Preliminary analysis of expressed sequences of genes in Genipa americana L. plant roots exposed to cadmium in nutrient solution

Abstract

ABSTRACT. Many cell functions are redundantly executed in cells, and the experimental approaches that analyze the group of proteins, whose expression is modified in a specific functional condition, enable the identification of the group of proteins that are expressed under stress conditions. The objective of the present study was the evaluation of the genetic expression induced by cadmium (Cd) in Genipa americana L. (Rubiaceae) plants cultivated in nutritive solution, in order to help further studies concerning its use as a plant phytoremediator of such a metallic element. Plants were exposed to increasing concentrations of Cd (0.5, 1, 2, 4, 8, and 16 mg/L), together with the control, in nutritive solution. After the application of the treatments, root tips were harvested for the construction of a cDNA library. Of the 165 expressed sequence tags (ESTs) generated with the construction of the cDNA library, 81 showed homology to genes deposited in the NCBI database, 67 did not show similarity to any available gene, and 17 ESTs ESTs of genes in G. americana exposed to cadmium demonstrated homology with unknown genes. Of the most abundant cDNAs, 16 ESTs were similar to sequences of metallothionein genes. The analysis of ESTs, obtained from the root of G. americana through the construction of a cDNA library, allowed the identification of genes probably associated with proteins and enzymes related to the defense mechanisms of plants when they undergo biotic and abiotic stresses.

Effect of Heavy Metal Treatment on Molecular Changes in Root Tips of Lupinus luteus L.

“…The same proteins were described by PrzymusińskI and Gwóźdź (1999) (PrzymusińskI et al 2004;Souza et al 2008). The protein extracts from lupine roots were used for detection of SOD activity.…”

Morphological, biochemical, molecular and ultrastructural changes induced by Cd toxicity in seedlings of Theobroma cacao L.

“…In comparison with 'Catongo' Â 'Catongo', CCN-10 Â SCA-6 exhibited a higher concentration of Cd in the roots. This study reveals that, during stress by Cd, the concentrations of this metal increase in the roots; yet, this is not due to the increased absorption of this element, but rather by the decreased accumulation of dry matter (Souza et al, 2008). Despite the fact that there is a high concentration of Cd in the roots, this element is also found in the leaves and stems, showing that Cd is not totally immobilized in the roots, but it can be translocated to the aerial parts just as in other plant species (Souza et al, 2008;Unterbrunner et al, 2007).…”

“…This study reveals that, during stress by Cd, the concentrations of this metal increase in the roots; yet, this is not due to the increased absorption of this element, but rather by the decreased accumulation of dry matter (Souza et al, 2008). Despite the fact that there is a high concentration of Cd in the roots, this element is also found in the leaves and stems, showing that Cd is not totally immobilized in the roots, but it can be translocated to the aerial parts just as in other plant species (Souza et al, 2008;Unterbrunner et al, 2007). The present study has verified that changes occurred during the absorption of certain nutrients -especially P, S, Cu, Fe and Znin the seedlings of both T. cacao progenies derived from seeds exposed to different Cd concentrations via seminal fluid.…”

“…Excess Cu is identified by associations with transcription factors. Moreover, it activates several defense mechanisms against abiotic stress, as for example the increased expression of metallothioneins, phytochelatins and antioxidants, which help to remove the "free" Cd and restore ionic homeostasis and cellular redox (Souza et al, 2008). These free metals are potentially dangerous and their absorption and cell concentration should be therefore adjusted.…”

“…The present study has verified that changes occurred during the absorption of certain nutrients -especially P, S, Cu, Fe and Znin the seedlings of both T. cacao progenies derived from seeds exposed to different Cd concentrations via seminal fluid. The toxicity of Cd in plants can influence the concentration of mineral elements in the tissues and thereby impair mineral nutrition (Souza et al, 2008). The presence of Cd in cells can affect the levels of polyvalent cations through competition for binding sites of proteins or transporters (Sandalio et al, 2001).…”