scholarly journals Expression of Ethylene Biosynthetic Genes in the Gynoecium and Receptacle Associated With Sepal Abscission During Senescence in Delphinium Grandiflorum

Author(s):  
Mitsutoshi Okamoto ◽  
Tomoko Niki ◽  
Mirai Azuma ◽  
Kenichi Shibuya ◽  
Kazuo Ichimura

Abstract Delphinium flowers are highly sensitive to ethylene and its sepals abscise during senescence, which is associated with increases in 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS) and ACC oxidase (ACO) activities and ethylene production in gynoecium and receptacle. Three ACS genes (DgACS1, DgACS2, and DgACS3) and three ACO genes (DgACO1, DgACO2, and DgACO3) were cloned from Delphinium grandiflorum cv. Super Grand Blue. To investigate the contribution of these genes to ethylene production, their expression was analyzed in these genes in the gynoecium and receptacle during natural senescence and following ethylene exposure and pollination. Ethylene production in the gynoecium and receptacle increased during natural flower senescence. The transcript levels of the ACS and ACO genes in these organs, excluding DgACS2 in the receptacle, increased during senescence. Exposure to ethylene accelerated sepal abscission and more strongly increased ethylene production in the receptacle than in the gynoecium. DgACS1 transcript levels in the gynoecium and DgACS2 and DgACO3 transcript levels in the receptacle were increased by ethylene exposure. Pollination accelerated sepal abscission and increased ethylene production in the gynoecium and receptacle. Pollination slightly affected ACS and ACO transcript levels in the gynoecium, whereas DgACO3 transcript level in the receptacle were markedly increased. These results reveal that ACS and ACO gene expression is differently regulated in the gynoecium and receptacle, and some of these genes are more strongly upregulated by ethylene exposure and pollination in the receptacle than in the gynoecium, suggesting the significance of the receptacle to sepal abscission.

1991 ◽  
Author(s):  
Sharman O'Neill ◽  
Abraham Halevy ◽  
Amihud Borochov

The project investigated the molecular genetic and biochemical basis of pollination-induced senescence of Phalaenopsis flowers. This experimental system offered unique advantages in that senescence is strictly regulated by pollination, providing the basis to experimentally initiate and synchronize senescence in populations of flowers. The postpollination syndrome in the Phalaenopsis orchid system was dissected by investigating the temporal and spatial regulation of ACC synthase gene expression. In the stigma, pollen-borne auxin induces the expression of the auxin-regulated ACC synthase (PS-ACS2) gene, resulting in ACC synthesis within 1 h following pollination. Newly formed ACC is oxidized by basal constitutive ACC oxidase to ethylene, which then induces the expression of the ethylene-regulated ACC synthase(PS-ACS1) and oxidase (ACO1) genes for further autocatalytic production of ethylene. It is speculated that during the 6-h period following pollination, emasculation leads to the production or release of a sensitivity factor that sensitizes the cells of the stigma to ethylene. ACC and ethylene molecules are translocated from the stigma to the labellum and perianth where ethylene induces the expression of PS-ACS1 and ACO1 resulting in an increased production of ACC and ethylene. Organ-localized ethylene is responsible for inrolling and senescence of the labellum and perianth. The regulation of ethylene sensitivity and signal transduction events in pollinated flowers was also investigated. The increase in ethylene sensitivity appeared in both the flower column and the perianth, and was detected as early as 4 h after pollination. The increase in ethylene sensitivity following pollination was not dependent on endogenous ethylene production. Application of linoleic and linoleic acids to Phalaenopsis and Dendrobium flowers enhanced their senescence and promoted ethylene production. Several major lipoxygenase pathway products including JA-ME, traumatic acid, trans-2-hexenal and cis-3-hexenol, also enhanced flower senescence. However, lipoxygenase appears to not be directly involved in the endogenous regulation of pollination-induced Phalaenopsis and Dendrobium flower senescence. The data suggest that short-chain saturated fatty acids may be the ethylene "sensitivity factors" produced following pollination, and that their mode of action involves a decrease in the order of specific regions i the membrane lipid bilayer, consequently altering ethylene action. Examination of potential signal transduction intermediates indicate a direct involvement of GTP-binding proteins, calcium ions and protein phosphorylation in the cellular signal transduction response to ethylene following pollination. Modulations of cytosolic calcium levels allowed us to modify the flowers responsiveness to ethylene.


