A Branched SNF1-Related Protein Kinase 2 Signalling Cascade Controls ABA-Induced Ethylene Production and Regulates Both Fruit Ripening and Reproductive Growth.

Effects of temperature, light and leaf age on ethylene production and symptom expression in virus-infected tobacco leaves

The process of fruit ripening is normally viewed distinctly in climacteric and non-climacteric fruits. But, many fruits such as guava, melon, Japanese plum, Asian pear and pepper show climacteric as well as non-climacteric behaviour depending on the cultivar or genotype. Investigations on in planta levels of CO2 and ethylene at various stages of fruits during ripening supported the role and involvement of changes in the rate of respiration and ethylene production in non-climacteric fruits such as strawberry, grapes and citrus. Non-climacteric fruits are also reported to respond to the exogenous application of ethylene. Comparative analysis of plant-attached and plant-detached fruits did not show similarity in their ripening behaviour. This disparity is being explained in view of 1. Hypothetical ripening inhibitor, 2. Differences in the production, release and endogenous levels of ethylene, 3. Sensitivity of fruits towards ethylene and 4. Variations in the gaseous microenvironment among fruits and their varieties. Detailed studies on genetic and inheritance patterns along with the application of '-omics' research indicated that ethylene-dependent and ethylene-independent pathways coexist in both climacteric and non-climacteric fruits. Auxin levels also interact with ethylene in regulating ripening. These findings therefore reveal that the classification of fruits based on climacteric rise and/or ethylene production status is not very distinct or perfect. However, presence of a characteristic rise in CO2 levels and a burst in ethylene production in some non-climacteric fruits as well as the presence of system 2 of ethylene production point to a ubiquitous role for ethylene in fruit ripening.

Ethylene has long been known to be a critical signal controlling the ripening of climacteric fruits; however, the signaling mechanism underlying ethylene production during fruit development is unknown. Here, we report that two FERONIA-like receptor kinases (FERLs) regulate fruit ripening by modulating ethylene production in the climacteric fruit, apple (Malus×domestica). Bioinformatic analysis indicated that the apple genome contains 14 members of the FER family (MdFERL1–17), of these 17 FERLs, MdFERL6 was expressed at the highest level in fruit. Heterologous expression of MdFERL6 or MdFERL1, the apple homolog of Arabidopsis FER, in another climacteric fruit, tomato (Solanum lycopersicum) fruit delayed ripening and suppressed ethylene production. Overexpression and antisense expression of MdFERL6 in apple fruit calli inhibited and promoted ethylene production, respectively. Additionally, virus-induced gene silencing (VIGS) of SlFERL1, the tomato homolog of FER, promoted tomato fruit ripening and ethylene production. Both MdFERL6 and MdFERL1 physically interacted with MdSAMS (S-adenosylmethionine synthase), a key enzyme in the ethylene biosynthesis pathway. MdFERL6 was expressed at high levels during early fruit development, but dramatically declined when fruit ripening commenced, implying that MdFERL6 might limit ethylene production prior to fruit development and the ethylene production burst during fruit ripening. These results indicate that FERLs regulate apple and tomato fruit ripening, shedding light on the molecular mechanisms underlying ripening in climacteric fruit.

Carphology CRANIAL FIFTH COLUMNISTSOver time, and more rapidly in some disorders, our brains accumulate genetic mutations that we were not born with.A total of 131 human brains (44 neurotypical, 19 with Tourette syndrome, 9 with schizophrenia and 59 with autism) were analysed for somatic mutation following whole genome sequencing.Then rate of accumulating these variants were not uniform; most brains had 20-60 detectable single-nucleotide mutations, but 6% of brains harboured hundreds of somatic mutations.Mutations were more frequent at greater age and brains with autism showed an excess of variation in genes associated with transcription factor binding motifs in enhancerlike regions in the developing brain.If you are now worried about the health of your mutating bonce, can A Fo Ben reassure you that you cannot/have not passed these changes on to your children?

