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The role of the integuments in pollen tube guidance in flowering plants
Author(s) -
Lora Jorge,
Laux Thomas,
Hormaza José I.
Publication year - 2019
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.15420
Subject(s) - ovule , integument , pollen tube , biology , arabidopsis , pollen , botany , mutant , arabidopsis thaliana , microbiology and biotechnology , anatomy , genetics , pollination , gene
Summary In angiosperms, pollen tube entry into the ovule generally takes place through the micropyle, but the exact role of the micropyle in pollen tube guidance remains unclear. A limited number of studies have examined eudicots with bitegmic micropyles, but information is lacking in ovules of basal/early‐divergent angiosperms with unitegmic micropyles. We have evaluated the role of the micropyle in pollen tube guidance in an early‐divergent angiosperm ( Annona cherimola ) and the evolutionarily derived Arabidopsis thaliana by studying γ‐aminobutyric acid ( GABA ) and arabinogalactan proteins ( AGP s) in wild‐type plants and integument‐defective mutants. A conserved inhibitory role of GABA in pollen tube growth was shown in A. cherimola , in which AGP s surround the egg apparatus. In Arabidopsis , the micropyle formed only by the outer integument in wuschel‐7 mutants caused a partial defect in pollen tube guidance. Moreover, pollen tubes were not observed in the micropyle of an inner no outer ( ino ) mutant in Arabidopsis , but were observed in homologous ino mutants in Annona . The similar distribution of GABA and AGP s observed in the micropyle of Arabidopsis and Annona , together with the anomalies from specific integument mutants, support the role of the inner integument in preventing multiple tube entrance (polytubey) in these two phylogenetically distant genera.