PRELIMINARY INVESTIGATIONS INTO THE STRUCTURE OF THE ROOTS OF THE MANGROVES, <i>AVICENNIA MARINA</i> AND <i>BRUGUIERA GYMNORRHIZA</i>, IN RELATION TO ION UPTAKE

Lawton, June R.; Todd, Ann E.; Naidoo, D. K.

doi:10.1111/j.1469-8137.1981.tb01748.x

Cited by 64 publications

(30 citation statements)

References 15 publications

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“…Rhizophora mangle is not provided with salt glands, but it keeps the xylem sap essentially free of NaCl by ultrafiltration at the membranes of root cells (Scholander et al 1966;Scholander 1968). The concentration of xylem sap is about one-tenth than that of seawater (Lawton et al 1981). Furthermore, in B. gymnorrhiza, hypocotyls function as an additional filter to retain salt from the shoot (Lawton et al 1981).They maintain ionic balance through K ?…”

Section: Salt Secretion Salt Exclusion and Salt Accumulationmentioning

confidence: 99%

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Salt tolerance mechanisms in mangroves: a review

Parida

Jha

2010

Trees

328

230

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Mangroves are woody plants which form the dominant vegetation in tidal, saline wetlands along tropical and subtropical coasts. The current knowledge concerning the most striking feature of mangroves i.e., their unique ability to tolerate high salinity is summarized in the present review. In this review, we shall discuss recent studies that have focused on morphological, anatomical, physiological, biochemical, molecular and genetic attributes associated with the response to salinity, some of which presumably function to mediate salt tolerance in the mangroves. Here we shall also review the major advances recently made at both the genetic and the genomic levels in mangroves. Salinity tolerance in mangroves depends on a range of adaptations, including ion compartmentation, osmoregulation, selective transport and uptake of ions, maintenance of a balance between the supply of ions to the shoot, and capacity to accommodate the salt influx. The tolerance of mangroves to a high saline environment is also tightly linked to the regulation of gene expression. By integrating the information from mangroves and performing comparisons among species of mangroves and non-mangroves, we could give a general picture of salt tolerance mechanisms of mangroves, thus providing a new avenue for development of salt tolerance in crop plants through effective breeding strategies and genetic engineering techniques.

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Section: Salt Secretion Salt Exclusion and Salt Accumulationmentioning

confidence: 99%

“…The concentration of xylem sap is about one-tenth than that of seawater (Lawton et al 1981). Furthermore, in B. gymnorrhiza, hypocotyls function as an additional filter to retain salt from the shoot (Lawton et al 1981).They maintain ionic balance through K ? /Na ?…”

Section: Salt Secretion Salt Exclusion and Salt Accumulationmentioning

confidence: 99%

Salt tolerance mechanisms in mangroves: a review

Parida

Jha

2010

Trees

328

230

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“…As a consequence, they grow in a waterlogged soil with a more limited oxygen supply for root respiration and, in common with other mangrove species growing in anoxic soil conditions with a long inundation period, they have a special anatomical structure, the aerenchyma tissue, in their submerged roots 10,20 . Lawton et al 21 reported that root structure of the related A. marina is composed of large air spaces in the cortex.…”

Section: Resultsmentioning

confidence: 99%

Quantitative analysis of the root system of Avicennia alba based on the pipe model theory

Rodtassana¹,

Poungparn

2012

ScienceAsia

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Reliable estimation of the root biomass is essential to quantify the total amount and proportion of the carbon sink of a forest, especially for mangrove forests that exhibit various extensive root systems. One way to estimate root biomass is to use a quantitative root-system measurement based on the pipe model theory (PMT), which assumes that the total cross-sectional area of roots is identical among the different root-size classes for an individual plant. The PMT states that the cross-sectional area of the tree stem at the ground level supports a fixed total weight of roots. Therefore, estimation of the root weight of a tree is possible from measuring the stem diameter if that species conforms to the model. Using a water pump, the whole root system of three Avicennia alba trees, a pioneer species commonly dominating the mud flats and river edges of secondary mangrove forests in Thailand, were excavated. The living roots were sorted into diameter classes and their individual dry weights obtained. A significant inverse linear relationship was obtained between the root diameter and the number of roots of each sampled tree, with the regression slopes not statistically different from −2.0 (range −2.19 to −2.83 for the three trees) conforming to the PMT. The ratio between the total root weight and the basal area of the stem at the ground level ranged from 0.0340-0.0389, which is smaller and larger than that for Sonneratia caseolaris and Xylocarpus granatum, respectively, two other mangrove tree species previously reported to conform to the PMT.

