Molecular mechanisms of stress resistance in sorghum: Implications for crop improvement strategies

Abiotic stresses, such as drought, salt, extreme temperatures, and heavy metal pollution, are the main environmental factors that limit crop growth and yield. Sorghum, a C4 grass plant with high photosynthetic efficiency, can grow in adverse environmental conditions due to its excellent stress resistance characteristics. Therefore, unraveling the stress-resistance mechanism of sorghum could provide a theoretical basis for developing and cultivating various stress-resistant crops. This understanding could also help to create a conducive environment for using marginal soil in agriculture and ensuring food security. In this review, we discuss the adaptation mechanisms of sorghum under drought, salinity, temperature, and soil heavy metal stresses, the specific response to stress, the screening of sorghum-resistant germplasm, and the identification and functional analysis of the relevant genes and quantitative trait loci(QTL). In addition, we discuss the application potential of different stress-tolerant sorghum germplasms reported to date and emphasize the feasibility and potential use in developing and promoting highly stress-tolerant sorghum in marginal soil.

Study on Germplasm Resources of Peach Cultivars

[Objectives]To study the germplasm resources of excellent peach cultivars.[Methods]Five peach cultivars were introduced,in-cluding‘Jinxiu’peach,‘Jinxiang’peach,‘Chunxiao’peach,‘Hujingmilu’peach and‘018 nectarine’peach.Then,these five cultivars were used to study the biological characteristics of peach trees,namely,as phenology,fruit quality,heat resistance,cold resistance and other resistance.[Results]Five cultivars of peach plants grew fast and robust,among which‘018 nectarine’had very crisp fruit,‘Jinxiu’,‘Jinxiang’,‘Chunxiao’and‘Hujingmilu’had very sweet fruitꎻthe peach trees of these five cultivars have good water resistance,heat resist-ance and cold resistance.[Conclusions]The results of this study can not only provide a reference for the introduction of peach trees,but also provide a practical basis for the large-scale planting of peach trees.

Hypoxic Preconditioning Eliminates Differences in the Innate Resistance of Rats to Severe Hypoxia

Hypoxic preconditioning is able to increase the body’s resistance to hypoxic/ischemic stress. Understanding how to apply the hypoxic response to initiate the protective mechanism of ischemic preconditioning is a high priority. However, the relationship between innate resistance to hypoxic stress and preconditioning efficiency of moderate hypoxia has been poorly studied. In our work, the efficiency of single moderate hypobaric hypoxia (HBH) for resistance to severe hypobaric hypoxia (SHBH) was studied on intact rats and those pre-tested under SHBH with low, intermediate and high resistance to hypoxia. HBH has a significant preconditioning action on the resistance to hypoxia over a wide range from 270 to 1464 s (4.5 to 24.5 min) and at the same time eliminates the differences in the endurance under SHBH between all rat groups. It is concluded that 1) HBH preconditioning efficiency does not depend on an innate resistance to SHBH and prior hypoxic experience of rats;and 2) the pretesting to severe hypoxia has no value for predicting the hypoxic preconditioning efficiency and study of adaptive mechanisms.

Integration of animal behaviors under stresses with different time courses

We used animal models of ＂forced swim stress＂ and ＂chronic unpredictable stress＂, and tried to reveal whether a passive coping style of high flotation behavior in forced swim stress predicts an- hedonia behavior after chronic unpredictable stress, and whether the dopamine system regulates floating and anhedonia behaviors. Our results confirmed that depression-prone rats use ＂floating behavior＂ as a coping strategy in forced swim stress and more readily suffer from anhedonia during chronic unpredictable stress. Intraperitoneal injection or nucleus accumbens microin- jection of the dopamine 2/3 receptor subtype agonist ropinirole reduced floating behaviors in depression-prone animals, but increased sucrose preference in rats showing anhedonia. These data indicate that floating behavior is a defensive mode that is preferred by susceptible individ- uals under conditions of acute stress. Simultaneously, these animals more readily experienced anhedonia under long-term stress; that is, they were more readily affected by depression. Our results suggest that dopamine 2/3 receptor subtypes in the nucleus accumbens play an important role in floating behaviors and anhedonia.

