scholarly journals Programmed chloroplast destruction during leaf senescence involves 13-lipoxygenase (13-LOX)

2016 ◽  
Vol 113 (12) ◽  
pp. 3383-3388 ◽  
Author(s):  
Armin Springer ◽  
ChulHee Kang ◽  
Sachin Rustgi ◽  
Diter von Wettstein ◽  
Christiane Reinbothe ◽  
...  
Keyword(s):  
Leaf Senescence ◽  
Critical Role ◽  
Transit Peptide ◽  
Physiological Changes ◽  
Pathogen Defense ◽  
Chloroplast Transit Peptide ◽  
Selective Destruction ◽  
Plastid Envelope ◽  
Volatile Aldehydes

Leaf senescence is the terminal stage in the development of perennial plants. Massive physiological changes occur that lead to the shut down of photosynthesis and a cessation of growth. Leaf senescence involves the selective destruction of the chloroplast as the site of photosynthesis. Here, we show that 13-lipoxygenase (13-LOX) accomplishes a key role in the destruction of chloroplasts in senescing plants and propose a critical role of its NH2-terminal chloroplast transit peptide. The 13-LOX enzyme identified here accumulated in the plastid envelope and catalyzed the dioxygenation of unsaturated membrane fatty acids, leading to a selective destruction of the chloroplast and the release of stromal constituents. Because 13-LOX pathway products comprise compounds involved in insect deterrence and pathogen defense (volatile aldehydes and oxylipins), a mechanism of unmolested nitrogen and carbon relocation is suggested that occurs from leaves to seeds and roots during fall.

scholarly journals TaClpS1, Negatively Regulates Wheat Resistance Against Puccinia striiformis f. sp. tritici

2020 ◽  
Author(s):  
Qian Yang ◽  
Md Ashraful Islam ◽  
Kunyan Cai ◽  
Shuxin Tian ◽  
Yan Liu ◽  
...  
Keyword(s):  
Immune Response ◽  
Ubiquitin Ligase ◽  
Puccinia Striiformis ◽  
E3 Ubiquitin Ligase ◽  
Transit Peptide ◽  
26S Proteasome ◽  
Plant Responses ◽  
Virus Induced Gene Silencing ◽  
Chloroplast Transit Peptide

Abstract Background: The degradation of intracellular proteins plays an essential role in plant responses to stressful environments. ClpS1 and E3 ubiquitin ligase function as adaptors for selecting target substrates in caseinolytic peptidase (Clp) proteases pathways and the 26S proteasome system, respectively. Currently, the role of E3 ubiquitin ligase in the plant immune response to pathogens is well defined. However, the role of ClpS1 in the plant immune response to pathogens remains unknown. Results: Here, we identified and characterized wheat (Triticum aestivum) ClpS1 (TaClpS1). TaClpS1 encoded 161 amino acids, contained a conserved ClpS domain and a chloroplast transit peptide (1-32 aa). TaClpS1 was found to be specifically localized in the chloroplast when expressed transiently in wheat protoplasts. The transcript level of TaClpS1 in wheat was significantly induced during infection by Puccinia striiformis f. sp. tritici (Pst). Knock-down of TaClpS1 via virus-induced gene silencing (VIGS) resulted in an increase in resistance against Pst, accompanied by an increase in the hypersensitive response (HR), accumulation of reactive oxygen species (ROS) and expression of TaPR1 and TaPR2, and a reduction in the growth of Pst. Furthermore, heterologous expression of TaClpS1 in Nicotiana benthamiana enhanced the infection by Phytophthora parasitica. Conclusions: These results suggest that TaClpS1 negatively regulates the resistance of wheat to Pst.

scholarly journals TaClpS1, Negatively Regulates Wheat Resistance Against Puccinia striiformis f. sp. tritici

