Department of Crop Sciences, University of Illinois Urbana-Champaign, 1201 W Gregory Drive, Urbana, IL 61801, USA.
J Exp Bot. 2010;61(2):511-9. doi: 10.1093/jxb/erp324. Epub 2009 Nov 16.
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.
母体源和子代汇在控制玉米（Zea mays L.）子粒组成中的相对作用尚不清楚，并且可能受到基因型和氮供应的影响。本研究的目的是确定来自营养体源的同化产物供应和谷物汇对玉米子粒最终组成的利用对最终子粒组成的影响。在田间种植具有不同浓度胚乳淀粉的互交 B73xMo17 重组自交系（IBM RIL），并在授粉后 15 天（DAP）通过穗切除（减少 45%）来改变源供应。在 19 DAP 时使用琼脂陷阱技术确定进入子粒的同化产物供应，并测量最终的子粒组成。还确定了氮供应和子粒穗位对商业杂种最终子粒组成的影响。子粒蛋白和淀粉的浓度可以通过基因型或氮供应改变，但在穗的长度上保持相当稳定。穗切除也会产生胚乳淀粉和蛋白质浓度的一系列变化。19 DAP 时同化产物供应的 C/N 比与最终子粒组成直接相关，成熟胚乳中淀粉和蛋白质的浓度呈反比关系。玉米子粒中淀粉和蛋白质的积累在穗上是均匀的，但在基因型限制内具有适应性，表明玉米子粒的组成受源限制。
