Soluble Starch Research Articles

Starch and sucrose metabolism plays an important role in the stem development in Medicago sativa

The forage quality of alfalfa (Medicago sativa) stems is greater than the leaves. Sucrose hydrolysis provides energy for stem development, with starch being enzymatically converted into sucrose to maintain energy homeostasis. To understand the physiological and molecular networks controlling stem development, morphological characteristics and transcriptome profiles in the stems of two alfalfa cultivars (Zhungeer and WL168) were investigated. Based on transcriptome data, we analysed starch and sugar contents, and enzyme activity related to starch-sugar interconversion. Zhungeer stems were shorter and sturdier than WL168, resulting in significantly higher mechanical strength. Transcriptome analysis showed that starch and sucrose metabolism were significant enriched in the differentially expressed genes of stems development in both cultivars. Genes encoding INV, bglX, HK, TPS and glgC downregulated with the development of stems, while the gene encoding was AMY upregulated. Weighted gene co-expression network analysis revealed that the gene encoding glgC was pivotal in determining the variations in starch and sucrose contents between the two cultivars. Soluble carbohydrate, sucrose, and starch content of WL168 were higher than Zhungeer. Enzyme activities related to sucrose synthesis and hydrolysis (INV, bglX, HK, TPS) showed a downward trend. The change trend of enzyme activity was consistent with gene expression. WL168 stems had higher carbohydrate content than Zhungeer, which accounted for more rapid growth and taller plants. WL168 formed hollow stems were formed during rapid growth, which may be related to the redistribution of carbohydrates in the pith tissue. These results indicated that starch and sucrose metabolism play important roles in the stem development in alfalfa.

Effect of protein from endosperm on the structure and gelatinization behavior of corn starch under radio frequency treatment

Thermal treatments affect the interactions between protein and starch that play an important role in the structure and properties of starch–based foods. This study investigated the effects of protein from endosperm on the structure and gelatinization behavior of corn starch under hot air (HA) assisted radio frequency (RF) treatment. As the temperature increased to 70 °C, the amylose content in dent and flint corn starch increased from 10.76% to 20.65% and 10.80% to 22.43%, respectively. Protein from endosperm increased the crystallinity, short–range ordered structure, and gelatinization temperatures, while inhibited the swelling and reduced the water solubility of starch. Meanwhile, protein hindered the formation of a dense network gel structure, which decreased the rheological properties and apparent viscosity of starch gels. The finding will enrich the theory knowledge of effects of HA-RF treatment on the starch–protein interaction, and have important implications for the development of carbohydrate–restricted diets and desirable function foods.

Effect of atmospheric pressure plasma jet on the structure and physicochemical properties of wheat starch

The effect of atmospheric pressure plasma jet (APPJ) with different discharge power (0, 400, 600, and 800 W) on the structure and physicochemical properties of wheat starch were evaluated in this study. After APPJ treatments, significant declines in peak viscosity, breakdown viscosity, and final viscosity of wheat starch pasting parameters were observed with increase of plasma treatment power. Being treated with discharge power of 800 W, the PV and BD value of wheat starch paste significantly dropped to 2,578 and 331 cP, respectively. Apparently, APPJ could raise the solubility of wheat starch, while reduce the swelling capacity, and also lower the G′ and G″ value of wheat starch gel. Roughness and apparent scratch was observed on the surface of the treated wheat starch granules. Although APPJ treatment did not alter wheat starch’s crystallization type, it abated the relative crystallinity. APPJ treatment might be useful in producing modified wheat starch with lower viscosity and higher solubility.

