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Abstract:
The impact of parentally provided factors on fertilization and early embryogenesis in plants is poorly understood. Recently, we described the Pelle/IRAK-like cytoplasmic kinase SHORT SUSPENSOR that links the onset of embryogenesis with the fertilization event by a novel parent-of-origin effect. To identify further mutations with similar effect on early embryogenesis, we conducted a forward genetic screen for paternal effect mutations. While the majority of mutations that could be found disturbs fertilization and therefore presumably comprises gametophytic mutations, we were able to identify a small subset that directly affects embryogenesis. Here, we describe a mutant with reduced elongation of the zygote and shorter suspensor cells. Because of the position of the embryo within the seed, we called the corresponding gene NIMNA after the Sanskrit word for “sunken” or “low”. NIMNA codes for an apoplastic polygalacturonase presumably involved in cell wall modifications. Haploinsufficiency of NIMNA reveals a predominant role of the paternal allele in cell elongation of suspensor cells.
