Figure 8.

Nitrogen Remobilization Efficiency Is Reduced in Maize atg12 Mutants.

(A) Overview of ¹⁵N labeling and subsequent N partitioning. Wild-type W22, atg12-1, and atg12-2 plants were grown on soil under high-¹⁴N conditions, pulse labeled at 40 DAG with ¹⁵NO₃⁻ for 2 d, and then grown on high-¹⁴N thereafter. At maturity (110 DAG), total N and the ¹⁵N/¹⁴N ratio of various tissues were analyzed by mass spectrometry. Two biological replicates each containing six plants were used for data analysis (n = 12). Values are adjusted means (±sd). Asterisks highlight values for atg12-1 and atg12-2 plants that are significantly different from the wild type as determined by Student’s t test (P < 0.05). See Supplemental Figure 9 for ¹⁵N labeling efficiency at 47 DAG.

(B) Biomass accumulation as measured by DW of remains (DWr = DW of stalk + upper leaves + lower leaves).

(C) DWs of seeds.

(D) HI as measured by the DW ratio of seeds to the aboveground portions of the plants.

(E) NHI as measured by the partitioning of total plant nitrogen in seeds.

(F) NHI:HI ratio as an estimate of NUE.

(G) to (J) Partitioning of total ¹⁵N in stalk, upper leaves, lower leaves, and seeds, respectively.

(K) ¹⁵NHI:HI ratio as an indicator of NRE.