Oomycete pathogens can secrete hundreds of effectors into plant cells to interfere with the plant immune system during infection. Here, we identified a Arg-X-Leu-Arg (RXLR) effector protein from the most destructive pathogen of litchi (Litchi chinensis Sonn.), Peronophythora litchii, and named it P. litchii avirulence homolog 202 (PlAvh202). PlAvh202 could suppress cell death triggered by infestin 1 or avirulence protein 3a/resistance protein 3a in Nicotiana benthamiana and was essential for P. litchii virulence. In addition, PlAvh202 suppressed plant immune responses and promoted the susceptibility of N. benthamiana to Phytophthora capsici. Further research revealed that PlAvh202 could suppress ethylene (ET) production by targeting and destabilizing plant S-adenosyl-L-methionine synthetase (SAMS), a key enzyme in the ET biosynthesis pathway, in a 26S proteasome-dependent manner without affecting its expression. Transient expression of LcSAMS3 induced ET production and enhanced plant resistance, whereas inhibition of ET biosynthesis promoted P. litchii infection, supporting that litchi SAMS (LcSAMS) and ET positively regulate litchi immunity toward P. litchii. Overall, these findings highlight that SAMS can be targeted by the oomycete RXLR effector to manipulate ET-mediated plant immunity.

Detached ripening of non-climacteric strawberry impairs aroma profile and fruit quality

gamma-Irradiation of early climacteric (breaker) cherry tomatoes (Lycopersicon pimpinellifollium L.) caused a sharp burst in ethylene production during the first hour. The extent of ethylene production was dose dependent and was maximum at about 3 kilograys. The content of 1-aminocyclopropane-1-carboxylic acid (ACC), followed the same evolution as ethylene production, while malonyl ACC increased steadily with time in irradiated fruits. The burst in ethylene production was accompanied by a sharp stimulation of ACC synthase activity which began 15 minutes after irradiation. The stimulation was completely prevented by cycloheximide, but not by actinomycin d or cordycepin. In contrast with irradiation, mechanical wounding continuously stimulated ethylene production over several hours. gamma-Irradiation and cordycepin applied to wounded tissues both caused the cessation of this continuous increase, but the initial burst was still persisting. These data suggest that gamma-irradiation, like wounding, stimulates the translation of preexisting mRNAs. It also reduces, at least temporarily, the subsequent transcription-dependent stimulation of ethylene production. gamma-Irradiation greatly inhibited the activity of ethylene-forming enzyme at doses higher than 1 kilogray. Such sensitivity is in accordance with a highly integrated membranebound enzyme.

Ethylene biosynthesis and signaling are pivotal pathways in various plant aging processes, including fruit ripening. Kinetic models can be used to better understand metabolic pathways, but modeling of the ethylene-related pathways is limited and the link between these pathways remains unsolved. A transcriptomics-based kinetic model was developed, consisting of ordinary differential equations describing ethylene biosynthesis and signaling pathways in tomato during fruit development and ripening, both on- and off-vine. This model was calibrated against a large volume of transcriptomic, proteomic, and metabolic data during on-vine fruit development and ripening of tomato fruit grown in winter and summer. The model was validated using data on off-vine ripening of mature green harvested fruit grown in the same seasons. The ethylene biosynthesis pathway under different conditions appeared to be largely driven by gene expression levels. The ethylene regulation of fruit ripening of a heat tolerant tomato grown in different seasons was organised similarly but with quantitative differences at the targeted omics levels. This is reflected by some of the same parameters with distinct values for summer and winter fruit. The current model approach is a first attempt to model the ethylene signaling pathway starting from gene expression, the various protein-protein interactions, including a link with ethylene production, internal ethylene levels, and ethylene binding to its receptors.

Delayed ripening and improved fruit processing quality in tomato by RNAi-mediated silencing of three homologs of 1-aminopropane-1-carboxylate synthase gene

The banana, a typical climacteric fruit, undergoes a postharvest ripening process followed by a burst in ethylene production that signals the beginning of the climacteric period. Postharvest ripening plays an important role in improving the quality of the fruit as well as limiting its shelf life. To investigate the role of glutamate decarboxylase (GAD) in climacteric ethylene biosynthesis and fruit ripening in postharvest banana, a GAD gene was isolated from banana, designated MuGAD . Coincidently with climacteric ethylene production, MuGAD expression as well as the expression of the genes encoding the Musa 1-aminocyclopropane-1-carboxylate synthase ( MaACS1 ) and Musa 1-aminocyclopropane-1-carboxylate oxidase ( MaACO1 ) greatly increased during natural ripening and in ethylene-treated banana. Moreover, ethylene biosynthesis, ripening progress, and MuGAD , MaACS1 , and MaACO1 expression were enhanced by exogenous ethylene application and inhibited by 1-methylcyclopropene (1-MCP). Taken together, our results suggested that MuGAD is involved in the fruit ripening process in postharvest banana.

