Limits...
Relationship of source and sink in determining kernel composition of maize.

Seebauer JR, Singletary GW, Krumpelman PM, Ruffo ML, Below FE - J. Exp. Bot. (2009)

Bottom Line: Intermated B73xMo17 recombinant inbred lines (IBM RILs) which displayed contrasting concentrations of endosperm starch were grown in the field with deficient or sufficient N, and the source supply altered by ear truncation (45% reduction) at 15 d after pollination (DAP).The C/N ratio of the assimilate supply at 19 DAP was directly related to the final kernel composition, with an inverse relationship between the concentrations of starch and protein in the mature endosperm.The accumulation of kernel starch and protein in maize is uniform along the ear, yet adaptable within genotypic limits, suggesting that kernel composition is source limited in maize.

View Article: PubMed Central - PubMed

Affiliation: Department of Crop Sciences, University of Illinois Urbana-Champaign, 1201 W Gregory Drive, Urbana, IL 61801, USA.

ABSTRACT
The relative role of the maternal source and the filial sink in controlling the composition of maize (Zea mays L.) kernels is unclear and may be influenced by the genotype and the N supply. The objective of this study was to determine the influence of assimilate supply from the vegetative source and utilization of assimilates by the grain sink on the final composition of maize kernels. Intermated B73xMo17 recombinant inbred lines (IBM RILs) which displayed contrasting concentrations of endosperm starch were grown in the field with deficient or sufficient N, and the source supply altered by ear truncation (45% reduction) at 15 d after pollination (DAP). The assimilate supply into the kernels was determined at 19 DAP using the agar trap technique, and the final kernel composition was measured. The influence of N supply and kernel ear position on final kernel composition was also determined for a commercial hybrid. Concentrations of kernel protein and starch could be altered by genotype or the N supply, but remained fairly constant along the length of the ear. Ear truncation also produced a range of variation in endosperm starch and protein concentrations. The C/N ratio of the assimilate supply at 19 DAP was directly related to the final kernel composition, with an inverse relationship between the concentrations of starch and protein in the mature endosperm. The accumulation of kernel starch and protein in maize is uniform along the ear, yet adaptable within genotypic limits, suggesting that kernel composition is source limited in maize.

Show MeSH

Related in: MedlinePlus

Relationship between the transport rates of total sugars and amino acids into agar traps situated for 4 h in place of developing endosperm at 19 DAP. Starch class types, either high or low based on endosperm starch concentration, were each represented by two IBM RILs. Data are the mean of two replications, grown at two N supplies and including two ear sink size treatments (full versus truncated) (n=8). High starch class types are represented by filled diamonds, and low starch class types are open diamonds.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC2803218&req=5

fig5: Relationship between the transport rates of total sugars and amino acids into agar traps situated for 4 h in place of developing endosperm at 19 DAP. Starch class types, either high or low based on endosperm starch concentration, were each represented by two IBM RILs. Data are the mean of two replications, grown at two N supplies and including two ear sink size treatments (full versus truncated) (n=8). High starch class types are represented by filled diamonds, and low starch class types are open diamonds.

Mentions: Although the C/N ratios of transported assimilates segregated into two discrete class types relating to the high or low starch inbreds (genotypes), the same was not true for the absolute rates of total sugar or amino-N transport (Fig. 5). Discerning this difference was made possible by the large range of sugar transport rates, especially for high starch inbreds, and amino acid transport rates, especially for low starch inbreds, produced by employing ear reduction and N fertilizer treatments. More specifically, across the ear and N treatments it was observed that some high and low starch inbreds had similar transport rates of total sugar, while similar comparisons showed that other high and low starch inbreds had comparable rates of transported amino-N. Even though inbreds could not be classified as high or low starch based on absolute rates of sugar or amino-N transported, in all cases the parental genotype controlled the proportion of sugar and amino acid transported such that the inbreds could be discerned as high or low starch types regardless of ear and N treatments (Fig. 5).