2020 ◽  
Author(s):  
Qian Yang ◽  
Md Ashraful Islam ◽  
Kunyan Cai ◽  
Shuxin Tian ◽  
Yan Liu ◽  
...  
Keyword(s):  
Immune Response ◽  
Ubiquitin Ligase ◽  
Puccinia Striiformis ◽  
E3 Ubiquitin Ligase ◽  
Transit Peptide ◽  
26S Proteasome ◽  
Plant Responses ◽  
Virus Induced Gene Silencing ◽  
Chloroplast Transit Peptide

Abstract Background: The degradation of intracellular proteins plays an essential role in plant responses to stressful environments. ClpS1 and E3 ubiquitin ligase function as adaptors for selecting target substrates in caseinolytic peptidase (Clp) proteases pathways and the 26S proteasome system, respectively. Currently, the role of E3 ubiquitin ligase in the plant immune response to pathogens is well defined. However, the role of ClpS1 in the plant immune response to pathogens remains unknown. Results: Here, wheat (Triticum aestivum) ClpS1 (TaClpS1) was studied and resulted to encode 161 amino acids, containing a conserved ClpS domain and a chloroplast transit peptide (1-32 aa). TaClpS1 was found to be specifically localized in the chloroplast when expressed transiently in wheat protoplasts. The transcript level of TaClpS1 in wheat was significantly induced during infection by Puccinia striiformis f. sp. tritici (Pst). Knockdown of TaClpS1 via virus-induced gene silencing (VIGS) resulted in an increase in wheat resistance against Pst, accompanied by an increase in the hypersensitive response (HR), accumulation of reactive oxygen species (ROS) and expression of TaPR1 and TaPR2, and a reduction in the number of haustoria, length of infection hypha and infection area of Pst. Furthermore, heterologous expression of TaClpS1 in Nicotiana benthamiana enhanced the infection by Phytophthora parasitica. Conclusions: These results suggest that TaClpS1 negatively regulates the resistance of wheat to Pst.

scholarly journals TaClpS1, Negatively Regulates Wheat Resistance Against Puccinia striiformis f. sp. tritici

2020 ◽  
Author(s):  
Qian Yang ◽  
Md Ashraful Islam ◽  
Kunyan Cai ◽  
Shuxin Tian ◽  
Yan Liu ◽  
...  
Keyword(s):  
Immune Response ◽  
Ubiquitin Ligase ◽  
Puccinia Striiformis ◽  
E3 Ubiquitin Ligase ◽  
Transit Peptide ◽  
26S Proteasome ◽  
Plant Responses ◽  
Virus Induced Gene Silencing ◽  
Chloroplast Transit Peptide

Abstract Background: The degradation of intracellular proteins plays an essential role in plant responses to stressful environments. ClpS1 and E3 ubiquitin ligase function as adaptors for selecting target substrates in caseinolytic peptidase (Clp) proteases pathways and the 26S proteasome system, respectively. Currently, the role of E3 ubiquitin ligase in the plant immune response to pathogens is well defined. However, the role of ClpS1 in the plant immune response to pathogens remains unknown. Results: Here, wheat (Triticum aestivum) ClpS1 (TaClpS1) was studied and resulted to encode 161 amino acids, containing a conserved ClpS domain and a chloroplast transit peptide (1-32 aa). TaClpS1 was found to be specifically localized in the chloroplast when expressed transiently in wheat protoplasts. The transcript level of TaClpS1 in wheat was significantly induced during infection by Puccinia striiformis f. sp. tritici (Pst). Knockdown of TaClpS1 via virus-induced gene silencing (VIGS) resulted in an increase in wheat resistance against Pst, accompanied by an increase in the hypersensitive response (HR), accumulation of reactive oxygen species (ROS) and expression of TaPR1 and TaPR2, and a reduction in the number of haustoria, length of infection hypha and infection area of Pst. Furthermore, heterologous expression of TaClpS1 in Nicotiana benthamiana enhanced the infection by Phytophthora parasitica. Conclusions: These results suggest that TaClpS1 negatively regulates the resistance of wheat to Pst.

scholarly journals TaClpS1, Negatively Regulates Wheat Resistance Against Puccinia striiformis f. sp. tritici

