Effect of low temperature on ethanolic fermentation in rice seedlings

Genome-wide identification and characterization of ADH gene family and the expression under different abiotic stresses in tomato (Solanum lycopersicum L.)

The SlADH gene plays a key role in environmental stress response. However, limited studies exist regarding the tomato SlADH gene. In this study, we identified 35 SlADH genes in tomato by genome-wide identification. Among the 12 chromosomes of tomato, SlADH gene is distributed on 10 chromosomes, among which the 7th and 10th chromosomes have no family members, while the 11th chromosome has the most members with 8 family members. Members of this gene family are characterized by long coding sequences, few amino acids, and introns that make up a large proportion of the genetic structure of most members of this family. Moreover, the molecular weight of the proteins of the family members was similar, and the basic proteins were mostly, and the overall distribution was relatively close to neutral (pI = 7). This may indicate that proteins in this family have a more conserved function. In addition, a total of four classes of cis-acting elements were detected in all 35 SlADH promoter regions, most of which were associated with biotic and abiotic stresses. The results indicate that SlADH gene had a certain response to cold stress, salt stress, ABA treatment and PEG stress. This study provides a new candidate gene for improving tomato stress resistance.

Genome-wide association study identifies variants of GhSAD1 conferring cold tolerance in cotton

Cold stress is a major environmental factor affecting plant growth and development. Although some plants have developed resistance to cold stress, the molecular mechanisms underlying this process are poorly understood. Using genome-wide association mapping with 200 cotton accessions collected from different regions, we identified variations in the short chain alcohol dehydrogenase gene, GhSAD1, that responds to cold stress. Virus-induced gene silencing and overexpression in Arabidopsis revealed that GhSAD1 fulfils important roles in cold stress responses. Ectopic expression of a haploid genotype of GhSAD1 (GhSAD1HapB) in Arabidopsis increased cold tolerance. Silencing of GhSAD1HapB resulted in a decrease in abscisic acid (ABA) content. Conversely, overexpression of GhSAD1HapB increased ABA content. GhSAD1HapB regulates cold stress responses in cotton through modulation of C-repeat binding factor activity, which regulates ABA signalling. GhSAD1HapB induces the expression of COLD-REGULATED (COR) genes and increases the amount of metabolites associated with cold stress tolerance. Overexpression of GhSAD1HapB partially complements the phenotype of the Arabidopsis ABA2 mutant, aba2-1. Collectively, these findings increase our understanding of the mechanisms underlying GhSAD1-mediated cold stress responses in cotton.

The Anaerobic Product Ethanol Promotes Autophagy-Dependent Submergence Tolerance in Arabidopsis

In response to hypoxia under submergence, plants switch from aerobic respiration to anaerobic fermentation, which leads to the accumulation of the end product, ethanol. We previously reported that Arabidopsis thaliana autophagy-deficient mutants show increased sensitivity to ethanol treatment, indicating that ethanol is likely involved in regulating the autophagy-mediated hypoxia response. Here, using a transcriptomic analysis, we identified 3909 genes in Arabidopsis seedlings that were differentially expressed in response to ethanol treatment, including 2487 upregulated and 1422 downregulated genes. Ethanol treatment significantly upregulated genes involved in autophagy and the detoxification of reactive oxygen species. Using transgenic lines expressing AUTOPHAGY-RELATED PROTEIN 8e fused to green fluorescent protein (GFP-ATG8e), we confirmed that exogenous ethanol treatment promotes autophagosome formation in vivo. Phenotypic analysis showed that deletions in the alcohol dehydrogenase gene in adh1 mutants result in attenuated submergence tolerance, decreased accumulation of ATG proteins, and diminished submergence-induced autophagosome formation. Compared to the submergence-tolerant Arabidopsis accession Columbia (Col-0), the submergence-intolerant accession Landsberg erecta (Ler) displayed hypersensitivity to ethanol treatment; we linked these phenotypes to differences in the functions of ADH1 and the autophagy machinery between these accessions. Thus, ethanol promotes autophagy-mediated submergence tolerance in Arabidopsis.

