Type 4 metallothionein genes are involved in regulating Zn ion accumulation in late embryo and in controlling early seedling growth in Arabidopsis.
Type 4 metallothionein (MT) genes are recognized for their specific expression in higher plant seeds, but their functions are still unclear. In this study, the functions of two Arabidopsis metallothionein genes, AtMT4a and AtMT4b, are investigated in seed development, germination and early seedling growth. Transcriptional analysis showed that these two genes are specifically expressed in late embryos. Subcellular localization displayed that both AtMT4a and AtMT4b are widespread distributed in cytoplasm, nucleus and membrane. Co-silencing RNAi of AtMT4a and AtMT4b reduced seed weight and influenced the early seedling growth after germination, whereas overexpression of these two genes caused the opposite results. Detailed analysis showed clearly the correlation of AtMT4a and AtMT4b to the accumulation of some important metal ions in late embryos, especially to Zn ion storing in seeds, which then serves as part of early Zn ion resources for post-germinated seedling growth. Furthermore, phytohormone abscisic acid (ABA) and gibberellic acid (GA) may play roles in regulating the expression and function of AtMT4a and AtMT4b during seed development; and this may influence Zn accumulation in seeds and Zn ion nutrient supplementation in the early seedling growth after germination.
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China.
Yujun
Y
Ren
Yang
Y
Liu
Hongyu
H
Chen
Gang
G
Li
Xuelian
X
Zhang
Jie
J
Zhao
D000040:Abscisic Acid / Q000378:metabolism; D017360:Arabidopsis / Q000196:embryology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D018533:Biomass; D003300:Copper / Q000032:analysis / Q000378:metabolism; D018548:Cotyledon / Q000196:embryology / Q000235:genetics / Q000254:growth & development; D015870:Gene Expression / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D018525:Germination; D005875:Gibberellins / Q000378:metabolism; D018546:Hypocotyl / Q000196:embryology / Q000235:genetics / Q000254:growth & development; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism*; D018517:Plant Roots / Q000196:embryology / Q000235:genetics / Q000254:growth & development; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D036226:Seedlings / Q000196:embryology / Q000235:genetics / Q000254:growth & development; D012639:Seeds / Q000196:embryology / Q000235:genetics / Q000254:growth & development; D015398:Signal Transduction / Q000235:genetics; D015032:Zinc / Q000032:analysis / Q000378:metabolism*
D029681:Arabidopsis Proteins; C000589633:AtMT4a, protein, Arabidopsis; D005875:Gibberellins; D010937:Plant Growth Regulators; D000040:Abscisic Acid; D003300:Copper; D008668:Metallothionein; C007842:gibberellic acid; D015032:Zinc