Cultivar Differences in N Redistribution in Soybeans<sup>1</sup>

Zeiher, Carolyn A.; Egli, D. B.; Leggett, J. E.; Reicosky, David A.

doi:10.2134/agronj1982.00021962007400020027x

Cited by 92 publications

(100 citation statements)

References 13 publications

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“…The size of the soybean reproductive sink (number of pods allowed to develop) is inversely correlated with the amount of leaf VSP accumulation and can account for 50% of the soluble leaf protein in completely depodded plants (17). In contrast to early maturing soybean cultivars, late maturing cultivars, which obtain more seed N from redistribution and less from current N2 fixation and soil N (27), may rely more on the accumulation of VSP to effectively process vegetative N destined for developing seeds. Current research with soybean indicates that the highly regulated gene expression of the low mol wt VSPs provides an important mechanism to accommodate temporarily the storage of vegetative N and influence the N economy of this monocarpic dicot (19).…”

Section: Discussionmentioning

confidence: 99%

Wheat Vegetative Nitrogen Compositional Changes in Response to Reduced Reproductive Sink Strength

MacKown¹,

Sanford²,

Zhang³

1992

Plant Physiol.

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N redistribution patterns and the N composition of vegetative tissues above the peduncle node of wheat (Triticum aestivum L.) plants with altered reproductive sink strength were evaluated to determine the role of vegetative storage proteins in the temporary storage of excess N destined for export. The degree of leaf senescence symptoms (loss of chlorophyll, total N, and ribulose-1,5-bisphosphate carboxylase/oxygenase) were quirements for N export or gene expression of VSP for the temporary storage of excess N.Leaf tissue of wheat (Triticum aestivum L.), as well as many other monocotyledon and dicotyledon species, induces proteins in response to MeJA treatment (6). The molecular mass and immunological properties of these induced proteins vary markedly among species, and considerable quantitative differences in the level of expression of MeJA-induced proteins apparently occur among barley (Hordeum vulgare L.) cultivars (6). In response to depodding, JA, MeJA, and other treatments given to soybean (Glycine max [L.] Merr.) plants, abundant levels of the same specific vegetative proteins (molecular masses of 27, 29, and 94 kD) accumulate predominantly in the vacuoles of PVM cells of leaves (5,7,18,19,21). The 94-kD protein was recently identified as a member of the vegetative lipoxygenase family and proposed to be a bifunctional zymogen capable of catalyzing the hydroperoxidation of lipids and storing excess N temporarily (21).The effects of an altered reproductive sink demand on accumulation of VSP have been limited to studies of soybean (5,18,19,25,26). Because depodding, JA, and MeJA elicit similar VSP accumulation responses in soybean, other monocarpic annuals that express MeJA-induced proteins also may accumulate proteins with VSP characteristics when reproductive sink demand is altered. In wheat, redistribution of vegetative N accumulated before anthesis normally provides the major source of grain N (1, 16, 22). During reproductive growth, the extent of vegetative N redistribution depends on sink size. Removal of all spikes from multiculm wheat plants delays physiological and biochemical processes associated with leaf senescence and net mobilization of N (2, 4, 15). Partial reduction of the reproductive sink, however, has a relatively small effect on the initiation and extent of N mobilization from the flag leaf of a partially degrained culm of wheat (9,10

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Section: Discussionmentioning

confidence: 99%

Wheat Vegetative Nitrogen Compositional Changes in Response to Reduced Reproductive Sink Strength

MacKown¹,

Sanford²,

Zhang³

1992

Plant Physiol.

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“…This initiates an extensive remobilization of N, primarily from the leaves (6), but also from the stems, podwalls (19), and roots (JH Thorne, unpublished data). Approximately 33 to 100% of the N in mature soybean seeds is derived from remobilization from other tissues (6,17,19) suggesting that, during this period, significant changes may occur in the relative concentrations of sucrose versus specific amino acids in the phloem.…”

Section: Discussionmentioning

confidence: 99%

“…4) and high conversion efficiency, 0.7 at 40 h in the 46-d cotyledons versus 0.27 in the 35-d cotyledons, points to a maintained metabolic activity. Clearly this appears to be of significance to seed development, for much of the final N in soybean seeds is obtained by remobilization from other tissues (6,17,19). Thus, although glutamine is the principal amino acid delivered to developing cotyledons by the maternal seed coat at midpodfill, the relative composition of incoming assimilates may change late in seed development as leaf senescence occurs.…”

Section: Discussionmentioning

confidence: 99%

Cessation of Assimilate Uptake in Maturing Soybean Seeds

Vernooy¹,

Thorne²,

Lin³

et al. 1986

Plant Physiol.