Facilitation drives tree seedling survival at alpine treelines

Abstract Alpine treelines are considered ecological monitors recording the impacts of climate change on trees and forests. To date, most treeline research has focused on how climate change drives treeline dynamics. However, little is known about how biotic interactions mediate treeline shifts, particularly in the case of tree recruitment, a bottleneck of treeline dynamics. We hypothesized that interspecific and intraspecific facilitation determined the establishment and survival of tree seedlings at alpine treelines. To test this hypothesis, 630 Abies georgei var. smithii seedlings with different ages (4–6, 7–9, and 10–15 years old) were transplanted into three growth habitats (canopy-in, canopy-out, and meadow) across the alpine treeline ecotone (4300–4500 m) in the Sygera Mountains, on the southeastern Qinghai-Tibetan Plateau. Microclimate, height growth, mortality rates, and leaf functional traits of transplanted seedlings were measured over three years. We found that the variations in leaf functional traits were driven by microclimate. After the transplantation, the leaf concentrations of soluble sugars and starch and C:P ratio increased, whereas leaf size decreased. The resource use of seedlings gradually shifted to a more conservative strategy as indicated by changes in non-structural carbohydrates and nutrient concentrations. Radiation, temperature, and moisture conditions, mediated by plants interactions, influenced seedling mortality and annual growth by affecting leaf morphological traits. Our findings illustrate how facilitation plays a crucial role in altering solar radiation and leaf trait functioning, determining seedling survival and growth at alpine treelines. We provide new insights into the underlying mechanisms for tree establishment and alpine treeline shifts in response to climate change.

Creation of Organic/Inorganic Hybrids in Two‐Dimensional Organized Films Using Natural Materials and Control of Their Morphology

AbstractStarch, an insoluble natural polymer, can be spread into a Langmuir monolayer on the surface of water as amylodextrin by solubilization, where it forms a spherical single‐particle layer at the air–water interface. In this study, we fabricated a two‐dimensional mixed monolayer from soluble starch and organo‐modified montmorillonite and attempted to control its morphology by varying the mixing ratio. The behavior of the organo‐modified montmorillonite was dependent on the spreading solvent and miniaturization was possible using a suitable solvent for spreading insoluble starch. Although both materials formed phase‐separated systems, nearly homogeneous particle layers were formed in some cases because of clay miniaturization. However, X‐ray photoelectron spectroscopy showed that the clay components remained intact and a rectangular morphology derived from aluminosilicate was observed in the mixed film with a high clay ratio. Functionalization as a mixed film clearly demonstrated the hydrophilic properties imparted by the starch particles and the selective adsorption of biomolecules on the clay surface.

Functional Characterization of the MeSSIII-1 Gene and Its Promoter from Cassava.

Soluble starch synthases (SSs) play important roles in the synthesis of cassava starch. However, the expression characteristics of the cassava SSs genes have not been elucidated. In this study, the MeSSIII-1 gene and its promoter, from SC8 cassava cultivars, were respectively isolated by PCR amplification. MeSSIII-1 protein was localized to the chloroplasts. qRT-PCR analysis revealed that the MeSSIII-1 gene was expressed in almost all tissues tested, and the expression in mature leaves was 18.9 times more than that in tuber roots. MeSSIII-1 expression was induced by methyljasmonate (MeJA), abscisic acid (ABA), and ethylene (ET) hormones in cassava. MeSSIII-1 expression patterns were further confirmed in proMeSSIII-1 transgenic cassava. The promoter deletion analysis showed that the -264 bp to -1 bp MeSSIII-1 promoter has basal activity. The range from -1228 bp to -987 bp and -488 bp to -264 bp significantly enhance promoter activity. The regions from -987 bp to -747 bp and -747 bp to -488 bp have repressive activity. These findings will provide an important reference for research on the potential function and transcriptional regulation mechanisms of the MeSSIII-1 gene and for further in-depth exploration of the regulatory network of its internal functional elements.