2020 ◽  
Author(s):  
Qian Yang ◽  
Md Ashraful Islam ◽  
Kunyan Cai ◽  
Shuxin Tian ◽  
Yan Liu ◽  
...  
Keyword(s):  
Immune Response ◽  
Ubiquitin Ligase ◽  
Puccinia Striiformis ◽  
E3 Ubiquitin Ligase ◽  
Transit Peptide ◽  
26S Proteasome ◽  
Plant Responses ◽  
Virus Induced Gene Silencing ◽  
Chloroplast Transit Peptide

Abstract Background: The degradation of intracellular proteins plays an essential role in plant responses to stressful environments. ClpS1 and E3 ubiquitin ligase function as adaptors for selecting target substrates in caseinolytic peptidase (Clp) proteases pathways and the 26S proteasome system, respectively. Currently, the role of E3 ubiquitin ligase in the plant immune response to pathogens is well defined. However, the role of ClpS1 in the plant immune response to pathogens remains unknown. Results: Here, wheat (Triticum aestivum) ClpS1 (TaClpS1) was studied and resulted to encode 161 amino acids, containing a conserved ClpS domain and a chloroplast transit peptide (1-32 aa). TaClpS1 was found to be specifically localized in the chloroplast when expressed transiently in wheat protoplasts. The transcript level of TaClpS1 in wheat was significantly induced during infection by Puccinia striiformis f. sp. tritici (Pst). Knockdown of TaClpS1 via virus-induced gene silencing (VIGS) resulted in an increase in wheat resistance against Pst, accompanied by an increase in the hypersensitive response (HR), accumulation of reactive oxygen species (ROS) and expression of TaPR1 and TaPR2, and a reduction in the number of haustoria, length of infection hypha and infection area of Pst. Furthermore, heterologous expression of TaClpS1 in Nicotiana benthamiana enhanced the infection by Phytophthora parasitica. Conclusions: These results suggest that TaClpS1 negatively regulates the resistance of wheat to Pst.

scholarly journals Leaf senescence and clonal growth of white clover

1996 ◽  
Vol 6 ◽  
pp. 171-173
Author(s):  
S.M. Butcher ◽  
D.W. Fountain ◽  
M.T. Mcmanus
Keyword(s):  
Leaf Senescence ◽  
White Clover ◽  
Trifolium Repens ◽  
Clonal Growth ◽  
Plant Hormone ◽  
Leaf Tissue ◽  
Physiological Changes ◽  
Genes Encoding ◽  
Trifolium Repens L

Leaf senescence is a programmed event where resources are mobilised from older tissues to the meristematic regions of the plant. In white clover (Trifolium repens L.), leaf and stolon senescence have an important impact on the persistence of the legume in pasture. As part of our investigation of leaf senescence, we have evidence for a central role for the plant hormone ethylene and have identified genes encoding ethylene biosynthetic enzymes. In this paper we include data showing some physiological changes as leaf tissue undergoes senescence and present evidence for the role of ethylene in regulating this process. Keywords: chlorophyll, ethylene, senescence, stolon, leaf, Trifolium repens L.

scholarly journals TaClpS1, Negatively Regulates Wheat Resistance Against Puccinia Striiformis f. sp. Tritici

2020 ◽  
Author(s):  
Qian Yang ◽  
Kunyan Cai ◽  
Shuxin Tian ◽  
Yan Liu ◽  
Zhensheng Kang ◽  
...  
Keyword(s):  
Immune Response ◽  
Puccinia Striiformis ◽  
Transit Peptide ◽  
Transcript Level ◽  
26S Proteasome ◽  
Plant Responses ◽  
Virus Induced Gene Silencing ◽  
Chloroplast Transit Peptide ◽  
Clp Proteases