The sex peptide receptor in the Asian gypsy moth,Lymantria dispar,is involved in development and stress resistance

The G protein-coupled receptor(GPCR)regulates downstream genes by binding to a heterotrimeric G protein.However,the function of sex peptide receptor(SPR)in lepidopteran species is mostly unknown.Understanding the physiological functions of SPR in insects is essential for exploring new insecticidal targets.In the present study,the functions of an SPR in Lymantria dispar(Asian gypsy moth;LdSPR)were investigated.The expression of LdSPR was the highest in the 6 th instar larval stage,and there was a large difference in expression between male and female adults.After LdSPR gene silencing,L.dispar larvae showed increased sensitivity to high temperature,starvation,and oxidative stress,indicating that LdSPR enhances stress resistance.These results enrich our knowledge of the function of the insect SPRs,which will lead to a better understanding of other insect GPCR family members and the identification of new targets for the development of environmentally friendly pesticides.

Osmotic Stress Resistance of Transgenic Tobacco Expressed Soybean Lysine-rich Protein Gene

PM2 gene （accession number： M80664） with high lysine content from soybean （Glycine max） was found in GenBank by changing three BLASTp parameters. Amino acid composition analysis of PM2 showed that Lys content was on the high level of 18.22%. Protein encoded by PM＇2 also belonged to the family of late embryogenesis abundant （LEA） proteins, which was considered that it had a strong relation with the abiotic stress resistance. In this experiment, PM2 gene was obtained from dry soybean seeds by RT-PCR, plant expression vector pEMTPM2 was constructed, and then transformed into tobacco by using agrobacterium-mediated method. Eight salt and drought tolerant lines were obtained from 31 differentiated lines. Real-time PCR showed that PM2 gene overexpressed in all four PCR positive lines with the osmotic stress resistance. These results confirmed that the overexpression of PM2 gene enhanced the osmotic stress resistance of transgenic tobacco.

Application of Molecular Marker Technologies in Stress Resistance Breeding of Rapeseed

Rapeseed is the largest source of China's edible vegetable oil and plays a pivotal role in China's edible oil market.With global warming and frequent occurrence of various extreme climates,traditional hybrid breeding has been unable to meet the production requirements for rape yield and stress resistance.In recent years,the rapid development and maturity of molecular marker technologies have opened up new ways for stress resistance breeding in rape.This article mainly discusses several types of molecular marker technologies commonly used in rapeseed breeding,such as RFLP,SSR,and SNP,the advantages of molecular marker technologies over conventional breeding and other genetic marker technologies,as well as the application of molecular marker technologies in rapeseed disease resistance,drought resistance,cold resistance and lodging resistance breeding,the current problems and development prospects in breeding.

Protein changes in rice seedlings during the enhancement of chilling resistance by different stress pretreatment

The changes of proteins in the rice (Oryzasativa L.) Tesanai 2 seedling under salt (NaCl,4 g/L), heat shock (42℃, 3h ), and cold(14℃, 3d ) pretreatments were compared toexplore the mechanism of the cross adaptationto different environmental stresses. The chill-ing resistance of rice seedling after 1℃, 150pmol·msPFD(photo flux density) for 2d was enhanced distinctly by salt, heat shock,

Relationship between changes of endogenous ABA level and resistance in hybrid rice under temperature stress

We studied the relationship between endogenous ABA and resistance to temperature stress in seedlings of hybrid rice. The hybrid rice Combinations Shanyou 63, Shanyou 287, Weiyou 63, and Weiyou 287 were treated under 2℃ and 42℃ respectively for 48 h. Endogenous ABA concentrations were obtained by gas chromatography with electron capture detector (GC-ECD) and a nickel labelled external standard. Leakage of electrolytes were determined. At optimal temperature (27℃), there was difference between the level of endogenous ABA and the leakage of electrolytes in hybrid rice combinations, which attributed to genetic difference. ABA level in Weiyou system was higher than that in Shanyou, and there were distinctions between Shanyou system itself (see table). At 2℃, the ABA content of rice seedling was increased. ABA level of Weiyou system maintained higher than Shanyou system at 27℃. The leakage quantities of

Study on Adaptability of Introduced Pear Varieties

[Objectives]To study the adaptability of introduced pear.[Methods]Five pear varieties,"Aidang"pear,"Taiwan Zaomi"pear,"Cuiguan"pear,"Tianjin Yali"pear and"Zaosheng Xinshui"pear,were introduced.Then,using these five varieties,the phenology of pear trees,various characters of fruit,stress resistance(heat tolerance and cold tolerance)of varieties were studied.[Results]The plants of 5 varieties of pear trees grew fast and were robust;in late March,it went into the flowering period;"Aidang"pear fruit had a certain number of stone cells;"Taiwan Zaomi"pear had the highest sweetness;"Cuiguan"pear had the largest fruit;these five varieties of pear trees had good water resistance,heat resistance and cold resistance.[Conclusions]This study can provide a reference for the introduction of pear trees,and can also provide a practical basis for the large-scale planting of pear trees.

