High impact information on FIS2

• Maintenance of FIS2 imprinting depends on DNA methylation, whereas loss of DNA methylation does not affect MEA imprinting [1].
• DNA methylation targets a small region upstream of FIS2 distinct from the target of DNA methylation associated with FWA [1].
• FEM111/AGL80 is required for the expression of two central cell-expressed genes, DEMETER and DD46, but not for a third central cell-expressed gene, FERTILIZATION-INDEPENDENT SEED2 [2].
• Positional cloning of EMF2 revealed that it encodes a zinc finger protein similar to FERTILIZATION-INDEPENDENT SEED2 and VERNALIZATION2 of Arabidopsis [3].
• The parent-of-origin-determined differential activity of MEA, FIS2, and FIE is not dependent on DNA methylation, but methylation does control some gene(s) that have key roles in seed development [4].

Biological context of FIS2

• We show that FWA and FIS2 imprinting requires the maintenance of DNA methylation throughout the plant life cycle, including male gametogenesis and endosperm development [1].
• FIS2 encodes a protein with a C2H2 zinc-finger motif and three putative nuclear localization signals, indicating that it is likely to be a transcription factor [5].
• We have cloned two genes, FIS1 and FIS2, that control both fertilization independent seed development and postpollination embryo development in Arabidopsis [5].
• Despite similarities between the fis2 mutant phenotype and those of some other plant Pc-G members, it has remained unclear how the FIS2/EMF2/VRN2 class Pc-G genes interact with the others [6].
• Finally, both cap1 and cap2 mutant endosperms, like wild-type endosperms, expressed the paternally inactive endosperm-specific FIS2 promoter GUS fusion transgene only when the transgene was introduced via the embryo sac, indicating that imprinting was not affected [7].

Anatomical context of FIS2

• The behaviour of fie2, however, was a surprise: no alleles were methylated in the gametes, although paternally contributed fie2 is methylated and silent in the endosperm, indicating that, in some cases, plant imprinting requires de novo DNA methylation [8].

Physical interactions of FIS2

• Analysis in yeast further indicates a potential for the CLF and SWN proteins to interact with the other VEFS domain proteins VRN2 and FIS2 [6].

Other interactions of FIS2

• The wild-type alleles of MEA or FIS2 are not required [4].
• In Arabidopsis, the EMBYRONIC FLOWER2 (EMF2), VERNALISATION2 (VRN2) and FERTILISATION INDEPENDENT ENDOSPERM2 (FIS2) genes encode related Polycomb-group (Pc-G) proteins [6].

References