The induction of flowering under long‐day conditions is an important adaptation by short‐day plants, such as adzuki beans (Vigna angularis), to high‐latitude environments. This study clarified the genetic control underlying the long‐day insensitivity of adzuki bean cultivar ‘Shumari’. ‘Shumari’ was found to be insensitive to a 16‐h day, whereas landrace Acc2265 was highly sensitive. When grown under natural long‐day conditions at Obihiro (42°9′N), Acc2265 initiated flowering at least 80 days after ‘Shumari’. When 86 recombinant inbred lines (RILs) derived from crosses between ‘Shumari’ and Acc2265 were grown under these conditions, their flowering dates ranged from the middle of July to the end of October. The distinct bimodal distribution in the RIL population was due to a single major gene, designated Flowering Date1 (FD1). Molecular mapping showed that FD1 was located between the SSR markers Az02‐37M3 and Az02‐40M9, at distances of 6 and 10.4 cM, respectively, on linkage group 2. RILs carrying FD1S lacked long‐day sensitivity, whereas RILs carrying FD1A were sensitive to long‐day conditions, confirming that FD1 controls long‐day sensitivity.
The soybean cyst nematode (SCN) (
Heterodera glycines
Ichinohe) is a devastating pest of soybean (
Glycine max
(L.) Merr.) in the world. Three soybean QTLs for resistance to SCN race 1 were detected through QTL analyses using recombinant inbred lines (RILs) derived from a cross between ‘Tokei 758’ (susceptible) and ‘To-8E’ (resistant to races 1 and 3, derived from ‘PI 84751’ and ‘Gedenshirazu’). Two of the three QTLs appear to be
rhg1
and
Rhg4
from their locations on the linkage map. The third QTL, detected around Satt359 on chromosome 11, was tentatively identified as
rhg2
. All RILs resistant to race 1 had all three QTLs. We developed lines carrying the three loci in various combinations, including all and none, from descendants of a cross between ‘NIL-SCN’ (with resistance derived from ‘PI 84751’ in the ‘Natto-shoryu’ background) and ‘Natto-shoryu’. Evaluating these lines in a race 1-infected field in Mito, Ibaraki, showed that resistance to race 1 required all three loci. Through field evaluation of 10 recombinant fixed pairs that we developed, we located the
rhg2
locus to an 821 kb-region between SSR markers Sat_123 (=WGSP11_0140) and BARCSOYSSR11_1420 on chromosome 11.
Wheat yellow mosaic (WYM) is a soilborne disease caused by Wheat yellow mosaic virus (WYMV). Symptoms include yellow mosaic coloring of leaves, stunting, and growth inhibition. Severe infection may result in yield loss. WYM is one of the most serious diseases affecting wheat production in East Asia. The most effective control is through breeding resistant cultivars. A winter wheat cultivar, 'OW104', shows little to no symptoms in heavily WYMV-infested fields in Hokkaido, Japan. Here we detected Qym4, a QTL accounting for 45%-57% of WYMV resistance, in the vicinity of the markers Xcfd49, Xbarc183, and Xgpw4357 on wheat chromosome arm 6DS. F 3 progenies with 'OW104' allele at Qym4 showed significantly higher resistance than those with 'Hokushin' homozygote or heterozygote. We developed 'Hokushin' near-isogenic lines by backcrossing with 'Hokushin' as the recurrent parent and 'OW104' as the resistance donor. All the WYMV-resistant BC 5 F 1 /BC 4 F 1 plants carried 'OW104' allele only at Xcfd49. Our results suggest that the introduction of Qym4 confers resistance to WYMV in winter wheat.
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