Caracterização cromossômica de Diatraea saccharalis (Crambidae, Lepidoptera) com ênfase nos cromossomos sexuais e DNAs repetitivos
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2021-11-08
Autores
Silva, Ana Elisa Gasparotto da
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Universidade Estadual Paulista (Unesp)
Resumo
A família de mariposas Crambidae incluem representantes que causam prejuízos econômicos às lavouras agrícolas, como a broca da cana-de-açúcar Diatraea saccharalis. Embora espécies de Crambidae apresentem extensa radiação adaptativa e importância econômica, pouco se sabe sobre sua arquitetura genômica e evolução cromossômica. Neste trabalho, caracterizamos os cromossomos e DNAs repetitivos de D. saccharalis, através do sequenciamento genômico e associação de métodos citogenéticos e bioinformáticos, com ênfase nos cromossomos sexuais. O número diploide foi diferente entre os sexos, i.e., 2n = 33 (fêmeas) e 2n = 34 (machos), além disso, foi observado a ocorrência de um sistema sexual múltiplo WZ₁Z₂/Z₁Z₁Z₂Z₂. A sonda telomérica revelou um forte sinal intersticial no cromossomo W e este cromossomo foi associado a dois cromossomos Z (Z₁ e Z₂), confirmando a presença do trivalente sexual WZ₁Z₂ como resultado de uma fusão cromossômica. Acerca dos DNAs repetitivos, os Elementos de Transposição (TEs) representaram cerca de 39,18% (machos) a 41,35% (fêmeas) enquanto que os DNAs satélites (DNAsat) representaram apenas 0,214% do genoma de machos e 0,215% de fêmeas. O mapeamento por FISH revelou distinta organização cromossômica para os DNAsat, como único sinal clusterizado, sinais dispersos e repeats não clusterizados. Os dois TEs mapeados apresentaram sinais espalhados. Embora nota-se um pequeno enriquecimento de alguns DNAsat no genoma de fêmeas, eles não foram diferencialmente enriquecidos no cromossomo W. Entretanto, notamos o enriquecimento dos sinais de TEs no cromossomo W, sugerindo seu envolvimento na degeneração e diferenciação deste cromossomos. Esses resultados revelam o dinamismo da estrutura geral do cariótipo e DNAs repetitivos em D. saccharalis, principalmente como resultado de fusão cromossômica e disseminação ou amplificação local de DNAs repetitivos. Por fim, nossos dados contribuem para o entendimento geral do genoma das espécies que podem auxiliar em futuros estudos genômicos.
Crambidae lepidopterans include pests that causes economic losses to agricultural crops, as the sugarcane borer Diatraea saccharalis. Although the crambid moths have extensive adaptive radiation and economic importance, little is known about their genome architecture and chromosomal evolution. Here we characterized the chromosomes and repetitive DNAs of D. saccharalis by association of low pass genome sequencing, bioinformatic and cytogenetic methods, with an emphasis on sex chromosomes. Diploid numbers differed between sexes, i.e., 2n=33 females and 2n=34 males, and occurrence of a multiple sex system WZ₁Z₂/Z₁Z₁Z₂Z₂ was noticed. Telomeric probe revealed one strong interstitial signal on the W chromosome, and this chromosome was associated to two chromosomes Z (Z₁ and Z₂), confirming the occurrence of a sex trivalent WZ₁Z₂, as result of a chromosomal fusion. Concerning the repetitive DNAs, the TEs represented about 39,18% (males) to 41,35% (females), while satDNAs comprised only 0,214% of male genome and 0,215% of female genome. FISH mapping revealed distinct chromosomal organization for satDNAs, as single located clusters, spread signals and non-clustered repeats. The two TEs mapped by FISH were scattered. Although we noticed slightly enrichment of some satDNAs on female genome, they were not differentially enriched on the W chromosome. On the other hand, we noticed enrichment of FISH signals on the W chromosome for TEs, suggesting their involvement on W chromosome degeneration and differentiation. These data reveal dynamism of general karyotype structure and repetitive DNAs of D. saccharalis, mainly as result of chromosomal fusions and spread or local amplification of repetitive DNAs. Finally, our data can help in future structural and functional genomic analysis that could be also useful in pest control programs.
Crambidae lepidopterans include pests that causes economic losses to agricultural crops, as the sugarcane borer Diatraea saccharalis. Although the crambid moths have extensive adaptive radiation and economic importance, little is known about their genome architecture and chromosomal evolution. Here we characterized the chromosomes and repetitive DNAs of D. saccharalis by association of low pass genome sequencing, bioinformatic and cytogenetic methods, with an emphasis on sex chromosomes. Diploid numbers differed between sexes, i.e., 2n=33 females and 2n=34 males, and occurrence of a multiple sex system WZ₁Z₂/Z₁Z₁Z₂Z₂ was noticed. Telomeric probe revealed one strong interstitial signal on the W chromosome, and this chromosome was associated to two chromosomes Z (Z₁ and Z₂), confirming the occurrence of a sex trivalent WZ₁Z₂, as result of a chromosomal fusion. Concerning the repetitive DNAs, the TEs represented about 39,18% (males) to 41,35% (females), while satDNAs comprised only 0,214% of male genome and 0,215% of female genome. FISH mapping revealed distinct chromosomal organization for satDNAs, as single located clusters, spread signals and non-clustered repeats. The two TEs mapped by FISH were scattered. Although we noticed slightly enrichment of some satDNAs on female genome, they were not differentially enriched on the W chromosome. On the other hand, we noticed enrichment of FISH signals on the W chromosome for TEs, suggesting their involvement on W chromosome degeneration and differentiation. These data reveal dynamism of general karyotype structure and repetitive DNAs of D. saccharalis, mainly as result of chromosomal fusions and spread or local amplification of repetitive DNAs. Finally, our data can help in future structural and functional genomic analysis that could be also useful in pest control programs.
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Palavras-chave
Fusão cromossômica, FISH, Cromossomo holocêntrico, DNAs repetitivos, Cromatina sexual, Chromosome fusion, Holocentric chromosome, Repetitive DNAs, W-chromatin