Experimental Research on Pomegranate Varieties

[Objectives]To study the introduction performance of pomegranate(Punica granatum)varieties in Shanghai area.[Methods]In this experiment,five pomegranate varieties were introduced,namely‘American 002’pomegranate,‘Huohulu’pomegranate,‘Wanli No.1’pomegranate,‘Yicheng Hongpitian’pomegranate,and‘American Qingpisuan’pomegranate.Then,using these five varieties,various biological traits such as phenology and fruit quality of pomegranate,as well as stress resistance such as heat resistance and cold resistance were studied.[Results]Five varieties of pomegranates began to mature in succession in early September;the smallest single fruit weight was 90 g,and the largest was 110 g;the plants grew fast,the plants were strong,the flowers were single petal,and plants bore fruits which were ornamental and edible.In addition,the pomegranates of these five varieties had good water tolerance and heat resistance,and good cold resistance.[Conclusions]This study is intended to provide a certain reference for the introduction of pomegranate varieties,and also provide a practical basis for the large-scale planting of pomegranate.

Mechanism of antagonistic effects of Andrographis paniculata methanolic extract against Staphylococcus aureus

Objective: To investigate the effects of Andrographis paniculata(Burm.f.) Wall. Ex Nees(A. paniculata) on expressions and activities of catalase, superoxide dismutase and alkylhydroperoxide reductase C in Staphylococcus aureus(S. aureus) with respect to its survival in vitro. Methods: Antioxidative property of methanolic leaves extract of A. paniculata(0.06 mg/m L). Minimum inhibitory concentration(MIC) was determined by its ability to reduce hydrogen peroxide(H_2O_2) toxicity against S. aureus ATCC 25923(3.8×10~8 cfu/m L). Effects of the extract on expressions of kat A(encoding catalase), sod A and sod M [encoding superoxide dismutases(SODs)], and ahp C [encoding alkylhydroperoxide reductase C(AhpC)] in S. aureuswere determined by RT-q PCR and corresponding enzyme activity assays were performed. Nitroblue tetrazolium reduction(NBT) assay was performed to determine effects of the extract on intracellular and extracellular levels of O_2-in S. aureus. Results: Cells challenged with 7.5 mmol/L H_2O_2 showed 0% survival in 30 min whereas 25% survived after treatment with the extract and H_2O_2. Cells that were treated with the extract alone had 43% survival in the same exposure period. Expressions of sod A and sod M genes in extract-treated cells were lowered 0.8-fold and 0.7-fold, respectively with decrease in total SOD activity of 26.8 U compared to untreated cells, 32.4 U(P<0.05). In contrast, extract-treated S. aureus cells showed 3.3-fold increase in kat A expression with corresponding increase in catalase activity of 1.828 U compared to untreated cells which was 1.248 U,(P<0.05). More profoundly, ahp C expression was increased 61-fold in extract-treated cells,(P<0.05) with corresponding increase in Ahp C activity of 0.018 U compared to untreated cells, 0.012U,(P<0.05). Extract-treated cells had significantly lower intra-and extracellular O_2-levels with absorbance readings(A_(575nm)) of 0.340 and 0.524 compared to untreated cells which were 0.516 and 0.928(P<0.05), respectively. Conclusions: Taken together these results suggest that the low MIC of A. paniculatamethanolic leaves extract(0.06 mg/m L) reduce H_2O_2 toxicity and more importantly, was in itself effectively inhibitory against S. aureus. Further, our observations suggest that a probable mode of its inhibitory mechanism against S. aureus is by reducing total SOD activity through downregulation of sod A and sod M expressions.

Identification of Differentially Expressed Genes Induced by Ammonium Nitrogen in Rice Using mRNA Differential Display

RNAs isolated from ammonium- and nitrate-treated rice leaves were used to screen differentially expressed genes through mRNA differential display. A total of 72 bands appeared significant differences and some of them were further confirmed by reverse Northern and Northern blot. The results showed that two genes, A-02 （Oryza sativa drought stress related mRNA） and A-03 （Zea mays partial mRNA for TFIIB-related protein） were highly up-regulated in the ammonium-fed rice leaves. The enzyme assays showed that the activities of the two anti-oxidative enzymes, catalase and peroxidase, and the content of a non-enzymic antioxidant, glutathione, were significantly higher in the ammonium-fed rice leaves than those in the nitrate-fed ones, indicating that the ammonium nutrition might be beneficial for rice plants to improve the stress resistance during growth and development.

