scholarly journals A Silk-Expressed Pectin Methylesterase Confers Cross-Incompatibility Between Wild and Domesticated Strains of Zea mays

2019 ◽  
Author(s):  
Yongxian Lu ◽  
Samuel A. Hokin ◽  
Jerry L. Kermicle ◽  
Mathew M. S. Evans

AbstractDespite being members of the same species, some strains of wild teosinte maintain themselves as a distinct breeding population by blocking fertilization by pollen from neighboring maize plants. These teosinte strains may be in the process of evolving into a separate species, since reproductive barriers that block gene flow are critical components in speciation. This trait is conferred by the Teosinte crossing barrier1-s (Tcb1-s) haplotype, making Tcb1 a speciation gene candidate. Tcb1-s contains a female gene that blocks non-self-type pollen and a male function that enables self-type pollen to overcome that block. The Tcb1-female gene encodes a Pectin Methylesterase, implying that modification of the pollen cell wall by the pistil is a key mechanism by which these teosinte females reject foreign (but closely related) pollen.One sentence summaryThe Tcb1-female gene encodes a Pectin Methylesterase that in teosinte silks prevents fertilization by maize pollen.


Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1649
Author(s):  
Hyang-Lan Eum ◽  
Seung-Hyun Han ◽  
Eun-Jin Lee

Improved methods are needed to extend the shelf life of strawberry fruits. The objective of this study was to determine the postharvest physiological mechanism of high-CO2 treatment in strawberries. Harvested strawberries were stored at 10 °C after 3 h of exposure to a treatment with 30% CO2 or air. Pectin and gene expression levels related to cell wall degradation were measured to assess the high-CO2 effects on the cell wall and lipid metabolism. Strawberries subjected to high-CO2 treatment presented higher pectin content and firmness and lower decay than those of control fruits. Genes encoding cell wall-degrading enzymes (pectin methylesterase, polygalacturonase, and pectate lyase) were downregulated after high-CO2 treatment. High-CO2 induced the expression of oligogalacturonides, thereby conferring defense against Botrytis cinerea in strawberry fruits, and lowering the decay incidence at seven days after its inoculation. Our findings suggest that high-CO2 treatment can maintain strawberry quality by reducing decay and cell wall degradation.





1991 ◽  
Vol 279 (2) ◽  
pp. 343-350 ◽  
Author(s):  
J Nari ◽  
G Noat ◽  
J Ricard

The hydrolysis of p-nitrophenyl acetate catalysed by pectin methylesterase is competitively inhibited by pectin and does not require metal ions to occur. The results suggest that the activastion by metal ions may be explained by assuming that they interact with the substrate rather than with the enzyme. With pectin used as substrate, metal ions are required in order to allow the hydrolysis to occur in the presence of pectin methylesterase. This is explained by the existence of ‘blocks’ of carboxy groups on pectin that may trap enzyme molecules and thus prevent the enzyme reaction occurring. Metal ions may interact with these negatively charged groups, thus allowing the enzyme to interact with the ester bonds to be cleaved. At high concentrations, however, metal ions inhibit the enzyme reaction. This is again understandable on the basis of the view that some carboxy groups must be adjacent to the ester bond to be cleaved in order to allow the reaction to proceed. Indeed, if these groups are blocked by metal ions, the enzyme reaction cannot occur, and this is the reason for the apparent inhibition of the reaction by high concentrations of metal ions. Methylene Blue, which may be bound to pectin, may replace metal ions in the ‘activation’ and ‘inhibition’ of the enzyme reaction. A kinetic model based on these results has been proposed and fits the kinetic data very well. All the available results favour the view that metal ions do not affect the reaction through a direct interaction with enzyme, but rather with pectin.



Genes ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 755
Author(s):  
Angyan Ren ◽  
Rana Ahmed ◽  
Huanyu Chen ◽  
Linhe Han ◽  
Jinhao Sun ◽  
...  

