The pollen grain is a unique tricellular structure suitable for the delivery of the sperm cells to the ovule. All nutrients required for microspore and pollen cell growth are derived by passage through the anther locule and secretion by the tapetum lining. During later stages the tapetum degenerates but contributes to produce pigments, waxes, lipids and proteins which form the pollen coat and function in signaling between male (pollen) and female (pistil) tissues. The development of both normal pollen and tapetum is necessary for the fertilization processes in rice and would be exploited for the induction of male-sterility which is very useful to improve economic value of crops. We aredeveloping new approaches using a conditional male-sterility for the F1 hybrid seed production in rice. The conventional three parental systems for F1 hybrid seed production requirethe following three lines: male-sterile line, maintainer line, and restorer line. In this system, a critical requirement is to maintain the male-sterile inbred lines. Here we suggest molecular approaches, in which the engineered male-sterile plants are generated by regulating endogenous hormonal balance through the loss-of-function of genes. We can expect the male-sterility can be restored by exogenous applications of hormones such as gibberellin or jasmonic acid. Based on two parental systems, we will address the answer onfollowing question: how can we maintain a male-sterile line producing 100% male-sterile progenies without a maintainer? This work was supported by grants from Crop Functional Genomics Center of the 21C Frontier Program (CG1517), RepublicKorea.

The production of hybrid onion (Allium cepa L.) seed is economically feasible using systems of cytoplasmic-genic male sterility(CMS). The identification of cytoplasm types might be helpful to development of sterile and maintainer lines. Due to this reason, a knowledge of the cytoplasm type is essential for hybrid breeding in onion. Especially, due to the biennial generation time of onion, to distinguish of onion cytoplasm type in individual plant may be helpful to reduce the efforts in a breeding program, when new sterile lines and the corresponding maintainer lines be developed. In our study, we applied the PCR-marker (orfA-501) to identify the cytoplasmic genotypes of collected 100 accessions of bulb onion. Among accessions, S-cytoplasm was found in 57 accessions. Nineteen accessions possessed only N-cytoplasm and twenty four accessions possessed both S- and N-cytoplasm.

토천궁은 개화는 되지만 종자 결실이 이루어지지 않아 주로 종근이나 뇌두에 의해 번식하므로 번식율이 매우 저조한 특성이 있다. 따라서 이의 원인을 구명하고자 자웅배우체 형성과정과 자가수분을 통한 수정현상을 보기 위하여 조사하였던 바 그 결과는 다음과 같다. 토천궁은 대소포자에서 감수분열이 정상적으로 이루어지고 배낭형성에서 난장치는 50% 정도가 정상적으로 이루어지고, 화분형성에서는 90%이상이 잘 이루어졌다. 토천궁의 배낭은 주심조직의 세포가 작아 모든 기관분열에서 관찰하기가 어려웠고 특히 토천궁은 배낭 형성체가 난장치로 발달되는 꽃은 거의 없었으며 화분립은 일부가 형성 되었다.

Rye has been a major winter forage crop in Korea. Varietal improvement of rye has been practiced either by hybrid or population breeding systems. Hybrid breeding offers important advantages over population breeding since it is normally a cross-pollinated crop. The hybrid breeding in rye has been possible since cytoplasmically inherited forms of male sterility (CMS) and corresponding nuclear restorer genes were found. The objectives of this research were to develop the maintainer and restorer lines of Korean inbred lines and to estimate the effect of 'Pampa' type of CMS cytoplasm on yield and its related characteristics. For easy discrimination of male-sterile status of plants, anther scoring and the restore index system in which seed-setting and pollen quantity of viability were taken into account were established. High significant correlation between pollen quantity and pollen viability was found. For "Pampa" cytoplasm, four of 14 Korean inbred lines tested turned out to be a maintainer but no restorer was found. But for "235b" CMS cytoplasm, seven inbred lines acted as complete restorers. The Korean inbred rye lines acted mainly as maintainers in "Pampa" cytoplasm but acted mainly as restorer in "235b" cytoplasm. The 'Pampa' cytoplasm inducing male sterility reduced cohn length and plant height and increased the number of tiller, so forage yield and grain yield were enhanced. However, heading date was slightly delayed compared to the normal cytoplasm.elayed compared to the normal cytoplasm.