Accumulation Of Soluble Sugars Research Articles

Potassium is a potential toxicant for Arabidopsis thaliana under saline conditions

AbstractBackground and aims: Most physiological and biochemical studies on salt stress are NaCl‐based. However, other ions (e.g., K+, Ca2+, Mg2+, and ) also contribute to salt stress in special circumstances. In this study, salt stress induced by various salts was investigated for a better understanding of salinity.Methods: Arabidopsis thaliana plants were stepwise acclimated to five iso‐osmotic salts as follows: NaCl, KCl, Na2SO4, K2SO4, and CaCl2.Results and Conclusions: Exposure to KCl and K2SO4 led to more severe toxicity symptoms, smaller biomass, and lower level of chlorophyll than exposure to NaCl and Na2SO4, indicating that Arabidopsis plants are more sensitive to potassium salts. The strongly reduced growth was negatively correlated with the accumulation of soluble sugars observed in KCl‐ and K2SO4‐treated plants, suggesting a blockage in the utilization of sugars for growth. We found that exposure to KCl and K2SO4 suppressed or even blocked sucrose degradation, thus leading to strong accumulation of sucrose in shoots, which then probably inhibited photosynthesis via feedback inhibition. Moreover, K+ was more accumulated in shoots than Na+ after corresponding potassium or sodium salt treatments, thus resulting in decreased Ca2+ and Mg2+ concentrations in response to KCl and K2SO4. However, K2SO4 caused more severe toxicity symptoms than iso‐osmotic KCl, even when the K+ level was lower in K2SO4‐treated plants. We found that Na2SO4 and K2SO4 induced strong accumulation of tricarboxylic acid intermediates, especially fumarate and succinate which might induce oxidative stress. Thus, the severe toxicity symptoms found in K2SO4‐treated plants were also attributed to in addition to the massive accumulation of K+.

Cold acclimation and freezing tolerance in three Eucalyptus species: A metabolomic and proteomic approach

The ability of plants to cope with frost events relies on the physiological and molecular responses triggered by cold temperatures. This process, named acclimation, involves reprogramming gene expression in order to adjust metabolism. Planted Eucalyptus species are highly productive but most of them are frost sensitive. However, acclimation process varies among species and environmental conditions, promoting more or less frost damage in young plantations of frost-prone areas. To identify metabolites and proteins responsible for these differences, two acclimation regimes were imposed to seedling of Eucalyptus grandis Hill ex Maiden (Eg), Eucalyptus dunnii Maiden (Ed) and Eucalyptus benthamii Maiden Cambage (Eb), and leaves submitted to biochemical and molecular analyses. Further, seedlings were used for simulated frosts in order to test the acclimation status effect on frost tolerance. Eb showed higher frost tolerance than Ed and Eg under control and acclimation scenarios, possibly due to its higher accumulation of phenolics, anthocyanins and soluble sugars as well as lower levels of photosynthetic pigments and related proteins. Also, a rise in frost tolerance and in osmoprotectants and antioxidants was observed for all the species due to cold acclimation treatment. Interestingly, metabolic profiles differed among species, suggesting different mechanisms to endure frosts and, probably, different requirements for cold acclimation. Shotgun proteomics reinforced differences and commonalities and supported metabolome observations. An in depth understanding of these responses could help to safeguard planted forests productivity through breeding of tolerant genetic material.

Role of Glycine max in improving drought tolerance in Zanthoxylum bungeanum.

Intercropping may improve community stability and yield under climate change. Here, we set up a field experiment to evaluate the advantages of cultivating Z anthoxylum bungeanum with Capsicum annum, and Z. bungeanum with Glycine max as intercrops, compared with cultivating Z. bungeanum in monoculture. Effects of extreme drought stress conditions on morphological, physiological, and biochemical traits of the three crop species cultivated in the three contrasting planting systems were compared. Results showed that extreme drought conditions induced negative impacts on Z. bungeanum grown in monoculture, due to reduced growth and metabolic impairment. However, limited stomatal conductance, reduced transpiration rate (Tr), and increased water use efficiency, carotenoid content, catalase activity, and accumulation of soluble sugars in Z. bungeanum indicated its adaptive strategies for tolerance of extreme drought stress conditions. Compared with cultivation in monoculture, intercropping with C. annum had positive effects on Z. bungeanum under extreme drought stress conditions, as a result of improved crown diameter, leaf relative water content (LRWC), net photosynthetic rate, and proline content, while intercropping with G. max under extreme drought stress conditions increased net CO2 assimilation rates, LRWC, Tr, and superoxide dismutase (SOD) activity. In conclusion, Z. bungeanum has an effective defense mechanism for extreme drought stress tolerance. Intercropping with G. max enhanced this tolerance potential primarily through its physio-biochemical adjustments, rather than as a result of nitrogen fixation by G. max.