The respiratory climacteric, ethylene evolution and activities and expression of ethylene biosynthesis enzymes show a characteristic pattern in banana during ethylene induced ripening. A unique biphasic respiratory climacteric with a 10 and 6 fold increment in respiration rates on days 2 and 6 respectively after ethylene treatment is preceded by ethylene evolution on days 1 and 4 with 8.3 and 6.93 fold increments respectively. This represents a unique feature of ripening in banana. While ACC synthase transcript accumulation matched the respiratory climacteric, the ACC synthase activity and ACC oxidase transcript accumulation showed a different pattern. The most significant observation was the effect of 1-MCP on ACC content and in vitro ACC oxidase activity. Though 1-MCP treated fruit did not show any respiratory climacteric or burst in ethylene production, it did not inhibit completely ACC accumulation and in vitro ACC oxidase activity. No transcript accumulation of ACC synthase was observed at any time in 1-MCP treated fruits, whereas a basal level of ACC oxidase transcript was detected throughout. It is concluded that ethylene induced ripening of banana is characteristically different from that of other climacteric fruits and that ethylene biosynthesis may have more than one mechanisms operating during ripening which are tightly controlled at various levels.

Effects of methyl jasmonate on expression of genes involved in ethylene biosynthesis and signaling pathway during postharvest ripening of apple fruit

Heavy-metal-induced ethylene production in Arabidopsis thaliana

The economic value of fruit is reduced by having a short shelf life. Whangkeumbae is a type of sand pear (Pyrus pyrifolia) considered a climacteric fruit. The pear is famous for its smooth surface and good flavor. However, its shelf life is very short because of senescence and disease after harvest and a burst of ethylene (ET) production prompting the onset of fruit ripening. In plants, ETHYLENE INSENSITIVE3 (EIN3) and EIN3like (EIL), located in the nucleus, are important components of the ET signaling pathway and act as transcription factors. EIN3s and EILs belong to a small family involved in regulating the expression of ethylene response factor gene (ERF), whose encoding protein is the final component in the ET signaling pathway. The mutation of these components will cause defects in the ethylene pathway. In this study, one gene encoding an EIN3 was cloned and identified from Whangkeumbae and designated PpEIN3b. The deduced PpEIN3b contained a conserved EIN3 domain, a bipartite nuclear localization signal profile (NLS_BP), and an N-6 adenine-specific DNA methylase signature (N6_MTASE). PpEIN3b belongs to the EIN3 super-family by phylogenetic analysis. Quantitative RT-PCR (qRT-PCR) analysis revealed that PpEIN3b was preferentially expressed in fruit. Additionally, its expression was developmentally regulated during fruit ripening and senescence. Furthermore, PpEIN3b transcripts were obviously repressed by salicylic acid (SA) and glucose treatment in pear fruit and in diseased fruit, while it was significantly induced by 1-aminocyclopropane-1-carboxylic acid (ACC) treatment. Taken together, our results reveal the expression and regulation profiles of PpEIN3b and suggest that PpEIN3b might integrate SA, glucose, and ACC signaling to regulate fruit ripening and senescence in pear, which would provide a candidate gene for this regulation to obtain fruit with a long shelf life and improved economic value.

Although the role of the gynoecium in natural senescence of the carnation flower has long been suggested, it has remained a matter of dispute because petal senescence in the cut carnation flower was not delayed by the removal of gynoecium. In this study, the gynoecium was snapped off by hand, in contrast to previous investigations where removal was achieved by forceps or scissors. The removal of the gynoecium by hand prevented the onset of ethylene production and prolonged the vase life of the flower, demonstrating a decisive role of the gynoecium in controlling natural senescence of the carnation flower. Abscisic acid (ABA) and indole-3-acetic acid (IAA), which induced ethylene production and accelerated petal senescence in carnation flowers, did not stimulate ethylene production in the flowers with gynoecia removed (-Gyn flowers). Application of 1-aminocyclopropane-1-carboxylate (ACC), the ethylene precursor, induced substantial ethylene production and petal wilting in the flowers with gynoecia left intact, but was less effective at stimulating ethylene production in the -Gyn flowers and negligible petal in-rolling was observed. Exogenous ethylene induced autocatalytic production of the gas and petal wilting in the -Gyn flowers. These results indicated that ethylene generated in the gynoecium triggers the onset of ethylene production in the petals of carnation during natural senescence.