Characterization and comparisons of five N2‐fixing Azolla‐Anabaena associations, I. Optimization of growth conditions for biomass increase and N content in a controlled environment*

Peters, Gerald A.; Toia, Robert E.; Evans, William; Crist, Deborah; Mayne, Berger C.; Poole, Rebecca E.

doi:10.1111/1365-3040.ep11581825

Cited by 28 publications

(8 citation statements)

References 20 publications

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“…The growth rates measured are in the range reported in literature 32 , 34 – 37 . However, higher RGRs may be obtained when growing Azolla under optimal conditions using synthetic media in aquaculture 1 , 38 . Self-crowding may also result in lower RGRs of the fern, however, during the experiment the biomass was lower than the self-crowding threshold of 2 kg FW m −2 and was therefore not responsible for the biphasic growth response 39 .…”

Section: Discussionmentioning

confidence: 99%

Azolla along a phosphorus gradient: biphasic growth response linked to diazotroph traits and phosphorus-induced iron chlorosis

Temmink

Harpenslager

Smolders

et al. 2018

Sci Rep

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Azolla spp., a water fern often used for phytoremediation, is a strong phosphorus (P) accumulator due to its high growth rate and N2 fixing symbionts (diazotrophs). It is known that plant growth is stimulated by P, but the nature of the interactive response of both symbionts along a P gradient, and related changes in growth-limiting factors, are unclear. We determined growth, and N and P sequestration rates of Azolla filiculoides in N-free water at different P concentrations. The growth response appeared to be biphasic and highest at levels ≥10 P µmol l−1. Diazotrophic N sequestration increased upon P addition, and rates were three times higher at high P than at low P. At 10 µmol P l−1, N sequestration rates reached its maximum and A. filiculoides growth became saturated. Due to luxury consumption, P sequestration rates increased until 50 µmol P l−1. At higher P concentrations (≥50 µmol l−1), however, chlorosis occurred that seems to be caused by iron- (Fe-), and not by N-deficiency. We demonstrate that traits of the complete symbiosis in relation to P and Fe availability determine plant performance, stressing the role of nutrient stoichiometry. The results are discussed regarding Azolla’s potential use in a bio-based economy.

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Section: Discussionmentioning

confidence: 99%

Azolla along a phosphorus gradient: biphasic growth response linked to diazotroph traits and phosphorus-induced iron chlorosis

Temmink

Harpenslager

Smolders

et al. 2018

Sci Rep

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“…This interpretation of events is conid complement of phy-sistent with the findings in a recent study of the ultrastructural allophycocyanin (APC) ontogeny of the leaf cavity trichomes and our current underintact main stem axes; standing of this symbiosis (3,14). is based on three to five A prior study showed that the energy absorbed by PBP effec-D. (20).…”

Section: Resultsmentioning

confidence: 99%

“…Analyses were conducted using both individual leaves and pairs of leaves sequentially dissected from the axes beginning with the apical segment. Triplicate samples of single leaves, and pooled leafpairs of the same developmental stage, were placed in 1 ml vials containing 0.25 ml of N-free growth medium (20) and allowed to equilibrate at 25°C in the light, 200 ,E.m-2-ss', for 90 min.…”

Section: Methodsmentioning

confidence: 99%

“…A symbiotic, heterocystous cyanobacterium, Anabaena azollae Strasb., which occurs in specialized cavities formed in the fern's aerial dorsal leaf lobes (4,12,14), can provide the associations with their total N requirements via N2 fixation (17,20 increases with the increasing heterocyst frequency. Therefore, most analyses of nitrogenase activity associated with progressively older leaves, or groups of leaves, from stem axes ofAzolla caroliniana (10, 19), Azolla filiculoides (9,26), and Azolla pinnata (26), have revealed negligible activity in the apical segments followed by a rapid increase, a leveling off, and a decline as the leaves senesce.…”

Section: Abstracimentioning

confidence: 99%

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confidence: 99%

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The Azolla-Anabaena azollae Relationship

Kaplan¹,

Calvert²,

Peters³

1986

Plant Physiol.

