Mung bean seedlings (Vigna radiata L.) of the cultivar Tainan No. 5 (a chilling-sensitive cultivar) pretreated with multiple sprays of 200 mm H2O2 showed a tolerance to chilling at 4 °C for 36 h, measured by electrolyte leakage, that was greater than that induced by a single treatment and similar to that induced by cold-acclimation at 10 °C for 48 h. Two H2O2 treatments at an interval of 3 h gave the optimum chilling tolerance. Tolerance induced by H2O2 could be distinguished from that induced by acclimation at 10 °C according to length at 4 °C and corresponding electrolyte leakage. Chilling tolerance induced by H2O2 depended on accumulation of glutathione (GSH), which could be significantly reversed by pretreatment with buthionine sulfoximine (BSO). In contrast, tolerance induced by incubation at 10 °C for 48 h in light was neither accompanied by accumulation of GSH nor reversed by BSO, suggesting that there are at least two independent mechanisms of developing chilling tolerance. Chilling tolerance of both cold-acclimated and H2O2-treated seedlings was decreased by ethyleneglycol-bis(aminoethylether)-N,N′-tetraacetic acid (EGTA) but not by ruthenium red, indicating that the influx of Ca2+ from extracellular, but not intracellular, pools is an important signal in the induction of tolerance. In confirmation, sprays of Ca2+ could be substituted for H2O2.
Shu Hsien Hung, Chun Chi Wang, Sergei Veselinov Ivanov, Vera Alexieva and Chih Wen Yu
Ching-San Kuan, Chih-Wen Yu, Mei-Li Lin, Hsin-Tszu Hsu, Duane P. Bartholomew and Chin-Ho Lin
Natural flowering of pineapple is a serious problem for commercial growers of pineapple because it disrupts fruiting schedules, decreases harvesting efficiency and increases costs, and may reduce the percentage of marketable fruit. Aviglycine ([S]-trans-2-amino-4-(2 aminoethoxy)-3-butenoic acid hydrochloride), an inhibitor of ethylene biosynthesis, was applied as a foliar spray to evaluate its potential to prevent natural flowering in 1-year-old `Tainon 18' pineapple. Two experiments were conducted between 10 Oct. and 10 Apr. during the 2001-02 and 2002-03 production seasons. For the 2001-02 season, single or double applications of aviglycine at 100 mg L-1 had no significant effect on natural flowering. A double application of aviglycine at 500 mg L-1 first applied on 9 Nov. reduced flowering from 95.0% in the control to 51.3% when evaluated on 25 Feb. 2002. In the 2002-03 production season, triple applications of aviglycine applied at 20-day intervals beginning on 10 Nov. 2002 significantly reduced natural flowering when evaluated on 28 Mar. 2003. There was 95.8% flowering in the control, 64.6% with 250 and 375 mg L-1 aviglycine, and 50% with 500 mg L-1 aviglycine. Aviglycine has the potential to partially control precocious flowering of pineapple, which will reduce crop losses associated with such flowering.
Choun-Sea Lin, Nien-Tzu Liu, De-Chih Liao, Jau-Song Yu, Chuang-Hwei Tsao, Chao-Hsiung Lin, Chih-Wen Sun, Wann-Neng Jane, Hsing Sheng Tsay, Jeremy Jian-Wei Chen, Erh-Min Lai, Na-Sheng Lin, Wei-Chin Chang and Chung-Chih Lin
The chloroplast genome of an albino mutant isolated from tissue culture of the bamboo Bambusa edulis Munro was examined to identify aberrations. A number of the chloroplast genes encoding ATP synthases, photosystem II subunits, NADH dehydrogenase, and ribosomal proteins had been deleted, at least partially, in the albino mutant. Comparison of the two-dimensional electrophoresis profiles of albino and green bamboos revealed three spots of reduced intensity, indicating repression of these proteins in the albino mutants. Mass spectroscopic analysis subsequently revealed that two of these proteins are 33-kDa subunits of the photosystem II oxygen-evolving protein complex (PsbO) and one is a 23-kDa subunit of photosystem II oxygen-evolving protein complex (PsbP). The genes encoding these two proteins were cloned from B. edulis, and were denoted BePsbO (accession no. EF669513) and BePsbP (accession no. EF669512). Reverse transcription polymerase chain reaction and two-dimensional gel analyses of BePsbO and BePsbP in green and albino bamboos grown in the light or dark revealed that the albino mutant, similar to its green counterpart, sensed the light signal, resulting in the induction of BePsbO and BePsbP transcription, but it did not accumulate the protein products. We conclude that the repression of protein-expressing BePsbO and BePsbP is because of a defect in post-transcriptional regulation in the albino mutant.