Abstract Background The degradation of intracellular proteins plays an essential role in plant responses to stressful environments. ClpS1 and ubiquitin ligases (E3) function as adaptors for selecting target substrates in caseinolytic peptidase (Clp) proteases pathways and the 26S proteasome system, respectively. Currently, the role of E3 in the plant immune response to pathogens is well defined. However, the role of ClpS1 in the plant immune response to pathogens remains unknown. Results Here, we identified and characterized wheat ClpS1 (TaClpS1). TaClpS1 encoded 161 amino acids, contained a conserved ClpS domain and a chloroplast transit peptide (1–32 aa). TaClpS1 was found to be specifically localized in the chloroplast when expressed transiently in wheat protoplasts. The transcript level of TaClpS1 in wheat was significantly induced during infection by Puccinia striiformis f. sp. tritici (Pst). Knock-down of TaClpS1 via virus-induced gene silencing (VIGS) resulted in an increase in resistance against Pst, accompanied by an increase in the hypersensitive response (HR), accumulation of reactive oxygen species (ROS) and expression of TaPR1 and TaPR2, and a reduction in the growth of Pst. Furthermore, heterologous expression of TaClpS1 in Nicotiana benthamiana enhanced the infection by Phytophthora parasitica. Conclusions These results suggest that TaClpS1 negatively regulates the resistance of wheat to Pst.

Increased growing-season productivity drives earlier autumn leaf senescence in temperate trees

Science ◽  
2020 ◽  
Vol 370 (6520) ◽  
pp. 1066-1071 ◽  
Author(s):  
Deborah Zani ◽  
Thomas W. Crowther ◽  
Lidong Mo ◽  
Susanne S. Renner ◽  
Constantin M. Zohner
Keyword(s):  
Leaf Senescence ◽  
Critical Role ◽  
Biotic Interactions ◽  
Growing Season ◽  
Environmental Drivers ◽  
Light Levels ◽  
Temperate Trees ◽  
Autumn Leaf

Changes in the growing-season lengths of temperate trees greatly affect biotic interactions and global carbon balance. Yet future growing-season trajectories remain highly uncertain because the environmental drivers of autumn leaf senescence are poorly understood. Using experiments and long-term observations, we show that increases in spring and summer productivity due to elevated carbon dioxide, temperature, or light levels drive earlier senescence. Accounting for this effect improved the accuracy of senescence predictions by 27 to 42% and reversed future predictions from a previously expected 2- to 3-week delay over the rest of the century to an advance of 3 to 6 days. These findings demonstrate the critical role of sink limitation in governing the end of seasonal activity and reveal important constraints on future growing-season lengths and carbon uptake of trees.

scholarly journals TaClpS1, negatively regulates wheat resistance against Puccinia striiformis f. sp. tritici

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Qian Yang ◽  
Md Ashraful Islam ◽  
Kunyan Cai ◽  
Shuxin Tian ◽  
Yan Liu ◽  
...  
Keyword(s):  
Immune Response ◽  
Ubiquitin Ligase ◽  
Puccinia Striiformis ◽  
E3 Ubiquitin Ligase ◽  
Transit Peptide ◽  
26S Proteasome ◽  
Plant Responses ◽  
Virus Induced Gene Silencing ◽  
Chloroplast Transit Peptide

Abstract Background The degradation of intracellular proteins plays an essential role in plant responses to stressful environments. ClpS1 and E3 ubiquitin ligase function as adaptors for selecting target substrates in caseinolytic peptidase (Clp) proteases pathways and the 26S proteasome system, respectively. Currently, the role of E3 ubiquitin ligase in the plant immune response to pathogens is well defined. However, the role of ClpS1 in the plant immune response to pathogens remains unknown. Results Here, wheat (Triticum aestivum) ClpS1 (TaClpS1) was studied and resulted to encode 161 amino acids, containing a conserved ClpS domain and a chloroplast transit peptide (1–32 aa). TaClpS1 was found to be specifically localized in the chloroplast when expressed transiently in wheat protoplasts. The transcript level of TaClpS1 in wheat was significantly induced during infection by Puccinia striiformis f. sp. tritici (Pst). Knockdown of TaClpS1 via virus-induced gene silencing (VIGS) resulted in an increase in wheat resistance against Pst, accompanied by an increase in the hypersensitive response (HR), accumulation of reactive oxygen species (ROS) and expression of TaPR1 and TaPR2, and a reduction in the number of haustoria, length of infection hypha and infection area of Pst. Furthermore, heterologous expression of TaClpS1 in Nicotiana benthamiana enhanced the infection by Phytophthora parasitica. Conclusions These results suggest that TaClpS1 negatively regulates the resistance of wheat to Pst.

