Endopolyploidy Variation in Wild Barley Seeds across Environmental Gradients in Israel

Abstract

Wild barley is abundant, occupying large diversity of sites, ranging from the northern mesic Mediterranean meadows to the southern xeric deserts in Israel. This is also reflected in its wide phenotypic heterogeneity. We investigated the dynamics of DNA content changes in seed tissues in ten wild barley accessions that originated from an environmental gradient in Israel. The flow cytometric measurements were done from the time shortly after pollination up to the dry seeds. We show variation in mitotic cell cycle and endoreduplication dynamics in both diploid seed tissues (represented by seed maternal tissues and embryo) and in the triploid endosperm. We found that wild barley accessions collected at harsher xeric environmental conditions produce higher proportion of endoreduplicated nuclei in endosperm tissues. Also, a comparison of wild and cultivated barley strains revealed a higher endopolyploidy level in the endosperm of wild barley, that is accompanied by temporal changes in the timing of the major developmental phases. In summary, we present a new direction of research focusing on connecting spatiotemporal patterns of endoreduplication in barley seeds and possibly buffering for stress conditions.

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Investigations on Nuclear DNA Content and DNA Synthesis in Plants and Fungi Using Flow Cytometry and Fluorescence Microscopy

“…Changes in endoreduplication intensity during seed development makes the measurement of endopolyploidy suitable for estimating seed maturity, and it can also be related to stress conditions. Nowicka et al [ 9 ] estimated endopolyploidy in different tissues (embryo, endosperm, and maternal tissues) of wild barley grains originating from mesic, semi-mesic, semi-xeric, and xeric ecogeographic sites in Israel collected at different developmental stages from 4 to about 65 days after pollination. According to the obtained results, in wild barley grains, endoreduplication is higher than those of cultivated barley, and the proportion of endoreduplicated nuclei in the endosperm is higher in xeric accessions.…”