Adaptation of plants to environmental conditions requires that sensing external stimuli be linked mechanisms morphogenesis. The Arabidopsis TCH (for touch) genes are rapidly upregulated in expression response stimuli, but a connection between this molecular and developmental alterations has not been established. We identified TCH4 as xyloglucan endotransglycosylase by sequence similarity enzyme activity. Xyloglucan endotransglycosylases most likely modify cell walls, fundamental determinant...

Nonessential metal ions such as cadmium are most likely transported across plant membranes via transporters for essential cations. To identify possible pathways Cd 2+ transport we tested putative cation uptake activity by expressing cDNAs in Saccharomyces cerevisiae and found that expression of one clone, LCT1 , renders the growth yeast more sensitive to cadmium. Ion flux assays showed sensitivity is correlated with an increase uptake. -dependent saturable, lies high-affinity range (apparent...

This paper presents the problem of tolerance plants to heavy metals. Induction, development and stability are described. Multiple co-tolerance presented in context specificity acquired Phenomena involved uptake distribution metals plant tissues along with mechanisms exclusion accumulation discussed. The is also light nutritional conditions that most often encounter contaminated environments.

Phytochelatins, heavy-metal-binding polypeptides, are synthesized by phytochelatin synthase (PCS) (EC 2.3.2.15). Previous studies on plants overexpressing PCS genes yielded contrasting phenotypes, ranging from enhanced cadmium tolerance and accumulation to hypersensitivity. This paper compares the effects of overexpression AtPCS1 CePCS in tobacco (Nicotiana tabacum var. Xanthi), demonstrates how introduction single homologous affects a different extent cellular metabolic pathways leading...

The Arabidopsis touch (TCH) genes are up-regulated in response to various environmental stimuli, including touch, wind, and darkness. Previously, it was determined that TCH1 encodes a calmodulin; TCH2 TCH3 encode calmodulin-related proteins. Here, we present the sequence genomic organization of TCH3. is composed three repeats; remarkably, first two repeats share 94% identity, introns 99% identical. conceptual product 58 60% identical known calmodulins; however, unlike calmodulin, which has...

Ectopic expression in tobacco (Nicotiana tabacum v. Xanthi) of the export protein AtHMA4 (responsible Arabidopsis for control Zn/Cd root to shoot translocation) resulted decreased Cd uptake/accumulation roots and shoots. This study contributes understanding mechanisms underlying this Cd-dependent phenotype help predict consequences transgene potential phytoremediation/biofortification-based strategies. Microarray analysis was performed identify metal homeostasis genes that were...

Root-to-shoot translocation of zinc (Zn) and cadmium (Cd) depends on the concentrations both metals in medium. A previous study tobacco (Nicotiana tabacum) pointed to contribution NtZIP1, NtZIP2, NtZIP4 NtIRT1-like regulation this phenomenon. To learn more, Zn Cd accumulation, root/shoot distribution expression ZIP genes were investigated apical, middle basal root parts.We show that Zn/Cd status-dependent root-shoot was related distinct metal accumulation parts. At low medium, apical part...

Abstract A gene family encoding xyloglucan endotransglycosylase (XET)-related proteins exists in Arabidopsis. TCH4, a member of this family, is strongly up-regulated by environmental stimuli and encodes an XET capable modifying cell wall xyloglucans. To investigate localization we generated antibodies against the TCH4 carboxyl terminus. The recognized possibly other XET-related proteins. These data indicate that XETs accumulate expanding cells, at sites intercellular airspace formation,...

Engineering enhanced transport of zinc to the aerial parts plants is a major goal in bio-fortification. In Arabidopsis halleri, high constitutive expression AhHMA4 gene encoding metal pump P(1B)-ATPase family necessary for both Zn hyperaccumulation and full extent Cd hypertolerance that are characteristic this species. study, an cDNA was introduced into N. tabacum var. Xanthi under control its endogenous A. halleri promoter known confer cell-type specific levels non-hyperaccumulator...

Genetic modification of Zn/Cd accumulation in roots and shoots for biofortification or phytoremediation is a focus this manuscript. We expressed AtHMA4 (a P(₁B) ATPase involved Zn Cd transport), AtHMA4-trunc (lacking the C-terminal region) AtHMA4-C terminus (the region alone) tobacco under CaMV 35S constitutive promoter examined tolerance to both metals. Expression enhanced translocation only at 10 μM but not 0.5, 100 200 Zn. did show effect instead reduced shoot. AtHMA4-expressing plants...

Heterologous expression of HMA4 (P(1B) -ATPase) in plants is a useful strategy to engineer altered metal distribution tissues for biofortification or phytoremediation purposes. This study contributes understanding mechanisms underlying complex Zn-dependent phenotypes observed transgenic and better predict the consequences transgene expression. Tomato was transformed with AhHMA4(p1) ::AhHMA4 from Arabidopsis halleri encoding Zn export protein involved xylem loading Zn. Homozygous lines were...

This study links changes in the tobacco endogenous metal-homeostasis network caused by transgene expression with engineering of novel features. It also provides insight into concentration-dependent mutual interactions between Zn and Cd, leading to differences metal partitioning wild-type transgenic plants. In tobacco, export protein AtHMA4 modified Zn/Cd root/shoot distribution, but pattern depended on their concentrations medium. To address this phenomenon, genes identified suppression...