Net sodium fluxes change significantly at anatomically distinct root zones of rice (Oryza sativa L.) seedlings

Zhou, Quan; Wang, Li; Cai, Xia; Wang, Di; Hua, Xuejun; Qu, Le-Qing; Lin, Jinxing; Chen, Tong

doi:10.1016/j.jplph.2011.01.017

Cited by 12 publications

(11 citation statements)

References 36 publications

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“…The first reason could lay in the poor control of activity of plasma membrane transporters in the xylem parenchyma cells. It was also suggested earlier in the literature that high shoot Na + in rice may be explained by some specific anatomical features of its roots – namely, the presence of the bypass flow resulting from the breakage of the integrity of Casparian band by lateral roots (Ranathunge et al , Faiyue et al , Krishnamurthy et al , Zhou et al ). In this work, the salt stress was applied to plants, which were 17 days old, and thus may have already developed such bypass flow.…”

Section: Discussionmentioning

confidence: 81%

Control of xylem Na⁺ loading and transport to the shoot in rice and barley as a determinant of differential salinity stress tolerance

Ishikawa

Shabala

2018

Physiologia Plantarum

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Control of xylem Na loading has often been named as the essential component of salinity tolerance mechanism. However, it is less clear to what extent the difference in this trait may determine differential salinity tolerance between species. In this study, barley (Hordeum vulgare L. cv. CM72) and rice (Oryza sativa L. cv. Dongjin) plants were grown under two levels of salinity. Na and K concentrations in the xylem sap, and shoot and root tissues were measured at different time points after stress onset. Salt-exposed rice plants prevented xylem Na loading for several days, but failed to control this process in the longer term, ultimately resulting in a massive Na shoot loading. Barley plants quickly increased xylem Na concentration and its delivery to the shoot (most likely for the purpose of osmotic adjustment) but were able to reduce this process later on, keeping most of accumulated Na in the root, thus maintaining non-toxic shoot Na level. Rice plants increased shoot K concentration, while barley plants maintained higher root K concentration. Control of xylem Na loading is remarkably different between rice and barley; this difference may differentiate the extent of the salinity tolerance between species. This trait should be investigated in more detail to be used in the breeding programs aimed to improve salinity tolerance in crops.

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Section: Discussionmentioning

confidence: 81%

Control of xylem Na⁺ loading and transport to the shoot in rice and barley as a determinant of differential salinity stress tolerance

Ishikawa

Shabala

2018

Physiologia Plantarum

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“…The relative bypass flow ( RRBF , unitless, 0–1) is thus calculated as a function of the root suberin content 35 :where ( T 1) RRBF min (%) is the bypass flow when the suberin content is maximum; SC (mg g −1 ) is the root suberin content ; ( T 1) SCmax (mg g −1 ) is the maximum suberin content; SC min (mg g −1 ) is the minimum root suberin concentration at which bypass flow starts to be reduced. The root suberin content is derived as a function of plant age (equation 4) and of the genotype sensitivity to salinity (equation 5) 34, 36 : where DVS (unitless; 0–2) is a SUCROS-type development stage code (0: emergence; 1: anthesis; 2: maturity); F sc (unitless; 0–1) is deposition of suberin in response to salinity; ( T 1) SubDepEff (unitless; 0–1) is the suberin deposition efficiency (genotype specific) ; [ Na + ] ext and Max [ Na + ] ext (mM) are, respectively, the actual and maximum (at which the suberin deposition is maximum) Na + concentrations in the external medium. Therefore, the amount of Na + actually delivered to the shoot via bypass-flow ( NaUptake AP , mg ha −1 ) is: …”

Section: Resultsmentioning

confidence: 99%

Trait-based model development to support breeding programs. A case study for salt tolerance and rice

Paleari

Movedi

Confalonieri

2017

Sci Rep

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Eco-physiological models are increasingly used to analyze G × E × M interactions to support breeding programs via the design of ideotypes for specific contexts. However, available crop models are only partly suitable for this purpose, since they often lack clear relationships between parameters and traits breeders are working on. Taking salt stress tolerance and rice as a case study, we propose a paradigm shift towards the building of ideotyping-specific models explicitly around traits involved in breeding programs. Salt tolerance is a complex trait relying on different physiological processes that can be alternatively selected to improve the overall crop tolerance. We developed a new model explicitly accounting for these traits and we evaluated its performance using data from growth chamber experiments (e.g., R2 ranged from 0.74 to 0.94 for the biomass of different plant organs). Using the model, we were able to show how an increase in the overall tolerance can derive from completely different physiological mechanisms according to soil/water salinity dynamics. The study demonstrated that a trait-based approach can increase the usefulness of mathematical models for supporting breeding programs.

