We searched for genetic resources of a soybean with reduced propensity towards green stem disorder (GSD) than ‘Fukuyutaka’, the leading cultivar in Northern Kyushu area, and considered whether the occurrence of GSD in soybean can be evaluated stably by pod removal at the seed filling stage. The occurrence of GSD in 26 soybean cultivars that can be grown in Northern Kyushu area, as well as that in 11 soybean lines developed at the Fukuoka Agriculture and Forestry Research Center, was examined from 2015 to 2017, of which the occurrence of GSD in ‘Suzuotome’ was the lowest. In addition, using 4 soybean cultivars, ‘Fukuyutaka’, ‘Sachiyutaka’, ‘Suzuotome’ and ‘Chikushi-B5’, the occurrence of GSD in ‘Suzuotome’ was significantly lower than in ‘Fukuyutaka’ and ‘Sachiyutaka’ under high-temperature and drought conditions from R3 (beginning of pod setting) to R5 (beginning of seed filling), when GSD is likely to accelerate. Furthermore, varietal differences in the occurrence of GSD by 50% pod removal at the seed filling stage became apparent compared with no treatment in the 4 soybean cultivars above, and the occurrence of GSD in ‘Suzuotome’ was significantly lower than that in ‘Fukuyutaka’ and ‘Sachiyutaka’. These results revealed that ‘Suzuotome’ may be the genetic resource of soybean with the greatest GSD insensitivity, and 50% pod removal at seed filling stage is useful for evaluating GSD in soybean in Northern Kyushu area.
Breeding barley with a high content of dietary fiber, namely β-glucan, is required because β-glucan is attracting attention for its health functionalities such as suppression of postprandial blood glucose elevation. We analyzed the relationship between the β-glucan content and the starch synthase IIIa (ssIIIa) marker type, which is located near the region affecting the high amylose content amo1 mutation. The ssIIIa marker types were detected, and the β-glucan content, SKCS grain hardness, steely grain rate, thousand-grain weight, and hollow grain rate were measured for each of the 94 waxy lines (F5) derived from a cross between ‘Hokuriku 54’ (later ‘Yukihanarokujo’) and the amo1 waxy variety ‘YonRkei3755’, and for each of the 165 waxy lines (F5) derived from a cross between ‘YonRkei3755’ and the waxy variety ‘Haneumamochi’. As a result, there were significant differences in the β-glucan content, SKCS grain hardness, and steely grain rate depending on the ssIIIa marker type in each post-interbreeding line. The β-glucan content was about 1.6 times higher, the SKCS grain hardness was 23 points higher, and the steely grain rate was 7% higher in the ‘YonRkei3755’ ssIIIa type than that of the wild type. The β-glucan content was highly correlated with the SKCS grain hardness of r = 0.75 to 0.84 in the breeding line derived from both crosses. These results suggest that selection based on the ssIIIa marker type and/or the SKCS grain hardness are effective in breeding amo1 varieties with a high content of β-glucan.
Many papers about rice genes related to yield are published every year, but few of these genes have been used in practical rice breeding. Therefore, we generated or received near-isogenic lines (NILs) of nine alleles related to yield in the genetic backgrounds of Japanese rice cultivars, and performed simultaneous comparative cultivation tests. Significant increases in brown rice yield were detected in the NILs for qCTd11Takanari, SD1DGWG, and a combination of TGW6Kasalath and SD1DGWG in the genetic background of ‘Koshihikari’ and a NIL for DEP1Ballila in the genetic background of ‘Akidawara’. These alleles and QTLs may have the genetic potential to improve rice yield, even in the genetic background of Japanese cultivars. On the other hand, an increase in the brown rice yield of NILs for qLIA3Takanari, GPSTakanari, GS3Oochikara, GW2BG1, and GN1ATakanari was not detected in the ‘Koshihikari’ genetic background probably due to small direct effects to increase sink size by these alleles and QTLs or a relative reduction of their source abilities to the total sink sizes increased in these NILs. In addition, analysis using multiple NILs in the ‘Koshihikari’ genetic background showed a negative correlation between panicle weight and panicle number. This indicated that an increase in the number of panicles did not subsequently increase yield because of the tradeoff to reduce the weight of one panicle and the thousand grain weight; this was considered the main reason why GW2BG1, GS3Oochikara, and GN1ATakanari, which were expected to increase sink capacity, did not increase yield. We considered that the alleles increasing sink capacity are not sufficient to increase yield in the genetic background of Japanese cultivars and need to be combined with alleles, such as qCTd11Takanari, expected to improve the source ability by increasing photosynthesis per unit leaf area or alleles to improve canopy structure including SD1DGWG and DEP1Ballila.
Wintering ability is an important trait in barley, particularly in northern Japan. Although fructan is known to be related to wintering ability in wheat and temperate forage grasses, its contribution to wintering ability in barley remains unclear. To clarify the role of fructan with respect to wintering ability in barley, we analyzed the relationships among wintering ability, shoot fructan content, and the allelic variation of five fructan metabolic enzyme genes, 1-FEH, 6-FEH, 1-FFT, 1-SST, and 6-SFT, in 105 Japanese barley cultivars and breeding lines. The cultivars and breeding lines developed in the colder northern region of Japan exhibited a superior wintering ability and greater fructan content accumulated prior to snow cover than those bred in the warmer southern region. In our sequence analyses of the five fructan metabolic enzyme genes, 6 to 10 genotypes were found in each of the genes in the tested barley cultivars and lines. Cultivars and lines with the same combination of fructan metabolic enzyme gene genotypes were grouped, and the average wintering ability and fructan content values of the different groups were compared. A significant correlation was detected between fructan content and wintering ability, specifically, groups with a higher fructan content prior to snow cover, especially in stem tissue, exhibited a superior wintering ability. The group with the highest wintering ability possessed a unique 6-SFT genotype. The cultivars and breeding lines were classified into three groups with a high, medium, and low wintering ability based on the 1-FEH genotypes. We developed derived cleaved amplified polymorphic sequence (dCAPS) markers that identify the 6-SFT and 1-FEH genotypes observed in the group with the highest wintering ability and in the groups with a high, medium, and low wintering ability, respectively.