Effect of electron beam irradiation pretreatment and different fatty acid types on the formation, structural characteristics and functional properties of starch-lipid complexes

The effects of different electron beam irradiation doses (2, 4, 8 KGy) and various types of fatty acids (lauric acid, stearic acid, and oleic acid) on the formation, structure, physicochemical properties, and digestibility of starch-lipid complex were investigated. The complexing index of the complexes was higher than 85 %, indicating that the three fatty acids could easily form complexes with starch. With the increase of electron beam irradiation dose, the complexing index increased first and then decreased. The highest complexing index was lauric acid (97.12 %), stearic acid (96.80 %), and oleic acid (97.51 %) at 2 KGy radiation dose, respectively. Moreover, the microstructure, crystal structure, thermal stability, rheological properties, and starch solubility were analyzed. In vitro digestibility tests showed that adding fatty acids could reduce the content of hydrolyzed starch, among which the resistant starch content of the starch-oleic acid complex was the highest (54.26 %). The lower dose of electron beam irradiation could decrease the digestibility of starch and increase the content of resistant starch.

Biological characterization of emerging fungal pathogen Colletotrichum associated with mango (Mangifera indica L.) post-harvest anthracnose from Vietnam.

Post-harvest anthracnose (PHA) of mango is a devastating disease, which results in huge loss to mango producers and importers. Various species of PHA, diverse pathogenicity, and different resistance towards fungicides make it essential to evaluate the pathogen taxonomic status and biological characterization. Two strains DM-1 and DM-2 isolated from the fruit of DaQing mango from Vietnam were identified as Colletotrichum fructicola and C. asianum respectively, based on the morphological features, along with the phylogenetic tree of ITS and ApMat combined sequences. The growth status of different Colletotrichum strains under different conditions was analyzed to reveal the biological characteristics. The optimum growth temperature of DM-1 and DM-2 was 28°C and mycelia grew rapidly in the dark. Both strains could grow in media with pH 4-11, while the optimum pH value was 6. Maltose and soluble starch were the most suitable carbon source for DM-1 and DM-2 respectively, and the peptone was the most suitable nitrogen source for both strains. The lethal temperatures were recorded as 55°C 5min for DM-1, and 50°C 10min for DM-2. To the best of our knowledge, it is the first study reporting the identification of the pathogens: C. fructicola and C. asianum responsible for postharvest fruit anthracnose of mango in Vietnam.

New gas sensitive films containing anthocyanin/curcumin for real-time monitoring of strawberries quality

Gas sensitive films (GSFs) of polyvinyl alcohol (PA), soluble starch (SS), and polyethylene glycol bis (3-aminopropyl) ether (PGE) containing blueberry anthocyanin (BA), curcumin (CU), and anthocyanin/curcumin complexes were created to monitor the quality changes of strawberries during storage (room temperature, 24 ± 2 °C). Using headspace-gas chromatography-mass spectrometry (HS-GC-MS), the volatile aroma gases released during storage of strawberries were analyzed. Results showed that the release of aldehydes was more closely associated to the quality of the strawberries. The BA, CU and BA/CU complexes (mass ratio: 1:2 and 2:1) were well dispersed in GSFs and improved the films' hydrophilicity, however, there was no effect on the water vapor permeability. The four GSFs were employed to monitor strawberry quality changes over the course of storage. The results showed that the changes in color of the four GSFs had a strong correlation with the quality of strawberries, which could be classified as fresh, sub-fresh and spoiled.

Properties of Potato Resistant Starch and Its Effect on the Growth of Probiotics

This study uses potato starch as raw material to prepare potato resistant starch (PRS3) using a pressure heating dual enzyme method and purifies it. The physicochemical indicators such as swelling power, solubility, freeze-thaw stability, transparency, oil absorption, milk absorption, and water holding capacity of purified PRS3 are measured. The growth and proliferation of probiotics (Lactobacillus acidophilus, Lactobacillus bulgaricus, Bifidobacterium, Streptococcus thermophilus, and Lactobacillus paracasei) under different carbon source concentrations of PRS3 medium, soluble starch medium, and glucose medium, as well as their effects on the growth process are studied. The authors also discusses the effects of glucose medium and PRS3 medium on salt and acid tolerance of probiotics. The results show that the freeze-thaw stability, solubility, and milk absorption capacity of PRS3 are stronger than those of original potato starch, but its oil absorption, water holding capacity, swelling capacity, and transparency are weaker than those of original potato starch. When the carbon source concentration is 2.0%, the proliferative effect of PRS3 on five bacteria is in descending order: Lactobacillus acidophilus, Lactobacillus bulgaricus, Bifidobacterium, Streptococcus thermophilus, and Lactobacillus paracasei. The ability of PRS3 medium to promote the proliferation of probiotics is stronger than that of glucose medium and soluble starch medium. It has a protective effect on probiotics in low pH environments and can improve their resistance to bile salts.