Research Progress on Lonicera japonica Thunb.Affected by Environmental Stress

Lonicera japonica Thunb.is widely distributed in China.It has strong adaptability to the environment and can maintain normal growth and development under a variety of stress conditions.It is commonly used as a medicine with its dry flower buds or newly opened flowers,named honeysuckle,and with both economic value and ecological application value.The research progress of L.japonica Thunb.under stress conditions such as temperature,drought,light,salt,heavy metals and diseases,pests and endophytic bacteria was reviewed,and the current research situation of the physiological and biochemical response mechanism,changes of photosynthetic fluorescence and accumulation of secondary metabolites of honeysuckle under different stresses was discussed,so as to provide a reference for deep-level exploring the resistance mechanism of L.japonica Thunb.in the future and lay a theoretical foundation for the high-quality authentic ecological cultivation of L.japonica Thunb.

Genome-Wide Characterization of the Cellulose Synthase Gene Superfamily in Tea Plants(Camellia sinensis)

The cellulose synthase gene superfamily,including Cellulose synthase A(CesA)and cellulose synthase-like(Csl)gene families,is responsible for the synthesis of cellulose and hemicellulose,respectively.The CesA/Csl genes are vital for abiotic stress resistance and shoot tenderness regulation of tea plants(Camellia sinensis).However,the CesA/Csl gene family has not been extensively studied in tea plants.Here,we identified 53 CsCesA/Csl genes in tea plants.These genes were grouped into five subfamilies(CsCesA,CsCslB,CsCslD,CsCslE,CsCslG)based on the phylogenetic relationships with Arabidopsis and rice.The analysis of chromosome distribution,gene structure,protein domain and motif revealed that most genes in CsCesA,CsCslD and CsCslE subfamilies were conserved,whereas CsCslB and CsCslG subfamily members are highly diverged.The transcriptome analysis showed that most CsCesA/Csl genes displayed tissue-specific expression pattern.In addition,members of CsCslB4,CsCesA1/3/6,CsCslB3/4,CsCslD3,CsCslE1 and CsCslG2/3 subfamilies were up-regulated under drought and cold stresses,indicating their potential roles in regulating stress tolerance in tea plants.Furthermore,the expression levels of CsCslG2_6 and CsCslD3_5 in different tissues and cultivars,respectively,were positively correlated with the cellulose content that is negatively related with shoot tenderness.Thus,these two genes were speculated to be involved in the regulation of shoot tenderness in tea plants.Our findings may help elucidate the evolutionary relationships and expression patterns of the CsCesA/Csl genes in tea plants,and provide more candidate genes responsible for stress tolerance and tenderness regulation in tea plants for future functional research.

Physiological Effects of Alkaline Stress on Seedlings of Lonicera caerulea L.

[Objectives]This study was conducted to clarify the saline-alkali tolerance in seedlings of Lonicera caerulea L.[Methods]The L.caerulea seedling variety,Lanjingling,was used as the test material,and alkaline solution(NaHCO 3)with different concentration gradients was used for stress treatment to observe physiological effects on L.caerulea seedlings.[Results]L.caerulea seedlings were most affected by alkaline stress at a treatment concentration of 100 mmol/L,and their osmotic substances(proline,soluble sugar,soluble protein)and antioxidant enzymes(CAT,SOD and POD)were higher in content at a concentration of 100 mmol/L compared with the alkaline stresses in this range.The contents were generally higher,and even in the detection of proline,soluble sugar,SOD and POD,the contents of these substances and enzymes reached a peak at 100 mmol/L.The contents of soluble sugar,CAT,SOD,POD and malondialdehyde were generally higher than that of the control check(CK),and the contents of proline and soluble protein in each treatment concentration were generally higher than that of the CK.[Conclusions]The metabolic physiology of L.caerulea seedlings has a certain adaptability to alkaline stress.

The ERF transcription factor LTF1 activates DIR1 to control stereoselective synthesis of antiviral lignans and stress defense in Isatis indigotica roots

Lignans are a powerful weapon for plants to resist stresses and have diverse bioactive functions to protect human health.Elucidating the mechanisms of stereoselective biosynthesis and response to stresses of lignans is important for the guidance of plant improvement.Here,we identified the complete pathway to stereoselectively synthesize antiviral(-)-lariciresinol glucosides in Isatis indigotica roots,which consists of three-step sequential stereoselective enzymes DIR1/2,PLR,and UGT71B2.DIR1 was further identified as the key gene in respoJanuary 2024nse to stresses and was able to trigger stress defenses by mediating the elevation in lignan content.Mechanistically,the phytohormone-responsive ERF transcription factor LTF1 colocalized with DIR1 in the cell periphery of the vascular regions in mature roots and helped resist biotic and abiotic stresses by directly regulating the expression of DIR1.These systematic results suggest that DIR1 as the first common step of the lignan pathway cooperates with PLR and UGT71B2 to stereoselectively synthesize(-)-lariciresinol derived antiviral lignans in I.indigotica roots and is also a part of the LTF1-mediated regulatory network to resist stresses.In conclusion,the LTF1-DIR1 module is an ideal engineering target to improve plant Defenses while increasing the content of valuable lignans in plants.