Model-assisted comparison of sugar accumulation patterns in ten fleshy fruits highlights differences between herbaceous and woody species.

Sugar concentration is a key determinant of fruit quality. Soluble sugars and starch concentrations in fruits vary greatly from one species to another. The aim of this study was to investigate similarities and differences in sugar accumulation strategies across ten contrasting fruit species using a modelling approach. We developed a coarse-grained model of primary metabolism based on the description of the main metabolic and hydraulic processes (synthesis of compounds other than sugar and starch, synthesis and hydrolysis of starch, and water dilution) involved in the accumulation of soluble sugars during fruit development. Statistical analyses based on metabolic rates separated the species into six groups according to the rate of synthesis of compounds other than sugar and starch. Herbaceous species (cucumber, tomato, eggplant, pepper and strawberry) were characterized by a higher synthesis rate than woody species (apple, nectarine, clementine, grape and kiwifruit). Inspection of the dynamics of the processes involved in sugar accumulation revealed that net sugar importation, metabolism and dilution processes were remarkably synchronous in most herbaceous plants, whereas in kiwifruit, apple and nectarine, processes related to starch metabolism were temporally separated from other processes. Strawberry, clementine and grape showed a distinct dynamic compared with all other species. Overall, these results provide fresh insights into species-specific regulatory strategies and into the role of starch metabolism in the accumulation of soluble sugars in fleshy fruits. In particular, inter-specific differences in development period shape the co-ordination of metabolic processes and affect priorities for carbon allocation across species. The six metabolic groups identified by our analysis do not show a clear separation into climacteric and non-climacteric species, possibly suggesting that the metabolic processes related to sugar concentration are not greatly affected by ethylene-associated events.

Do halophytes and glycophytes differ in their interactions with arbuscular mycorrhizal fungi under salt stress? A meta-analysis

BackgroundHalophytes are better than glycophytes at employing mechanisms to avoid salt injury, but both types of plants can undergo damage due to high soil salinity. Arbuscular mycorrhizal fungi (AMF) can mitigate the damage from salt stress in both halophytes and glycophytes by enhancing salt tolerance and improving energy efficiency. However, variations in mycorrhizal symbiotic efficiency between halophytes and glycophytes were still poorly understood. Therefore, we evaluated the magnitude of AMF effects on plant growth and determined the mechanisms that regulate the growth response of halophytes and glycophytes by performing a meta-analysis of 916 studies (from 182 publications).ResultsArbuscular mycorrhizal fungi significantly enhance biomass accumulation, osmolytes synthesis (soluble sugar and soluble protein), nutrients acquisition (nitrogen, phosphorus, and potassium ion), antioxidant enzyme activities (superoxide dismutase and catalase), and photosynthetic capacity (chlorophyll and carotenoid contents, photosynthetic rate, stomatal conductance, and transpiration rate). AMF also substantially decreased sodium ion acquisition and malondialdehyde levels in both halophytes and glycophytes under salt stress conditions. Mycorrhizal halophytes deploy inorganic ions (potassium and calcium ions) and limited organic osmolytes (proline and soluble sugar) to achieve energy-efficient osmotic adjustment and further promote biomass accumulation. Mycorrhizal glycophytes depend on the combined actions of soluble sugar accumulation, nutrients acquisition, sodium ion exclusion, superoxide dismutase elevation, and chlorophyll synthesis to achieve biomass accumulation.ConclusionsArbuscular mycorrhizal fungi inoculation is complementary to plant function under salt stress conditions, not only facilitating energy acquisition but also redistributing energy from stress defence to growth. Glycophytes are more dependent on AMF symbiosis than halophytes under salt stress conditions.

