Apomixis: A Foresight from Genetic Mechanisms to Molecular Perspectives

Susmita, C.; Kumar, Sunil; Chintagunta, Anjani Devi; Agarwal, Dinesh

doi:10.1007/s12229-021-09266-y

Cited by 7 publications

(4 citation statements)

References 223 publications

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“…Apomixis results in the production of clonal offspring of which the excellent traits of the female parent are maintained through seed (Conner et al, 2015;Shirasawa et al, 2015;Hojsgaard et al, 2019). Apomixis can be divided into two categories according to the formation mechanism of diploid clonal embryos: the rst type is gametophytic apomixis, which refers to the development of egg cells (parthenogenesis) or other cells (apogamy) that bypass meiosis in the embryo sac, resulting in the formation of diploid asexual embryo in the absence of fertilization, and the second type is sporophytic apomixis, in which any diploid somatic cell in the ovule can develop into a clonal embryo that coexists with the zygotic embryo and shares the same endosperm, resulting in polyembryony (Susmita et al, 2021). At present, more than 140 angiosperm genera have been reported to have apomictic characteristics (Carman, 2010).…”

Section: Introductionmentioning

confidence: 99%

WITHDRAWN: High-frequency of twin-embryo seeds with clonal and sexually produced embryos drives apomixis in hybrid rice

Dan

Xia

Zhan

et al. 2022

Preprint

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Heterosis is a common phenomenon in biology, and fixation of heterosis can be achieved via artificially induced apomixis. Sundaresan's team used mitosis instead of meiosis (MiMe) rice mutants that ectopically expressed BBM1 in egg cells to induce the production of clonal seeds. In this study, we ectopically expressed BBM1 in MiMe mutants, and 62.50% of the seeds produced by Yongyou 4949 hybrid rice were clonal. More importantly, a high frequency of twin seedlings (33.56%) was detected. Moreover, a low frequency (1.41%) of twin seedlings was obtained only when BBM1 was ectopically expressed, and no twin seedlings were found when the genome of the MiMe mutant was edited. These findings suggest that the high frequency of twin seedlings resulted from the ectopic expression of BBM1 combined with MiMe. The embryo sacs of the twin seedlings were removed and subjected to cytological observations. One sperm combined with the polar nucleus to develop into the endosperm, and the other sperm combined with the egg cell to form a zygotic embryo. Moreover, a synergid cell near the egg cell developed into an embryo through apogamy, thus resulting in the formation of two embryos. The results showed that AtDD45-driven BBM1 could induce synergid cells to develop into embryos autonomously through normal fertilization of egg cells, resulting in the formation of twin seedlings. This study provides a theoretical reference and new ideas for research on apomixis in hybrid rice and is important for promoting the fixation of heterosis of hybrid rice.

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Section: Introductionmentioning

confidence: 99%

WITHDRAWN: High-frequency of twin-embryo seeds with clonal and sexually produced embryos drives apomixis in hybrid rice

Dan

Xia

Zhan

et al. 2022

Preprint

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“…Diversity in plant genetic resources often enhances the opportunity of plant breeders to breed new and improved cultivars with desirable characteristics [ 9 ]. Thus, information on genetic diversity of soybean genotypes could obviously help breeders and geneticists to interpret the germplasm architecture, facilitate the selection of parents with higher levels of diversity, predict superior combinations that deliver best off-spring and accelerate in broadening the genetic base [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

Molecular characterization and genetic diversity studies of Indian soybean (Glycine max (L.) Merr.) cultivars using SSR markers