Characterization and Drug Release Properties of Curcumin Loaded Native and Nano‐Sized Starches of Pigeon Pea (Cajanus cajan) and Bambara Nut (Vigna subterranean)

AbstractStarches from underutilized sources such as Bambara nut (BAM) and pigeon pea (PP) can serve as new sources of starch. Starch nanoparticles (SNP) of BAM (BAMnp) and PP (PPnp) are prepared by nanoprecipitation. The physicochemical and pasting properties of the native and SNP are evaluated. The scanning electron microscopy, fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), drug loading, and release studies of curcumin‐loaded starches and SNP are carried out. The flow, swelling, and solubility of the native starches improve with nanoparticle fabrication. Setback viscosities of the starches are in the order PPnp < BAMnp < PP < BAM. The integrity of the starch granules is maintained after modification. The FTIR of loaded starches shows no interaction between the entities. Reduction in crystallinity of the SNP is observed in the XRD diffractogram. The drug loading efficiency of BAM, PP, BAMnp, and PPnp are 48.55 ± 0.11, 49.00 ± 0.11, 55.44 ± 0.40, and 54.72 ± 0.11, respectively. The drug release is improved when curcumin is loaded on the SNP. The release after 6 h is 33%, 25%, and 2% for BAMnp, PPnp, and pure curcumin, respectively. The properties of the SNP showed that they are potential candidates for the delivery of curcumin, a poorly water soluble drug.

Iodine/soluble starch cryogel: An iodine-based antiseptic with instant water-solubility, improved stability, and potent bactericidal activity

Iodine (I2) as a broad-spectrum antiseptic has been widely used for treating bacterial infections. However, I2 has low water-solubility and sublimes under ambient conditions, which limits its practical antibacterial applications. The highly specific and sensitive reaction between I2 and starch discovered 200 years ago has been extensively applied in analytical chemistry, but the antibacterial activity of the I2 − starch complex is rarely investigated. Herein, we develop a novel type of iodine-based antiseptics, iodine−soluble starch (I2-SS) cryogel, which can dissolve in water instantly and almost completely kill bacteria in 10 min at 2 μg/mL of I2. Although KI3 and the commercially available povidone‑iodine (I2-PVP) solutions show similar antibacterial efficacy, the high affinity of I2 to SS largely enhances the shelf stability of the I2-SS solution with ~75 % I2 left after one-week storage at room temperature. In sharp contrast, ~8 % and ~ 3 % I2 are detected in KI3 and I2-PVP solutions, respectively. Mechanistic study reveals that the potent antibacterial effect of I2-SS originates from its attack on multiple bacterial targets. The outstanding antibacterial activity, capability of accelerating wound healing, and good biocompatibility of I2-SS are verified through further in vivo experiments. This work may promote the development of next-generation iodine-based antiseptics for clinical use.

