Separation of seed development from monocarpic senescence in soybeans

Noodén, Larry D.; Rupp, D.; Derman, Belma D.

doi:10.1038/271354a0

Cited by 41 publications

(31 citation statements)

References 7 publications

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“…Subsequently, it has been assumed that partial male-sterile soybean plants fix dinitrogen at approximately the same rate as do their fertile isolines (2,11). This assumption, however, is seemingly inconsistent with the reports that senescence is delayed in depodded soybean plants (7) and that the duration of dinitrogen fixation is prolonged in fertile soybean plants that exhibit delayed leaf senescence (1). Thus, one might expect that a partial male-sterile plant displaying delayed leafsenescence would fix more dinitrogen than would a normal fertile plant.…”

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confidence: 40%

Dinitrogen Fixation in Male-Sterile Soybeans

Imsande¹,

Ralston²

1982

Plant Physiol.

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Partial male-sterile (ms4/ms4) soybeans (Glycine max L. Merr.) and their fertile isoline (Ms4/Ms4) were grown in adjoining field plots. From 62 until 92 days after emergence, the nitrogenase activity, assayed by acetylene reduction, of the average male-sterile plant was approximately twice that of the average fertile plant. At approximately 100 days after emergence, the assayable nitrogenase activity of the fertile plants fell to zero, whereas the nitrogenase of the partial male-sterile plants continued to be active for two additional weeks. Thus, this male-sterile plant seems to fix dinitrogen both at a higher rate and over a longer duration than does its fertile isoline.Partial male-sterile soybean plants were first described in 1970 (3). The homozygous recessive ms/ms plants are easily recognized, because they produce very few pods, and their leaves usually remain green long after the fertile isoline has reached full maturity (8,12). In 1978, it was reported that homozygous ms1/ms, plants fix the same amount of dinitrogen as do heterozygous (Msi/msi) fertile plants (12). Subsequently, it has been assumed that partial male-sterile soybean plants fix dinitrogen at approximately the same rate as do their fertile isolines (2, 11). This assumption, however, is seemingly inconsistent with the reports that senescence is delayed in depodded soybean plants (7) and that the duration of dinitrogen fixation is prolonged in fertile soybean plants that exhibit delayed leaf senescence (1). Thus, one might expect that a partial male-sterile plant displaying delayed leafsenescence would fix more dinitrogen than would a normal fertile plant. Because of these apparent inconsistencies, we investigated both the rate and the duration of dinitrogen fixation in ms4/ms4 (male-sterile) soybeans and in their Ms4/Ms4 (fertile) isoline. Modeling clay was used to form a seal between the stem of the plant and the notch in the rubber stopper (5). Air (50 ml) was removed from the jar with a syringe, and 50 ml acetylene was injected through the septum. Gas samples were removed from the jar at three or more 10-min intervals with a 10-,ul Hamilton syringe, and the gas mixture was analyzed immediately on a gas chromatograph equipped with a hydrogen flame detector. The ratio of acetylene to ethylene was determined from the heights of the respective peaks. A correction for the effect of diffusion on peak height was made.Analysis of Data. Data were analyzed by two-way analysis of variance. For these calculations, logarithmic transformations of the raw data for total nitrogenase activity, nodule specific activity, nodule dry weight, and partitioning efficiency were used to obtain homogeneity of variance. In addition, t tests comparing the means of the two genotypes at each time point were performed. The efficiency with which each plant fixed dinitrogen was estimated. This partitioning efficiency is defined as ,umol ethylene formed per h per g fresh weight.RESULTS AND DISCUSSION A partial male-sterile soybean plant produces only a few pods. T...

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confidence: 40%

Dinitrogen Fixation in Male-Sterile Soybeans

Imsande¹,

Ralston²

1982

Plant Physiol.

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“…The main mechanisms left are: the seeds (a) produce a senescence-inducing hormone(s) which travels up into the leaf with the xylem sap and (b) divert nutrients (or cytokinin) away from the leaves (9,11). The nutrient (cytokinin) diversion idea is not consistent with other data which are discussed elsewhere (9,11,12). Whatever the nature ofthe senescence signal, it can be transmitted via the xylem to the leaves where it initiates breakdown of Chl and probably other leaf constituents leading to death.…”

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confidence: 39%

“…Recently, it has been shown that, in surgically modified soybean plants, seed growth (with the accompanying nutrient drain and diversion) can occur without producing the senescence response (12) which raises doubts about the role of nutrient exhaustion in the induction of monocarpic senescence (9,11). Nonetheless, where senescence does occur, important constituents, especially nitrogen, move out ofthe leaves, and this seems to be an important, even if secondary, component of the senescence of attached leaves (9,10).…”

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confidence: 99%

Transmission of the Monocarpic Senescence Signal via the Xylem in Soybean

Noodén¹,

Murray²

1982

Plant Physiol.