1996 ◽  
Vol 23 (4) ◽  
pp. 479 ◽  
Author(s):  
M Gallardo ◽  
I Sanchez-Calle ◽  
PMD Rueda ◽  
AJ Matilla

Germination of chickpea (Cicer arietinum L.) was inhibited by supraoptimal temperatures of 30 or 35�C, but the inhibition was alleviated by a relatively low concentration (1 mM) of putrescine (Put). This allevation may be due to (a) stimulation of the 1-aminocyclopropane-1-carboxylate (ACC) synthase and ACC oxidase activities; (b) increased levels of ACC and decreased levels of 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC); or (c) strongly increased ethylene production. Put at 10 mM did not alleviate thermoinhibition, although, as with Put at 1 mM, it did inhibit adenosyl-methionine (AdoMet) decarboxylase. Alleviation conditions resulted in: (a) an induced accumulation of free Put (S) and Put conjugated to substances of low (HS) and high (HP) molecular weight; (b) a decrease in spermidine (Spd) and spermine (Spm) (S and HP); and (c) no alteration in the levels of Spd and Spm (HS) with respect to the absence of Put (1 mM) at 30�C. In the presence of Put (10 mM), increased accumulation of Put (S, HS and HP) was detected, but with a sharp decrease of Spd and Spm (S and HS).


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sandhya Rani Kuanar ◽  
Kutubuddin Ali Molla ◽  
Krishnendu Chattopadhyay ◽  
Ramani Kumar Sarkar ◽  
Pravat Kumar Mohapatra

AbstractIn the recent time, Submergence1 (Sub1)QTL, responsible for imparting tolerance to flash flooding, has been introduced in many rice cultivars, but resilience of the QTL to stagnant flooding (SF) is not known. The response of Sub1-introgression has been tested on physiology, molecular biology and yield of two popular rice cultivars (Swarna and Savitri) by comparison of the parental and Sub1-introgression lines (SwarnaSub1 and SavitriSub1) under SF. Compared to control condition SF reduced grain yield and tiller number and increased plant height and Sub1- introgression mostly matched these effects. SF increased ethylene production by over-expression of ACC-synthase and ACC-oxidase enzyme genes of panicle before anthesis in the parental lines. Expression of the genes changed with Sub1-introgression, where some enzyme isoform genes over-expressed after anthesis under SF. Activities of endosperm starch synthesizing enzymes SUS and AGPase declined concomitantly with rise ethylene production in the Sub1-introgressed lines resulting in low starch synthesis and accumulation of soluble carbohydrates in the developing spikelets. In conclusion, Sub1-introgression into the cultivars increased susceptibility to SF. Subjected to SF, the QTL promoted genesis of ethylene in the panicle at anthesis to the detriment of grain yield, while compromising with morphological features like tiller production and stem elongation.


1999 ◽  
Vol 5 (3) ◽  
pp. 223-228 ◽  
Author(s):  
C. Larrigaudiere ◽  
I. Recasens ◽  
J. Graell ◽  
M. Vendrell

Changes in 1-aminocyclopropane-1-carboxylic acid metabolism in apples ( Malus domestica Borkh cv Granny Smith) were studied in relation to cold storage. Emphasis was given to the differential re sponsiveness of fruits to cold treatment as a function of stage of maturity at harvest. Fruits were held at 1 or 20 °C for 30 days, respectively, or exposed to 1 °C for 10 days and then storaged at 20 °C for up to 30 days. Fruits at 20 °C showed typical climacteric behavior. Differences at 1 °C between maturity stages in ethylene production and ACC oxidase activity were abolished, which showed that cold treatment is an important inducer of climacteric rise in preclimacteric Granny Smith apples. At 1 °C, ethylene production was lower than at 20 °C and the maxima in production were similar for all the stages of maturity, but took place at different times which corresponded exactly to the initial differ ences in harvest dates. After the transfer to 20 °C, fruits exhibited similar behavior as regards ethyl ene production, ACC oxidase activity, and ACC and MACC levels in relation to a harmonization process which is discussed in this study.