The Relationship between CmADHs and the Diversity of Volatile Organic Compounds of Three Aroma Types of Melon (Cucumis melo)

Alcohol dehydrogenase (ADH) plays an important role in aroma volatile compounds synthesis of plants. In this paper, we tried to explore the relationship between CmADHs and the volatile organic compounds (VOCs) in oriental melon. Three different aroma types of melon were used as materials. The principle component analysis of three types of melon fruit was conducted. We also measured the CmADHs expression level and enzymatic activities of ADH and alcohol acyl-transferase (AAT) on different stages of fruit ripening. An incubation experiment was carried out to investigate the effect of substrates and inhibitor (4-MP, 4-methylpyrazole) on CmADHs expression, ADH activity, and the main compounds of oriental melon. The results illustrated that ethyl acetate, hexyl acetate (E,Z)-3,6-nonadien-1-ol and 2-ethyl-2hexen-1-ol were the four principal volatile compounds of these three types of melon. AAT activity was increasing with fruit ripening, and the AAT activity in CH were the highest, whereas ADH activity peaked on 32 DAP, 2 days before maturation, and the ADH activity in CB and CG were higher than that in CH. The expression pattern of 11 CmADH genes from 24 to 36 day after pollination (DAP) was found to vary in three melon varieties. CmADH4 was only expressed in CG and the expression levels of CmADH3 and CmADH12 in CH and CB were much higher than that in CG, and they both peaked 2 days before fruit ripening. Ethanol and 4-MP decreased the reductase activity of ADH, the expression of most CmADHs and ethyl acetate or hexyl acetate contents of CB, except for 0.1 mM 4-MP, while aldehyde improved the two acetate ester contents. In addition, we found a positive correlation between the expression of CmADH3 and CmADH12 and the key volatile compound of CB. The relationship between CmADHs and VOCs synthesis of oriental melon was discussed.

Molecular identification and characterization of the pyruvate decarboxylase gene family associated with latex regeneration and stress response in rubber tree

In plants, ethanolic fermentation occurs not only under anaerobic conditions but also under aerobic conditions, and involves carbohydrate and energy metabolism. Pyruvate decarboxylase (PDC) is the first and the key enzyme of ethanolic fermentation, which branches off the main glycolytic pathway at pyruvate. Here, four PDC genes were isolated and identified in a rubber tree, and the protein sequences they encode are very similar. The expression patterns of HbPDC4 correlated well with tapping-simulated rubber productivity in virgin rubber trees, indicating it plays an important role in regulating glycometabolism during latex regeneration. HbPDC1, HbPDC2 and HbPDC3 had striking expressional responses in leaves and bark to drought, low temperature and high temperature stresses, indicating that the HbPDC genes are involve in self-protection and defense in response to various abiotic and biotic stresses during rubber tree growth and development. To understand ethanolic fermentation in rubber trees, it will be necessary to perform an in-depth study of the regulatory pathways controlling the HbPDCs in the future.

Research advances in major cereal crops for adaptation to abiotic stresses

With devastating increase in population there is a great necessity to increase crop productivity of staple crops but the productivity is greatly affected by various abiotic stress factors such as drought, salinity. An attempt has been made a brief account on abiotic stress resistance of major cereal crops viz. In spite of good successes obtained on physiological and use molecular biology, the benefits of this high cost technology are beyond the reach of developing countries. This review discusses several morphological, anatomical, physiological, biochemical and molecular mechanisms of major cereal crops related to the adaptation of these crop to abiotic stress factors. It discusses the effect of abiotic stresses on physiological processes such as flowering, grain filling and maturation and plant metabolisms viz. photosynthesis, enzyme activity, mineral nutrition, and respiration. Though significant progress has been attained on the physiological, biochemical basis of resistance to abiotic stress factors, very little progress has been achieved to increase productivity under sustainable agriculture. Therefore, there is a great necessity of inter-disciplinary research to address this issue and to evolve efficient technology and its transfer to the farmers' fields.

