A cytological study on Apluda mutica L. revealed that this species was a facultative apomict with 60.74% of apomictic embryo sac formation. Its sexual reproduction exhibited the characteristics of polygonum_type embry...A cytological study on Apluda mutica L. revealed that this species was a facultative apomict with 60.74% of apomictic embryo sac formation. Its sexual reproduction exhibited the characteristics of polygonum_type embryo sac formation. After the 3 megaspores at the micropylar end had degenerated, leaving only the chalazal megaspore in the nucellus, a nucellar cell adjacent to the megaspore differentiated into an aposporous initial, which later developed into a panicum_type embryo sac. It was an aposporous 4_nucleate embryo sac without chromosome reduction and composed of an egg, a single synergid and a central cell with 2 polar nuclei. The chalazal megaspore degenerated before the onset of the division in the aposporous initial cell.展开更多
In hybrid plants,heterosis often produces large,vigorous plants with high yields;however,hybrid seeds are generated by costly and laborious crosses of inbred parents.Apomixis,in which a plant produces a clone of itsel...In hybrid plants,heterosis often produces large,vigorous plants with high yields;however,hybrid seeds are generated by costly and laborious crosses of inbred parents.Apomixis,in which a plant produces a clone of itself via asexual reproduction through seeds,may produce another revolution in plant biology.Recently,synthetic apomixis enabled clonal reproduction of F_(1) hybrids through seeds in rice(Oryza sativa),but the inheritance of the synthetic apomixis trait and superior heterotic phenotypes across generations remained unclear.Here,we propagated clonal plants to the T_(4) generation and investigated their genetic and molecular stability at each generation.By analyzing agronomic traits,as well as the genome,methylome,transcriptome,and allele-specific transcriptome,we showed that the descendant clonal plants remained stable.Unexpectedly,in addition to normal clonal seeds,the plants also produced a few aneuploids that had eliminated large genomic segments in each generation.Despite the identification of rare aneuploids,the observation that the synthetic apomixis trait is stably transmitted through multiple generations helps confirm the feasibility of using apomixis in the future.展开更多
<正> SAR-1 is a new germplasm which was discovered in the breeding material of southern multiplication in spring, 1988. The material showing high sterility of pollens is able to set seeds spontaneously. Under is...<正> SAR-1 is a new germplasm which was discovered in the breeding material of southern multiplication in spring, 1988. The material showing high sterility of pollens is able to set seeds spontaneously. Under isolation, the seed-setting highest rate may reach 55.33%. The florets emasculated by clipping spikelet and lukewarm water still set seeds at certain rates. The completely sterile florets, after being emasculated and checked under microscope one by one, still set seeds, and the highest setting rate is 41.80%. Cytoembryological research indicates that the egg of SAR-1, without fertilization, divides independently into an embryo, which follows the normal process to maturity. Adventitious embryos originate from ovary wall cells. Therefore, it is deduced that SAR-1 has multiple mechanisms of apomixis, and the unfertilized polar nuclei fuse and develop into endosperm cells. The endosperm provids the embryo with nutrient for development. The automatic formation of the endosperm is an obvious feature of SAR-1.展开更多
文摘A cytological study on Apluda mutica L. revealed that this species was a facultative apomict with 60.74% of apomictic embryo sac formation. Its sexual reproduction exhibited the characteristics of polygonum_type embryo sac formation. After the 3 megaspores at the micropylar end had degenerated, leaving only the chalazal megaspore in the nucellus, a nucellar cell adjacent to the megaspore differentiated into an aposporous initial, which later developed into a panicum_type embryo sac. It was an aposporous 4_nucleate embryo sac without chromosome reduction and composed of an egg, a single synergid and a central cell with 2 polar nuclei. The chalazal megaspore degenerated before the onset of the division in the aposporous initial cell.
基金supported by the National Natural Science Foundation of China(U20A2030,32025028,and 32188102)the Central Public-interest Scientific Institution Basal Research Fund(Y2022QC20)+1 种基金the Hainan Yazhou Bay Seed Laboratory(#B21HJ0215)the Agricultural Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences(CAAS-ZDRW202001).
文摘In hybrid plants,heterosis often produces large,vigorous plants with high yields;however,hybrid seeds are generated by costly and laborious crosses of inbred parents.Apomixis,in which a plant produces a clone of itself via asexual reproduction through seeds,may produce another revolution in plant biology.Recently,synthetic apomixis enabled clonal reproduction of F_(1) hybrids through seeds in rice(Oryza sativa),but the inheritance of the synthetic apomixis trait and superior heterotic phenotypes across generations remained unclear.Here,we propagated clonal plants to the T_(4) generation and investigated their genetic and molecular stability at each generation.By analyzing agronomic traits,as well as the genome,methylome,transcriptome,and allele-specific transcriptome,we showed that the descendant clonal plants remained stable.Unexpectedly,in addition to normal clonal seeds,the plants also produced a few aneuploids that had eliminated large genomic segments in each generation.Despite the identification of rare aneuploids,the observation that the synthetic apomixis trait is stably transmitted through multiple generations helps confirm the feasibility of using apomixis in the future.
基金Project supported by National Natural Science Foundation of China, Sichuan Science Committee, Sichuan Education Committee and Rockefeller Foundation.
文摘<正> SAR-1 is a new germplasm which was discovered in the breeding material of southern multiplication in spring, 1988. The material showing high sterility of pollens is able to set seeds spontaneously. Under isolation, the seed-setting highest rate may reach 55.33%. The florets emasculated by clipping spikelet and lukewarm water still set seeds at certain rates. The completely sterile florets, after being emasculated and checked under microscope one by one, still set seeds, and the highest setting rate is 41.80%. Cytoembryological research indicates that the egg of SAR-1, without fertilization, divides independently into an embryo, which follows the normal process to maturity. Adventitious embryos originate from ovary wall cells. Therefore, it is deduced that SAR-1 has multiple mechanisms of apomixis, and the unfertilized polar nuclei fuse and develop into endosperm cells. The endosperm provids the embryo with nutrient for development. The automatic formation of the endosperm is an obvious feature of SAR-1.
