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The maize lilliputian1 (lil1) gene, encoding a brassinosteroid cytochrome P450 C-6 oxidase, is involved in plant growth and drought response

Castorina, Giulia, Persico, Martina, Zilio, Massimo, Sangiorgio, Stefano, Carabelli, Laura, Consonni, Gabriella
Annals of botany 2018 v.122 no.2 pp. 227-238
Zea mays, alleles, biosynthesis, brassinosteroids, corn, cytochrome P-450, drought, epicuticular wax, epistasis, genetic analysis, gravitropism, leaves, mutants, mutation, oxygenases, plant adaptation, plant development, plant growth, plant hormones, pleiotropy, seedlings, transposons, water stress
Brassinosteroids (BRs) are plant hormones involved in many developmental processes as well as in plant–environment interactions. Their role was investigated in this study through the analysis of lilliputian1-1 (lil1-1), a dwarf mutant impaired in BR biosynthesis in maize (Zea mays). We isolated lil1-1 through transposon tagging in maize. The action of lil1 was investigated through morphological and genetic analysis. Moreover, by comparing lil1-1 mutant and wild-type individuals grown under drought stress, the effect of BR reduction on the response to drought stress was examined. lil1-1 is a novel allele of the brassinosteroid-deficient dwarf1 (brd1) gene, encoding a brassinosteroid C-6 oxidase. We show in this study that lil1 is epistatic to nana plant1 (na1), a BR gene involved in earlier steps of the pathway. The lill-1 mutation causes alteration in the root gravitropic response, leaf epidermal cell density, epicuticular wax deposition and seedling adaptation to water scarcity conditions. Lack of active BR molecules in maize causes a pleiotropic effect on plant development and improves seedling tolerance of drought. BR-deficient maize mutants can thus be instrumental in unravelling novel mechanisms on which plant adaptations to abiotic stress are based.