Enzyme production by the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae and their application in the control of nematodes (Haemonchus spp. and Meloidogyne incognita) in vitro

Brazil is affected by the infection of gastrointestinal nematodes (Haemonchus spp.) because it causes subclinical diseases in small ruminants that directly affect weight and milk production and, in turn, generate a health risk for the animals. In the same way root-knot nematodes (Meloidogyne incognita) is a serious disease, which parasitize the roots of tomato plants causing damage such as poor nutrient absorption leading to significant yield losses. In order to minimize the economic impact of these nematodes, it is important to establish new control strategies. Beauveria bassiana and Metarhizium anisopliae are two main mycoinsecticides used to control many orders of insects, such as Lepidoptera and Hemiptera. These fungi have the ability to produce extracellular enzymes, which play an important role to control in the pest infection process. The aim of this study was to evaluate the production of proteases and chitinases by the entomopathogenic fungi B. bassiana and M. anisopliae on different solid and liquid culture media and their application in vitro to the control of Haemonchus spp and Meloidogyne incognita. To achieve this goal, enzymes were produced under solid and liquid fermentation conditions to determine the highest chitinolytic and proteolytic activity of commercial two strain of B. bassiana (IBCB 66 and ESALQ PL63) and M. anisopliae (IBCB 425 and ESALQ E9) in liquid media: SDY broth, YPG culture medium, synthetic, and soluble starch with yeast extract. The solid media tested were: rice supplemented with whey and chrysalis flour mixed with rice. In addition, the nematicidal action of their extracts (containing concentrated enzymes and without fungal cells) was measured. The results showed that the best culture medium (p< 0.01) for protease was solid serum rice medium, with a value for M. anisopliae IBCB 425 of 52 U/mg, and for B. bassiana ESALQ PL63 the value was 36 U/mg, compared to all the tested media. On the other hand, for chitinase of M. anisopliae strain IBCB 425, the activity value was close to 0.60 U/mg. In contrast, for B. bassiana isolate ESALQ PL63, SDY medium was the best inducer for chitinase production, with a value of 0.90 U/mg. Regarding the nematicidal activity of the crude extracts, the reduction percentages were 58% for ESALQ PL63 and 100% for IBCB 425 in the case of animal parasites. For plant parasites, the reduction percentages were 19% for ESALQ PL63 and 71% for IBCB 425. Thus, the use of enzyme-rich crude extracts presents promising control options for pest control.

Identification the Pathogen Cause a New Apple Leaf Blight in China and Determination the Controlling Efficacy for Five Botanical Fungicides.

Alternaria leaf blight has recently been described as an emerging fungal disease of apple trees which is causing the significant damage in the apple-growing areas of Tianshui and Jingning, Gansu, China. In the present study, the pathogen species involved in apple leaf blight and its biological characteristics were identified, and the inhibitory activity of different botanical fungicides against the pathogen was evaluated in vitro. Four strains were isolated from the symptomatic areas of necrotic apple leaves, and initially healthy leaves showed similar symptoms to those observed in orchards after inoculation with the ABL2 isolate. The ABL2 isolate was identified as Alternaria tenuissima based on the morphological characteristics of its colonies, conidiophores, and conidia, and this was also confirmed by multi-gene sequence (ITS, OPA10-2, Alta-1, and endoPG) analysis and phylogenic analysis. The optimum temperature, pH, carbon source, and nitrogen source for the growth of A. tenuissima mycelia were 28 °C, 6-7, soluble starch, and soy flour, respectively. In addition, the botanical fungicide eugenol exhibited the highest inhibitory effect on the mycelial growth and conidia germination of A. tenuissima, and the median effective concentration (EC50) values were 0.826 and 0.755 μg/mL, respectively. The protective and curative efficacy of eugenol were 86.85% and 76.94% after inoculation in detached apple leaves at a concentration of 4 μg/mL. Our research provides new insights into the control of apple leaf blight disease by applying botanical fungicides.

Selective adsorption of soluble starch on the cassiterite surface for effective flotation separation of scheelite from cassiterite

Tungsten and tin are important strategic resources. Scheelite and cassiterite have similar physical and chemical properties and face the challenge of flotation separation. This study proposes soluble starch (SS) as an effective depressant for the flotation separation of scheelite from cassiterite. The depression mechanism of SS was investigated using micro-flotation, zeta potential, total organic carbon, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectroscopy. SS exhibited a good selective depressive effect on cassiterite and was able to efficiently separate scheelite from cassiterite. The results of artificial mixed mineral test showed that the recovery of scheelite and cassiterite were 79.35 % and 9.48 %, respectively and the grade were 70.15 % and 8.11 %, respectively at pH 10. The macromolecular organic depressant SS has abundant hydrophilic groups, such as hydroxyl groups, which cause the material to stably adsorb on Sn active sites on the surface of cassiterite and hinder the adsorption of the collector sodium oleate (NaOL, C17H33CO2Na). The selective adsorption of SS on the surface of cassiterite results in efficient flotation separation of the two minerals.

