shygrl1 is a mutant affected in multiple aspects of photomorphogenesis

We have used a counter-selection strategy based on aberrant phytochrome reg ulation of an Lhcb gene to isolate an Arabidopsis mutant designated shygrl1 (shg1). shg1 seedlings have reduced phytochrome-mediated induction of the Lhcb gene family, but normal phytochrome-mediated induction of several othe r genes, including the rbcS1a gene. Additional phenotypes observed in shg1 plants include reduced chlorophyll in leaves and additional photomorphogeni c abnormalities when the seedlings are grown on medium containing sucrose. Mutations in the TATA-proximal region of the Lhcb1*3 promoter that: are kno wn to be important for phytochrome regulation affected reporter gene expres sion in a manner similar to the shg1 mutation. Our results are consistent w ith the possibility that the mutation either leads to defective chloroplast development or to aberrant phytochrome regulation. They also add to the ev idence of complex interactions between light-and sucrose-regulated pathways .