Calcium and soluble sugar enrichments and physiological adaptation to mild NaCl salt stress in sweet potato (Ipomoea batatas) genotypes

ABSTRACT Physiological adaptations, biochemical changes and growth performances of two sweet potatoes, Japanese Yellow (JPY) and Blackie (BLK), under NaCl salt stress were evaluated. Fallen leaves in JPY under 50 mM NaCl for 21 d were evidently observed, resulting in reduced leaf area (~60% reduction to that of control). Na+ content in the root of sweet potato BLK under salt stress was higher (54.18 mg g–1 DW) compared to the stem and leaf, whereas in case of JPY, all the plant organs were enriched by Na+, leading to reduced net photosynthetic rate (Pn) (71% reduction to that of control). Ca2+ and soluble sugar enrichments appeared to be the first line of defence mechanism in sweet potato to alleviate the Na+ toxicity, especially in BLK. A negative relation between Na+ accumulation and chlorophyll b content and a positive relation between chlorophyll b and Pn were demonstrated. Reduction in Pn in JPY under salt stress consequently reduced the leaf area, shoot height and fresh weight. It appeared that the Na+ enrichment, Ca2+ signalling and soluble sugars accumulation in the root tissues of cv. BLK played a key role in salt tolerance keeping Na+ in the vacuoles and maintaining growth of plants exposed to salt stress.

Responses to Water Deficit and Salt Stress in Silver Fir (Abies alba Mill.) Seedlings

Forest ecosystems are frequently exposed to abiotic stress, which adversely affects their growth, resistance and survival. For silver fir (Abies alba), the physiological and biochemical responses to water and salt stress have not been extensively studied. Responses of one-year-old seedlings to a 30-day water stress (withholding irrigation) or salt stress (100, 200 and 300 mM NaCl) treatments were analysed by determining stress-induced changes in growth parameters and different biochemical markers: accumulation of ions, different osmolytes and malondialdehyde (MDA, an oxidative stress biomarker), in the seedlings, and activation of enzymatic and non-enzymatic antioxidant systems. Both salt and water stress caused growth inhibition. The results obtained indicated that the most relevant responses to drought are based on the accumulation of soluble carbohydrates as osmolytes/osmoprotectants. Responses to high salinity, on the other hand, include the active transport of Na+, Cl− and Ca2+ to the needles, the maintenance of relatively high K+/Na+ ratios and the accumulation of proline and soluble sugars for osmotic balance. Interestingly, relatively high Na+ concentrations were measured in the needles of A. alba seedlings at low external salinity, suggesting that Na+ can contribute to osmotic adjustment as a ‘cheap’ osmoticum, and its accumulation may represent a constitutive mechanism of defence against stress. These responses appear to be efficient enough to avoid the generation of high levels of oxidative stress, in agreement with the small increase in MDA contents and the relatively weak activation of the tested antioxidant systems.

Assessment of sugar and sugar accumulation-related gene expression profiles reveal new insight into the formation of low sugar accumulation trait in a sweet orange (Citrus sinensis) bud mutant.

The accumulation of soluble sugars in fleshy fruits largely determines their sweetness or taste. A spontaneous sweet orange mutant 'Hong Anliu' (HAL, Citrus sinensis) accumulates low soluble sugar content in fruit juice sacs than its wild type, 'Anliu' (AL) orange; however, the cause of reduced sugar content in 'HAL' fruit remains unclear. In this study, sugar content and expression profiles of genes involved in sugar metabolism and transport were compared between 'HAL' and 'AL' fruit juice sacs. In both cultivars, fructose and glucose displayed the increasing trends with significantly lower contents in 'HAL' than 'AL' after 160 DAF; moreover, sucrose had a declining trend in 'HAL' and increasing trend in 'AL' with fruit development. On the other hand, transcript levels of VINV, CWINV1, CWINV2, SUS4, SUS5, SPS1, SPS2, VPP-1, VPP-2, and some sugar transporter genes were significantly decreased in 'HAL' compared with 'AL' after 100 DAF or 160 DAF. Interestingly, the transcript levels of SPS2 and SUT2 exhibited a similar trend as it was found for sucrose content in both cultivars. These results suggested that the low sugar accumulation in 'HAL' fruit JS is accompanied by the reduced sink strength, sucrose-synthesis ability, and vacuolar storage ability compared with 'AL'; reduction of CWINVs, VINV, SPS2, SUT2, VPP-1, and VPP-2 transcript levels possibly plays a key role in the low storage of soluble sugars in the vacuoles of mutant juice sacs.

