Biomass increase under zinc deficiency caused by delay of early flowering in Arabidopsis

Plants generally produce more biomass when all nutrients are available in sufficient amounts. In addition to environmental constraints, genetic and developmental factors, such as the transition from vegetative to reproductive growth, restrict maximal yield. Here we report the peculiar observation that a subset of early flowering Arabidopsis thaliana accessions produced larger shoot rosette diameters when grown in zinc (Zn)-deficient conditions, compared with Zn-sufficient conditions. This was associated with early flowering that restricted the leaf length under Zn sufficiency. Zinc deficiency repressed FLOWERING LOCUS T (FT) expression, a major regulator of flowering. Repression or loss of FT increased the rosette diameter by a delay of the transition to flowering, a longer phase of leaf proliferation and increased leaf number. The transition to flowering reduced, but not terminated, the proliferation of established leaves. The size of individual leaf mesophyll cells was not affected by Zn deficiency or loss of FT , indicating that the larger rosette diameter was caused by maintained proliferation of vegetative tissue. As a consequence, early flowering accessions under Zn deficiency grew larger rosette diameters due to a delay of flowering, which explains the unusual increase of vegetative biomass under nutrient deficiency. Highlight An increase in biomass of some Arabidopsis accessions under Zn-deficiency is caused by retardation of flowering, prolonging vegetative growth. Abbreviations DAS days after sowing GWA genome-wide association SNP single nucleotide polymorphism Zn zinc