Orchestration of three transporters and distinct vascular structures in node for intervascular transfer of silicon in rice.
Requirement of mineral elements in different plant tissues is not often consistent with their transpiration rate; therefore, plants have developed systems for preferential distribution of mineral elements to the developing tissues with low transpiration. Here we took silicon (Si) as an example and revealed an efficient system for preferential distribution of Si in the node of rice (Oryza sativa). Rice is able to accumulate more than 10% Si of the dry weight in the husk, which is required for protecting the grains from water loss and pathogen infection. However, it has been unknown for a long time how this hyperaccumulation is achieved. We found that three transporters (Lsi2, Lsi3, and Lsi6) located at the node are involved in the intervascular transfer, which is required for the preferential distribution of Si. Lsi2 was polarly localized to the bundle sheath cell layer around the enlarged vascular bundles, which is next to the xylem transfer cell layer where Lsi6 is localized. Lsi3 was located in the parenchyma tissues between enlarged vascular bundles and diffuse vascular bundles. Similar to Lsi6, knockout of Lsi2 and Lsi3 also resulted in decreased distribution of Si to the panicles but increased Si to the flag leaf. Furthermore, we constructed a mathematical model for Si distribution and revealed that in addition to cooperation of three transporters, an apoplastic barrier localized at the bundle sheath cells and development of the enlarged vascular bundles in node are also required for the hyperaccumulation of Si in rice husk.
Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan;
Naoki
N
Yamaji
Ecosystem Informatics Division, National Institute for Agro-Environmental Sciences, Tsukuba 305-8604, Japan.
Gen
G
Sakurai
Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan;
Namiki
N
Mitani-Ueno
Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan; maj@rib.okayama-u.ac.jp.
Jian Feng
JF
Ma
D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport / Q000235:genetics; D005260:Female; D018506:Gene Expression Regulation, Plant; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D019697:Onions / Q000166:cytology; D009865:Oocytes / Q000378:metabolism; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D019441:Plant Epidermis / Q000166:cytology / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D058526:Plant Vascular Bundle / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012825:Silicon / Q000378:metabolism*; D014981:Xenopus; D052584:Xylem / Q000166:cytology / Q000235:genetics / Q000378:metabolism
D008164:Luminescent Proteins; D026901:Membrane Transport Proteins; D010940:Plant Proteins; D020033:Protein Isoforms; D012825:Silicon
apoplastic barrier; mathematical model; node; rice transporter; silicon distribution