Showing papers by "Tony H. H. Chen published in 2004"
TL;DR: Introducing the biosynthetic pathway of GB into tomato through metabolic engineering is an effective strategy for improving chilling tolerance and oxidative tolerance in GB-accumulating codA transgenic plants.
Abstract: Tomato (Lycopersicon esculentum Mill.) plants, which normally do not accumulate glycinebetaine (GB), are susceptible to chilling stress. Exposure to temperatures below 10 degrees C causes various injuries and greatly decreases fruit set in most cultivars. We have transformed tomato (cv. Moneymaker) with a chloroplast-targeted codA gene of Arthrobacter globiformis, which encodes choline oxidase to catalyze the conversion of choline to GB. These transgenic plants express codA and synthesize choline oxidase, while accumulating GB in their leaves and reproductive organs up to 0.3 and 1.2 micromol g(-1) fresh weight (FW), respectively. Their chloroplasts contain up to 86% of total leaf GB. Over various developmental phases, from seed germination to fruit production, these GB-accumulating plants are more tolerant of chilling stress than their wild-type counterparts. During reproduction, they yield, on average, 10-30% more fruit following chilling stress. Endogenous GB contents as low as 0.1 micromol g(-1) FW are apparently sufficient to confer high levels of tolerance in tomato plants, as achieved via transformation with the codA gene. Exogenous application of either GB or H2O2 improves both chilling and oxidative tolerance concomitant with enhanced catalase activity. These moderately increased levels of H2O2 in codA transgenic plants, as a byproduct of choline oxidase-catalyzed GB synthesis, might activate the H2O2-inducible protective mechanism, resulting in improved chilling and oxidative tolerances in GB-accumulating codA transgenic plants. Thus, introducing the biosynthetic pathway of GB into tomato through metabolic engineering is an effective strategy for improving chilling tolerance.
231 citations
TL;DR: Experiments focusing on plant growth regulators and combina- tions, mineral salt formulations, and TDZ pretreatment formations were conducted to optimize in vitro shoot regeneration from leaf and petiole explants of ʻMarionʼ black- berry.
Abstract: Additional index words. Rubus, tissue culture, thidiazuron Abstract. Experiments focusing on plant growth regulatorsʼconcentrations and combina- tions, mineral salt formulations, and TDZ pretreatment formations were conducted to optimize in vitro shoot regeneration from leaf and petiole explants of ʻMarionʼ black- berry. Optimum shoot formation was obtained when stock plants were incubated in TDZ pretreatment medium for 3 weeks before culturing leaf explants on regeneration medium (Woody Plant Medium with 5 µM BA and 0.5 µM IBA) in darkness for 1 week before transfer to light photoperiod (16-hour photoperiod at photosynthetic photon flux of ≈50 µmol·m-2 ·s -1 ) at 23 °C ± 2 °C for 4 weeks. Under these conditions, ≈70% of leaf explants formed ≈40 shoots per petri dish that could be harvested and rooted to form plantlets. Chemical names used: N6 -benzyladenine (BA); 2,4-dichlorophenoxyacetic acid (2,4-D); gibberellic acid (GA 3); indole-3-acetic acid (IAA); indole-3-butyric acid (IBA); α-naph- thaleneacetic acid (NAA); N-phenyl-Nʼ-1,2,3-thidiazol-5-ylurea (thidiazuron (TDZ)).
36 citations