this study, a step-by-step resource utilization study of algae-containing wastewater generated from microalgae treatment of swine wastewater was carried out. When wheat seedlings were cultivated in the effluent after microalgae separation, the root fresh weight, seedling fresh weight, and total seedling length were increased by 3.44%, 14.45%, and 13.64%, respectively, compared with that of the algae-containing wastewater, and there was no significant difference in seedling fresh weight, total seedling length, maximum quantum yields of PSII photochemistry (Fv/Fm), and performance index (PIABS) from that of the Hogland solution group, which has the potential to be an alternative liquid fertilizer. Under salt stress, microalgae extract increased the contents of GA3, IAA, ABA, and SA in wheat seedlings, antioxidant enzymes maintained high activity, and the PIABS value increased. Low-dose microalgae extract (1 mL/L) increased the root fresh weight, seedling fresh weight, longest seedling length, and total seedling length by 30.73%, 31.28%, 16.43%, and 28.85%, respectively. Algae extract can act as a plant biostimulant to regulate phytohormone levels to attenuate the damage of salt stress and promote growth.

Plant growth regulators mitigate oxidative damage to rice seedling roots by NaCl stress.

The aim of this experiment was to investigate the effects of exogenous sprays of 5-aminolevulinic acid (5-ALA) and 2-Diethylaminoethyl hexanoate (DTA-6) on the growth and salt tolerance of rice (Oryza sativa L.) seedlings. This study was conducted in a solar greenhouse at Guangdong Ocean University, where 'Huanghuazhan' was selected as the test material, and 40 mg/L 5-ALA and 30 mg/L DTA-6 were applied as foliar sprays at the three-leaf-one-heart stage of rice, followed by treatment with 0.3% NaCl (W/W) 24 h later. A total of six treatments were set up as follows: (1) CK: control, (2) A: 40 mg⋅ L-1 5-ALA, (3) D: 30 mg⋅ L-1 DTA-6, (4) S: 0.3% NaCl, (5) AS: 40 mg⋅ L-1 5-ALA + 0.3% NaCl, and (6) DS: 30 mg⋅ L-1 DTA-6+0.3% NaCl. Samples were taken at 1, 4, 7, 10, and 13 d after NaCl treatment to determine the morphology and physiological and biochemical indices of rice roots. The results showed that NaCl stress significantly inhibited rice growth; disrupted the antioxidant system; increased the rates of malondialdehyde, hydrogen peroxide, and superoxide anion production; and affected the content of related hormones. Malondialdehyde content, hydrogen peroxide content, and superoxide anion production rate significantly increased from 12.57% to 21.82%, 18.12% to 63.10%, and 7.17% to 56.20%, respectively, in the S treatment group compared to the CK group. Under salt stress, foliar sprays of both 5-ALA and DTA-6 increased antioxidant enzyme activities and osmoregulatory substance content; expanded non-enzymatic antioxidant AsA and GSH content; reduced reactive oxygen species (ROS) accumulation; lowered malondialdehyde content; increased endogenous hormones GA3, JA, IAA, SA, and ZR content; and lowered ABA content in the rice root system. The MDA, H2O2, and O2- contents were reduced from 35.64% to 56.92%, 22.30% to 53.47%, and 7.06% to 20.01%, respectively, in the AS treatment group compared with the S treatment group. In the DS treatment group, the MDA, H2O2, and O2- contents were reduced from 24.60% to 51.09%, 12.14% to 59.05%, and 12.70% to 45.20%. In summary, NaCl stress exerted an inhibitory effect on the rice root system, both foliar sprays of 5-ALA and DTA-6 alleviated damage from NaCl stress on the rice root system, and the effect of 5-ALA was better than that of DTA-6.

Direct Organogenesis of Citrus Cultivars from Shoot Tip Nodal Segments.

Citrus cultivar improvement via conventional breeding strategies is impeded by factors related to its reproductive biology. The orange is a hybrid between pomelo (Citrus maxima) and mandarin (Citrus reticulata). Among various orange cultivars, Valencia oranges have a bit of bitter tang mixed in with their sweetness, as Navel oranges are, the most widely cultivated citrus species, quite sweeter, and also don't contain any seeds. Tangelo mandarin orange cultivar is a hybrid of C. reticulata × C. maxima or × C. paradisi. The present study was undertaken to optimize the hormonal composition of the media with regard to plant growth regulators for in vitro propagation of sweet orange cultivars from nodal segment explants. The nodal segment explants were collected from three citrus cultivars, Washington Navel, Valencia and Tangelo. Murashige and Skoog (MS) medium supplemented with sucrose and different concentrations of growth regulators was used for shoot proliferation and root induction, and the optimum medium composition was assessed. The patent for Citrus Tissue Culture was obtained from the Office of Research Affairs, Haramaya University. The results indicate that the highest shoot response was recorded for Washington's navel with maximum shoot proliferation rate (99.75%), shoot number per explant (1.76), shoot length (10.70 cm), leaf number per explants (3.54) after three weeks of culture. In all experiments, no growth was observed for the basal MS medium. Phytohormone combinations of IAA (1.2 mg/L) and kinetin (2.0 mg/L) were found to be the best for shoot proliferation. Among the cultivars, there were significant differences for the highest rooting rate (81.255), root number (2.22), and root length (2.95 cm) variables for Washington Navel. The lowest rooting rate (48.45%), root number (1.47) and root length (2.26 cm) were observed for Valencia. The highest rooting rate (84.90%), root number per microshoot (2.22) and root length (3.05 cm) was on MS medium supplemented with 1.5 mg/L NAA. A comparison of different concentrations of IAA and NAA on root induction of microshoots from nodal segments of citrus cultivars demonstrated NAA was a more effective hormone than IAA.

Integrated transcriptomics and metabolomics analysis provide insights into the alleviation of waterlogging stress in maize by exogenous spermidine application

Waterlogging stress has been found to have adverse impacts on plant growth, subsequently reducing crop yields. Spermidine (Spd), a second messenger, positively affects the growth of plants under waterlogging stress. However, the molecular mechanisms of exogenous Spd application alleviating waterlogging stress remained unclear. In this study, we performed physiological analysis and multi-omics to underlying the effect of Spd application on waterlogging stress. Spd application increased genes expression level of light-harvesting complex (LHC) and photosynthesis-related and starch-related pathway, inhibited chlorophyll degradation and maintained higher photosynthetic rate, thus increased biomass accumulation under waterlogging stress. The activation of genes related trehalose and Spd biosynthesis would result in high accumulation of trehalose and endogenous Spd. Inhibiting 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (ACO,) expression contributed to reduced ethylene emission. All those changes increased maize resistance to waterlogging. After Spd sparying, auxin-related genes up-regulated and IAA content was increased, those favor cell elongation in maize and thus keep normal growth after Spd application under waterlogging stress. Most of genes involved in lipids were up-regulated and thus increased lipids content and protected cell membranes in maize after Spd application under waterlogging conditions. All those changes contributed to increasing the resistance to waterlogging stress. These findings broaden our understanding of the regulatory roles of Spd in alleviating waterlogging damage and will provide evidence for breeding waterlogging-tolerant maize varieties.