Insights into the Musa genome: syntenic relationships to rice and between Musa species.
BACKGROUND
Musa species (Zingiberaceae, Zingiberales) including bananas and plantains are collectively the fourth most important crop in developing countries. Knowledge concerning Musa genome structure and the origin of distinct cultivars has greatly increased over the last few years. Until now, however, no large-scale analyses of Musa genomic sequence have been conducted. This study compares genomic sequence in two Musa species with orthologous regions in the rice genome.


RESULTS
We produced 1.4 Mb of Musa sequence from 13 BAC clones, annotated and analyzed them along with 4 previously sequenced BACs. The 443 predicted genes revealed that Zingiberales genes share GC content and distribution characteristics with eudicot and Poaceae genomes. Comparison with rice revealed microsynteny regions that have persisted since the divergence of the Commelinid orders Poales and Zingiberales at least 117 Mya. The previously hypothesized large-scale duplication event in the common ancestor of major cereal lineages within the Poaceae was verified. The divergence time distributions for Musa-Zingiber (Zingiberaceae, Zingiberales) orthologs and paralogs provide strong evidence for a large-scale duplication event in the Musa lineage after its divergence from the Zingiberaceae approximately 61 Mya. Comparisons of genomic regions from M. acuminata and M. balbisiana revealed highly conserved genome structure, and indicated that these genomes diverged circa 4.6 Mya.


CONCLUSIONS
These results point to the utility of comparative analyses between distantly-related monocot species such as rice and Musa for improving our understanding of monocot genome evolution. Sequencing the genome of M. acuminata would provide a strong foundation for comparative genomics in the monocots. In addition a genome sequence would aid genomic and genetic analyses of cultivated Musa polyploid genotypes in research aimed at localizing and cloning genes controlling important agronomic traits for breeding purposes.
Lescot
Magali
M
French Agricultural Research Center for International Development, UMR 1096, Avenue Agropolis, TA40/03, FR-34398, Montpellier, Cedex 5, France. magali.lescot@igs.cnrs-mrs.fr
Piffanelli
Pietro
P
Ciampi
Ana Y
AY
Ruiz
Manuel
M
Blanc
Guillaume
G
Leebens-Mack
Jim
J
da Silva
Felipe R
FR
Santos
Candice M R
CM
D'Hont
Angélique
A
Garsmeur
Olivier
O
Vilarinhos
Alberto D
AD
Kanamori
Hiroyuki
H
Matsumoto
Takashi
T
Ronning
Catherine M
CM
Cheung
Foo
F
Haas
Brian J
BJ
Althoff
Ryan
R
Arbogast
Tammy
T
Hine
Erin
E
Pappas
Georgios J
GJ
Sasaki
Takuji
T
Souza
Manoel T
MT
Miller
Robert N G
RN
Glaszmann
Jean-Christophe
JC
Town
Christopher D
CD
D017360:Arabidopsis / Q000235:genetics; D001482:Base Composition; D022202:Chromosomes, Artificial, Bacterial; D004251:DNA Transposable Elements / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D019143:Evolution, Molecular; D020224:Expressed Sequence Tags; D020440:Gene Duplication; D017343:Genes, Plant / Q000235:genetics; D018745:Genome, Plant / Q000235:genetics*; D028521:Musa / Q000145:classification* / Q000201:enzymology / Q000235:genetics*; D012275:Oryza / Q000201:enzymology / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D045868:Sorghum / Q000235:genetics; D013045:Species Specificity; D026801:Synteny / Q000235:genetics*
D004251:DNA Transposable Elements; D018076:DNA, Complementary