Tailoring the physicochemical properties of starch: impact of integrated ultrasonic and ethanol pretreatment on the oil uptake of infrared fried ginkgo seeds.

The structural changes of starch would have a more crucial impact on oil absorption and quality changes in starch-rich fruits and vegetables during frying process with enhanced heat transfer (such as infrared frying). In the present study, the influence of integrated ultrasonic and ethanol (US + ethanol) pretreatment on oil uptake in infrared fried (IF) ginkgo seeds was evaluated regarding modifications in the physicochemical properties of starch. The pretreatment was performed with ultrasonic (40 kHz, 300 W) and ethanol osmotic (95%, v/v) treatment individually or integrated for 40 min. The mass transfer in the pretreatment was facilitated by combined ultrasound and ethanol. The swelling power, solubility, and gelatinization degree of starch was significantly increased. Low-frequency-NMR curves and images revealed that the bound water fraction in ginkgo seeds was increased and the water distribution was homogenized. The results of Fourier transform-infrared spectrum and differential scanning calorimeter revealed that the crystalline regions of starch were reduced and the thermal enthalpy was decreased after US + ethanol pretreatment. The total, surface and structural oil content in IF ginkgo seeds with US + ethanol pretreatment was reduced by 29.10%, 34.52% and 29.73%, respectively. The US + ethanol pretreatment led to a thinner crust layer with increased porosity and smaller-sized pores in the IF ginkgo seeds as observed by stereo microscopy and scanning electron microscopy. The changes in structural and physicochemical properties of starch by combined ultrasound and ethanol affect the crust ratio and pore characteristics in fried high-starch fruits and vegetables, thereby reducing oil absorption. © 2024 Society of Chemical Industry.

Ozonation effects on structural and functional characteristics of starch

Ozone oxidation leads to the substitution of hydroxyl groups in the starch molecules with carboxyl or carbonyl groups, thereby increasing the degree of substitution. A thorough examination of how ozone treatment impacts the composition of various cereal crops, including wheat, rice, and maize, is provided. This review explores the repercussions of ozone on starch rheology, germination ability, and storage stability.The present review also explores the textural qualities of food products such as bread, noodles, and cakes prepared with ozonized grains. Ozone treatment is found to significantly reduce swelling capacity and solubility of natural starch, and differential scanning calorimetry reveals that the gelatinization and retrogradation temperature profiles of oxidized starches remain comparable to those of native starch. The evidence that ozone treatment holds substantial promise for enhancing the functionality of starch in various applications while simultaneously upholding the essential standards of food safety has also been explained in detail. The findings synthesized in this review shed light on the intricate interplay between ozone and starch, providing valuable insights for both the scientific community and the food industry.

Particle Size of Calcium Hydroxide Prepared by Wet Digestion: Influencing Factors and Mechanism

AbstractThe wet dissolution process of lime is an effective approach for synthesizing calcium hydroxide. Process parameters and additives exert influence on the product particle. Among the process parameters, lime particle size, reaction temperature, and time have a significant impact on product particle size, followed by liquid‐solid ratio and stirring speed. The experiment proved that reaction time affects product particle size by affecting the crystal growth, while other process parameters affect the particle size by affecting the ion diffusion behavior. In terms of inorganic additives, Ca(OH)2 has minimal effect on product particle size; however, NaOH and CaCl2 can significantly enhance it with a greater dose leading to a larger increase. The experiment proved that Ca(OH)2, NaOH, and CaCl2 influence particle size through their impact on ion diffusion behavior. Regarding organic additives, soluble starch exhibits the greatest effect on product size followed by triethanolamine and polyvinylpyrrolidone K30. The experiment proved that soluble starch, triethanolamine, and polyvinylpyrrolidone K30 affect product particle size by influencing its crystallization position. Finally, an ultrafine slurry of calcium hydroxide was prepared using the lime wet digestion method based on the aforementioned research, with particle size distribution characterized by D10, D50, and D90 values of 0.303, 1.750, and 4.534 µm respectively.

