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Endosperm variability: from endoreduplication within a seed to higher ploidy across species, and its competence

Published online by Cambridge University Press:  17 June 2020

Parimalan Rangan Open the ORCID record for Parimalan Rangan [Opens in a new window]
Parimalan Rangan*
Affiliation:
Division of Genomic Resources, ICAR-National Bureau of Plant Genetic Resources, New Delhi110012, India Queensland Alliance for Agriculture and Food Innovation, University of Queensland, St Lucia, QLD4072, Australia
*
Author for Correspondence: Parimalan Rangan, E-mail:r.parimalan@icar.gov.in; p.rangan@uq.edu.au
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Abstract

Endosperm tissue that nourishes the embryo during seed development, upon maturity, nourishes the global population with special reference to cereal crops like maize, wheat and rice. In about 70% of the angiosperms, endosperm genome content is ‘3n’ with 2:1 (maternal:paternal) contribution, as a result of the second fertilization event. However, angiosperms evolution also documents diversity in endosperm genome content from ‘2n’ to ‘15n’, in scale with the corresponding maternal genome dosage variability (‘1n’ to ‘14n’), whereas paternal contribution is invariable. In apomicts, due to lack of fertilization, or pseudogamy (fertilization of the central cell for endosperm formation), endosperm genome dosage (m:p) has been reported to range between 1:1 and 8:3. Exceptionally, the central cell with one unreduced nucleus and fused with a reduced sperm cell, with 2:1 normal genome dosage, has been reported in Panicum. Altered genome dosage levels are reportedly correlative with eccentricities among maternal and paternal contribution to seed resource allocation. Besides endosperm ploidy variability between species of angiosperms, the present review gives an overview of the ploidy variability in endosperm cells within a seed, up to ‘690n’. In addition to genome-scale variability in the endosperm, some taxa of angiosperms exhibit chlorophyllous endosperms and some chlorophyllous embryos. Also, endosperm cell number during seed development is reported to have a strong association with grain weight at maturity. Genes underlying these traits of variability are unknown, and the present review underscores the variability and highlights the potential of the single-cell sequencing techniques towards understanding the genetic mechanisms associated with these variable traits.

Keywords

apomixiscerealsdosage levelendoreduplicationendosperm variabilityplant genetic resourcessingle-cell sequencing
Type
Review Paper
Information
Seed Science Research , Volume 30 , Issue 3 , September 2020 , pp. 173 - 185
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Copyright
Copyright © The Author(s), 2020. Published by Cambridge University Press

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Footnotes

This article is dedicated to the great academician Nikolay Ivanovich Vavilov (25 November 1887 to 26 January 1943), who had envisioned a hunger-free world but, ironically, died of hunger and malnutrition.

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