QTL analysis for sugar-regulated leaf senescence supports flowering-dependent and -independent senescence pathways

The aim of this work was to determine the genetic basis of sugar-regulated senescence and to explore the relationship with other traits, including flowering and nitrogen-use efficiency. Quantitative trait loci (QTLs) for senescence were mapped in the Arabidopsis Bay-0 × Shahdara recombinant-inbred line (RIL) population after growth on glucose-containing medium, which accelerates senescence. The extent of whole-rosette senescence was determined by imaging the maximum quantum yield of photosystem II (F _v/F_m). A major QTL on the top of chromosome 4 colocalized with FRI, a major determinant of flowering. This QTL interacted epistatically with a QTL on chromosome 5, where the floral repressor FLC localizes. Vernalization accelerated senescence in late-flowering lines with functional FRI and FLC alleles. Comparison with previous results using the Bay-0 × Shahdara population showed that rapid rosette senescence on glucose-containing medium was correlated with early flowering and high sugar content in compost-grown plants. In addition, correlation was found between the expression of flowering and senescence-associated genes in Arabidopsis accessions. However, an additional QTL on chromosome 3 was not linked to flowering, but to nitrogen-use efficiency. The results show that whole-rosette senescence is genetically linked to the vernalization-dependent control of flowering, but is also controlled by flowering-independent pathways.