Reference "Characterization of the major fragance gene from an aromatic japonica rice and analysis of its diversity in Asian cultivated rice"

Reference ID

42998

Title

Characterization of the major fragance gene from an aromatic japonica rice and analysis of its diversity in Asian cultivated rice

Source

Theor Appl Genet, 2008, vol. 117, pp. 353-368

Authors (9)

Bourgis-F	Guyot-R
Gherbi-H	Tailliez-E
Amabile-I	Salse-J
Lorieux-M	Delseny-M
Ghesquiere-A

Abstract

In Asian cultivated rice (Oryza sativa L.), aroma is one of the most valuable
traits in grain quality and 2-ACP is the main volatile compound contributing to
the characteristic popcorn-like odour of aromatic rices. Although the major
locus for grain fragrance (frg gene) has been described recently in Basmati
rice, this gene has not been characterised in true japonica varieties and
molecular information available on the genetic diversity and evolutionary origin
of this gene among the different varieties is still limited. Here we report on
characterisation of the frg gene in the Azucena variety, one of the few aromatic
japonica cultivars. We used a RIL population from a cross between Azucena and
IR64, a non-aromatic indica, the reference genomic sequence of Nipponbare
(japonica) and 93-11 (indica) as well as an Azucena BAC library, to identify the
major fragance gene in Azucena. We thus identified a betaine aldehyde
dehydrogenase gene, badh2, as the candidate locus responsible for aroma, which
presented exactly the same mutation as that identified in Basmati and Jasmine-
like rices. Comparative genomic analyses showed very high sequence conservation
between Azucena and Nipponbare BADH2, and a MITE was identified in the promotor
region of the BADH2 allele in 93-11. The badh2 mutation and MITE were surveyed
in a representative rice collection, including traditional aromatic and non-
aromatic rice varieties, and strongly suggested a monophylogenetic origin of
this badh2 mutation in Asian cultivated rices. Altogether these new data are
discussed here in the light of current hypotheses on the origin of rice genetic
diversity.