The contribution of autophagy in the maternal tissue to the development of Arabidopsis seeds

Autophagy is a primary route for nutrient recycling in eukaryotes, by which superfluous or damaged cytoplasmic material and organelles are encapsulated and delivered to the vacuole or lysosome for breakdown. In Arabidopsis thaliana, about 40 autophagy related (ATG) genes, have been identified. One of the hallmark phenotypes of atg mutant plants in reduced seed yield. During embryogenesis the mother plant deposits and transfers nutrients to the developing embryo. Recent transcriptome data and microscopic evidence strongly suggest that autophagy occurs both in the plant mother and developing embryo. Yet, the contribution of autophagy in both sources to seed development unknown. Therefore, we wanted to study the role of maternal autophagy in seed development.

Germination test preformed on heterozygote seeds from two sets of reciprocal crosses (WT X atg5, WT X atg7), revealed early germination of seeds who matured in autophagy mutant siliques. In the first stages of germination, the radicle protrudes the seed coat which is external embryonic tissue that is derived from the integuments of the ovule. Due to seed coat’s participation in germination and its maternal origins, we examined the cells that comprise seed coat by scanning electron microscopy. When the mother plant was an autophagy mutant, the cells of the seed coat had abnormal shape and size. Further research such as staining mucilage, metabolic profiling including lipid analysis and ABA content is needed in order to fully understand the role of autophagy in the maternal tissue to seed development.