REVIEW ARTICLE Centromeric histone H3 protein: from basic study to plant breeding applications Anshul Watts 1 • Vajinder Kumar 1 • Shripad Ramachandra Bhat 1 Received: 8 December 2015 / Accepted: 27 May 2016 Ó Society for Plant Biochemistry and Biotechnology 2016 Abstract Centromere is the defining unit of a chromosome where kinetochore complex assembles and facilitates chromosome segregation. Centromeres contain unique repetitive sequences and are enriched with transposons and retrotransposons. Although how centromere is determined is still not clearly understood, binding of a key protein, namely, the Centromeric Histone H3 (CENH3) to cen- tromeric repetitive DNA sequences has been found to be critical for the specification of centromere. Hence, cen- tromeres are said to be epigenetically specified by CENH3. Despite considerable variation in size and sequence, CENH3 protein shows significant conservation of structure and function. CENH3 disruption or overexpression shows severe defects in spindle fiber attachment and ultimately leads to embryo lethality. Basic studies on complementa- tion of CENH3 in Arabidopsis thaliana have led to the development of a novel method of haploid production through selective elimination of one set of parental chro- mosomes in the zygote. These findings have also shed new light on selective loss of chromosomes in interspecific crosses of Hordeum vulgare 9 H. bulbosum. Here, we briefly review unique features of CENH3 and discuss the new plant breeding opportunities that have emerged from the study of CENH3. Keywords Apomixis Á Centromere Á Chromosome elimination Á Haploid Á Reverse breeding Abbreviations CATD CENP-A targeting domain CID Centromere identifier CPAR-1 Centromeric protein A related 1 CSE4 Chromosome segregation 4 HCP3 Holocentric protein 3 HFD Histone fold domain HTR12 Histone three related 12 Introduction One of the key requirements of genetic inheritance is faithful transmission of the genetic material from one generation to the next generation. Genetic material in almost all organisms is organized in structures called chromosomes. Prokaryotes have mostly single circular chromosomes, while in most eukaryotes, chromosomes are linear and their numbers and size vary greatly among species. Structurally, a typical eukaryotic chromosome consists of chromatids, centromere and telomeres. Cen- tromere appears as a conspicuous constriction on the chromosome during cell division to which chromatids are joined, while telomeres are the ends of the chro- mosomes. Since position of centromere on a chromo- some is fixed, cytologists have used centromere to classify and identify chromosomes. A typical eukaryotic chromosome consists of DNA–protein complex. Besides the DNA binding histone proteins, various non-histone proteins (both enzymatic and structural) help in pack- aging of DNA into chromosomes. DNA is wrapped around an octamer of histone proteins comprising two subunits each of the histones H2A, H2B, H3 and H4 to form a nucleosome, and nucleosomes are linked together by the linker histone H1. & Shripad Ramachandra Bhat srbhat@nrcpb.org 1 ICAR-National Research Centre on Plant Biotechnology, New Delhi 110012, India 123 J. Plant Biochem. Biotechnol. DOI 10.1007/s13562-016-0368-4