Phytochelatin is not a primary factor in determining copper tolerance

Abstract

Phytochelatin (PC) is involved in the detoxification of harmful, non-essential heavy metals and the homeostasis of essential heavy metals in plants. Its synthesis can be induced by either cadmium (Cd) or copper (Cu), and can form stable complexes with either element. This might suggest that PC has an important role in determining plant tolerance to both. However, this is not clearly apparent, as evidenced by a PC.deficient and Cd-sensitive Arabidopsis mutant (cad1-3) that shows no significant increase in its sensitivity to copper. Therefore, we investigated whether the mechanism for Cu tolerance differed from that for Cd by analyzing copper sensitivity in Cd-tolerant transgenics and Cd-sensitive mutants of Arabidopsis. Cadmium-tolerant transgenic plants that over-expressed A. thaliana phytochela. tin synthase I (AtPCS1) were not tolerant of copper stress, thereby supporting the hypothesis that PC is not primarily involved in this tolerance mechanism. We also investigated Cu tolerance in cad2-1, a Cd-sensitive and glutathione (GSH)-deficient Arabidopsis mutant. Paradoxically, cad2-1 was more resistant to copper stress than were wild-type plants. This was likely due to the high level of cysteine present in that mutant. However, when the growth medium was supplemented with cysteine, the wild types also exhibited copper tolerance. Moreover, Saccharomyces cerevisiae that expressed AtPCS1 showed tolerance to Cd but hypersensitivity to Cu. All these results indicate that PC is not a major factor in determining copper tolerance in plants.

Copper toxicity in Chinese cabbage is not influenced by plant sulphur status, but affects sulphur metabolism‐related gene expression and the suggested regulatory metabolites

“…). It is, therefore, possible that Cu interfers with the regulation of sulphate uptake by the root and its subsequent assimilation (Clemens ; Inouhe ; Lee & Kang ; Sirko & Gotor ). Exposure of Chinese cabbage to elevated Cu concentrations (≥1 μ m ) results in strong accumulation of water‐soluble non‐protein thiols in the root and, to a lesser extent, in the shoot.…”

Effect of Phytochelatin Synthase Expression on Degradation of Fungicide Tolclofos-methyl in Mutant Plant and Transformed yeast

“…상추 잎에 살포한 tolclofos-methyl은 7일 후에도 반 정도는 분해가 일 어나지 않았으며 나머지는 P-O-aryl 연결이 끊어지고 메틸 기에 산화가 일어나서 malonylglucose와 gucose conjugates 로 분해 된다 는 PCS(+) vector 10) 에 존재하는 것을 pYES2 vector (Invitrogen, Carlsbad, CA)의 BamHI/SstI 자리에 넣어 pYES2:AtPCS1를 만들었고 이를 효모형질전환 에 사용하였다 (Fig. 1).…”

Uptake and Translocation of Tri- and Hexa-Valent Chromium and Their Effects on Black Gram (Vigna mungo L. Hepper cv. Co4) Roots

“…Using metal-accumulating plants to remove these excessive heavy metals from soil has been proposed as a solution (Ahmad et al, 2005). In addition, the knowledge of uptake, translocation or compartmentation of heavy metals in plants is also biotechnologically important (Han et al, 2004;Lee and Kang, 2005). In the present study, we have used black gram as test plant belong to the family Leguminaceae, because it is characterized by rapid growth, high biomass, fast growing and an appreciable capacity to absorb Cr as well as other toxic metals from soil.…”