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ABSTRACINitrogenase activity was measured in leaves along the main stem axes ofAzolla pianata R. Br. The activity was negligible in leaves of the apical region, rapidly increased to a maximum as leaves matured, and declined in aging leaves. In situ absorption and fluorescence emission spectra were obtained for individual vegetative cells and heterocysts in filaments of the A. pinnata and AzolIa caroliniana endophytes removed from the cavities of progressively older leaves. These spectra unequivocally demonstrate the occurrence of phycobiliproteins in the two cell types of both endophytes at the onset of heterocyst differentiation in filaments from young leaves, during the period of maximal nitrogenase activity in filaments from mature leaves, and in filaments from leaves entering senescence. Phycobiliproteins of the A. caroliniana endophyte were purified and extinction coefficients determined for the phycoerythrocyanin, phycocyanin, and allophycocyanin. The phycobiliprotein content and complement of sequential leaf segments from main stem axes and of vegetative cell and heterocyst preparations were measured in crude extracts. There was no obvious alteration of the phycobiliprotein complement associated with increasing heterocyst frequency of the endophyte in sequential leaf segments and the phycobiliprotein complement of heterocysts was not appreciably different from that of vegetative cells. These findings indicate that the phycobiliprotein complement of the vegetative cell precursor is retained in the heterocysts of the endophyte.Sporophytes of the heterosporous aquatic ferns in the genus Azolla exhibit floating, multibranched stems bearing deeply bilobed leaves and adventitious roots (14). A symbiotic, heterocystous cyanobacterium, Anabaena azollae Strasb., which occurs in specialized cavities formed in the fern's aerial dorsal leaf lobes (4,12,14), can provide the associations with their total N requirements via N2 fixation (17,20 increases with the increasing heterocyst frequency. Therefore, most analyses of nitrogenase activity associated with progressively older leaves, or groups of leaves, from stem axes ofAzolla caroliniana (10, 19), Azolla filiculoides (9,26), and Azolla pinnata (26), have revealed negligible activity in the apical segments followed by a rapid increase, a leveling off, and a decline as the leaves senesce. An exception is a report of two distinct maxima of nitrogenase activity, and a suggestion of two separate generations of heterocysts, in A. caroliniana and A. pinnata (1).The phycobiliproteins of heterocystous cyanobacteria often are considered to be associated primarily with PSII in vegetative cells and to be absent, or greatly diminished, in the heterocysts since they exhibit only PSI activity (7). However, PBP3 occur in the heterocysts ofAnabaena variabilis (11,21) AZOLLA ENDOPHYTE PHYCOBILIPROTEINSPhycobiliprotein Extraction and Determination of Extinction Coefficients. Anabaena azollae was isolated from A. caroliniana leaf cavities using the gentle roller method (17). Isolation ...

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Seasonal variation in the phytomass, chemical composition and nutritional value of Azolla filiculoides Lam. along the water courses in the Nile Delta, Egypt

2012

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The present study aims to assess phenological behaviour, phytomass production, chemical composition and nutritional value of Azolla filiculoides in the water courses of the Nile Delta, Egypt. The sampling process was carried out seasonally using twenty‐five plots (each of 1 × 1 m) distributed along 15 irrigation canals and 10 drainage canals in the study area. Sprouting of A. filiculoides had its maximum activity during winter, vegetative growth during spring and summer and withering during autumn. Maximum seasonal phytomass (285.2 g DW m‐2) was found during spring. The annual mean was significantly higher in drainage canals (278.3 g DW m‐2) than in irrigation canals (144.4 g DW m‐2). The concentrations of Ca, Mg and Na in A. filiculoides from drainage canals were significantly higher than in those from irrigation canals. Regarding the type of water courses, there were no significant differences in organic contents and nutritive values between the irrigation and drainage canals. The analysis of growth characteristics indicated that A. filiculoides can grow quite well in drainage canals; its macronutrient (N, Ca, Mg, Na and Fe) contents are high enough to allow it to be used as a bio‐fertilizer. On the other hand, A. filiculoides could be considered as a ‘nutrients and heavy metals remover’ especially in drainage canals for wastewater treatment if the plant is harvested during its maximum phytomass. As feed supplement for animals, this plant could be considered as excellent forage because its high levels of carbohydrate, protein, crude fat, total digestible nutrients and the lower crude fiber contents (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Characterization and comparisons of five N₂‐fixing Azolla‐Anabaena associations, I. Optimization of growth conditions for biomass increase and N content in a controlled environment^*

Cited by 28 publications

References 20 publications

Azolla along a phosphorus gradient: biphasic growth response linked to diazotroph traits and phosphorus-induced iron chlorosis

Azolla along a phosphorus gradient: biphasic growth response linked to diazotroph traits and phosphorus-induced iron chlorosis

The Azolla-Anabaena azollae Relationship

Seasonal variation in the phytomass, chemical composition and nutritional value of Azolla filiculoides Lam. along the water courses in the Nile Delta, Egypt

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