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ABSTRACIIn vitro assimilate uptake and metabolism were evaluated in embryos of known age isolated from seeds at mid-podfilling through physiological maturity. The capacity of isolated Wye soybean embryos to take up exogenous ['4Cjsucrose dropped nearly 4-fold in less than 1 week at incipient cotyledon yellowing. This drop in rate of sucrose uptake coincided with cessation of seed growth as well as rapid decline in leaf photosynthetic rate that preceded leaf yellowing. Conversely, the rate of j3Hjglutamine uptake by cotyledons increased as they yellowed. Yellow cotyledons also rapidly converted exogenous VFHjglutamine to ethanolinsoluble components, but converted little exogenous 1'4Cjsucrose to ethanol-insoluble components, primarily because of greatly reduced sucrose uptake. Sustained import and metabolism of amino acids remobilized from senescing leaves may prolong seed growth beyond loss of photosynthetic competency and sucrose availability.Studies of grain filling in several cereal crops have indicated that the end of photosynthate import and grain growth is related to the crushing of specific cells involved in photosynthate import and the formation of an impenetrable black layer in the hilum region (4, 5). Perhaps in a similar manner, the phloem terminus in soybean seed coats may be crushed as the cotyledons mature (3). From studies of the import of '4C-labeled assimilates into developing soybean seeds, Tekroni et al. (12) concluded that transport in vivo essentially ceased at about the time that the seed coat color changed from green to yellow. Developmental studies by Konno (8) We determined the fresh weight, respiration rate, and dry weight of freshly dissected fruit tissue. Respiration rates were determined from CO2 production by known weights of pods, seed coats or embryos in sealed containers at 260C using IR gas analysis of small samples withdrawn by syringe. We also determined the uptake and metabolism of '4C-labeled sucrose or 3H-labeled glutamine in embryos freshly isolated at given periods after flowering (2, 11, 15). Seeds were frozen, lyophilized, dry weight determined, the relative '4C or 3H determined by combusting one cotyledon in a biological oxidizer (15). Photosynthetic rate of the upper, most recent fully expanded leaf was determined with "'CO2 on plants with seeds of known age as described previously (18). Other experimental details are described in the text and figure legends. This study was conducted twice, in 1982 and 1983. Minor differences between the studies are noted in the text.In other experiments, plants were grown and flowers tagged as before, but populations were seeded on dates such that, at the initiation of the experiment, a large number of 35-and 46-d-

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“…Soybean leaves have been shown repeatedly to be the primary donors of N for mobilization to seed tissue (Zeiher et al, 1982;Loberg et aL, 1984;Egli and Leggett, 1985;Shibles and Sundberg, 1998). We have demonstrated their importance as providers of S as well.…”

Section: General Conclusionmentioning

confidence: 58%

“…Thirty to one hundred percent of the seed's N comes from mobilized N in soybean (Zeiher et aL, 1982;Egli et aL, 1983). Soybean seed-N is composed of approximately one-half mobilized N under normal field growth conditions (Hanway and 29 Weber, 1971;Loberg et al, 1984; Irasande and Edwards, 1988), whereas soybean mobilizes 66 to 79% of its vegetative-N (Vasilas et al, 1995).…”

Section: Distribution and Mobilization Of Sulfur During Soybean Repromentioning

confidence: 99%

Distribution and Mobilization of Sulfur during Soybean Reproduction

Naeve

Shibles

2005

Crop Science

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This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer.The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely aflFect reproduction.In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion.Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand comer and continuing from left to right in equal sections with small overiaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book.Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. UMI GENERAL INTRODUCTION Dissertation OrganizationA discussion of results obtained from studies conducted on soybean sulfur metabolism is presented here as two manuscripts for the eventual submission for publication in Crop Science. A general introduction precedes these manuscripts giving a broad overview of plant sulfur metabolism, sulfur transpon, and soybean seed protein accumulation. A general conclusion chapter follows, summarizing findings of the two studies presented here.References cited in this dissertation are coalesced and listed at the end of the dissertation.The first manuscript paper discusses the distribution and mobilization of sulfur acquired by soybean during seed development, while the second takes up nitrogen and sulfur stress effects on mobilization of sulfur to developing soybean seed. RationaleSoybean seed is an important source of dietary protein for livestock and humans;however, soybean seed protein itself contains low, potentially growth-limiting concentrations of the sulfur-containing amino acids, methionine (met) and cysteine (cys), when used as the sole protein source for monogastric mammals. Methionine and cys are considered "essential amino acids" indicating that they cannot be synthesized de novo by monogastric mammals (Food and Agricultural Organization and World Health Organization, 1989). Methionine is the primary essential amino acid that is deficient in legume proteins (DeLumen et al., 1997), and soybean seed proteins contain about half of the met found in FAO's (Food and 2 Agricultural Organization) egg protein standard (Burton et al., 1982). This limitation reveals itself in high protein rations when the majority of the ingested protein is derived from soybean....

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Cultivar Differences in N Redistribution in Soybeans¹

Cited by 92 publications

References 13 publications

Wheat Vegetative Nitrogen Compositional Changes in Response to Reduced Reproductive Sink Strength

Wheat Vegetative Nitrogen Compositional Changes in Response to Reduced Reproductive Sink Strength

Cessation of Assimilate Uptake in Maturing Soybean Seeds

Distribution and Mobilization of Sulfur during Soybean Reproduction

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Cultivar Differences in N Redistribution in Soybeans1

Cited by 92 publications

References 13 publications

Wheat Vegetative Nitrogen Compositional Changes in Response to Reduced Reproductive Sink Strength

Wheat Vegetative Nitrogen Compositional Changes in Response to Reduced Reproductive Sink Strength

Cessation of Assimilate Uptake in Maturing Soybean Seeds

Distribution and Mobilization of Sulfur during Soybean Reproduction

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Cultivar Differences in N Redistribution in Soybeans¹