Mutants at Xantha and Albina Loci in Relation to Chloroplast Biogenesis in Barley (Hordeum vulgare L.) 1993. Biologiske Skrifter,42). 115 black&white pls. 20 tabs. figs. 349 p. Lex8vo. Paper bd.

Abstract: Recessive lethal mutants of the xantha and albina phenotypesaffecting chloroplast development in barley (Hordeum vulgare L.) havebeen studied by electron microscopy and spectroscopic analysis ofpigments. Nuclear gene loci with functions in differentiation ofetioplasts and chloroplasts were identified. Mutants at loci xan-f, -g, -h and alb-e are blocked in protochlorophyllide synthesis andcompletely blocked mutants fail to form prolamellar body membranes.The loci xan-f, -g, -h and alb-e determine a function in conversion ofprotoporphyrin IX to Mg protoporphyrin, while locus xan-l is involvedin conversion of Mg protoporphyrin to protochlorophyllide. Mutants atloci xan-a, -i, =-k and -u are defective in prolamellar bodymembrane assembly. Mutants at loci xan-j and alb-f are defective inprolamellar body membrane dispersal, lack the 684 to 672 nm spectralshift and are deficient in esterification of chlorophyllide. Mutants atloci xan-m, -o, -p, -q, -s, -t and alb-c and -e are blocked at thetwo-disc grana stage. Mutants at loci xan-b, -c, -d and -e are blockedlate in the assembly of photosynthetic membranes.