New sexual approaches to transfer of genes in wide crosses.

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1) The main objective of the Indian group was to develop methods for genetic improvement of Brassica juncea. (1) Through embryo rescue culture, over 20 intergeneric hybrids between wild species and different cultivars have been produced. Attempts were also made to achieve in vitro fertilization to overcome pre-fertilization barriers, but without success. Cytoplasmic male sterile lines of B.juncea with the cytoplasmic background of Diplotaxis siifolia has been reached an advanced stage (Shivanna). (2) In B.juncea, the Production of androgenic embryo were extremely poor and another problem of the pollen embryos was the inability to germinate normally. As the results on attempts to improve conditions of the donar plant and methods of tissue culture, the pollen embryo have become to germinate with high efficiency. Moreover, preliminary attempts were made to transform the pollen embryos. The construct pBI 121 loaded on gold particles were bombarded into the pollen embryos, in the University of Tokyo (Bhojwani).2) The Japanese group have studied to develop the new techniques different from the Indian group. (1) When the method of polyornithine was applied to in vitro pollination in Tabacco, transient GUS expression in pollen tubes was confirmed (Yoshida and Takeda). (2) The medium containing cytokinin and high temperature conditions were effective for overcoming hybrid lethality in Nicotiana. In Oryza, high temperature conditions were also effective (marubashi). (3) The results on differential screening using RT-PCR indicated a high potential to isolate genes that preferentially express during somatic and zygotic embyogenesis (Yoshida). (4) It was suggested as a new technique for agronomic strategies that Bialaphos resistant rice plants expressing a chimeric gene which were inoculated withmycelia of the sheath blight disease pathogen and subsequently treated with the herbicide were completely protected from symptomatic infection (Uchimiya).