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Kamdee C.,Kasetsart University | Kamdee C.,Phetchaburi Rajabhat University | Kirasak K.,Kasetsart University | Kirasak K.,Khon Kaen Field Crops Research Center | And 3 more authors.
Journal of Plant Physiology | Year: 2015

Cut Iris flowers (Iris x hollandica, cv. Blue Magic) show visible senescence about two days after full opening. Epidermal cells of the outer tepals collapse due to programmed cell death (PCD). Transmission electron microscopy (TEM) showed irregular swelling of the cell walls, starting prior to cell collapse. Compared to cells in flowers that had just opened, wall thickness increased up to tenfold prior to cell death. Fibrils were visible in the swollen walls. After cell death very little of the cell wall remained. Prior to and during visible wall swelling, vesicles (paramural bodies) were observed between the plasma membrane and the cell walls. The vesicles were also found in groups and were accompanied by amorphous substance. They usually showed a single membrane, and had a variety of diameters and electron densities. Cut Dendrobium hybrid cv. Lucky Duan flowers exhibited visible senescence about 14 days after full flower opening. Paramural bodies were also found in Dendrobium tepal epidermis and mesophyll cells, related to wall swelling and degradation. Although alternative explanations are well possible, it is hypothesized that paramural bodies carry enzymes involved in cell wall breakdown. The literature has not yet reported such bodies in association with senescence/PCD. © 2015 Elsevier GmbH. Source

Ngamhui N.-O.,Khon Kaen University | Akkasaeng C.,Khon Kaen University | Zhu Y.J.,Hawaii Agriculture Research Center | Tantisuwichwong N.,Khon Kaen University | And 2 more authors.
Plant OMICS | Year: 2012

In many areas of the world, water stress is the major constraint limiting the productivity of sugarcane. The objective of this study was to identify proteins that were differentially expressed in sugarcane leaves in response to a water deficit treatment to describe the sugarcane responses at the cellular and molecular levels. Drought-tolerant sugarcane cultivar Khon Kaen 3 stalk cuttings were grown under a controlled environment in a growth chamber where a water deficit treatment was imposed by withholding watering for 5 days. The treatment group continuously received an adequate water supply. Soil moisture content (SMC), leaf water potential (LWP) and relative water content (RWC) were recorded to quantify the water deficit stress. Leaf proteins from non- and water-stressed plants were separated using two-dimensional electrophoresis (2-DE). Image analysis was performed on the electrophoresis gel to locate proteins that were differentially expressed between treatments, which were then identified using liquid chromatography coupled with electrospray ionization ion trap subjected to mass spectrometry/mass spectrometry analysis (LC-ESI-IT-MS/MS) and characterized. Two proteins involved in light-dependent reactions, chlorophyll a-b binding protein 1B-21 and chloroplastic and oxygen-evolving enhancer protein 1, were up-regulated by the stress treatment. Enzymes known to participate in antioxidant networks, including chloroplastic copper-zinc superoxide dismutase (CuZn-SOD), two-cysteine peroxiredoxin (2-Cys Prx) BAS1, superoxide dismutase [manganese] (SOD [Mn]) 3.1, SOD [Mn] 3.4, and isoflavone reductase (IFR) homolog IRL, were also up-regulated. These enzymes all used NADPH as the reducing equivalent, suggesting that linear electron flow (LEF) may dominate the total electron transport activities in sugarcane leaves under water deficit. In addition, two isoforms of ATP synthase beta and ATP synthase alpha subunits were up-regulated under water deficit, indicating that LEF was coupled to the generation of electrochemical gradients across the thylakoid membranes, leading to an increased abundance of ATP synthase beta and ATP synthase alpha subunits. There was increased abundance of a 16.9 kDa class I heat shock protein (HSP) and two isoforms of the elongation factor (EF-Tu) proteins, which are associated with heat tolerance. The identification of proteins regulated by water stress could lead to a better understanding of the cellular response to dehydration, which is an important and fundamental part of improving the stress tolerance of crops. Source

Van Doorn W.G.,University of California at Davis | Kirasak K.,Kasetsart University | Kirasak K.,Khon Kaen Field Crops Research Center | Ketsa S.,Postharvest Technology Innovation Center | Ketsa S.,Kasetsart University
Autophagy | Year: 2013

