Zygote elongation and suspensor development are influenced by a MAP kinase signaling pathway including the MAPKKK YODA (YDA). This pathway appears to be a potent regulator of suspensor formation, since yda loss-of-function mutants lack a recognizable suspensor structure while constitutively-active versions of YDA can transform the whole embryo into suspensor-like cells.
Little is known about this embryonic YODA signaling pathway on the molecular level.
Recently, we described a gene for the sperm-specific receptor-like cytoplasmic kinase SHORT SUSPENSOR (SSP) that controls the elongation of the zygote and suspensor formation through an unusual parent-of-origin effect. Our data suggests that SSP mRNA is accumulating specifically in sperm-cells of mature pollen and is delivered to the zygote during fertilization. Translation of these inherited transcripts leads to transient accumulation of SSP protein in the zygote where it participates in YODA activation.
Simplified model of the embryonic YODA signaling pathway