Negative effects of calcium on magnesium and potassium benefit for adaptability of Chinese prickly ash (Zanthoxylum bungeanum) grown on poor soils

The aim of this study was to provide information about how calcium (Ca), magnesium (Mg) and potassium (K) respond to changes in the sugar concentrations and carbon isotopic compositions (δ13C) of Chinese prickly ash under field condition, therefore, to show why negative effect of Ca on Mg and K would be beneficial for adaptability of Chinese prickly ash grown on poor soils. Chinese prickly ash samples were collected in the six areas with different mean annual precipitation. Drought stress was evaluated via carbon isotope signatures. Additionally, concentrations of Mg, Ca, K and sugar concentrations in foliage, roots and soils were analyzed. Increased soil available Ca concentrations did significantly inhibit foliar Mg partitioning, implying that Ca did negatively affect Mg partitioning. Changes of foliar Mg concentrations were strongly controlled by variations of balance between soil available Ca and Mg. Thus, an accurate assessment of plant nutrient status should be useful for precision nutrient management in the fields. Magnesium deficiency did significantly induce foliar sugar accumulation, therefore, there were negative relationships between Mg concentrations and δ13C values in foliage. In addition, increased sugar concentrations did significantly increase δ13C values, implying that drought or water stress induced the accumulation of sugar in foliage. Linear and power function regression analysis revealed that negative effects of Ca on Mg and K should be responsible for accumulation of soluble sugar in foliage, which may enhance a plant’s adaptability on poor soils.

Differential effects of high light duration on growth, nutritional quality, and oxidative stress of hydroponic lettuce under red and blue LED irradiation

In this study, effects of high light irradiation (HLI, 500 μmol m−2·s-1) duration in the middle of light period (16 h, 150 μmol m−2·s-1) provided by red (R) and blue (B) LEDs (4R:1B) on the growth, nutritional quality, and oxidative stress of hydroponic purple leaf lettuce grown in an environmentally controlled plant factory were examined on the 10th and 20th day after treatment. Set up five treatments with 0 h (CK), 0.5 h (HL0.5), 1 h (HL1), 2 h (HL2), and 4 h (HL4) HLI, respectively. We found that the shoot fresh weight of lettuce increased first and then decreased with the prolongation of HLI duration, whether in the early or late growth stage. On the 10th day after treatment, the root fresh weight and specific leaf weight of lettuce increased linearly with the prolongation of HLI duration, while the shoot/root ratio decreased linearly. On the 20th day after treatment, the lettuce of HL1 had the highest shoot fresh weight, leaf area, and shoot dry weight, followed by HL2. Besides, HL4 promoted the accumulation of soluble sugar, anthocyanin, flavonoid, and total phenolic simultaneously decreased the maximum quantum efficiency compared with others on the 10th day after treatment. On the 20th day after treatment, HL0.5 and HL4 stimulated the accumulation anthocyanin, flavonoid, total phenolic, and ascorbic acid compared with other treatments. The results showed that short-term HLI promotes biomass production and secondary metabolite accumulation, but HL4 caused photo-oxidative damage to lettuce. Therefore, lettuce growth and qualities can be purposely adjusted by adopting different duration of HLI provided by red and blue light in the plant factory, also these responses depended on lettuce growth stage closely.

