Enhanced metal tolerance correlates with heterotypic variation in SpMTL, a metallothionein-like protein from the hyperaccumulator Sedum plumbizincicola.
Mechanistic insight into metal hyperaccumulation is largely restricted to Brassicaceae plants; therefore, it is of great importance to obtain corresponding knowledge from system outside the Brassicaceae. Here, we constructed and screened a cDNA library of the Cd/Zn hyperaccumulator Sedum plumbizincicola and identified a novel metallothionein-like protein encoding gene SpMTL. SpMTL showed functional similarity to other known MT proteins and also to its orthologues from non-hyperaccumulators. However, three additional cysteine residues were observed in SpMTL and appeared to be hyperaccumulator specific. Removal of these three residues significantly decreased its ability to tolerate Cd and the stoichiometry of Cd against SpMTL (molar ratio of Cd/SpMTL) to a level comparable to those of Cd/SaMTL and Cd/SeMTL in the corresponding non-hyperaccumulating relatives. SpMTL expressed in S. plumbizincicola roots at a much higher level than those of its orthologues in the non-hyperaccumulator roots. Interestingly, a positive correlation was observed between transcript levels of SpMTL in roots and Cd accumulation in leaves. Taking these results together, we propose that elevated transcript levels and heterotypic variation in protein sequences of SpMTL might contribute to the trait of Cd hyperaccumulation and hypertolerance in S. plumbizincicola.
National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
Jia-Shi
http://orcid.org/0000-0001-6534-0485
JS
Peng
National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.|Crops Research Institute, Jiangxi Academy of Agricultural Sciences, Nanchang, 330200, China.
Ge
http://orcid.org/0000-0002-5157-1116
G
Ding
National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
Shuan
S
Meng
National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
Hong-Ying
HY
Yi
National Key Laboratory of Plant Molecular Genetics and National Center for Plant Gene Research (Shanghai), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
Ji-Ming
JM
Gong
D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D001692:Biological Transport; D002104:Cadmium / Q000378:metabolism; D002614:Chelating Agents / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008658:Inactivation, Metabolic; D008668:Metallothionein / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008670:Metals / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D031963:Sedum / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013045:Species Specificity; D015032:Zinc / Q000378:metabolism
D002614:Chelating Agents; D008670:Metals; D010940:Plant Proteins; D012333:RNA, Messenger; D002104:Cadmium; D008668:Metallothionein; D015032:Zinc; D003545:Cysteine
cadmium; cysteine