Relationship of source and sink in determining kernel composition of maize.

Seebauer JR, Singletary GW, Krumpelman PM, Ruffo ML, Below FE - J. Exp. Bot. (2009)

Relationship between the transport rates of total sugars and amino acids into agar traps situated for 4 h in place of developing endosperm at 19 DAP. Starch class types, either high or low based on endosperm starch concentration, were each represented by two IBM RILs. Data are the mean of two replications, grown at two N supplies and including two ear sink size treatments (full versus truncated) (n=8). High starch class types are represented by filled diamonds, and low starch class types are open diamonds.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2803218&req=5

fig5: Relationship between the transport rates of total sugars and amino acids into agar traps situated for 4 h in place of developing endosperm at 19 DAP. Starch class types, either high or low based on endosperm starch concentration, were each represented by two IBM RILs. Data are the mean of two replications, grown at two N supplies and including two ear sink size treatments (full versus truncated) (n=8). High starch class types are represented by filled diamonds, and low starch class types are open diamonds.
Mentions: Although the C/N ratios of transported assimilates segregated into two discrete class types relating to the high or low starch inbreds (genotypes), the same was not true for the absolute rates of total sugar or amino-N transport (Fig. 5). Discerning this difference was made possible by the large range of sugar transport rates, especially for high starch inbreds, and amino acid transport rates, especially for low starch inbreds, produced by employing ear reduction and N fertilizer treatments. More specifically, across the ear and N treatments it was observed that some high and low starch inbreds had similar transport rates of total sugar, while similar comparisons showed that other high and low starch inbreds had comparable rates of transported amino-N. Even though inbreds could not be classified as high or low starch based on absolute rates of sugar or amino-N transported, in all cases the parental genotype controlled the proportion of sugar and amino acid transported such that the inbreds could be discerned as high or low starch types regardless of ear and N treatments (Fig. 5).

Bottom Line: Intermated B73xMo17 recombinant inbred lines (IBM RILs) which displayed contrasting concentrations of endosperm starch were grown in the field with deficient or sufficient N, and the source supply altered by ear truncation (45% reduction) at 15 d after pollination (DAP).The C/N ratio of the assimilate supply at 19 DAP was directly related to the final kernel composition, with an inverse relationship between the concentrations of starch and protein in the mature endosperm.The accumulation of kernel starch and protein in maize is uniform along the ear, yet adaptable within genotypic limits, suggesting that kernel composition is source limited in maize.

View Article: PubMed Central - PubMed

Affiliation: Department of Crop Sciences, University of Illinois Urbana-Champaign, 1201 W Gregory Drive, Urbana, IL 61801, USA.

ABSTRACT
The relative role of the maternal source and the filial sink in controlling the composition of maize (Zea mays L.) kernels is unclear and may be influenced by the genotype and the N supply. The objective of this study was to determine the influence of assimilate supply from the vegetative source and utilization of assimilates by the grain sink on the final composition of maize kernels. Intermated B73xMo17 recombinant inbred lines (IBM RILs) which displayed contrasting concentrations of endosperm starch were grown in the field with deficient or sufficient N, and the source supply altered by ear truncation (45% reduction) at 15 d after pollination (DAP). The assimilate supply into the kernels was determined at 19 DAP using the agar trap technique, and the final kernel composition was measured. The influence of N supply and kernel ear position on final kernel composition was also determined for a commercial hybrid. Concentrations of kernel protein and starch could be altered by genotype or the N supply, but remained fairly constant along the length of the ear. Ear truncation also produced a range of variation in endosperm starch and protein concentrations. The C/N ratio of the assimilate supply at 19 DAP was directly related to the final kernel composition, with an inverse relationship between the concentrations of starch and protein in the mature endosperm. The accumulation of kernel starch and protein in maize is uniform along the ear, yet adaptable within genotypic limits, suggesting that kernel composition is source limited in maize.

Show MeSH
Related in: MedlinePlus