Osmolyte accumulation in leaves and Na+ exclusion by roots in two salt–treated forage grasses

AbstractThe responses of Urochloa brizantha and Megathyrsus maximus young seedlings to salt stress with NaCl at 0 (control), 25, 50 and 100 mmol/L under hydroponic conditions were studied. The relative growth rate of U. brizantha leaves was reduced at 50 and 100 mmol/L NaCl, whereas that of M. maximus leaves was not affected. Moreover, high oxidative damages, low chlorophyll content and severe reduction of osmotic potential were observed in U. brizantha leaves when subjected to 100 mmol/L NaCl. This grass also showed high accumulation of proline and soluble sugars in leaves and roots. M. maximus efficiently regulated leaf K+ concentration and restricted Na+ transport by retention in roots. The leaf K+/Na+ ratio was higher in M. maximus than in U. brizantha at 50 and 100 mmol/L NaCl. Overall, both grasses displayed different mechanisms to reduce the deleterious effects of salinity, but the control of ion homeostasis exhibited by M. maximus contributed notably to improved performance of this grass when grown under saline conditions.

Effects of two yellowing process on colour, taste and nonvolatile compounds of bud yellow tea

AbstractThe current method for processing bud yellow tea usually results in astringent taste that is not sufficiently yellowing. Therefore, two factors in the production phase that affect tea quality were studied: number of times the tea leaves undergo the yellowing process and predrying of leaves to reduce their water content before a second yellowing process. We then evaluated the colour and nonvolatile compounds of the produced tea. Results revealed that gallated catechins and the polyphenol–amino acid ratio decreased significantly, and the colour of the tea changed from green to yellow after two yellowing processes. Predrying leaves to a lower water content resulted in the accumulation of free amino acids and soluble sugars, and an increase in the brightness and yellow colour of tea infusion. Bud yellow tea with the highest taste evaluation score and yellowness was obtained when the leave samples underwent two yellowing processes and the water content in the leaves was 40%.

Mass Modelling and Effects of Fruit Position on Firmness and Adhesiveness of Banana Variety Nipah

Abstract Fruits including banana are susceptible to damage especially during transportation. Nipah banana, also known as Musa acuminata balbisiana, has irregular shape and is short in length. This paper focuses on the physical and mechanical properties of Nipah banana. Mathematical models were developed to predict the mass of banana fruit based on the physical properties. Changes during ripening period in terms of the firmness and adhesiveness of Nipah banana were investigated at room temperature (25 °C) for three different positions in a finger. Peak positive and negative force was taken as firmness and adhesiveness, respectively. Results showed that the multiple regression modelling based on three dimensions had the highest R 2 value. Values of firmness and adhesiveness decreased with the ripening days due to starch degradation and accumulation of soluble sugars. A similar trend was observed on the firmness for all three positions.

Physiological change and screening of differentially expressed genes of wild Chinese Vitis yeshanensis and American Vitis riparia in response to drought stress

Drought is a major environmental stress factor, which seriously affects the growth and development of common grapes (Vitis vinifera L.). However, V. yeshanensis, a wild grape species native to North China, is highly resistant to drought and an important germplasm resource. Studying the key drought-resistant genes in V. yeshanensis for molecular breeding has a significant meaning. In this study, we conducted a physiological and transcriptome analysis of potted plants of wild V. yeshanensis accession Yanshan-1 (drought-resistant) and V. riparia acc. He’an (♀) (drought-sensitive) subjected to drought for 0, 8, 16, and 24 d. Under drought stress, the leaf wilting degree of acc. Yanshan-1 was much lower than that of acc. He’an (♀); Yanshan-1 also exhibited higher proline (Pro) and soluble sugar accumulation and chlorophyll content as well as lower malondialdehyde (MDA) accumulation compared to He’an (♀); superoxide anion free radical (O2−) accumulation decreased in Yanshan-1 while increased in He’an (♀). Moreover, antioxidant enzyme catalase (CAT) activity in Yanshan-1 was about 3-fold that in He’an (♀) at 16 d. Transcriptome analysis generated about 444 million clean reads from the eight libraries, and 76.29–81.16 % of these were mapped to the reference genome. A lot of differentially expressed genes (DEGs) related to photosynthesis, abiotic stimulus, osmotic adjustment substance, antioxidant-protection system and hormone signaling pathway were found through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. We also found a series of transcription factors (TFs) related to drought-stress-response. In addition, the expression trends of nine DEGs selected for qRT-PCR analyses were consistent with high-throughput sequencing basically, which proved the reliability of RNA-Seq. Genes that had much higher expression in V. yeshanensis than in V. riparia under drought stress may play an important role in drought resistance and will be key candidate genes for further research.

