Seed dormancy is an important adaptive mechanism to protect seeds under the unfavorable environments. Unlike to wild type species, the seed dormancy trait of cultivated crops has been weakened by breeding programs during the domestication period. Weak seed dormancy often causes preharvest sprouting (PHS) problem in many cereal crops that result in significant economic loss. The seed dormancy is a quantitative trait loci (QTL) controlled by multiple genetic and environmental factors. So far, many QTLs for seed dormancy have been identified from rice and wheat as well as in the model plant Arabidopsis. Unveiling of QTL genes and complex mechanisms underlying seed dormancy is accelerated by the rapid progress of crop genomics. In the present study, we reviewed current status of research progress on the seed dormancy QTLs and correlated genes in Arabidopsis and cereal crops.

Preharvest sprouting resistance (PHS) causes the reduction of grain yield and also affects the quality of grains, resulting significant economic losses. PHS and its related traits were evaluated and observed in wide range among the 137 diverse rice accessions. To mine the associated signals for PHS resistance, genome wide association study (GWAS) was performed using phenotype data and whole genome resequencing data of 137 diverse rice accessions. This study not only could detect the previously identified dormancy and PHS associated genes but also explore the new candidate genes associated with the PHS and related traits. An example of them is seed dormancy 4 (Sdr4) gene which was found to be associated with germination % at day 14 (D14). This study provided the potential associated candidate genes which might be very useful to improve the PHS resistance in future rice breeding.

Preharvest sprouting (PHS) not only causes reduction of grain yield, but also affects the quality of grains, resulting into significant economic losses. PHS is governed by multiple genes. Little is known about the large genetic variation of preharvest sprouting in rice. In the present study, genetic variations of four PHS genes, OsVP1, Osaba1, Alpha-amylase3D and OsGA20ox1 were studied by using whole-genome resequencing data of 84 accessions of rice core set. A total of haplotype groups; 27, 29, 6 and 14, for OsVP1, Osaba1, Alpha-amylase3D and OsGA20ox1, respectively, were detected among the 84 accessions. Some new SNPs and InDels were found in exon part of PHS related genes were expected to result in amino acid changes following analysis of the genetic code variations, and the germplasm or varieties which are resistant to preharvest sprouting were explored. Based on this step, phenotyping for PHS is ongoing, and the association mapping of PHS will be conducted by using SNPs resulted from the haplotyping data. The present results will be ultimately useful to the molecular breeding for the development of PHS resistant rice cultivars.

본 연구는 질소 추비 시용수준을 달리한 비배관리가 수발아에 미치는 영향을 구명코자 금강밀과 조경밀을 공시하여 질소 추비 처리 수준별로 출수기, 생육, 종실특성 및 수발아 관련 형질을 비교하였다. 질수수준 증가에 따라 간장,수장, 경수 및 영화수가 증가했으나, 임실율은 2010년에는질소 50% 증비(108 kg N/ha)에서 가장 높은 수치를 나타냈고, 2011년에는 100% 증비(144 kg N/ha)에서 가장 높은 수치를 나타냈다. 밀 종실 특성 중 천립중, 리터중 및 수분함량은 질소수준에 따라 큰 차이를 보이지 않았으나, 종실 수량은 질소 수준이 증가함에 따라 계속 증가하여 50% 증비에서 가장 높게 나타났으며 그 이후부터는 감소하였다. 종실의 단백질 함량을 살펴보면 질소수준이 증가함에 따라 점차 증가는 경향을 보였으며 100% 증비에서 가장 높은 함량을 나타냈고, 금강이 조경보다 높은 단백질 함량을 보였다.밀 종자의 수발아 관련 형질간 비교에서는 질수수준이 증가함에 따라 발아율, Germination index 및 ABA sensitivity가점차 감소했는데, 이는 종자의 수발아율을 낮추는 결과를가져왔다. 밀 종자의 Germination index는 금강의 경우 무비(추비)에서 가장 높게 나타났으며 그 이후에는 조경의 경우와 마찬가지로 질소 수준이 증가함에 따라 점차 감소하였다. 밀 종자의 수발아율은 조경의 경우 50% 감비에서24.7%, 금강의 경우 무비(추비)에서 19.6%로 가장 높게 나타났으나, 질소 처리 수준이 증가함에 따라 수발아율은 점차 감소하였다. ABA sensitivity와 수발아율 간에는 정의상관을 나타내어 ABA sensitivity를 간이 수발아 검정법으로 활용 가능할 것으로 보였다.