Sporophytic ovule tissues modulate the initiation and progression of apomixis in Hieracium

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dc.contributor.authorTucker, M.
dc.contributor.authorOkada, T.
dc.contributor.authorJohnson, S.
dc.contributor.authorTakaiwa, F.
dc.contributor.authorKoltunow, A.
dc.date.issued2012
dc.description.abstractApomixis in Hieracium subgenus Pilosella initiates in ovules when sporophytic cells termed aposporous initial (AI) cells enlarge near sexual cells undergoing meiosis. AI cells displace the sexual structures and divide by mitosis to form unreduced embryo sac(s) without meiosis (apomeiosis) that initiate fertilization-independent embryo and endosperm development. In some Hieracium subgenus Pilosella species, these events are controlled by the dominant LOSS OF APOMEIOSIS (LOA) and LOSS OF PARTHENOGENESIS (LOP) loci. In H. praealtum and H. piloselloides, which both contain the same core LOA locus, the timing and frequency of AI cell formation is altered in derived mutants exhibiting abnormal funiculus growth and in transgenic plants expressing rolB which alters cellular sensitivity to auxin. The impact on apomictic and sexual reproduction was examined here when a chimeric RNAse gene was targeted to the funiculus and basal portions of the ovule, and also when polar auxin transport was inhibited during ovule development following N-1-naphthylphthalamic acid (NPA) application. Both treatments led to ovule deformity in the funiculus and distal parts of the ovule and LOA-dependent alterations in the timing, position, and frequency of AI cell formation. In the case of NPA treatment, this correlated with increased expression of DR5:GFP in the ovule, which marks the accumulation of the plant hormone auxin. Our results show that sporophytic information potentiated by funiculus growth and polar auxin transport influences ovule development, the initiation of apomixis, and the progression of embryo sac development in Hieracium. Signals associated with ovule pattern formation and auxin distribution or perception may influence the capacity of sporophytic ovule cells to respond to LOA.
dc.description.statementofresponsibilityMatthew R. Tucker, Takashi Okada, Susan D. Johnson, Fumio Takaiwa, and Anna M. G. Koltunow
dc.identifier.citationThe Journal of Experimental Biology, 2012; 63(8):3229-3241
dc.identifier.doi10.1093/jxb/ers047
dc.identifier.issn0022-0949
dc.identifier.issn1460-2431
dc.identifier.orcidTucker, M. [0000-0003-4661-6700]
dc.identifier.orcidOkada, T. [0000-0002-7366-3767]
dc.identifier.urihttp://hdl.handle.net/2440/77846
dc.language.isoen
dc.publisherCompany of Biologists Ltd
dc.rights© 2012 The Author(s).This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
dc.source.urihttps://doi.org/10.1093/jxb/ers047
dc.subjectApomixis
dc.subjectauxin
dc.subjectgametophyte
dc.subjectovule
dc.subjectseed.
dc.titleSporophytic ovule tissues modulate the initiation and progression of apomixis in Hieracium
dc.typeJournal article
pubs.publication-statusPublished

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