2001 ◽  
Vol 28 (5) ◽  
pp. 409 ◽  
Author(s):  
Saichol Ketsa ◽  
Kanokporn Bunya-atichart ◽  
Wouter G. van Doorn

Dendrobium ‘Pompadour’ flowers fade early following pollination. This is associated with increased ethylene production and early epinasty. These effects are also produced by application of 1-aminocyclopropane-1-carboxylic acid (ACC) on the stigma. Pollen (one anther each) from Ruellia tuberosa L. (Acanthaceae) and Caesalpinia pulcherrima (L.) Sw. (Fabaceae) also increased ethylene production and caused early epinasty and fading. Pollen of Hibiscus schizopetalus (Mast.) Hook.f. (Malvaceae), in contrast, had no effect. R. tuberosa pollen increased ACC concentration and ACC synthase activity of the orchid flowers. Aminooxyacetic acid (AOA) pretreatment prior to R. tuberosa pollination prevented early fading, epinasty and the increase in ethylene production. It also prevented the increase in ACC concentration, and ACC synthase activity. Ovary growth was stimulated by Dendrobium ‘Pompadour’ pollinia, not by any of the incompatible pollen. Applied ACC did not promote ovary growth. It is concluded that incompatible pollen can hasten senescence and epinasty by increasing ACC synthase activity and ethylene production. Ovary growth, in contrast, is apparently not primarily regulated by ethylene.


2019 ◽  
pp. jcb.201904046 ◽  
Author(s):  
Jiah Kim ◽  
Neha Chivukula Venkata ◽  
Gabriela Andrea Hernandez Gonzalez ◽  
Nimish Khanna ◽  
Andrew S. Belmont

Many active genes reproducibly position near nuclear speckles, but the functional significance of this positioning is unknown. Here we show that HSPA1B BAC transgenes and endogenous Hsp70 genes turn on 2–4 min after heat shock (HS), irrespective of their distance to speckles. However, both total HSPA1B mRNA counts and nascent transcript levels measured adjacent to the transgene are approximately twofold higher for speckle-associated alleles 15 min after HS. Nascent transcript level fold-increases for speckle-associated alleles are 12–56-fold and 3–7-fold higher 1–2 h after HS for HSPA1B transgenes and endogenous genes, respectively. Severalfold higher nascent transcript levels for several Hsp70 flanking genes also correlate with speckle association at 37°C. Live-cell imaging reveals that HSPA1B nascent transcript levels increase/decrease with speckle association/disassociation. Initial investigation reveals that increased nascent transcript levels accompanying speckle association correlate with reduced exosome RNA degradation and larger Ser2p CTD-modified RNA polymerase II foci. Our results demonstrate stochastic gene expression dependent on positioning relative to a liquid-droplet nuclear compartment through “gene expression amplification.”


2001 ◽  
Vol 183 (24) ◽  
pp. 7371-7380 ◽  
Author(s):  
Jian-Ming Lee ◽  
Shehui Zhang ◽  
Soumitra Saha ◽  
Sonia Santa Anna ◽  
Can Jiang ◽  
...  

ABSTRACT We have developed an antisense oligonucleotide microarray for the study of gene expression and regulation in Bacillus subtilis by using Affymetrix technology. Quality control tests of the B. subtilis GeneChip were performed to ascertain the quality of the array. These tests included optimization of the labeling and hybridization conditions, determination of the linear dynamic range of gene expression levels, and assessment of differential gene expression patterns of known vitamin biosynthetic genes. In minimal medium, we detected transcripts for approximately 70% of the known open reading frames (ORFs). In addition, we were able to monitor the transcript level of known biosynthetic genes regulated by riboflavin, biotin, or thiamine. Moreover, novel transcripts were also detected within intergenic regions and on the opposite coding strand of known ORFs. Several of these novel transcripts were subsequently correlated to new coding regions.


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