Root physiological and biochemical responses of seashore paspalum and centipedegrass exposed to iso‐osmotic salt and drought stresses

AbstractDrought and salt are two major stresses of turfgrass. Both damage the plant root system by disrupting osmotic balance at the root–soil interface. The objectives of our hydroponic experiments were to understand root physiological and biochemical responses in two turfgrass species (seashore paspalum [Paspalum vaginatum Swartz] and centipedegrass [Eremochloa ophiuroides (Munro) Hack.]) with distinct salinity tolerance exposed to iso‐osmotic drought and salt stresses. Two seashore paspalum genotypes, ‘Seastar’ and ‘UGP113’, and a centipedegrass genotype, ‘TifBlair’, were exposed to three treatments: control, salt stress (−0.4 MPa by adding NaCl), and drought stress (−0.4 MPa by adding polyethylene glycol). Although equal in osmotic potential, drought stress damage was more evident compared with salt stress in terms of lipid peroxidation and decreased root viability in all three turfgrass genotypes. Salt stress reduced root viability only in the centipedegrass genotype, indicating ion toxicity effects in this turfgrass genotype. Seashore paspalum genotypes had greater total accumulation of Na+ and K+ for greater root osmotic adjustment than centipedegrass under salt stress. Seashore paspalum genotypes also had greater activities of root antioxidant enzymes such as superoxide dismutase, peroxidase, and glutathione reductase compared with centipedegrass under salt stress. In contrast, centipedegrass had greater total accumulation of total soluble sugar and proline for greater osmotic adjustment compared with seashore paspalum genotypes under drought stress. Despite greater accumulation of organic osmolytes, activities of superoxide dismutase, catalase, peroxidase, and glutathione reductase in centipedegrass were either lower or similar to those in seashore paspalum genotypes, and therefore centipedegrass accumulated similar oxidative damage as seashore paspalum genotypes under drought stress.

Exogenous Brassinolide Alleviates Salt Stress in Malus hupehensis Rehd. by Regulating the Transcription of NHX-Type Na+(K+)/H+ Antiporters.

Brassinolide (BL) mediates various physiological processes and improves plant tolerance to abiotic stresses. However, the effects and mechanism of exogenous BL on the salt tolerance of apple seedlings remain unclear. Herein, we investigated the role of BL in the salt stress response of Malus hupehensis Rehd., a widely grown apple rootstock. Salt-stressed apple seedlings showed significant decline in chlorophyll content and photosynthetic rate, and the application of 0.2 mg/L exogenous BL alleviated salt stress and maintained photosynthetic capacity. Exogenous BL application can strengthen the activities of superoxide dismutase and catalase and thereby eliminates reactive oxygen species (ROS) production induced by salt stress and promote the accumulation of proline and soluble sugar, thus maintaining osmotic balance. Furthermore, exogenous BL application decreased Na+ accumulation and increased K+ content in shoots and roots under salt stress by regulating the expression levels of Na+(K+)/H+ antiporter genes (MhNHXs). MhBZR1 and MhBZR2, which are the key transcription factors in the BR signal transduction pathway, can directly bind to the promoter of MhSOS1 and MhNHX4-1, respectively, and inhibit their expression. Our findings would provide a theoretical basis for analyzing the mechanism of exogenous BL application on the salt tolerance of apples.

Biochemical and physiological impacts of zinc sulphate, potassium phosphite and hydrogen sulphide in mitigating stress conditions in soybean.