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“…Other traits suggested to be associated with salt tolerance in various studies are compartmentation of Na + in older leaves and leaf sheaths and in the vacuoles, maintenance of mineral nutrient homeostasis, especially K + and Ca 2+ , high selectivity for K + and/or Ca 2+ uptake over that of Na + , limiting effects of reactive oxygen species (ROS scavenging), accumulation of compatible solutes to offset osmotic effects (osmotic adjustment), maintenance of leaf area index and maintenance of tiller number [5,9-13]. The importance of the apoplastic bypass flow in delivering Na + to the xylem, thus reducing leaf Na + concentration and improving tolerance, has also been noted [14-17]. During the reproductive stage, tolerant genotypes strongly exclude salt from flag leaves and developing panicles [6,18].…”

Section: Introductionmentioning

confidence: 99%

Salinity tolerance, Na+ exclusion and allele mining of HKT1;5 in Oryza sativa and O. glaberrima: many sources, many genes, one mechanism?

2013

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BackgroundCultivated rice species (Oryza sativa L. and O. glaberrima Steud.) are generally considered among the crop species most sensitive to salt stress. A handful of lines are known to be tolerant, and a small number of these have been used extensively as donors in breeding programs. However, these donors use many of the same genes and physiological mechanisms to confer tolerance. Little information is available on the diversity of mechanisms used by these species to cope with salt stress, and there is a strong need to identify varieties displaying additional physiological and/or genetic mechanisms to confer higher tolerance.ResultsHere we present data on 103 accessions from O. sativa and 12 accessions from O. glaberrima, many of which are identified as salt tolerant for the first time, showing moderate to high tolerance of high salinity. The correlation of salinity-induced senescence (as judged by the Standard Evaluation System for Rice, or SES, score) with whole-plant and leaf blade Na+ concentrations was high across nearly all accessions, and was almost identical in both O. sativa and O. glaberrima. The association of leaf Na+ concentrations with cultivar-groups was very weak, but association with the OsHKT1;5 allele was generally strong. Seven major and three minor alleles of OsHKT1;5 were identified, and their comparisons with the leaf Na+ concentration showed that the Aromatic allele conferred the highest exclusion and the Japonica allele the least. A number of exceptions to this association with the Oryza HKT1;5 allele were identified; these probably indicate the existence of additional highly effective exclusion mechanisms. In addition, two landraces were identified, one from Thailand and the other from Senegal, that show high tissue tolerance.ConclusionsSignificant variation in salinity tolerance exists within both cultivated Oryza species, and this is the first report of significant tolerance in O. glaberrima. The majority of accessions display a strong quantitative relationship between tolerance and leaf blade Na+ concentration, and thus the major tolerance mechanisms found in these species are those contributing to limiting sodium uptake and accumulation in active leaves. However, there appears to be genetic variation for several mechanisms that affect leaf Na+ concentration, and rare cases of accessions displaying different mechanisms also occur. These mechanisms show great promise for improving salt tolerance in rice over that available from current donors.

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Net sodium fluxes change significantly at anatomically distinct root zones of rice (Oryza sativa L.) seedlings

Cited by 12 publications

References 36 publications

Control of xylem Na⁺ loading and transport to the shoot in rice and barley as a determinant of differential salinity stress tolerance

Control of xylem Na⁺ loading and transport to the shoot in rice and barley as a determinant of differential salinity stress tolerance

Trait-based model development to support breeding programs. A case study for salt tolerance and rice

Salinity tolerance, Na+ exclusion and allele mining of HKT1;5 in Oryza sativa and O. glaberrima: many sources, many genes, one mechanism?

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Net sodium fluxes change significantly at anatomically distinct root zones of rice (Oryza sativa L.) seedlings

Cited by 12 publications

References 36 publications

Control of xylem Na+ loading and transport to the shoot in rice and barley as a determinant of differential salinity stress tolerance

Control of xylem Na+ loading and transport to the shoot in rice and barley as a determinant of differential salinity stress tolerance

Trait-based model development to support breeding programs. A case study for salt tolerance and rice

Salinity tolerance, Na+ exclusion and allele mining of HKT1;5 in Oryza sativa and O. glaberrima: many sources, many genes, one mechanism?

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Control of xylem Na⁺ loading and transport to the shoot in rice and barley as a determinant of differential salinity stress tolerance

Control of xylem Na⁺ loading and transport to the shoot in rice and barley as a determinant of differential salinity stress tolerance