Polypropylene crisper and 1-MCP delay the softening,lignification and transcription levels of related enzyme genes of golden needle mushrooms(Flammulina velutipes)

The fresh postharvest golden needle mushroom(Flammulina velutipes) sporocarp has a high moisture content and crisp texture, but it still has high physiological activity and respiration, leading to senescence and quality deterioration.Treatments with 1-methylcyclopropene(1-MCP) and polypropylene(PP) crispers were used to study the changes of lignification and softening of F. velutipes during storage. The main findings were as follows: the crisper packaging could effectively prolong the storage time of F. velutipes;either the 1-MCP treatment, crisper packaging or the combination of the two treatments could significantly inhibit the accumulation of lignin and the decreases in the contents of cellulose and pectin, and had certain inhibitory effects on the activities of enzymes involved in lignification and softening including phenylalanine ammonia-lyase(PAL), cinnamyl alcohol dehydrogenase(CAD), cellulase(Cx), pectin methylesterase(PME) and polygalacturonase(PG). Among them, the inhibitory effect of the crisper packaging was higher than the 1-MCP treatment, while the combination of the two treatments was the best. The results of transmission electron microscopy(TEM) and scanning electron microscopy(SEM) showed that the crisper packaging in combination with the 1-MCP treatment could effectively maintain the integrity and stability of the F. velutipes cellular structure and inhibit the emergence of plasmolysis to prevent cell membrane rupture. The transcription levels showed that the crisper packaging and the combination of the 1-MCP treatment and crisper packing could effectively affect the expression of genes for enzymes related to lignification and softening of F. velutipes. In conclusion, 1-MCP and PP crispers could delay the lignification and softening of F. velutipes during storage.

Metastasis-associated lung adenocarcinoma transcript 1 molecular mechanisms in gastric cancer progression

Gastric cancer(GC)remains among the most common cancers worldwide with a high mortality-to-incidence ratio.Accumulated evidence suggests that long noncoding RNAs(lncRNAs)are involved in gastric carcinogenesis.These transcripts are longer than 200 nucleotides and modulate gene expression at multiple molecular levels,inducing or inhibiting biological processes and diseases.Metastasis-associated lung adenocarcinoma transcript 1(MALAT1)is one of the best-studied lncRNAs with comprehensive actions contributing to cancer progression.This lncRNA regulates gene expression at the transcriptional and posttranscriptional levels through interactions with microRNAs and proteins.In the present review,we discussed the molecular mechanism of MALAT1 and summarized the current knowledge of its expression in GC.Moreover,we highlighted the potential use of MALAT1 as a biomarker,including liquid biopsy.

Diurnal Changes in the Transcription Profiles of Genes Encoding Starch Synthesis-related Enzymes in Wheat Grains under Field Conditions

[Objective] During the filling stage of plant growth and development, storage starch is diurnally synthesized and accumulated in the grains from cereal crops, but the underlying molecular mechanism is unclear. [Method] In this study, grains from the bread wheat cultivar Zhoumai 18 grown in fields were harvested at 15 d after anthesis, and quantitative real-time reverse transcription polymerase chain reaction(qPCR) was used to measure the transcriptional levels of 26 genes encoding starch synthesis-related enzymes at 2 h intervals throughout a diurnal cycle. [Result] Our findings indicated that storage starch was persistently synthesized in wheat grains throughout a 24 h period. The diurnal patterns of the transcriptional levels of 26 genes in wheat grains were classified into two groups. The 13 genes in Group 1 were temporally and highly expressed in wheat grains,and their encoded proteins could play crucial roles in starch synthesis. The other 13 genes in Group 2 were characterized by low or no transcription in wheat grains throughout a diurnal cycle, suggesting their function in the synthesis or degradation of transitory starches in wheat grains. [Conclusion] These results provide information on the molecular mechanism of storage starch synthesis in higher plants.

Identification and Functional Characterization of a NovelΔ12 Fatty Acid Desaturase Gene from Haematococcus pluvialis

The freshwater microalga Haematococcus pluvialis accumulates large amounts of fatty acids in response to adverse conditions.However,the key fatty acid desaturase genes in H.pluvialis remain unknown.In this study,we cloned and functionally characterized aΔ12 fatty acid desaturase gene,and designated it as HpFAD2.The open reading frame of HpFAD2 consisted of 1137 base pairs and encoded 378 amino acids.The deduced polypeptide showed 70%identity to other endoplasmic reticulumΔ12 fatty acid desaturases,whereas it had only 44%identity to plastidΔ12 fatty acid desaturases.The PSORT algorithm and phylogenetic analysis further confirmed its affiliation to the endoplasmic reticulumΔ12 fatty acid desaturases.Heterologous expression was performed in Saccharomyces cerevisiae cells transformed with the recombinant plasmid pYES2-HpFAD2.Two additional fatty acids(C16:2 and C18:2)were detected in the yeast transformants.The results indicatedΔ12 desaturation activity and substrate preference for C18:1 over C16:1.The transcriptional levels of H.pluvialis HpFAD2 at different growth stages were measured by quantitative polymerase chain reaction(PCR),indicating that the HpFAD2 transcriptional levels were significantly higher in red cells than those in green cells.Our study brings more insight into the fatty acid biosynthetic pathway of H.pluvialis.