et al. 2021

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Background The genetic base of soybean cultivars in India has been reported to be extremely narrow, due to repeated use of few selected and elite genotypes as parents in the breeding programmes. This ultimately led to the reduction of genetic variability among existing soybean cultivars and stagnation in crop yield. Thus in order to enhance production and productivity of soybean, broadening of genetic base and exploring untapped valuable genetic diversity has become quite indispensable. This could be successfully accomplished through molecular characterization of soybean genotypes using various DNA based markers. Hence, an attempt was made to study the molecular divergence and relatedness among 29 genotypes of soybean using SSR markers. Methods and results A total of 35 SSR primers were deployed to study the genetic divergence among 29 genotypes of soybean. Among them, 14 primer pairs were found to be polymorphic producing a total of 34 polymorphic alleles; and the allele number for each locus ranged from two to four with an average of 2.43 alleles per primer pair. Polymorphic information content (PIC) values of SSRs ranged from 0.064 to 0.689 with an average of 0.331. The dendrogram constructed based on dissimilarity indices clustered the 29 genotypes into two major groups and four sub-groups. Similarly, principal coordinate analysis grouped the genotypes into four major groups that exactly corresponded to the clustering of genotypes among four sub-groups of dendrogram. Besides, the study has reported eight unique and two rare alleles that could be potentially utilized for genetic purity analysis and cultivar identification in soybean. Conclusion In the present investigation, two major clusters were reported and grouping of large number of genotypes in each cluster indicated high degree of genetic resemblance and narrow genetic base among the genotypes used in the study. With respect to the primers used in the study, the values of PIC and other related parameters revealed that the selected SSR markers are moderately informative and could be potentially utilized for diversity analysis of soybean. The clustering pattern of dendrogram constructed based on SSR loci profile displayed good agreement with the cultivar’s pedigree information. High level of genetic similarity observed among the genotypes from the present study necessitates the inclusion of wild relatives, land races and traditional cultivars in future soybean breeding programmes to widen the crop gene pool. Thus, hybridization among diverse gene pool could result in more heterotic combinations ultimately enhancing genetic gain, crop yield and resistance to various stress factors.

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“…Apomixis not only accelerates breeding procedures and the fixation of heterosis but also enables farmers to reduce investment and receive more benefits. From the developmental perspective, most natural apomixis is classified as facultative, because it involves both sexual and asexual modes of reproduction for the advancement of generations; hence, apomixis is widely thought to be a controlled or deviant form of sexual reproduction ( Hand and Koltunow, 2014 ; Susmita et al., 2021 ; ( Van Dijk et al, 1999 ). This theory suggested that if the sexual pathway is not initiated in an ovule, the apomixis pathway remains functional to form embryos.…”

Section: Discussionmentioning

confidence: 99%

Double-seedlings and embryo-free seeds generated by genetic engineering

Xia

Wang

et al. 2022

Front. Plant Sci.

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Apomixis can fix the heterosis of Hybrid F1, by maintaining its heterozygous genotype, and is an ideal way for the development of hybrid rice. In this paper, we designed an engineering strategy for realizing apomictic reproduction of hybrid rice in the way of induce adventitious embryos. An embryogenesis gene, AtWUS, controlled by the ovule-specific promoter, a ribonuclease gene Barnase driven by the egg cell-specific promoter pDD45, and an inactivation gene ZmAA1 driven by the pollen-specific promoter pG47 were simultaneously integrated into one T-DNA, and co-transformed with the second T-DNA carrying a Barstar gene. Double-seedlings were observed in transgenic line. Whole-genome sequencing and ploidy levels confirmed by flow cytometry showed that one of the double-seedlings was heterozygous diploid and the other seedling was homozygous haploid, which confirmed that embryogenesis in one of the double-seedlings arises from the zygote after fertilization and the other derived from an unfertilized gamete. Meanwhile we obtained embryo-free seeds at frequencies of 2.6% to 3.8% in T1 generation, and 0.75% to 3% in T2 generation. Though we did not obtained adventitious embryos in hybrid rice in this study, the phenomenon of double-seedlings and embryo-free seeds in transgenic line was informative and strongly suggested that endosperm development is an autonomously organized process in rice, independent of egg cell fertilization and embryo-endosperm communication. This provides novel insights into the induction of haploid embryos and lends theoretical support to successful clonal propagation using synthetic apomixis

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Apomixis: A Foresight from Genetic Mechanisms to Molecular Perspectives

Cited by 7 publications

References 223 publications

WITHDRAWN: High-frequency of twin-embryo seeds with clonal and sexually produced embryos drives apomixis in hybrid rice

WITHDRAWN: High-frequency of twin-embryo seeds with clonal and sexually produced embryos drives apomixis in hybrid rice

Molecular characterization and genetic diversity studies of Indian soybean (Glycine max (L.) Merr.) cultivars using SSR markers

Double-seedlings and embryo-free seeds generated by genetic engineering

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