Asexual Female Gametogenesis Involves Contact with a Sexually-Fated Megaspore in Apomictic Hieracium

Plant Physiology
Martina JuranićA M Koltunow

Abstract

Apomixis results in asexual seed formation where progeny are identical to the maternal plant. In ovules of apomictic species of the Hieracium subgenus Pilosella, meiosis of the megaspore mother cell generates four megaspores. Aposporous initial (AI) cells form during meiosis in most ovules. The sexual pathway terminates during functional megaspore (FM) differentiation, when an enlarged AI undergoes mitosis to form an aposporous female gametophyte. Then, the mitotically programmed FM dies along with the three other megaspores by unknown mechanisms. Transcriptomes of laser-dissected AIs, ovule cells, and ovaries from apomicts and AI-deficient mutants were analyzed to understand the pathways involved. The steps leading to AI mitosis and sexual pathway termination were determined using antibodies against arabinogalactan protein epitopes found to mark both sexual and aposporous female gametophyte lineages at inception. At most, four AIs differentiated near developing megaspores. The first expanding AI cell to contact the FM formed a functional AI that underwent mitosis soon after megaspore degeneration. Transcriptome analyses indicated that the enlarged, laser-captured AIs were arrested in the S/G2 phase of the cell cycle and were m...Continue Reading

Citations

May 8, 2019·Journal of Experimental Botany·Jorge LoraMathew R Tucker
Jun 5, 2019·Plant Signaling & Behavior·Martina JuranićAnna M Koltunow
Apr 20, 2019·Frontiers in Plant Science·Diego Hojsgaard, Elvira Hörandl
Mar 25, 2019·Frontiers in Plant Science·Pankaj KaushalDevendra R Malaviya
Jan 25, 2020·Trends in Genetics : TIG·Peggy Ozias-Akins, Joann A Conner
Apr 5, 2021·Journal of Plant Research·Agnieszka Barbara JanasKrystyna Musiał
Aug 24, 2021·DNA Research : an International Journal for Rapid Publication of Reports on Genes and Genomes·Hui-Hui JiaWen-Wu Guo

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