Jasmonates differentially affect interconnected signal-transduction pathways of Pieris rapae-induced defenses in Arabidopsis thaliana

The jasmonic acid （JA） pathway is the main signal-transduction pathway induced by insect folivory. Mutant plants affected in the jasmonate pathway （18：0 and/or 16：0-oxylipin routes） were studied to assess the effects of JA and its oxylipin intermediates 12-oxophytodienoic acid （OPDA） and dinor-OPDA （dnOPDA） on interconnected signal- transduction pathways that underlie induced defenses in Arabidopsis. Our data show that the oxylipin jasmonates dnOPDA, OPDA and JA have different roles in defense signaling induced after feeding by the chewing-biting caterpillar Pieris rapae. Jasmonic acid, and not OPDA or dnOPDA, is the major signaling compound required for the induction of the defense-related genes LOX2 （Lipo：~vgenase 2）, OPR3 （12-Oxophytodienoate reductase 3）, ACX1 （Acyl-CoA oxidase 1） and PAL1 （Phenvlalanine ammonia-lyase 1）. Monitoring PAL1 transcript levels clearly showed that accumulation of JA upon P rapae feeding results in the induction of the salicylic acid pathway. Furthermore, JA is the major signaling compound required for the P rapae-induced expression of the defense-related gene HPL1 （Hydroperoxide lyase 1）. The jasmonate dnOPDA influences the induction of the HPk- branch as well, yet its effect is antagonistic to the effect of JA. Our data show that these jasmonates may be used to fine-tune Arabidopsis＇ herbivore-induced responses in terms of the HPL-branch from the oxylipin pathway.

Understanding the molecular mechanisms of trade-offs between plant growth and immunity

Trade-offs between plant growth and immunity are a well-known phenomenon in plants that are meant to ensure the best use of limited resources.Recently,many advances have been achieved on molecular regulations of the trade-offs between plant growth and immunity.Here,we provide an overview on molecular understanding of these trade-offs including those regulated at the transcriptional level or post-transcriptional level by transcriptional factors,microRNAs,and post-translational modifications of proteins,respectively.The understanding on the molecular regulation of these trade-offs will provide new strategies to breed crops with high yield and enhanced resistance to disease.

Methionine addition improves the acid tolerance of Lactiplantibacillus plantarum by altering cellular metabolic flux,energy distribution,lipids composition

This paper reported a wine-derived lactic acid bacterium,Lactiplantibacillus plantarum XJ25,which exhibited higher cell viability under acid stress upon methionine supplementation.Cellular morphology and the composition of the cytomembrane phospholipids revealed a more solid membrane architecture presented in the acid-stressed cells treated with methionine supplementation.Transcriptional analysis showed L.plantarum XJ25 reduced methionine transport and homocysteine biosynthesis under acid stress.Subsequent overexpression assays proved that methio-nine supplementation could alleviate the cell toxicity from homocysteine accumulation under acid stress.Finally,L.plantarum XJ25 employed energy allocation strategy to response environmental changes by balancing the uptake methionine and adjusting saturated fatty acids(SFAs)in membrane.These data support a novel mechanism of acid resistance involving methionine utilization and cellular energy distribution in LAB and provide crucial theoretical clues for the mechanisms of acid resistance in other bacteria.

FUNCTIONAL GAIN OF FRUIT NETTED-CRACKING IN AN INTROGRESSION LINE OF TOMATO WITH HIGHER EXPRESSION OF THE FNC GENE

Fruit cracking is a major disorder that affects the integrity of fruit and reduces the commercial value of tomato and other fleshy fruit.Here,we have found a novel fruit'netted-cracking'(FNC)phenotype in tomato introgression line IL4-4 which is present in neither the donor parent(LA0716)nor the receptor parent(M82).An F2 population was generated by crossing IL4-4 with M82 to genetically characterize the FNC gene and this showed that a single dominant gene determined fruit netted-cracking.Further map-based cloning narrowed down the FNC locus to a 230 kb region on chromosome 4.Sequencing and annotation analysis show that FNC(Solyc04 g082540)was the most likely candidate gene.Functional characterization of FNC by overexpressing FNC^c and FNC1^resulted in the fruit netted-cracking phenotype,suggesting that the FNC transcript level results in the functional gain of fruit netted-cracking.These findings were further confirmed by FNC ortholog in netted-cracking pepper and melon,indicating a common regulatory mechanism in different plant species.Furthermore,cytoplasm and nucleus-localized FNC indicates increased expression of genes involved in suberin,lignin,lipid transport and cell wall metabolism.These findings provide novel genetic insights into fruit netted-cracking and offer a way to promote molecular improvement toward cracking resistant cultivars.