To improve resistance to planthoppers and viral diseases, a new rice cultivar named ‘Drimi9ho’ was established. The F₁ population, derived from a cross between ‘Cheongcheong’ and ‘Nagdong’, was subjected to anther culture. Subsequent generations were advanced in the field under high selection pressure for agronomic traits and disease resistance. Ultimately, the line ‘CNDH-AC63-2-2-2-1’ was selected through the pedigree method and was named ‘Drimi9ho’ after undergoing yield trials and local adaptability tests. ‘Drimi9ho’ has a heading date of August 13, which corresponds to 107 days after sowing, making it a mid-late maturing variety that heads 3 d later than ‘Cheongcheong’. The culm length of ‘Drimi9ho’ is 57.3 cm, which is 15 cm shorter than that of ‘Cheongcheong’. This reduced culm length contributes to improved tolerance to field lodging. In addition, ‘Drimi9ho’ exhibits acquired resistance to rice black-streaked dwarf virus through introgression from ‘Nagdong’. Compared to ‘Cheongcheong’, ‘Drimi9ho’ shows lower protein content and higher amylose content, which resulted in a higher score for cooked-rice palatability. ‘Drimi9ho’ shows improved milling performance compared to ‘Cheongcheong’. The 1,000-grain weight of ‘Drimi9ho’ is 22.12±0.8 g, which is heavier than that of ‘Cheongcheong’ (19.42±0.8 g). The milled rice yield of ‘Drimi9ho’ is 546.6±3.8 kg/10a, representing a 4.7% increase compared to ‘Cheongcheong’ (522.2±5.8 kg/10a). However, ‘Drimi9ho’ is resistant only to bacterial leaf blight race K₁; thus, timely disease management is required to control other races such as K₂, K₃, and K_3a (Registration No. 10610).

‘Yechan’ is a high grain quality mid-late maturing rice cultivar with lodging tolerance and multiple disease resistance. It was a derived from a cross between ‘Hopum’ and ‘Iksan537’ (cultivar name ‘Haepum’). ‘Hopum’ is a high grain quality mid-late maturing rice cultivar with strong lodging tolerance and ‘Haepum’ is a high grain quality medium maturing rice cultivar with multiple disease resistance. To shorten the breeding period, another culture method was applied to the F₁ plants. ‘Yechan’ was selected through the pedigree method, yield trials, and local adaptability tests, with a high selection pressure for grain quality, lodging, and disease resistance. The heading date of ‘Yechan’ was August 14, one day later than that of ‘Nampyeong’. ‘Yechan’ is a cultivar tolerant to lodging and it has short culms. It has multiple disease resistance against rice blast, rice stripe virus, and bacterial blight, including the K3a race, the most virulent race in Korea. The yield of ‘Yechan’ was similar to that of ‘Nampyeong’. ‘Yechan’ showed excellent grain appearance, superior taste when cooked, and enhanced milling performance; thus, we concluded that it could contribute to the improvement of Korean japonica rice cultivar quality. ‘Yechan’, a high grain quality mid-late maturing rice cultivar with lodging tolerance and multiple disease resistance, would be suitable for cultivation in the southern plain area in Korea and has been utilized in the breeding programs aimed at enhancing the grain quality and stability for the cultivation of Korean japonica rice (Registration No. 7647).

Anther culture is useful and significant tool for producing haploid or doubled haploid (DH) plants in crop breeding system. Androgenesis is the way of inducing haploid and DH plants from anther (immature pollen) or microspore culture. In vitro androgenesis is efficient technique for introducing complete homozygous lines in one generation, thus less time and expense could be necessary than conventional plant breeding. In maize, anther culture is important system for shortening the breeding cycle and enhancing selection efficiency. Anther culture technique is also applicable to various researches such as molecular genetics, genetic engineering, genomics, and plant biotechnology. We review the past and present studies on anther culture and provide useful information for future researches on androgenesis in maize. The combination of androgenesis with other techniques such as molecular breeding and biotechnology is producing a variety of variety of maize species. In addition, we suggest strategy to develop androgenesis technique adapted to Korean research environment.

We tried to develop the protocol for embryogenesis and plant regeneration from anther culture of carrot (Daucus carota L.) genotype ‘S&P2342’. Anthers were cultured on MS medium with B5 vitamins containing different combinations of 2,4-D and NAA for 18 weeks in the dark. The best induction of callus and embryo was obtained in the medium containing 0.1 mg/L 2,4-D and 0.1 mg/L NAA, on which 22.0% callus and 2.0% embryo were induced. When primary embryos induced directly from anther culture were transferred to the regeneration medium, secondary embryos were initiated from primary embryos after 4 weeks of culture and 62.5% converted into plantlets after 8 weeks of culture. The plantlets with true leaves were obtained after 12 weeks of culture. When the calli derived from anther culture were transferred to the regeneration medium, 38.8% of the calli produced primary embryos and plantlets after 8 weeks of culture. The plantlets with 2 or more leaves cultured on the regeneration under the different light intensity for the growth of in vitro plantlets. The plantlets cultured at 100 μmol·m^-2·s^-1 showed the highest growth rate. For the acclimatization, the in vitro plantlets with 4 or more leaves cultivated under the different light intensity and temperature, respectively. The survival rate and growth of plantlets was best at 15℃ and 100 μmol·m^-2·s^-1, respectively. The plants were successfully acclimatized and had a normal phenotype. The anther culture system could be used to prepare the doubled haploid lines as an appropriate breeding material for F₁ hybrid breeding program.

This study was conducted to develop multi-resistant lines to brown planthopper, bacterial blight, and rice stripe virus using anther culture in rice. A total of 213 double haploid lines were developed the cross between HR26234-12-1-1 conferring resistant to bacterial blight and rice stripe virus and SR30071-3-7-23-6-2-1-1 conferring resistant to brown planthopper, bacterial bight, and rice stripe virus. Using DNA molecular marker, HR26234 and SR30071 were confirmed to have Xa3+xa5+Stvb-i and Bph18+Xa4+Stvb-i, respectively. All double haploid lines carried Stvb-i, and Bph18+Xa3, Bph18+Xa4, Bph18+Xa3+xa5, Bph18+Xa4+xa5, bph18+Xa3, bph18+Xa4, bph18+Xa3+xa5, and bph18+Xa4+xa5 combinations were identified. Segregation distortions such as no combinations carrying Bph18(or bph18)+xa5+Stvb-i and fewer lines carrying Bph18 than bph18 were occurred in DH population. Brown planthopper resistant lines carrying Bph18 showed longer culm length than susceptible lines. Selected Bph18+Xa4+xa5+Stvb-i combination lines with short culm conferred resistant to brown planthopper, bacterial blight, and rice stripe virus, while showed deleterious effects such as spikelet sterility, lower yield, and vulnerable to lodging than standard and comparative varieties. Using anther culture, we rapidly developed multi-resistant lines to brown planthopper, bacterial blight, and rice stripe virus. However, distorted segregation in DH population and linkage drag with Bph18 were obstacles to develop practical multi-resistant cultivars.