scholarly journals Enzymatic product formation impairs both the chloroplast receptor-binding function as well as translocation competence of the NADPH: protochlorophyllide oxidoreductase, a nuclear-encoded plastid precursor protein.

1995 ◽  
Vol 129 (2) ◽  
pp. 299-308 ◽  
Author(s):  
S Reinbothe ◽  
C Reinbothe ◽  
S Runge ◽  
K Apel
Keyword(s):  
Aminolevulinic Acid ◽  
Transit Peptide ◽  
Precursor Protein ◽  
Receptor Protein ◽  
Chloroplast Envelope ◽  
Dependent Manner ◽  
Envelope Membrane ◽  
Chloroplast Transit Peptide ◽  
Plastid Envelope

The key enzyme of chlorophyll biosynthesis in higher plants, the light-dependent NADPH:protochlorophyllide oxidoreductase (POR, EC 1.6.99.1), is a nuclear-encoded plastid protein. Its posttranslational transport into plastids of barley depends on the intraplastidic availability of one of its substrates, protochlorophyllide (PChlide). The precursor of POR (pPOR), synthesized from a corresponding full-length barley cDNA clone by coupling in vitro transcription and translation, is enzymatically active and converts PChlide to chlorophyllide (Chlide) in a light- and NADPH-dependent manner. Chlorophyllide formed catalytically remains tightly but noncovalently bound to the precursor protein and stabilizes a transport-incompetent conformation of pPOR. As shown by in vitro processing experiments, the chloroplast transit peptide in the Chlide-pPOR complex appears to be masked and thus is unable to physically interact with the outer plastid envelope membrane. In contrast, the chloroplast transit peptide in the naked pPOR (without its substrates and its product attached to it) and in the pPOR-substrate complexes, such as pPOR-PChlide or pPOR-PChlide-NADPH, seems to react independently of the mature region of the polypeptide, and thus is able to bind to the plastid envelope. When envelope-bound pPOR-PChlide-NADPH complexes were exposed to light during a short preincubation, the enzymatically produced Chlide slowed down the actual translocation step, giving rise to the sequential appearance of two partially processed translocation intermediates. However, ongoing translocation induced by feeding the chloroplasts delta-aminolevulinic acid, a precursor of PChlide, was able to override these two early blocks in translocation, suggesting that the plastid import machinery has a substantial capacity to denature a tightly folded, envelope-bound precursor protein. Together, our results show that pPOR with Chlide attached to it is impaired both in the ATP-dependent step of binding to a receptor protein component of the outer chloroplast envelope membrane, as well as in the PChlide-dependent step of precursor translocation.

The Role of the SLP in Autism Spectrum Disorder Screening and Assessment

2008 ◽  
Vol 15 (2) ◽  
pp. 50-59 ◽  
Author(s):  
Amy Philofsky
Keyword(s):  
Language Development ◽  
Critical Role ◽  
Children With Autism ◽  
Autism Spectrum ◽  
Children With Asd ◽  
Prevalence Estimates ◽  
Notable Increase ◽  
Screening Assessment ◽  
Critical Components

AbstractRecent prevalence estimates for autism have been alarming as a function of the notable increase. Speech-language pathologists play a critical role in screening, assessment and intervention for children with autism. This article reviews signs that may be indicative of autism at different stages of language development, and discusses the importance of several psychometric properties—sensitivity and specificity—in utilizing screening measures for children with autism. Critical components of assessment for children with autism are reviewed. This article concludes with examples of intervention targets for children with ASD at various levels of language development.

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