Root apoplastic barriers block Na+ transport to shoots in rice (Oryza sativa L.)

Rice is an important crop that is very sensitive to salinity. However, some varieties differ greatly in this feature, making investigations of salinity tolerance mechanisms possible. The cultivar Pokkali is salinity tolerant and is known to have more extensive hydrophobic barriers in its roots than...

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Main Authors:	Krishnamurthy, Pannaga, Ranathunge, Kosala, Nayak, Shraddha, Schreiber, Lukas, Mathew, M. K.
Format:	Online
Language:	English
Published:	Oxford University Press 2011
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3153681/

id	pubmed-3153681
recordtype	oai_dc
spelling	pubmed-31536812011-08-15 Root apoplastic barriers block Na+ transport to shoots in rice (Oryza sativa L.) Krishnamurthy, Pannaga Ranathunge, Kosala Nayak, Shraddha Schreiber, Lukas Mathew, M. K. Research Papers Rice is an important crop that is very sensitive to salinity. However, some varieties differ greatly in this feature, making investigations of salinity tolerance mechanisms possible. The cultivar Pokkali is salinity tolerant and is known to have more extensive hydrophobic barriers in its roots than does IR20, a more sensitive cultivar. These barriers located in the root endodermis and exodermis prevent the direct entry of external fluid into the stele. However, it is known that in the case of rice, these barriers are bypassed by most of the Na+ that enters the shoot. Exposing plants to a moderate stress of 100 mM NaCl resulted in deposition of additional hydrophobic aliphatic suberin in both cultivars. The present study demonstrated that Pokkali roots have a lower permeability to water (measured using a pressure chamber) than those of IR20. Conditioning plants with 100 mM NaCl effectively reduced Na+ accumulation in the shoot and improved survival of the plants when they were subsequently subjected to a lethal stress of 200 mM NaCl. The Na+ accumulated during the conditioning period was rapidly released when the plants were returned to the control medium. It has been suggested that the location of the bypass flow is around young lateral roots, the early development of which disrupts the continuity of the endodermal and exodermal Casparian bands. However, in the present study, the observed increase in lateral root densities during stress in both cultivars did not correlate with bypass flow. Overall the data suggest that in rice roots Na+ bypass flow is reduced by the deposition of apoplastic barriers, leading to improved plant survival under salt stress. Oxford University Press 2011-08 2011-05-09 /pmc/articles/PMC3153681/ /pubmed/21558150 http://dx.doi.org/10.1093/jxb/err135 Text en © 2011 The Author(s). This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.5), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. This paper is available online free of all access charges (see http://jxb.oxfordjournals.org/open_access.html for further details)
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Krishnamurthy, Pannaga Ranathunge, Kosala Nayak, Shraddha Schreiber, Lukas Mathew, M. K.
spellingShingle	Krishnamurthy, Pannaga Ranathunge, Kosala Nayak, Shraddha Schreiber, Lukas Mathew, M. K. Root apoplastic barriers block Na+ transport to shoots in rice (Oryza sativa L.)
author_facet	Krishnamurthy, Pannaga Ranathunge, Kosala Nayak, Shraddha Schreiber, Lukas Mathew, M. K.
author_sort	Krishnamurthy, Pannaga
title	Root apoplastic barriers block Na+ transport to shoots in rice (Oryza sativa L.)
title_short	Root apoplastic barriers block Na+ transport to shoots in rice (Oryza sativa L.)
title_full	Root apoplastic barriers block Na+ transport to shoots in rice (Oryza sativa L.)
title_fullStr	Root apoplastic barriers block Na+ transport to shoots in rice (Oryza sativa L.)
title_full_unstemmed	Root apoplastic barriers block Na+ transport to shoots in rice (Oryza sativa L.)
title_sort	root apoplastic barriers block na+ transport to shoots in rice (oryza sativa l.)
description	Rice is an important crop that is very sensitive to salinity. However, some varieties differ greatly in this feature, making investigations of salinity tolerance mechanisms possible. The cultivar Pokkali is salinity tolerant and is known to have more extensive hydrophobic barriers in its roots than does IR20, a more sensitive cultivar. These barriers located in the root endodermis and exodermis prevent the direct entry of external fluid into the stele. However, it is known that in the case of rice, these barriers are bypassed by most of the Na+ that enters the shoot. Exposing plants to a moderate stress of 100 mM NaCl resulted in deposition of additional hydrophobic aliphatic suberin in both cultivars. The present study demonstrated that Pokkali roots have a lower permeability to water (measured using a pressure chamber) than those of IR20. Conditioning plants with 100 mM NaCl effectively reduced Na+ accumulation in the shoot and improved survival of the plants when they were subsequently subjected to a lethal stress of 200 mM NaCl. The Na+ accumulated during the conditioning period was rapidly released when the plants were returned to the control medium. It has been suggested that the location of the bypass flow is around young lateral roots, the early development of which disrupts the continuity of the endodermal and exodermal Casparian bands. However, in the present study, the observed increase in lateral root densities during stress in both cultivars did not correlate with bypass flow. Overall the data suggest that in rice roots Na+ bypass flow is reduced by the deposition of apoplastic barriers, leading to improved plant survival under salt stress.
publisher	Oxford University Press
publishDate	2011
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3153681/
_version_	1611470199138025472

Root apoplastic barriers block Na+ transport to shoots in rice (Oryza sativa L.)

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