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MATERIALS AND METHODS During monocarpic senescence in soybean (Glycine max IL.I Merril cv.Anoka) there is a remobilization of nitrogen from the leaves to the seeds, and it has been hypothesized that this loss of nitrogen from the leaves induces foliar yellowing. The phloem in a smaUl segment of the petiole between the pods and the target leaf can be inactivated with a jet of steam. When a plant is depodded except for a single pod cluster in the center of the plant, the pod cluster induces yellowing of the nearest leaf even if the petiole contains a zone of dead phloem, whereas most of the rest of the plant remains green. The nitrogen content of these leaves with a dead phloem zone in their petioles does not decrease greatly, even though the leaves turn yellow. A similar treatment of a single leaf on a fuly depodded plant (leaves stay green) does not cause that leaf to turn yellow. Since nutrients would have to be withdrawn from the leaves via the phloem, the pods do not induce yellowing by pulling nutrients out of the leaf and must be able to exert their influence via the xylem.Historically, monocarpic senescence has been attributed to nutrient exhaustion (due to drain and diversion) from the vegetative parts by the developing fruit (7, 9). Because depodding (4) and deseeding (6) extend the life of soybean plants far beyond normal, the seeds must control monocarpic senescence in soybeans. For convenience, this influence of the seeds will be termed the senescence signal (6). In the soybean, the primary target of the senescence signal is the leaves (8).The theories which hold that the senescence signal is a nutrient deficiency have been questioned some years ago (4, 9-11). Recently, it has been shown that, in surgically modified soybean plants, seed growth (with the accompanying nutrient drain and diversion) can occur without producing the senescence response (12) which raises doubts about the role of nutrient exhaustion in the induction of monocarpic senescence (9, 11). Nonetheless, where senescence does occur, important constituents, especially nitrogen, move out ofthe leaves, and this seems to be an important, even if secondary, component of the senescence of attached leaves (9, 10).Photosynthates and other 'nutrients,' such as amino acids and hormones, being exported (withdrawn) from the leaf blade would have to travel down through the petiole via the phloem which is a living tissue (1, 2, 13). We decided to test the nutrient withdrawal hypothesis by killing a small segment of the petiole with steam (often called 'girdling' or 'ringing'). This does not interfere with the ability of the xylem (which is already dead at functional maturity) to supply water, nutrients, and hormones to the leaf blade. Soybeans (Glycine max [L.] Merrill) cv. Anoka were grown as described (5). Foliar senescence and fruit development were measured quantitatively following the visual procedures outlined elsewhere (5). Leaf yellowing measured in the visual procedure reflects the decline of essential functions during monocarpic s...

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“…Water stress reduces the direct supply of N to the seed by limiting leaf area expansion (Withers 1979b), photosynthesis (Boyer 1976), and N fixation (Sprent 1976) and thereby forces a greater dependence on N reserves thus stimulating and/or aggravating the 'self-destruction' cycle. If, however, the signal for senescence is hormonal (Nooden et al 1978;Williams & Williams 1978), water deficit may stimulate production of the hormone. Nooden et al (1978) suggested that the hormone travels only downward in the plant from the pod.…”

Section: Discussionmentioning

confidence: 99%

“…If, however, the signal for senescence is hormonal (Nooden et al 1978;Williams & Williams 1978), water deficit may stimulate production of the hormone. Nooden et al (1978) suggested that the hormone travels only downward in the plant from the pod. In lupin much of the leaf is above the pods, but, if the lower leaves were induced to senesce by a hormone the upper leaves would probably start a 'self destruction' cycle because of the demand for assimilates by the plant as a whole on a reduced supply from the smaller leaf area.…”

Section: Discussionmentioning

confidence: 99%

A comparison of several grain legumes at two sowing times

Withers

Watkin

Forde³

1981

New Zealand Journal of Agricultural Research

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The pattern of nitrogen distribution in field grown Lupinus albus, L. /uteus, Pisum sativum, and Vicia faba which were sown in August or October, was measured. Although rates ofN accumulation were similar, the start and duration of the rapid N accumulation phase differed between species. L. albus had the longest accumulation phase, which contributed to its superior seed protein yield. The data suggest that, in the field, timing of the initiation of the 'self destruction' cycle in grain legumes is an important determinant of seed protein yield and can be initiated by the effects of water stress. The exception to this was P. sativum in which, at the early sowing, self shading may have been an important factor. It was concluded that early sowing was important to ensure maximum N accumulation and seed protein yield. Relatively small extension to the growth period by irrigation or reliable summer rain should achieve significant increases in seed protein yield.

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Separation of seed development from monocarpic senescence in soybeans

Cited by 41 publications

References 7 publications

Dinitrogen Fixation in Male-Sterile Soybeans

Dinitrogen Fixation in Male-Sterile Soybeans

Transmission of the Monocarpic Senescence Signal via the Xylem in Soybean

A comparison of several grain legumes at two sowing times

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