Abscisic acid and stress treatment are essential for the acquisition of embryogenic competence by carrot somatic cells

Sugarcane (Saccharum spp.) is one of the most important crops for sugar, biofuel, and bioenergy production and has become an important commodity in the worldwide agricultural market in more than 100 countries. In this study, label-free quantitative proteomics and phosphoproteomics analyses were performed to investigate signaling events related to somatic embryo maturation and differentiation in sugarcane. Embryogenic callus (EC) at multiplication (EC0) and after 14 days (EC14) of maturation were compared. The EC14/EC0 comparison found that 251 phosphoproteins and 700 proteins were differentially regulated and accumulated, respectively. Metabolic pathway analysis showed that these proteins and phosphoproteins were enriched in lysine degradation and starch/sucrose metabolism during multiplication, whereas the differentiation of somatic embryos was found to involve the regulation of energetic metabolism, including the TCA cycle, oxidative phosphorylation, and carbon metabolism. Multiplication-related phosphoproteins were mainly associated with abscisic acid responses and transcriptional regulation of the TOPLESS (TPL), SNF1 kinase homolog 10 (KIN10), SEUSS (SEU), and LEUNIG_HOMOLOG (LUH) proteins. Among the maturation-related phosphoproteins, the phosphorylation of light harvesting complex photosystem ii, CURVATURE THYLAKOID 1B, vacuolar proton ATPase A1 and phytochrome interacting factor 3-LIKE 5 was found to be associated with bioenergetic metabolism and carbon fixation. A motif analysis revealed 15 phosphorylation motifs, and among these, the [D-pS/T-x-D] motif was unique among the phosphopeptides identified during somatic embryo differentiation. A coexpression network analysis of proteins and phosphoproteins revealed interactions among SNF1-related protein kinase 2 (SnRK2), abscisic acid responsive elements-binding factor 2 (ABF2), and KIN10, which indicated the role of these proteins in embryogenic competence in EC0. The interactions among ubiquitin-conjugating enzyme 5, ubiquitin-conjugating enzyme 35, small ubiquitin-like modifier 1, and histone deacetylase 1 may be involved in posttranslational protein modification during embryo maturation. Argonaute 1 (AGO1) also interacts with POLTERGEIST (POL) and may integrate gene silencing with the regulation of meristem identity during somatic embryo development. These results reveal novel dynamics of protein regulation in somatic embryogenesis and identify new potential players in somatic embryo differentiation and their phosphosites.

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Abscisic Acid Content and Sugar Metabolism of Peaches Grown under Water Stress

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.125.4.425 ◽

2000 ◽

Vol 125 (4) ◽

pp. 425-428 ◽

Cited By ~ 23

Author(s):

Kenji Kobashi ◽

Hiroshi Gemma ◽

Shuichi Iwahori

Keyword(s):

Abscisic Acid ◽

Water Stress ◽

Prunus Persica ◽

Sugar Metabolism ◽

Sugar Accumulation ◽

Stress Treatment ◽

Severe Water Stress ◽

Peach Trees ◽

The Relationship ◽

Abscisic Acid Content

A water stress treatment was imposed on peach trees [Prunus persica (L.) Batsch `Kansuke Hakuto' (Peach Group)] to elucidate the relationship among sugar accumulation, sugar metabolism, and abscisic acid (ABA) in fruit under water stress. Treatment was carried out on peach trees grown in containers from 8 July 1996 [80 days after full bloom (DAFB)] for 16 days, to achieve a predawn water potential of -0.8 to -1.1 MPa compared to that of -0.4 to -0.6 MPa in control trees. Levels of sorbitol, sucrose, and total sugars, as well as the activity of sorbitol oxidase increased in fruit of water stressed trees under moderate water stress (-0.8 MPa), whereas under severe water stress (-1.1 MPa), no difference between the waterstressed trees and the controls was observed. Water stress also induced an increase in ABA in the fruit. These initial results indicated that water-stress-induced ABA accelerated sugar accumulation in peaches by activating sorbitol metabolism.

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3-D examination of the cytoskeletal sheets of mammalian eggs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100124975 ◽

1992 ◽

Vol 50 (1) ◽

pp. 914-915

Author(s):

Carolyn A. Larabell ◽

David G. Capco ◽

G. Ian Gallicano ◽

Robert W. McGaughey ◽

Karsten Dierksen ◽

...

Keyword(s):

Actin Filaments ◽

Somatic Cells ◽

Freeze Fracture ◽

Blastocyst Stage ◽

Cell Cytoplasm ◽

Planar Structures ◽

Cytoskeletal Network ◽

Entire Cell ◽

Cytoskeletal Networks ◽

Mammalian Eggs

Mammalian eggs and embryos contain an elaborate cytoskeletal network of “sheets” which are distributed throughout the entire cell cytoplasm. Cytoskeletal sheets are long, planar structures unlike the cytoskeletal networks typical of somatic cells (actin filaments, microtubules, and intermediate filaments), which are filamentous. These sheets are not found in mammalian somatic cells nor are they found in nonmammalian eggs or embryos. Evidence that they are, indeed, cytoskeletal in nature is derived from studies demonstrating that 1) the sheets are retained in the detergent-resistant cytoskeleton fraction; 2) there are no associated membranes (determined by freeze-fracture); and 3) the sheets dissociate into filaments at the blastocyst stage of embryogenesis. Embedment-free sections of hamster eggs viewed at 60 kV show sheets running across the egg cytoplasm (Fig. 1). Although this approach provides excellent global views of the sheets and their reorganization during development, the mechanism of image formation for embedment-free sections does not permit evaluation of the sheets at high resolution.

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