Dissection of a complex seed phenotype: novel insights of FUSCA3 regulated developmental processes.
A T-DNA insertion mutant of FUSCA3 (fus3-T) in Arabidopsis thaliana exhibits several of the expected deleterious effects on seed development, but not the formation of brown seeds, a colouration which results from the accumulation of large amounts of anthocyanin. A detailed phenotypic comparison between fus3-T and a known splice point mutant (fus3-3) revealed that the seeds from both mutants do not enter dormancy and can be rescued at an immature stage. Without rescue, mature fus3-3 seeds are non-viable, whereas those of fus3-T suffer only a slight loss in their germinability. A series of comparisons between the two mutants uncovered differences with respect to conditional lethality, in histological and sub-cellular features, and in the relative amounts of various storage compounds and metabolites present, leading to a further dissection of developmental processes in seeds and a partial reinterpretation of the complex seed phenotype. FUS3 function is now known to be restricted to the acquisition of embryo-dependent seed dormancy, the determination of cotyledonary cell identity, and the synthesis and accumulation of storage compounds. Based on DNA binding studies, a model is presented which can explain the differences between the mutant alleles. The fus3-T lesion is responsible for loss of function only, while the fus3-3 mutation induces various pleiotropic effects conditioned by a truncation gene product causing severe mis-differentiation.
Tiedemann
Jens
J
Leibniz Institute für Pflanzengenetik und Kulturpflanzenforschung (IPK), Corrensstrasse 3, 06466, Gatersleben, Germany.
Rutten
Twan
T
Mönke
Gudrun
G
Vorwieger
Astrid
A
Rolletschek
Hardy
H
Meissner
Dirk
D
Milkowski
Carsten
C
Petereck
Silke
S
Mock
Hans-Peter
HP
Zank
Thorsten
T
Bäumlein
Helmut
H
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism; D000872:Anthocyanins / Q000378:metabolism; D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D001483:Base Sequence; D050260:Carbohydrate Metabolism; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010641:Phenotype; D017354:Point Mutation; D012639:Seeds / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
D000596:Amino Acids; D000872:Anthocyanins; C502726:FUSCA3 protein, Arabidopsis; D014157:Transcription Factors