Green emulsion liquid membrane for desalination: Prototype and techno-economic evaluation

Existence on Earth is presently in jeopardy due to a lack of sufficient water. Liquid membranes (LMs) have acquired widespread recognition as a viable separation technique. The current research seeks to advance desalination significantly using edible oils as a green emulsion liquid membrane (GELM) technique. The initial concentration (Ci), the treatment ratio (TR), which is the ratio of the emulsion to the doner phase (DP), the type of LM, the amount of sequestering agent (SA), and the power of ultrasonication (US) were all investigated as possible impacts on the desalination process. The experiments led to the following conclusions: the presence of SA in the receptor phase (RP) is essential for salt sequestration; the US yields a stable emulsion with a high salt extraction percentage. This study demonstrated the simplicity and efficacy of desalinating simulated seawater using the GELM approach with edible oils, which resulted in 99.9 % desalination without a mobile carrier or an ordinary emulsifier. Corn oil, when used as LM, has enhanced extraction capabilities. The preferred TR was 1:10, the preferred percentage of soluble starch (SS) as an emulsifier and SA was 1 %, the optimum Ci was 25 g l−1, and the optimum US power was 350 W. A techno-economic assessment for desalination by GELM reveals that the production cost is $1.02/m3.

Physiological responses to drought stress of three pine species and comparative transcriptome analysis of Pinus yunnanensis var. pygmaea

Drought stress can significantly affect plant growth, development, and yield. Fewer comparative studies have been conducted between different species of pines, particularly involving Pinus yunnanensis var. pygmaea (P. pygmaea). In this study, the physiological indices, photosynthetic pigment and related antioxidant enzyme changes in needles from P. pygmaea, P. elliottii and P. massoniana under drought at 0, 7, 14, 21, 28 and 35 d, as well as 7 days after rehydration, were measured. The PacBio single-molecule real-time (SMRT) and Illumina RNA sequencing were used to uncover the gene expression differences in P. pygmaea under drought and rehydration conditions. The results showed that the total antioxidant capacity (TAOC) of P. pygmaea was significantly higher than P. massoniana and P. elliottii. TAOC showed a continuous increase trend across all species. Soluble sugar (SS), starch content and non-structural carbohydrate (NSC) of all three pines displayed a "W" pattern, declining initially, increasing, and then decreasing again. P. pygmaea exhibits stronger drought tolerance and greater recovery ability under prolonged drought conditions. Through the PacBio SMRT-seq, a total of 50,979 high-quality transcripts were generated, and 6,521 SSR and 5,561 long non-coding RNAs (LncRNAs) were identified. A total of 2310, 1849, 5271, 5947, 7710, and 6854 differentially expressed genes (DEGs) were identified compared to the control (Pp0D) in six pair-wise comparisons of treatment versus control. bHLH, NAC, ERF, MYB_related, C3H transcription factors (TFs) play an important role in drought tolerance of P. pygmaea. KEGG enrichment analysis and Gene set enrichment analysis (GSEA) analysis showed that P. pygmaea may respond to drought by enhancing metabolic processes such as ABA signaling pathway, alpha-linolenic acid. Weighted gene co-expression network analysis (WGCNA) revealed GST, CAT, LEC14B, SEC23 were associated with antioxidant enzyme activity and TAOC. This study provides a basis for further research on drought tolerance differences among coniferous species.