Estudos de associação entre locos SSR e componentes da produção em arroz (Oryza sativa L.)
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2010-08-16
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Universidade Federal de Goiás
Resumo
Rice is consumed by more than half of the world population. The expectation of substantial
population growth and consequently the increase of the consumption has demontrated that
the present rice production will not supply the future’s demand. As a result, studies that aim
at the increase of the yield must be prioritized by scientific co&unity. Aiming to identify
genomic regions related to grain yield and its component traits (panicle number per meter,
grain panicle number and hundred grain mass), it was carried out the associative mapping
analysis. The analysis of association used two types of SSR markers: a) structural genome
derived markers, and b) transcriptome derived markers, i.e. developed from transcripts from
marker-anchored genomic regions previously related to yield and its components from 27
different QTL maps already published. The associative mapping methodology used included
the whole genome scanning and candidate genes approaches. The molecular characterization
used 186 accessions from Embrapa Rice Core Collection (ERiCC), whereas 76 accessions
from lowland system of cultivation, and 113 upland system of cultivation. The experimental
design was the randomized block with 4 repetitions, and included the cultivars BR Irga 409,
Metica 1 and BRS Caiapó as controls. It were evaluated the following traits: Panicle number
per meter (NPM), panicle (NGP), Hundred grain mass (PCG) and productivity. The 186
markers were genotyped by 29 transcript-derived SSR markers and 86 SSR markers derived
from structural genome. For the irrigated accessions was verified positive correlation for
panicle number per meter and productivity (0,2424; p<0,01) and by productivity and
hundred grain mass (p<0,05; 0,1457) and negative correlation for panicle number per meter
and grain number per panicle (-0,457; p<0,01). For the upland accessions it was observed
positive correlation for grain number per panicle and productivity (0,4243; p<0,01).
Negative correlations were observed for panicle number per meter and hundred grain weight
(p<0,01; -0,2114). Based on 44 SSR markers developed in this work, 181 alelles were
detected, an average of 5.5 alelles per locus, average PIC of 0.44 and 25 private alleles. The
analysis with 115 SSR markers identified 43 significant associations for grain number per
panicle considering the cultivation system upland and three associations for lowland system;
7 significant associations for panicle number per meter for lowland system, and 9 were
significant for upland cultivation systems; 14 associations were significant for hundred grain
mass in lowland system of cultivarion, and 43 were significant for upland system of
cultivarion; 3 associations were significant for grain yield in upland system of cultivarion.
The association analysis identified 61 SSR markers consistently associated to yield and its
components. It were detected 33 associations statiscally significant to one or more traits,
which validated the previous results obtained by QTL mapping. The markers RM125,
RM152 e Q69JE3 showed the higher number of associations per trait. The association
productivity and PCG, and NCP, respectively, were previously found in the literature. The
markers associated to the evaluated traits permit to initiate a scientific program to identify
the candidate genes and to proceed the marker assisted selection The accessions
CNA0001107, CNA0005478, CNA0010533, CNA0003287, IR 36, CNA0003602,
CNA0006413, CNA0006174, CNA0003289, CNA0002253, CNA0004098, CNA0001416,
CNA0003490 e CNA0000994 showed the highest number of favorable alleles considering
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the markers associated to yield and its components. The identified accessions from this work
as having the higher number of favorable alleles from the evaluated traits will be
recommended to be used as genitors in Brazilian rice breeding programs. The mixed
approaches to the associative mapping used in the present work was interesting to permit
that, even using a low marker density, in couple with the linkage disequilibrium found in
rice, some previously mapped markers from QTL analyses were again associated to traits
evaluated in field experiments. This strategy can be used to other traits of interest for rice,
such as drought and cold tolerance, and disease resistance.
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BUENO, Clistiane dos Anjos Mendes. Estudos de associação entre locos SSR e componentes da produção em arroz (Oryza sativa L.). 2010. 139 f. Dissertação (Mestrado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2010.