Hydraulic strategy of cactus root–stem junction for effective water transport

Hyejeong Kim, Kiwoong Kim, Sang Joon Lee

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Cactus roots function as a hydraulic safety valve by conducting available water quickly and preventing water loss under drought condition. In particular, the root–stem (R–S) junction is responsible for effective water transport by direct coupling of the water absorptive thin roots and the moisture-filled bulky stem. In this study, the morphological features of the R–S junction were observed by using X-ray micro-imaging technique. Their structural and functional characteristics were also elucidated according to a hydrodynamic viewpoint. With regard to the axial water transport through xylem, the R–S junction prevents water leakage by embolizing large-scale vessels with relatively high hydraulic conductivity. In addition, the axial theoretical hydraulic conductivity of xylem vessels fromthe roots to the stemdrastically increases to facilitate water absorption and prevent water loss. The cortex cell layer of a cactus is thinner than that of other plant species. In the viewpoint of radial conductivity, this property can be the hydraulic strategy of the cactus R–S junction to transport water quickly fromthe root surface into the xylem. These results suggest that the R–S junction functions as a hydraulic safety valve that can maximize water uptake in axial and radial directions at limited rainfall. This junction can also prevent the stem from leaking water under drought condition.

Original languageEnglish
Article number799
JournalFrontiers in Plant Science
Publication statusPublished - 2018 Jun 12
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP). (number 2017R1A2B3005415).

Publisher Copyright:
© 2018 Kim, Kim and Lee.


  • Cactus root
  • Hydraulic conductivity
  • Root-stem junction
  • Water transport
  • X-ray microimaging

ASJC Scopus subject areas

  • Plant Science


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