Membrane fluxes, bypass flows, and sodium stress in rice: the influence of silicon

作者：Flam Shepherd Rubens; Huynh Wayne Q; Coskun Devrim; Hamam Ahmed M; Britto Dev T; Kronzucker Herbert J^*

来源：Journal of Experimental Botany, 2018, 69(7): 1679-1692.

DOI：10.1093/jxb/erx460

• Apoplast
• efflux
• influx
• Oryza sativa L.
• cvs Pokkali and IR29
• rice
• salt stress
• silicon
• sodium accumulation
• sodium transport
• transpirational bypass flow

Provision of silicon (Si) to roots of rice (Oryza sativa L.) can alleviate salt stress by blocking apoplastic, transpirational bypass flow of Na+ from root to shoot. However, little is known about how Si affects Na+ fluxes across cell membranes. Here, we measured radiotracer fluxes of Na-24(+), plasma membrane depolarization, tissue ion accumulation, and transpirational bypass flow, to examine the influence of Si on Na+ transport patterns in hydroponically grown, salt-sensitive (cv. IR29) and salt-tolerant (cv. Pokkali) rice. Si increased growth and lowered [Na+] in shoots of both cultivars, with minor effects in roots; neither root nor shoot [K+] were affected. In IR29, Si lowered shoot [Na+] via a large reduction in bypass flow, while in Pokkali, where bypass flow was small and not affected by Si, this was achieved mainly via a growth dilution of shoot Na+. Si had no effect on unidirectional 24Na(+) fluxes (influx and efflux), or on Na+-stimulated plasma-membrane depolarization, in either IR29 or Pokkali. We conclude that, while Si can reduce Na+ translocation via bypass flow in some (but not all) rice cultivars, it does not affect unidirectional Na+ transport or Na+ cycling in roots, either across root cell membranes or within the bulk root apoplast.

• 出版日期2018-3-16