In Dendrobium flowers some tepal mesophyll cells showed cytoplasmic areas devoid of large organelles. Such amorphous areas comprised up to about 40% of the cross-section of a cell. The areas were not bound by a membrane. The origin of these areas is not known. We show data suggesting that they can be formed from vesicle-like organelles. The data imply that these organelles and other material become degraded inside the cytoplasm. This can be regarded as a form of autophagy. The amorphous areas became surrounded by small vacuoles, vesicles or double membranes. These seemed to merge and thereby sequester the areas. Degradation of the amorphous areas therefore seemed to involve macroautophagy. © 2013 Landes Bioscience. Source

Srivong T.,Khon Kaen University | Zhu Y.J.,Hawaii Agriculture Research Center | Pongdontri P.,Khon Kaen University | Pliansinchai U.,MitrPhol Sugarcane Research Center | And 4 more authors.
Chiang Mai Journal of Science | Year: 2015

The response of three sugarcane genotypes with differential sucrose accumulation to MS medium + 2, 4-dichlorophenoxyacetic acid (2, 4-D) and/or kinetin (kn) was investigated. On MS + 2, 4-D (2 mg/l) + kn (0.5 mg/l), Louisiana Purple (LAP) had the highest callus induction (95.80 %), followed by H65-7052 (82.68 %) and Molokai (MOL) (62.58 %). Rapid callus induction was optimized by using different concentrations of 2, 4-D (1, 2, 3, 4 and 5 mg/l) or 2, 4-D (2 mg/l) + kn (0.5 mg/l). The results revealed that increased callus weight was significantly different among genotypes and treatments. The value averaged over all the treatments was highest in H65-7052 (1.60 g), followed by LAP (0.93 g) and MOL (0.74 g). MS + 2, 4-D (1-2 mg/l) or MS + 2, 4-D (2 mg/l) + kn (0.5 mg/l) could cause rapid callus growth in all the three sugarcane genotypes. For plant regeneration, all cultured calli on different media exhibited good response to MS. The number of organogenic calli averaged over all the treatments was highest in MOL (61.6), followed by LAP (54.6) and H65-7052 (11.3). The most suitable culture medium for MOL and LAP was MS + 2, 4-D (1 mg/l), while MS + 2,4-D (1 mg/l) or MS + 2,4-D (2 mg/l) + kn (0.5 mg/l) was most appropriate for H65-7052. Moreover, sucrose accumulation in relation to the expression of soluble acid invertase (SAI) gene was measured in calli and plantlets. The highest callus sucrose concentration was found in LAP (141.28 μmol/g FW), followed by H65-7052 (133.79 μmol/g FW) and MOL (41.05 μmol/g FW). The plantlet sucrose concentration showed a similar pattern. The SAI expression in both the callus and plantlet of H65-7052 and LAP was lower than that of MOL. In both systems, sucrose accumulation was negatively correlated with the increase in SAI expression. It may be concluded that callus and plantlet can be used as the model system for investigating sucrose accumulation in sugarcane. © 2015, Chiang Mai University. All rights reserved. Source

van Doorn W.G.,University of California at Davis | Kirasak K.,Khon Kaen Field Crops Research Center | Ketsa S.,Kasetsart University | Ketsa S.,Academy of Science
Journal of Plant Physiology | Year: 2015

Prior to flower opening, mesophyll cells at the vascular bundles of Dendrobium tepals showed a large increase in vacuolar volume, partially at the expense of the cytoplasm. Electron micrographs indicated that this increase in vacuolar volume was mainly due to vacuole fusion. Macroautophagous structures typical of plant cells were observed. Only a small part of the decrease in cytoplasmic volume seemed due to macroautophagy. The vacuoles contained vesicles of various types, including multilamellar bodies. It was not clear if these vacuolar inclusions were due to macroautophagy or microautophagy. Only a single structure was observed of a protruding vacuole, indicating microautophagy. It is concluded that macroautophagy occurs in these cells but its role in vacuole formation seems small, while a possible role of microautophagy in vacuole formation might be hypothesized. Careful labeling of organelle membranes seems required to advance our insight in plant macro- and microautophagy and their roles in vacuole formation. © 2015 Elsevier GmbH. Source

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