Oscillatory growth in lily pollen tubes does not require aerobic energy metabolism

Oscillatory tip growth in pollen tubes depends on prodigious amounts of energy. We have tested the hypothesis that oscillations in the electron transport chain lead to growth oscillations in lily (Lilium formosanum). Using three respiratory inhibitors, oligomycin, antimycin A, and cyanide, we find that pollen tube growth is much less sensitive to respiratory inhibition than respiration is. All three block respiration at concentrations severalfold lower than necessary to inhibit growth. Mitochondrial NAD(P)H and potentiometric JC-1 fluorescence, employed as markers for electron transport chain activity, rise rapidly in response to oligomycin, as expected. Pollen tube growth stops for several minutes before resuming. Subsequent growth has a lower mean rate, but continues to oscillate, albeit with a longer period. NAD(P)H fluorescence no longer exhibits coherent oscillations, and mitochondria no longer congregate directly behind the apex: they distribute evenly throughout the cell. Postinhibition growth relies on aerobic fermentation for energy production as revealed by an increase in ethanol in the media. These data suggest that oscillatory growth depends not on a single oscillatory pacemaker but rather is an emergent property arising from a number of stable limit cycles.

Response of jujube fruits to exogenous oxalic acid treatment based on proteomic analysis

In this study, we found that oxalic acid (OA) at the concentration of 5 mM could delay jujube fruit sene-scence by reducing ethylene production, repressing fruit reddening and reducing alcohol content, which consequently increased fruit resistance against blue mold caused by Penicillium expansum. In order to gain a further understanding of the mechanism by which OA delays senescence and increases disease resistance of jujube fruit, we used a proteomics approach to compare soluble proteome of jujube fruits treated with water or 5 mM OA for 10 min. A total of 25 differentially expressed proteins were identified by using electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-Q-TOF-MS/MS). Among these proteins, alcohol dehydrogenase 1, which plays a direct role in ethanol metabolism, was repressed, and the abundances of three photosynthesis-related proteins was enhanced in jujube fruit after OA treatment. The protein identified as a cystathionine beta-synthase domain-containing protein, which can regulate ethylene precursors, was also induced by OA treatment. The activity of 1-aminocyclopropane-1-carboxylic acid synthase was significantly suppressed in OA-treated jujube fruit. In addition, three proteins related to the defense/stress response were up-regulated by OA, and contributed to the establishment of systemic resistance induced by OA in jujube fruits. These results indicated that OA treatment might affect ethanol and ethylene metabolism, resulting in delaying senescence, and increase resistance of jujube fruits against fungal pathogens.

Alterações fisiológicas em sementes de arroz expostas ao frio na fase de germinação

O frio é um dos principais problemas para o cultivo do arroz irrigado no Rio Grande do Sul, já que a grande maioria das cultivares em uso são de origem tropical. A ocorrência de baixas temperaturas pode causar sérios danos ao estabelecimento da lavoura, diminuindo o estande inicial e favorecendo por conseqüência, o estabelecimento de plantas daninhas. O objetivo desse trabalho foi avaliar alterações fisiológicas em diferentes cultivares de arroz, quando submetidos à baixa temperatura durante a fase de germinação. Foram utilizadas sementes provenientes das cultivares BRS Agrisul, BRS Chuí, Lemont e Oro, as quais foram avaliadas em relação à tolerância a baixa temperatura através do teste de frio. Para avaliação das alterações fisiológicas, realizou-se análise das isoenzimas esterase e álcool desidrogenase, nas temperaturas de 25ºC (ideal a germinação) e 13ºC (baixa temperatura). As demais características avaliadas foram germinação, índice de velocidade de germinação (IVG), comprimento do coleóptilo e massa seca, a 25ºC e 13ºC. De acordo com os resultados do teste de frio, as sementes das cultivares Lemont e Oro, foram as que melhor toleraram a baixa temperatura. Na análise isoenzimática, o frio provocou diminuição na expressão da enzima esterase e aumento na expressão da enzima álcool desidrogenase. Em relação às demais avaliações, o frio influenciou negativamente em todas as características avaliadas, principalmente nas cultivares BRS Agrisul e BRS Chuí.