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“…It has been reported that Rhizophora mangle does not have salt glands, but it keeps the xylem sap essentially free of NaCl by ultrafiltration at the membranes of root cells [41,49]. The Na þ concentration of xylem sap is about 10% than that of sea water [50]. Furthermore, in Bruguiera gymnorrhiza, hypocotyls function as an additional filter to retain salt from the shoot [50].…”

Section: Salt Exclusion By Ultrafiltration At the Membranes Of Root Cmentioning

confidence: 99%

“…The Na þ concentration of xylem sap is about 10% than that of sea water [50]. Furthermore, in Bruguiera gymnorrhiza, hypocotyls function as an additional filter to retain salt from the shoot [50]. They maintain ionic balance through K þ / Na þ exchange at the xylem parenchyma cells in the basal part and vacuolar K þ /Na þ exchange in transpiring leaves, and circulation of exchanged ions within the plants.…”

Section: Salt Exclusion By Ultrafiltration At the Membranes Of Root Cmentioning

confidence: 99%

Role of Na⁺/H⁺Antiporters in Na⁺Homeostasis in Halophytic Plants

Agarwal

Yadav

Jha

2013

Climate Change and Plant Abiotic Stress Tolerance

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Abiotic stresses affect adversely the growth and productivity of crops. Among abiotic stresses, salinity is one of the major factors leading to crop losses. According to the UN Food and Agriculture Organization, more than 800 Mha of land is salt-affected worldwide. The problem of soil salinization is becoming more serious due to scanty rainfall, repetitive sea water invasion, heavy utilization of ground water for agricultural and industrial purposes, and degradation of saline parent rock. The area under cultivation is fast getting depleted and becoming unsuitable for agricultural crops. Soil salinity adversely affects plant growth and development, and disturbs intracellular ion homeostasis, resulting in cellular toxicity. Plant adaptation to salinity stress involves a plethora of genes involved in ion transport and compartmentalization (ion homeostasis), compatible solutes/osmolytes, reactive oxygen species, and antioxidant defense mechanism. Transporters are an important group of genes that play a pivotal role in ion homeostasis in plants (Na þ /H þ antiporters like SOS1 and NHX1, and proton pump HKT1). Over the last two decades the major studies on the molecular mechanisms of salt tolerance have concentrated on glycophytes; however, only limited studies have been performed on halophytes. Halophytes have a unique genetic makeup that provides an advantage for the study of salt-tolerance mechanisms. Halophytes maintain a low salt concentration inside the cytosol by sequestration in vacuoles or extrusion of Na þ outside the plasma membrane or secretion of salt outside the plant (bladders, salt glands). Since halophytes are very important for the study of salt-tolerance mechanisms, this chapter is focused on the work carried out on transporter genes from halophytes present at the plasma membrane and tonoplast controlling Na þ homeostasis under salinity. IntroductionPlants face different major abiotic stresses such as high salinity, drought, and temperature extremes on a day-to-day basis. These abiotic stresses cause adverse 685

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PRELIMINARY INVESTIGATIONS INTO THE STRUCTURE OF THE ROOTS OF THE MANGROVES, AVICENNIA MARINA AND BRUGUIERA GYMNORRHIZA, IN RELATION TO ION UPTAKE

Cited by 64 publications

References 15 publications

Salt tolerance mechanisms in mangroves: a review

Salt tolerance mechanisms in mangroves: a review

Quantitative analysis of the root system of Avicennia alba based on the pipe model theory

Role of Na⁺/H⁺Antiporters in Na⁺Homeostasis in Halophytic Plants

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PRELIMINARY INVESTIGATIONS INTO THE STRUCTURE OF THE ROOTS OF THE MANGROVES, AVICENNIA MARINA AND BRUGUIERA GYMNORRHIZA, IN RELATION TO ION UPTAKE

Cited by 64 publications

References 15 publications

Salt tolerance mechanisms in mangroves: a review

Salt tolerance mechanisms in mangroves: a review

Quantitative analysis of the root system of Avicennia alba based on the pipe model theory

Role of Na+/H+Antiporters in Na+Homeostasis in Halophytic Plants

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Role of Na⁺/H⁺Antiporters in Na⁺Homeostasis in Halophytic Plants