AUTHOR=Iglesias-Fernández Raquel , Pastor-Mora Elena , Vicente-Carbajosa Jesús , Carbonero Pilar 

TITLE=A Possible Role of the Aleurone Expressed Gene HvMAN1 in the Hydrolysis of the Cell Wall Mannans of the Starchy Endosperm in Germinating Hordeum vulgare L. Seeds

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.01706

DOI=10.3389/fpls.2019.01706

ISSN=1664-462X

ABSTRACT=<p>The barley endo-β-mannanase (<italic>MAN</italic>) gene family (<italic>HvMAN1-6</italic>) has been identified and the expression of its members analyzed throughout different plant organs, and upon grain development and germination. The <italic>HvMAN1</italic> gene has been found to be highly expressed in developing and germinating grains. The MAN (EC 3.2.1.78) enzymatic activity gets a maximum in grains at 48 h of germination (post-germination event). Immunolocalization of mannan polymers in grains has revealed the presence of these polysaccharides in the endosperm cell walls (CWs). By mRNA <italic>in situ</italic> hybridization assays, the <italic>HvMAN1</italic> transcripts have been localized to the aleurone layer, but not to the dead starchy endosperm cells. These data suggest that MAN1 is synthesized in the aleurone layer during early grain imbibition and moves potentially through the apoplast to the endosperm where the hydrolysis of the mannan polymers takes place after germination <italic>sensu stricto</italic>. Hence, mannans in the starchy endosperm CWs, besides their structural function, could be used as reserve compounds upon barley post-germination.</p>