Cell walls are basically complex with dynamic structures that are being involved in several growth and developmental processes, as well as responses to environmental stresses and the defense mechanism. Pectin is secreted into the cell wall in a highly methylesterified form. It is able to perform function after the de-methylesterification by pectin methylesterase (PME). Whereas, the pectin methylesterase inhibitor (PMEI) plays a key role in plant cell wall modification through inhibiting the PME activity. It provides pectin with different levels of degree of methylesterification to affect the cell wall structures and properties. The PME activity was analyzed in six tissues of Sorghum bicolor, and found a high level in the leaf and leaf sheath. PMEI families have been identified in many plant species. Here, a total of 55 pectin methylesterase inhibitor genes (PMEIs) were identified from S. bicolor whole genome, a more detailed annotation of this crop plant as compared to the previous study. Chromosomal localization, gene structures and sequence characterization of the PMEI family were analyzed. Moreover, cis-acting elements analysis revealed that each PMEI gene was regulated by both internal and environmental factors. The expression patterns of each PMEI gene were also clustered according to expression pattern analyzed in 47 tissues under different developmental stages. Furthermore, some SbPMEIs were induced when treated with hormonal and abiotic stress. Taken together, these results laid a strong foundation for further study of the functions of SbPMEIs and pectin modification during plant growth and stress responses of cereal.



2020 ◽  
Vol 39 (9) ◽  
pp. 1185-1197
Author(s):  
Mohsin Abbas Zaidi ◽  
Stephen J. B. O’Leary ◽  
Christine Gagnon ◽  
Denise Chabot ◽  
Shaobo Wu ◽  
...  


1989 ◽  
Vol 67 (3) ◽  
pp. 817-821 ◽  
Author(s):  
A. Raymond Miller ◽  
Joseph P. Dalmasso ◽  
Dale W. Kretchman

Variation of cell wall degrading enzyme activities and tissue firmness from the petal senescence to overripe stages of fruit development was studied in greenhouse-grown cucumbers (Cucumis sativus L. cv. Heinz 3534). Cucumbers exhibited a typical sigmoidal growth curve with a short lag phase (0–8 days after pollination) and extended log phase (8–28 days) followed by a stationary phase. Mesocarp firmness decreased between 10 and 20 days after pollination, then increased until 32 days after pollination. This decrease of mesocarp firmness was accompanied by increased activity of cellulase (3.5-fold), polygalacturonase (20-fold), pectin methylesterase (4-fold), and xylanase (9-fold). By contrast, carpel tissue firmness declined from 8–20 days after pollination, and remained low until 32 days after pollination. Only polygalacturonase and xylanase activities exhibited significant increases (5- and 6-fold, respectively) during softening of this tissue. Further, these peaks of enzyme activity in the carpel occurred 10 days before the corresponding peaks in the mesocarp. These data suggest that mesocarp and carpel tissues of cucumber soften by similar, but not identical mechanisms.



1957 ◽  
Vol 10 (4) ◽  
pp. 426 ◽  
Author(s):  
KT Glasziou

It is shown that the plant auxins 3�indolylacetic acid, 2,4-dichlorophenoxyacetic acid, and a�naphthalene acetic acid are effective in binding pectin methylesterase (PME) to cell wall preparations from tobacco pith and tubers of the Jerusalem artichoke.



Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1558
Author(s):  
Nathan T. Reem ◽  
Lauran Chambers ◽  
Ning Zhang ◽  
Siti Farah Abdullah ◽  
Yintong Chen ◽  
...  

Pectin is a critical component of the plant cell wall, supporting wall biomechanics and contributing to cell wall signaling in response to stress. The plant cell carefully regulates pectin methylesterification with endogenous pectin methylesterases (PMEs) and their inhibitors (PMEIs) to promote growth and protect against pathogens. We expressed Aspergillus nidulans pectin methylesterase (AnPME) in Arabidopsis thaliana plants to determine the impacts of methylesterification status on pectin function. Plants expressing AnPME had a roughly 50% reduction in methylester content compared with control plants. AnPME plants displayed a severe dwarf phenotype, including small, bushy rosettes and shorter roots. This phenotype was caused by a reduction in cell elongation. Cell wall composition was altered in AnPME plants, with significantly more arabinose and significantly less galacturonic acid, suggesting that plants actively monitor and compensate for altered pectin content. Cell walls of AnPME plants were more readily degraded by polygalacturonase (PG) alone but were less susceptible to treatment with a mixture of PG and PME. AnPME plants were insensitive to osmotic stress, and their susceptibility to Botrytis cinerea was comparable to wild type plants despite their compromised cell walls. This is likely due to upregulated expression of defense response genes observed in AnPME plants. These results demonstrate the importance of pectin in both normal growth and development, and in response to biotic and abiotic stresses.



Cell ◽  
2019 ◽  
Vol 176 (4) ◽  
pp. 856-868.e10 ◽  
Author(s):  
Asja Radja ◽  
Eric M. Horsley ◽  
Maxim O. Lavrentovich ◽  
Alison M. Sweeney


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