An experiment was conducted and through distant hybridization a new promising forms of citruses were obtained. Namely, after hybridization of lemon Georgian and broad-leaved mandarin unshiu （mother components） with ...An experiment was conducted and through distant hybridization a new promising forms of citruses were obtained. Namely, after hybridization of lemon Georgian and broad-leaved mandarin unshiu （mother components） with early-ripening trifoliata and a hybrid of citrus ichangensis--＂Caucasus＂ （father components） a wide range of nucellar seedlings were obtained. It should be noted that nucellar seedlings of hybrid nature are practically closer to distant hybrids of sexual origin that are sharply inclined to the side of the mother component and produce good quality fruit. Unfortunately, such hybrids are either very rare or cannot be obtained at all. While, in the case of the study, through using new combinations in hybridization, the possibility of getting nucellar seedlings of the hybrid nature is much bigger. Distant hybridization turned out to be particularly interesting because of the polyembryony of citrus plants. Due to this, it gives opportunity to get new promising forms not only from the egg cell but from nucellar cells as well.展开更多
Rice with polyembryony characterized bytwin seedlings is a good genetic tool for apomixisresearch.A study on the effect of five plantgrowth regulators(IAA,KT,GA,2,4-D and6-BAP)on rate of twin seedlings in 3 rice varie...Rice with polyembryony characterized bytwin seedlings is a good genetic tool for apomixisresearch.A study on the effect of five plantgrowth regulators(IAA,KT,GA,2,4-D and6-BAP)on rate of twin seedlings in 3 rice varie.ties with polyembryony(Shuang 3,Shuang 13and Lu 52)was conducted.The results showed展开更多
The process of double fertilization and the characters of embryo and endosperm development in an autotetraploid polyembryonic mutant rice IR36-Shuang were studied with a laser scanning confocal microscopy. Some abnorm...The process of double fertilization and the characters of embryo and endosperm development in an autotetraploid polyembryonic mutant rice IR36-Shuang were studied with a laser scanning confocal microscopy. Some abnormalities including degenerated ovary, abortive embryo sac, single fertilization, double-ovule and double-embryo and so on. were found dudng double fertilization and embryo development in IR36-Shuang. The rate of the abnormalities was 46.67% in IR36-Shuang, significantly higher than that in the control, an autotetraploid rice line IR36-4X （33.00%）. Cytological and embryonic evidences were provided for seed setting decline and the initiation of additional embryo in IR36-Shuang.展开更多
A high-efficiency somatic embryogenesis protocol of Japanese larch （Larix leptolepis Gordon） has been established in our investigation. Calli were induced from immature zygotic embryos of female cones ofL. leptolepi...A high-efficiency somatic embryogenesis protocol of Japanese larch （Larix leptolepis Gordon） has been established in our investigation. Calli were induced from immature zygotic embryos of female cones ofL. leptolepis and then subcultured regularly on to a modified Gupta and Durzan （DCR） basal medium for 5 years. Embryogenic tissues showed distinct morphological changes dur- ing somatic embryo development when they were transferred to a maturation medium supplemented with abscisic acid （ABA） com- pared with the morphology in a medium lacking ABA. Histological observations indicated that polyembryony was a characteristic feature during early embryogeny and somatic embryos at later stages showed normal histodifferentiation. In addition, histochemical analysis revealed that abundant starch granules and proteins accumulated in mature embryos, indicating that they played important roles in the development and regeneration of normal plantlets from somatic embryos on hormone-free germination media展开更多
APIV is a rice mutant that develops poly-egg apparatus in its embryo sac.All the eggs thatmake up the poly-egg apparatus can be fertilized respectively resulting in the development of polyembryony.The routes taken in ...APIV is a rice mutant that develops poly-egg apparatus in its embryo sac.All the eggs thatmake up the poly-egg apparatus can be fertilized respectively resulting in the development of polyembryony.The routes taken in the development of polyembryony appear to fall mainly into three variant polygonum pattern types,designated as"5-2-1","5-3-0"and"6-2-0"types.Out of the embryo sacs of APIV studied about 50%exhibited variant polygonum type with associated abnormal nuclear behavior and microtubule organizational changes.Some of the major abnormal features shown by the three variant polygonum typeswere described and they included the following:For the"5-2-1"type-At the beginning of the four-nucleate embryo sac development,one pair of nuclei became located to the micropylar end and the other pair to the chalazal end.As embryo sac further developed,long connecting microtubule(MT)bundles that existed between the two nuclei in the chalazal end play