RESUMO
KEY MESSAGE: Chloroplast genome of Solanum commersonii and S olanum tuberosum were completely sequenced, and Indel markers were successfully applied to distinguish chlorotypes demonstrating the chloroplast genome was randomly distributed during protoplast fusion. Somatic hybridization has been widely employed for the introgression of resistance to several diseases from wild Solanum species to overcome sexual barriers in potato breeding. Solanum commersonii is a major resource used as a parent line in somatic hybridization to improve bacterial wilt resistance in interspecies transfer to cultivated potato (S. tuberosum). Here, we sequenced the complete chloroplast genomes of Lz3.2 (S. commersonii) and S. tuberosum (PT56), which were used to develop fusion products, then compared them with those of five members of the Solanaceae family, S. tuberosum, Capsicum annum, S. lycopersicum, S. bulbocastanum and S. nigrum and Coffea arabica as an out-group. We then developed Indel markers for application in chloroplast genotyping. The complete chloroplast genome of Lz3.2 is composed of 155,525 bp, which is larger than the PT56 genome with 155,296 bp. Gene content, order and orientation of the S. commersonii chloroplast genome were highly conserved with those of other Solanaceae species, and the phylogenetic tree revealed that S. commersonii is located within the same node of S. tuberosum. However, sequence alignment revealed nine Indels between S. commersonii and S. tuberosum in their chloroplast genomes, allowing two Indel markers to be developed. The markers could distinguish the two species and were successfully applied to chloroplast genotyping (chlorotype) in somatic hybrids and their progenies. The results obtained in this study confirmed the random distribution of the chloroplast genome during protoplast fusion and its maternal inheritance and can be applied to select proper plastid genotypes in potato breeding program.
Assuntos
Genoma de Cloroplastos , Hibridização Genética , Solanum/genética , Sequência de Bases , Códon/genética , Cruzamentos Genéticos , DNA Circular/genética , Marcadores Genéticos , Variação Genética , Genótipo , Mutação INDEL/genética , Filogenia , Reação em Cadeia da Polimerase , Sequências de Repetição em Tandem/genéticaRESUMO
Potato (Solanum tuberosum L.) is generally considered to be sensitive to drought stress. Even short periods of water shortage can result in reduced tuber production and quality. We previously reported that transgenic potato plants expressing the sweet potato orange gene (IbOr) under the control of the stress-inducible SWPA2 promoter (referred to as SOR plants) showed increased tolerance to methyl viologen-mediated oxidative stress and high salinity, along with increased carotenoid contents. In this study, in an effort to improve the productivity and environmental stress tolerance of potato, we subjected transgenic potato plants expressing IbOr to water-deficient conditions in the greenhouse. The SOR plants exhibited increased tolerance to drought stress under greenhouse conditions. IbOr expression was associated with slightly negative phenotypes, including reduced tuber production. Controlling IbOr expression imparted the same degree of drought tolerance while ameliorating these negative phenotypic effects, leading to levels of tuber production similar to or better than those of wild-type plants under drought stress conditions. In particular, under drought stress, drought tolerance and the production of marketable tubers (over 80g) were improved in transgenic plants compared with non-transgenic plants. These results suggest that expressing the IbOr transgene can lead to significant gains in drought tolerance and tuber production in potato, thereby improving these agronomically important traits.
Assuntos
Secas , Ipomoea batatas/genética , Ipomoea batatas/fisiologia , Peroxidases/genética , Pigmentação/genética , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/fisiologia , Solanum tuberosum/genética , Solanum tuberosum/fisiologia , Ipomoea batatas/química , Fotossíntese/genética , Tubérculos/metabolismo , Plantas Comestíveis , Reação em Cadeia da Polimerase , Solanum tuberosum/química , Estresse Fisiológico , Água/análiseRESUMO
Solanum commersonii Dunal is a well-known wild potato belonging to Solanaceae family and commonly used as materials for somatic hybridization due to various biotic and abiotic stress resistances. The complete chloroplast genome of S. commersonii was constituted by de novo assembly using a small amount of whole genome sequencing data. The chloroplast genome of S. commersonii was 155 525 bp in length, consisted of 86 013 bp of large single copy, 18 366 bp of small single copy region and 25 573 bp of a pair of inverted repeats. A total of 113 genes were annotated including 79 protein-coding genes, 30 tRNA genes and four rRNA genes. Maximum likelihood phylogenetic analysis with 14 Solanaceae species revealed that S. commersonii is much closely related to Solanum tuberosum and S. bulbocastanum.