Constituent and effects of polysaccharides isolated from Sophora moorcroftiana seeds on lifespan,reproduction,stress resistance,and antimicrobial capacity in Caenorhabditis elegans

Sophora moorcroftiana(S. moorcroftiana) is an endemic leguminous dwarf shrub in Tibet, China. Decoctions of the seeds have been used in Chinese folk medicine for dephlogistication, detoxication, and infectious diseases. The present study aimed to investigate the constituent and biological effects of polysaccharides from S. moorcroftiana seeds in Caenorhabditis elegans(C. elegans). Polysaccharides from S. moorcroftiana seeds(SMpol) were extracted with 60% ethanol and constituent was analyzed by GC-MS. SMpol was composed of glucose, galactose and inositol in the molar ratio of 35.7 : 1.3 : 17.0. Synchronized worms were treated with SMpol and then lifespan, motility, reproduction, stress resistance and antimicrobial activity were examined. Compared with the control group, the lifespan was increased to the average of 27.3 days and the number of laying eggs showed a 1.3-fold increase in nematodes treated with SMpol(4 mg×mL^(–1)). In SMpol(4 mg×mL^(–1)) treated worms, there was a 1.1-fold increase in 24-h survival of acute heat stress and a 1.6-fold increase in 2-h survival of oxidative stress The colonization of the bacteria in the SMpol treated nematode was significantly lower than that of the untreated group by 68.3%. In vivo studies showed SMpol significantly extended the life span, improved reproduction, increased stress resistance and antimicrobial capacity of C. elegans. In conclusion, those results indicated that the polysaccharides from S. moorcroftiana seeds were involved in a variety of biological activities leading to its modulatory effects on C. elegans which may be developed as a natural supplement agent.

Beyond dueling: roles of the type VI secretion system in microbiome modulation, pathogenesis and stress resistance

Bacteria inhabit diverse and dynamic environments,where nutrients may be limited and toxic chemicals can be prevalent.To adapt to these stressful conditions,bacteria have evolved specialized protein secretion systems,such as the type VI secretion system(T6SS)to facilitate their survival.As a molecular syringe,the T6SS expels various effectors into neighboring bacterial cells,eukaryotic cells,or the extracellular environment.These effectors improve the competitive fitness and environmental adaption of bacterial cells.Although primarily recognized as antibacterial weapons,recent studies have demonstrated that T6SSs have functions beyond interspecies competition.Here,we summarize recent research on the role of T6SSs in microbiome modulation,pathogenesis,and stress resistance.

Upregulation of the glycine-rich protein-encoding gene GhGRPL enhances plant tolerance to abiotic and biotic stressors by promoting secondary cell wall development

Abiotic and biotic stressors adversely affect plant survival,biomass generation,and crop yields.As the global availability of arable land declines and the impacts of global warming intensify,such stressors may have increasingly pronounced effects on agricultural productivity.Currently,researchers face the overarching challenge of comprehensively enhancing plant resilience to abiotic and biotic stressors.The secondary cell wall plays a crucial role in bolstering the stress resistance of plants.To increase plant resistance to stress through genetic manipulation of the secondary cell wall,we cloned a cell wall protein designated glycine-rich protein-like(GhGRPL)from cotton fibers,and found that it is specifically expressed during the period of secondary cell wall biosynthesis.Notably,this protein differs from its Arabidopsis homolog,AtGRP,since its glycine-rich domain is deficient in glycine residues.GhGRPL is involved in secondary cell wall deposition.Upregulation of GhGRPL enhances lignin accumulation and,consequently,the thickness of the secondary cell walls,thereby increasing the plant’s resistance to abiotic stressors,such as drought and salinity,and biotic threats,including Verticillium dahliae infection.Conversely,interference with GhGRPL expression in cotton reduces lignin accumulation and compromises that resistance.Taken together,our findings elucidate the role of GhGRPL in regulating secondary cell wall development through its influence on lignin deposition,which,in turn,reinforces cell wall robustness and impermeability.These findings highlight the promising near-future prospect of adopting GhGRPL as a viable,effective approach for enhancing plant resilience to abiotic and biotic stress factors.