a role in the movement and positioning of that nucleus.As a result of the activities of these MT,one of the nuclei in the chalazal end moved to the micropylar end resulting in the micropylar end having three nuclei and the chalazal end only one.For the"5-3-0"type-In the two-nucleate embryo sac of the"5-3-0"type,one nucleus remained at the micropylar end,while the other one became located near the central region.In the four-nucleate embryosac,the pair of nuclei aligned in parallel to the micropylar-chalazal axis often having one of its nucleirelocated to the micropylar end as a result of associated MT activities.For the"6-2-0"type-All the nuclei in the megaspore,two-and four-nucleate embryo sacs became located to the micropylar end.At the early stages of the eight-nucleate embryo sac development,the two nuclei in the central region of the embryo sac(originally at the micropylar end)became polar nuclei.All the other nuclei remained at themicropylar end were surrounded by reticulate MT.The relationship between abnormal behavior of nuclei and MT organi-zation in the development of rice embryo sac was discussed.展开更多
Polyembryony is a serious handicap in citrus breeding. To obtain zygotic off-springs, monoem-bryonic seed parents were usually used in breeding programs. Kiyomi, a superior monoembryonic tangor, was used as seed paren...Polyembryony is a serious handicap in citrus breeding. To obtain zygotic off-springs, monoem-bryonic seed parents were usually used in breeding programs. Kiyomi, a superior monoembryonic tangor, was used as seed parent in 7 cross combinations. When pollen parents was Chandler pummelo or Tarocco blood orange, only monoembryonic seeds were observed. However, when Washington Sanguine, Li-xing orange and Bing-tang orange were used as pollen parents, no more than 7. 2% of polyembryonic seeds were observed. Interestingly, while male parents were Nucellar3 Ponkan and Oota Ponkan, high ratio of polyembryonic seeds was observed. The ratio of polyembryonic seeds was steadily at about 30 % in two consecutive years and was obviously different from other results reported. Polyembronic seeds were observed in monoembryonic varieties sometimes, but normally their ratios were no more than 7%. Polyembryonic-seedlings were got by separating the multi-embryos in seeds of Kiyomi×Nucellar3 Ponkan and then their leaves were used in RAPD analysis. Identical bands of male parent and/or different bands from seed parent were found in most of the polyembryonic-seedlings and so it can be sure that these seedlings were of zygotic origin. Some pairs of polyembryonic-seedlings have identical bands in all tested primers and may be resulted from zygotic embryo divisions. Different bands were found in other pairs of polyembryonic-seedlings also and this may indicate multi-egg fertilization or other source of variation.展开更多
文摘An experiment was conducted and through distant hybridization a new promising forms of citruses were obtained. Namely, after hybridization of lemon Georgian and broad-leaved mandarin unshiu （mother components） with early-ripening trifoliata and a hybrid of citrus ichangensis--＂Caucasus＂ （father components） a wide range of nucellar seedlings were obtained. It should be noted that nucellar seedlings of hybrid nature are practically closer to distant hybrids of sexual origin that are sharply inclined to the side of the mother component and produce good quality fruit. Unfortunately, such hybrids are either very rare or cannot be obtained at all. While, in the case of the study, through using new combinations in hybridization, the possibility of getting nucellar seedlings of the hybrid nature is much bigger. Distant hybridization turned out to be particularly interesting because of the polyembryony of citrus plants. Due to this, it gives opportunity to get new promising forms not only from the egg cell but from nucellar cells as well.
文摘Rice with polyembryony characterized bytwin seedlings is a good genetic tool for apomixisresearch.A study on the effect of five plantgrowth regulators(IAA,KT,GA,2,4-D and6-BAP)on rate of twin seedlings in 3 rice varie.ties with polyembryony(Shuang 3,Shuang 13and Lu 52)was conducted.The results showed
基金supported by the National Science & Technology Pillar Program of China in the Tenth Five-Year Plan Period(Grant No.2001BA302B)the Education Department of Henan Province, China(Grant No.2008A208019)
文摘The process of double fertilization and the characters of embryo and endosperm development in an autotetraploid polyembryonic mutant rice IR36-Shuang were studied with a laser scanning confocal microscopy. Some abnormalities including degenerated ovary, abortive embryo sac, single fertilization, double-ovule and double-embryo and so on. were found dudng double fertilization and embryo development in IR36-Shuang. The rate of the abnormalities was 46.67% in IR36-Shuang, significantly higher than that in the control, an autotetraploid rice line IR36-4X （33.00%）. Cytological and embryonic evidences were provided for seed setting decline and the initiation of additional embryo in IR36-Shuang.
