M. Kawaguchi et al., Providing the basis for genomics in Lotus japonicus: the accessions Miyakojima and Gifu are appropriate crossing partners for genetic analyses, MOL GENET G, 266(2), 2001, pp. 157-166
Lotus japonicus has attracted attention as a model plant legume for molecul
ar genetic research, and several mutants defective in nodulation and mycorr
hizal symbiosis have been developed from the standard accession Gifu B-129.
However, as a model system, Gifu has long lacked an appropriate crossing p
artner for use in various genetic analyses. In a search for an appropriate
partner for Gifu, we have collected plants from 15 localities throughout Ja
pan, and analyzed their levels of DNA polymorphism (also in comparison to t
he African species L. filicaulis) by AFLP (Amplified Fragment Length Polymo
rphism) combined with the use of a high-throughput electrophoretic screenin
g system termed HEGS (High-efficiency genome scanning) developed by us, usi
ng 31 primer pairs. Plants of the accession Miyakojima MG-20 showed the hig
hest level of polymorphism relative to Gifu (over 4%). When HEGS is used fo
r screening, this level is sufficient to permit systematic positional cloni
ng of mutant genes. Segregation in the F-2 of the Gifu-derived symbiotic mu
tations Ljsym70, Ljsym72, Ljsym74-1 (alb1-1) and Ljsym78-1 from a cross wit
h Miyakojima was normal, while the ratios seen from a cross with L. filicau
lis were distorted. Miyakojima displays several traits that distinguish it
from other Japanese accessions: low concentrations of anthocyanin in the st
em and petals, few trichomes, a more upright habit, broad leaflets and peta
ls, and large black seeds. The first two traits, which are controlled by si
ngle recessive genes, serve as useful markers for following mutant crosses.