TITLE:
Microsatellites and the Polyploid Guarana Plant: Diversity under a Sea of Alleles
AUTHORS:
Paula Cristina da Silva Angelo, Maria do Perpétuo Socorro Lira, Manuella Villar Amado, Ana Takagaki Yamaguishi, Gilvan Ferreira Silva, Jorge Ivan Rebelo Porto, Spartaco Astofi-Filho, André Luiz Atroch
KEYWORDS:
Amazon Rainforest, Paullinia cupana var. sorbilis, SSR, MFT, Seed Germination
JOURNAL NAME:
Open Journal of Genetics,
Vol.4 No.3,
June
20,
2014
ABSTRACT:
Repeat blocks,
microsatellites or simple sequence repeats (SSRs) can produce good co-dominant
molecular markers for genetic diversity analysis and the determination of
self-pollination rates in progenies originating from open pollination of
selected genotypes. The enrichment of guarana genomic libraries was underway
when it was confirmed that we are working with a complex polyploid species with
210 chromosomes. The probes (CA)12, (CT)12 and (TC)14 were used to finish the enrichment of four libraries for repeat blocks and the
screening of a databank of expressed sequence tags (ESTs) from guarana
seeded-fruits was accomplished as well. Fifteen clonal cultivars were genotyped
with three replicas at 10 out of 27 identified loci using the 59 alleles that
passed the reproducibility criterion. A large number of short repeat blocks were
identified and this was considered to be a consequence of the recent
polyploidization event. However, blocks with eight or more repeats ideal for
genotyping were scarce. Annealing of most probes to short blocks by partial
complementarity could explain the scarcity of longer blocks in genomic
libraries but cannot explain why they were rare in the ESTs. Due to the
complexity of the genotypes, alleles were treated as dominant traits. ESTs
harboring repeat blocks had the functional annotation renewed. Locus GRN07 is
inserted in a homologue of the MOTHER OF
FLOWERING LOCUS T AND TFL1 (MFT), in which 3’-UTR displays clear
post-transcriptional regulatory features. MFT and its variants are probably involved in the determination of seed germination
and embryo growth characteristics. Other accessed loci can be involved in plant
architecture and defense reactions. It was concluded that the alleles described
in the present work can be used to distinguish guarana cultivars and possibly
to analyze segregation using the progenies of controlled pollinations between
divergent genitors. Also, the fingerprints obtained can be added to the
morphological and agronomic descriptors of the cultivars.