Rice blast caused by the fungal pathogen, Magnaporthe oryzae, is a serious disease affecting yield loss and decreasing its quality in rice production. Rice breeders in Korea have developed many japonica varieties showing resistance to blast. However, the blast resistance in most japonica varieties has broken down within a few years after they were released to farmers because of the spread of new virulent races of M. oryzae. There is the most effectiveness to look for novel resistant gene(s) that can express the resistance to broad-spectrum races in diverse environmental conditions. We identified a major QTL, qLB4.1 linked tightly to RM6352 and RM3643 in 52.6 cM region on chromosome 4 related to the resistance for isolate inoculation and nursery test, and neck blast from a Korean weedy rice, Geumleungaengmi33. This QTL explained 26.1∼28.6% and 45.3∼53.1% of total phenotypic variation by the allele of GL33 for isolate inoculation and nursery test, respectively. A line SR30058(52)-1-1 (Suweon545) that containing the QTL qLB4.1 was developed from Ilpum*4/GL33 by marker-assisted backcross method. This line showed resistant reactions to blast nursery test across regions and years, and resistance to neck blast at the hot-spot field in Jecheon. Suweon545 showed also durable resistance of lower 10% of diseased leaf areas (DLAs) in sequential planting method. This line screened by graphical mapping using 136 SSR markers that evenly distributed on 12 chomosomes. Suweon545 contained GL33 alleles of donor parent in a total of 12 loci (8.8%) including QTL region on chromosome 4. In future, Suweon545 would be useful to develop the broad-spectrum resistance variety in japonica rice breeding program.

Eating and cooking qualities are the most important trait in japonica rice breeding program in Korea. More improvements in grain quality to meet the demand of consumers are needed to develop new rice germplasm of high grain quality. In this study, we performed genetic analysis and grain quality evaluation in 96 Korean japonica rice germplasm including 26 varieties with 4 Japanese japonica high eating quality, 24 landraces, 22 weedy rices, and 14 breeding lines. These germplasm were analyzed using 13 DNA markers related to eating quality to conjecture the palatability of cooked rice (Lestari et al. 2009). Most varieties of high eating quality were clustered with germplasm of high expected quality (eq) varieties of similar genetic background of pedigree. The expected quality (eq) values of high eating quality varieties, Gopum, Ilpum, Samgwang, and Sugwang were 99.6∼104.5, and Koshihikari was 103.5. The eq of two weedy rices, Hoengseongaengmi 3 and Namjejuaengmi 6 were 101.9 and 101.6, respectively. However, Haiami of high eating quality was clustered with 15 weedy rice and 11 landrace germplasm of low eq value. The eq values of Haiami and Wandoaengmi 6 were 66.9 and 40.8, respectively, but they has 2 and 3 of palatability of cooked rice, and 73.6 and 78.6 of glossiness of cooked rice, respectively. We expect these germplasm would be new source for rice grain quality to develop japonica rice of high eating quality.

‘큰눈’은 다양한 전분 신소재를 육성할 목적으로 1991년 하계에 양질다수성 품종인 ‘일품벼’에 돌연변이처리(MNU)하여 중만생이며 배가 일반벼보다 큰 거대배아미인 ‘Ilpum MNU)36-2-GH1-2-10-1-2-3-2-1’ 계통을 선발하여 ‘수원492호’로 계통명을 부여하여, 2003년부터 2005년까지 3년간 지역적응시험 실시결과 그 우수성이 인정되어 2005년 12월 직무육성 신품종 선정위원회에서 국가목록등재 품종으로 선정됨과 동시에 ‘큰눈’으로 명명하였다. ‘큰눈’의 중부평야지의 평균 출수기는 8월 17일로 ‘화성벼’보다 6일 느리고, 남부평야지 평균 출수기는 8월 15일로 ‘남평벼’보다 1일 빠른 중생종이다. ‘큰눈’의 간장은 86 cm이며, 이삭길이는 23 cm로 ‘화성벼’와 비슷하고, 포기당 이삭수는 ‘화성벼’보다 적으나, 수당립수는 많고, 등숙비율은 낮은 편이며, 현미 천립중은 가벼운 편이다. ‘큰눈’은 도열병 저항성은 약한 반응을 보였으며, 흰잎마름병 및 바이러스병과 벼멸구 및 애멸구 저항성은 없었다. ‘큰눈’은 내냉성검정에서 ‘화성벼’에 비해 출수지연일수가 다소 길고, 냉수구 임실율이 낮아서 내냉성은 약한 편이며, 도복특성검정에서 좌절중은 낮고, 도복지수는 높은 편이나 포장 도복은 강한 편이다. ‘큰눈’은 현미장폭비가 1.62인 중단원립이고, 투명도가 다소 불량하고 심복백이 많아 외관 품위가 떨어지고, 아밀로스와 단백질 함량은 각각 17.5, 5.9%로 ‘화성벼’보다 낮은 편이며, 단당류 및 올리고당 함량은 ‘화성벼’보다 1.4배, 발아현미의 GABA 함량은 발아 2일에서 ‘일품벼’보다 2.8배 많았다. ‘큰눈’의 쌀수량은 보통기재배에서 평균 쌀수량이 4.52 MT/ha로 ‘화성벼’ 대비 89% 수준이었다. ‘큰눈’의 재배적지는 중부평야 및 남부평야지이다.