The complete nucleotide sequence of the chloroplast genome of sugarcane (Saccharum officinarum) was determined. It consists of 141,182 base-pairs (bp), containing a pair of inverted repeat regions (IR(A), IR(B)) of 22,794 bp each. The IR(A) and IR(B) sequences separate a small single copy region (12,546 bp) and a large single copy (83,048 bp) region. The gene content and relative arrangement of the 116 identified genes (82 peptide-encoding genes, four ribosomal RNA genes, 30 tRNA genes), with the 16 ycf genes, are highly similar to maize. Editing events, defined as C-to-U transitions in the mRNA sequences, were comparable with those observed in maize, rice and wheat. The conservation of gene organization and mRNA editing suggests a common ancestor for the sugarcane and maize plastomes. These data provide the basis for functional analysis of plastid genes and plastid metabolism within the Poaceae. The sugarcane chloroplast DNA sequence is available at GenBank under accession NC005878.
ABSTRACT.We assessed the agroindustrial performance of 25 sugarcane genotypes adapted to the edaphoclimatic conditions of the State of Pernambuco, Brazil, within the microregions Mata Norte, Mata Sul, Região Central, Litoral Norte, and Litoral Sul. The variables analyzed were POL tonnage per hectare, sugarcane tonnage per hectare, fiber and total recoverable sugar tonnage per hectare, using a randomized block design with four repetitions. Combined variance of experiments, genetic parameter estimates, decomposition of the genotype-environment interaction, and environment stratification were analyzed. Phenotype adaptability and stability were also analyzed. The various genotypes presented great potential for improvement and a similar response pattern to the microregions Centro and Mata Sul of the state of Pernambuco. Genotypes RB863129, RB867515, RB92579, RB953180, SP81-3250, RB75126, and RB942520 were better in productivity and phenotype
The best agro-industrial performance presented by a crop genotype in one environment may not be reproduced in another owing to complex edaphoclimatic variations. Therefore, breeding programs are constantly attempting to obtain, through artificial hybridization, novel genotypes with high adaptability and stability potential. The objective of this study was to analyze genetic divergence in sugarcane based on the genotypic values of adaptability and stability. A total of 11 sugarcane genotypes were analyzed for eight agro-industrial traits. The genotypic values of the traits were determined using mixed model methodology, and the genetic divergence based on phenotypic and genotypic values was measured using the Mahalanobis distance. The distance matrices were correlated using the Mantel test, and the genotypes were grouped using the Tocher method. Genetic divergence is more accurate when based on genotypic values free of genotype–environment interactions and will differ from genetic divergence based on phenotypic data, changing the genotype allocations in the groups. The above methodology can be applied to assess genetic divergence to obtain novel sugarcane genotypes with higher productivity that are adapted to intensive agricultural systems using diverse technologies. This methodology can also be tested in other crops to increase accuracy in selecting the parents to be crossed.
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