Barley albino lemma 1 (alm1) mutants exhibit conspicuous albinism in spikes, where they lack chlorophyll pigments in the hulls except for in discrete areas connecting to the awns, which are otherwise green. Taketa et al. (on pp. 447-457) used genetic analyses and positional cloning to map the alm1 mutation to a gene locus encoding one of two GOLDEN2-LIKE transcription factors in barley (HvGLK2). The alm1.g mutation caused a 34% reduction in spike photosynthesis, which likely accounts for the 15.8% reduction in the grain weight also observed in these plants. Further, expression analyses of HvGLK2 and its homologue HvGLK1 indicate distinct, non-redundant roles for HvGLK2, thus rendering it a useful genetic tool to further unravel the GLK transcriptional network in barley.
The cover image shows ~2 weeks old barley spikes of a wild-type (left) and alm1.g mutant (right) plant. Note that in the mutant, lemmas and paleas on the central rows are albino, while other tissues are green. Image supplied by Shin Taketa (University of Okayama, Japan).