Soybean is the most widely grown oilseed in the world. It is an important source of protein and oil which are derived from its seeds. Drought stress is a major constraint to soybean yields. Finding alternative methods to mitigate the water stress for soybean is useful to maintain adequate crop yields. The aim of this study was to evaluate the morpho-physiological, biochemical and metabolic changes in soybean plants in two ontogenetic stages, under exposure to water deficit and treatment with zinc sulphate (ZS), potassium phosphite (PP) or hydrogen sulphide (HS). We carried out two independent experiments in the V4 and R1 development stages consisting of the following treatments: well-watered control (WW, 100% maximum water holding capacity, MWHC), water deficit (WD, 50% MWHC), PP + WW, PP + WD, HS + WW, HS + WD, ZS + WW and ZS + WD. The experimental design consisted of randomized blocks with eight treatments with five replicates. Morphological, physiological and metabolic analyses were performed 8 days after the start of the treatments for both experiments. We identified two tolerance mechanisms acting in response to compound application during water stress: the first involved the upregulation of antioxidant enzyme activity and the second involved the accumulation of soluble sugars, free amino acids and proline to facilitate osmotic adjustment. Both mechanisms are related to the maintenance of the photosynthetic parameters and cell membrane integrity. This report suggests the potential agricultural use of these compounds to mitigate drought effects in soybean plants.

Gossypium Genomics: Trends, Scope, and Utilization for Cotton Improvement.

Cotton (Gossypium spp.) is the most important natural fiber crop worldwide. The diversity of Gossypium species also provides an ideal model for investigating evolution and domestication of polyploids. However, the huge and complex cotton genome hinders genomic research. Technical advances in high-throughput sequencing and bioinformatics analysis have now largely overcome these obstacles, bringing about a new era of cotton genomics. Here, we review recent progress in Gossypium genomics based on whole genome sequencing, resequencing, and comparative genomics, which have provided insights about the genomic basis of fiber biogenesis and the landscape of cotton functional genomics. We address current challenges and present multidisciplinary genomics-enabled breeding strategies covering the breadth of high fiber yield, quality, and environmental resilience for future cotton breeding programs.

Aphid fecundity and defenses in wheat exposed to a combination of heat and drought stress.

Plants are routinely subjected simultaneously to different abiotic and biotic stresses, such as heat, drought, and insect infestation. Plant-insect interactions in such complex stress situations are poorly understood. We evaluated the performance of the grain aphid (Sitobion avenae) in wheat (Triticum aestivum L.) exposed to a combination of heat and drought stresses. We also performed assays of the relative water content, nutritional quality, and responses of phytohormone signaling pathways. Lower relative water content and accumulation of soluble sugars and amino acids were observed in plants exposed to combined heat and drought stress. These conditions increased abscisic acid levels in the absence of aphids, as well as leading to higher levels of jasmonate-dependent transcripts. The grain aphid infestation further increased abscisic acid levels and the abundance of jasmonic acid- and salicylic acid-dependent defenses under the combined stress conditions. Aphids reared on plants grown under drought stress alone showed lower net reproductive rates, intrinsic rates of increase, and finite rates of increase compared with aphids reared on plants in the absence of stress. The heat-treated plants also showed a decreased aphid net reproductive rate. These findings demonstrate that exposure to a combination of stresses enhances plant defense responses against aphids as well as altering nutritional quality.

Hydrogen Sulfide Affects the Root Development of Strawberry During Plug Transplant Production

Hydrogen sulfide (H2S) is endogenously produced in plant cells and plays an essential role in root development. Given its potential for future agricultural applications, the optimal concentration of sodium hydrosulfide (NaHS, an H2S donor) and the potential mechanisms for root development in the strawberry ‘Seolhyang’ were investigated in this study. The results showed that NaHS with a concentration of 1.250 mM had a positive effect on root development in strawberry. Further experiments showed that exogenous NaHS elevated the H2S content in the root. The dry root weight was increased by the 1.250 mM NaHS treatment, but was reduced by the hypotaurine (an H2S scavenger) treatment. Similar changes were found between H2S and soluble sugar contents, indicating that H2S enhanced the accumulation of soluble sugar. Therefore, it is suggested that the accumulation of soluble sugar induced by H2S is either directly or indirectly involved in root development in strawberry during plug production. Moreover, superoxide dismutase was shown to have contributed to the elevated H2O2 contents. These results contribute to our understanding of the role that H2S plays and some of the relevant mechanisms in which H2S regulates root development.