The Symbiotic Synthesis of Auxin by Legumes and Nodule Bacteria and its Eole in Nodule Development

Kefford, NP; Brockwell, J; Zwar, JA

doi:10.1071/bi9600456

Cited by 101 publications

(28 citation statements)

References 13 publications

(17 reference statements)

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“…That is most likely to be the regulation of the hormone level, in particular that of auxin, by acting at the level of its synthesis and/or transport. These indirectly affect nodule formation (Kefford et al, 1960;Hunter, 1987;1989;Hirsch et al, 1989;Fukuhara et al, 1994;Wu et al, 1996) and the partitioning of photosynthates (Brenner and Cheikh, 1995). This is further supported by the synergistic response observed to HBR and auxin (Mandava, 1988).…”

Section: Resultssupporting

confidence: 56%

Nitrate reductase activity and yield of Lens culinaris sprayed with 28-homobrassinolide

Hayat

Ahmad

2003

Acta Agronomica Hungarica

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Thirty-day-old plants of Lens culinaris (L.) Medic. cv. Pusa-6 were sprayed with 10 -10 , 10 -8 or 10 -6 M aqueous solutions of 28-homobrassinolide (HBR). Root length and nodule number per plant decreased, whereas the leaf nitrate reductase activity (E.C. 1.6.6.1) at 60, 90 and 120 days after sowing and the seed yield at harvest increased significantly in plants sprayed with either concentration of HBR. The values increased at first with an increase in the concentration of HBR but decreased with a further increase above 10 -8 M, which proved best for improving seed production.

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Section: Resultssupporting

confidence: 56%

Nitrate reductase activity and yield of Lens culinaris sprayed with 28-homobrassinolide

Hayat

Ahmad

2003

Acta Agronomica Hungarica

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“…The It should be noted that the nutrient medium we used for most experiments was less complex than normal plant tissue culture media (18,29). Root nodule tissue is able to fix atmospheric N2 and is probably autonomous for the production of both auxin (9) and cytokinin (22). Nevertheless it is possible that the low growth rate of detached nodules may have been caused by a deficiency in some nutrient or growth factor such as the ethyl alcohol-soluble factor reported to interact with cytokinin to stimulate cell proliferation in pea root cortex explants (13).…”

Section: Resultsmentioning

confidence: 99%

Studies with Detached Lupin Root Nodules in Culture

Sutton¹,

Jepsen²

1975

Plant Physiol.

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A method has been developed for culturing detached nitrogen-fixing root nodules of lupin (Lupinus angustifolius L.) on a simple nutrient medium. Under the best conditions devised, the acetylene reduction activity of mature detached nodules was maintained at 10 to 25 nmoles of ethylene hr-1 mg-' fresh weight for 3 days. Under A recent report showed that at least one plant tissue, the immature pea cotyledon, can maintain a near normal developmental sequence for several days when excised and cultured in a nutrient medium (17). Since detached soybean root nodules can maintain a linear rate of acetylene reduction for several hr (26), it occurred to us that detached nodules supplied with a nutrient medium might be able to continue normal development and provide a useful third system for studying critical stages in nodule differentiation. MATERIALS AND METHODSThe slow growing, nonacid-producing Rhizobium strain NZP 2257, from the collection of Mr. R. M. Greenwood, Applied Biochemistry Division, D.S.I.R., was grown at 25 C on a medium containing 0.5 g of Difco yeast extract, 0.5 g of KH2PO4, 0.2 g of MgSO4 .7 H20, 0.1 g of NaCl, and 10 g of agar/l, adjusted to pH 6.8 with KOH.Seeds of L. angustifolius L. cv. Bitter Blue were sterilized with a 1:1 (v/v) mixture of 95% ethyl alcohol and 30% (w/w) H202, were germinated at 20 C in 0.5% agar, and were planted in stainless steel troughs of sterile pumice. Each seed was inoculated with an aliquot from a fresh slope culture of Rhizobium suspended in distilled H20. The troughs were placed in a controlled-environment cabinet set at a temperature regime of 25 C day, 20 C night, with a day length of 12 hr, and a light intensity over the 400 to 700 mm range of 130 w m-2. The troughs were watered with a nitrogen-free plant nutrient solution. No attempt was made to maintain sterility in the troughs after inoculation.Plants were prized out for harvesting after the pumice had been loosened with a spatula. Pumice granules adhering to the roots were removed under running water with a brush. The roots were then rinsed three times with distilled H20, drained, and the nodules were excised with forceps.For culture experiments, freshly excised nodules were placed with their broken surfaces down on a medium containing 0.7% (w/v) agar, 6% (w/v) sucrose, 20 ug/ml of D-threo-chloramphenicol, 5 mm potassium acetate, and 5 mm MES, adjusted to pH 5.5 with KOH. The cultures were maintained at 20 C.Acetylene reduction assays for nitrogenase activity (6) were performed at 25 C using 30 to 150 mg (fresh weight) samples of nodule tissue in 16-ml glass vials fitted with rubber serum caps. Each vial contained 90% air and 10% acetylene (v/v). Gas samples (0.3 ml) were withdrawn at intervals up to 1 hr and assayed for ethylene and acetylene using a Perkin-Elmer gas chromatograph, fitted with a 20 X 0.15 cm column of Poropak T maintained at 75 C. The sensitivity of these assays was approximately 0.01 nmole of ethylene hr-' mg-' fresh weight. Lupin nodules incubated in air alone produced less than 0.0...

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“…Nutman (13) has stated that, with few exceptions, only curled root hairs become infected. It has been suggested that IAA is involved in nodulation, but the mechanism of such an effect is not clear (9,13,16,20,21,22 Although there is evidence for a local effect of combined nitrogen on nodulation, few attempts have been made to propose a mechanism. Virtanen (26) has suggested that nitrate inhibition occurs through the formation of nitrite which reacts to form a nitriteleghemoglobin complex.…”

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confidence: 99%