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Chromosome constitution, meiotic behavior and genetic control of synapsis in the sugarcane variety SP80-3280

Grant number: 20/07741-0
Support type:Regular Research Grants
Duration: December 01, 2020 - November 30, 2022
Field of knowledge:Biological Sciences - Genetics - Plant Genetics
Principal researcher:Maria Lúcia Carneiro Vieira
Grantee:Maria Lúcia Carneiro Vieira
Home Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

Current varieties of sugarcanes (Saccharum spp.) are polyploids and accumulate aneuploid chromosomes due to the domestication process that they have been through and the interspecific origin, which involves the domesticated species S. officinarum (the 'noble cane') and the wild species S. spontaneum, both with polyploid evolutionary history. During the 'nobilization' process, the hybrids were backcrossed to S. officinarum, and selection was continued in successive generations, establishing the genetic basis of the modern cultivars. Interestingly, cytological classical studies on the meiosis of hybrids and derived cultivars have suggested that meiotic chromosome pairings are predominantly bivalent. Recently, our research group has confirmed the occurrence of bivalent pairing in the Brazilian variety IACSP93-3046, by using the FISH technique and probes that are homologous to centromeric sequences. Based on the findings reported in wheat (Triticum aestivum) and Brassica, we suggested that Saccharum should have a mechanism to genetically control the synapsis and recombination. In T. aestivum, meiosis is under the control of the Ph1 locus, which plays a dual role, i.e., favoring synapsis between homologs at the beginning of meiosis I and later suppressing recombination (crossovers) between homoeologs. Inserted in the Ph1 locus is the ZIP4 gene, and its role is to suppress crossovers (CO) between homoeologs. In this study, we propose to analyze using immunolocalization the meiotic proteins MLH1 and RAD51 associated with the CO sites and chromatin breakage, respectively, as well as the proteins that constitute the synaptonemal complex, ZYP1 and ASY1. Furthermore, we intend to analyze the expression of ZIP4 during prophase I in S. officinarum and S. spontaneum and the Brazilian variety SP80-3280, to which genetic and genomic information is available. The relevance of our project resides in understanding how the meiotic processing occurs in sugarcane and the mechanism responsible for the diploidization of this 'artificial' polyploid only a few generations (6,7) following the interspecific hybridization. (AU)

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