基金the National Natural Science Foundation of China （Grant No. 30471366） the National Science Fund of China for Distinguished Young Scholars （30225005）.
文摘A high-efficiency somatic embryogenesis protocol of Japanese larch （Larix leptolepis Gordon） has been established in our investigation. Calli were induced from immature zygotic embryos of female cones ofL. leptolepis and then subcultured regularly on to a modified Gupta and Durzan （DCR） basal medium for 5 years. Embryogenic tissues showed distinct morphological changes dur- ing somatic embryo development when they were transferred to a maturation medium supplemented with abscisic acid （ABA） com- pared with the morphology in a medium lacking ABA. Histological observations indicated that polyembryony was a characteristic feature during early embryogeny and somatic embryos at later stages showed normal histodifferentiation. In addition, histochemical analysis revealed that abundant starch granules and proteins accumulated in mature embryos, indicating that they played important roles in the development and regeneration of normal plantlets from somatic embryos on hormone-free germination media
文摘APIV is a rice mutant that develops poly-egg apparatus in its embryo sac.All the eggs thatmake up the poly-egg apparatus can be fertilized respectively resulting in the development of polyembryony.The routes taken in the development of polyembryony appear to fall mainly into three variant polygonum pattern types,designated as"5-2-1","5-3-0"and"6-2-0"types.Out of the embryo sacs of APIV studied about 50%exhibited variant polygonum type with associated abnormal nuclear behavior and microtubule organizational changes.Some of the major abnormal features shown by the three variant polygonum typeswere described and they included the following:For the"5-2-1"type-At the beginning of the four-nucleate embryo sac development,one pair of nuclei became located to the micropylar end and the other pair to the chalazal end.As embryo sac further developed,long connecting microtubule(MT)bundles that existed between the two nuclei in the chalazal end play a role in the movement and positioning of that nucleus.As a result of the activities of these MT,one of the nuclei in the chalazal end moved to the micropylar end resulting in the micropylar end having three nuclei and the chalazal end only one.For the"5-3-0"type-In the two-nucleate embryo sac of the"5-3-0"type,one nucleus remained at the micropylar end,while the other one became located near the central region.In the four-nucleate embryosac,the pair of nuclei aligned in parallel to the micropylar-chalazal axis often having one of its nucleirelocated to the micropylar end as a result of associated MT activities.For the"6-2-0"type-All the nuclei in the megaspore,two-and four-nucleate embryo sacs became located to the micropylar end.At the early stages of the eight-nucleate embryo sac development,the two nuclei in the central region of the embryo sac(originally at the micropylar end)became polar nuclei.All the other nuclei remained at themicropylar end were surrounded by reticulate MT.The relationship between abnormal behavior of nuclei and MT organi-zation in the development of rice embryo sac was discussed.
文摘Polyembryony is a serious handicap in citrus breeding. To obtain zygotic off-springs, monoem-bryonic seed parents were usually used in breeding programs. Kiyomi, a superior monoembryonic tangor, was used as seed parent in 7 cross combinations. When pollen parents was Chandler pummelo or Tarocco blood orange, only monoembryonic seeds were observed. However, when Washington Sanguine, Li-xing orange and Bing-tang orange were used as pollen parents, no more than 7. 2% of polyembryonic seeds were observed. Interestingly, while male parents were Nucellar3 Ponkan and Oota Ponkan, high ratio of polyembryonic seeds was observed. The ratio of polyembryonic seeds was steadily at about 30 % in two consecutive years and was obviously different from other results reported. Polyembronic seeds were observed in monoembryonic varieties sometimes, but normally their ratios were no more than 7%. Polyembryonic-seedlings were got by separating the multi-embryos in seeds of Kiyomi×Nucellar3 Ponkan and then their leaves were used in RAPD analysis. Identical bands of male parent and/or different bands from seed parent were found in most of the polyembryonic-seedlings and so it can be sure that these seedlings were of zygotic origin. Some pairs of polyembryonic-seedlings have identical bands in all tested primers and may be resulted from zygotic embryo divisions. Different bands were found in other pairs of polyembryonic-seedlings also and this may indicate multi-egg fertilization or other source of variation.
