Fruit set and plant regeneration in cassava following interspecific pollination with castor bean

Baguma, J.K.; Mukasa, Settumba B.; Kawuki, R.; Tugume, Arthur K.; Buttibwa, M.; Nalela, Polycarp; Eyokia, M.; Oshaba, B.; Ceballos, Hernán; Lentini, Zaida; Baguma, Yona

doi:10.4314/acsj.v27i1.8

Cited by 5 publications

(4 citation statements)

References 32 publications

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“…To determine the germinability of the pollen and ovule fertilization, about three hand-pollinated flowers were picked at two-to-three days after pollination (DAP), fixated in a solution containing glacial acetic acid and 96% ethanol (in a ratio of 1:3) and then stained with 0.1% aniline blue in 0.1% K2HPO4 before being examined for pollen tube growth as previously described in [64]. The pistils were removed from the stain, placed in a drop of glycerol on a glass slide, stigmas cut off and the ovaries dissected to extract ovules.…”

Section: In Vivo Pollen Germination and Ovule Fertilizationmentioning

confidence: 99%

Assessment of Cassava Pollen Viability and Ovule Fertilizability under Red-Light and Plant-Growth-Regulator Treatments

Baguma,

Mukasa,

Ochwo-Ssemakula

et al. 2024

Preprint

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Understanding pollen and ovule fertility as factors influencing fruit and seed set is important in cassava breeding. Red light (RL) and plant growth regulators (PGRs) have been used to induce or enhance flowering and fruit set in cassava without any reference to effects on pollen viability or ovule fertilizability. This study investigated effects of field-applied RL and PGR on pollen viability and ovule fertilizability. Panels of cassava genotypes, with early or moderate flowering responses were used. RL was administered from dusk to dawn. Two PGRs, a cytokinin (6-benzyl adenine, BA) and an anti‑ethylene (silver thiosulphate, STS) were applied. Pollen viability was assessed basing on pollen grain diameter, in vitro stainability, in vivo germinability, ovule fertilizability and ploidy level. Treating flowers with RL led to increased pollen diameter from 143.6 to 148.5µm, stainability from 82.9 to 93.0%, ovule fertilizability from 52.0 to 56.9% in treated female flowers and 47.7 to 64.3% on using pollen from treated male flowers. Fruit set increased from 51.5 to 71.8% in RL-treated female flowers and from 53.7 to 71.1% when pollen from RL-treated male flowers was used. Seed set followed a trend similar to that of fruit set. Ploidy level of pollen from RL-treated flowers increased slightly and positively correlated with pollen diameter (R2 = 0.09*), ovule fertilization (R2 = 0.20*), fruit (R2 = 0.59*) and seed set (R2 = 0.60*); but negatively correlated with pollen stainability. Treating flowers with PGR did not affect pollen diameter and stainability, but increased ovule fertilizability from 42.9 to 64.9% and fruit set from 23.2 to 51.9% in treated female flowers and 31.3 to 54.7% when pollen from treated male flowers was used. Application of combined BA+STS on male flowers caused the highest ovule fertilizability, fruit and seed set efficiency, though this varied among study genotypes. These results show that RL and PGR treatment of flowers increases pollen viability and ovule fertilizability. This is important for planning pollination strategies in cassava breeding programmes.

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Section: In Vivo Pollen Germination and Ovule Fertilizationmentioning

confidence: 99%

Assessment of Cassava Pollen Viability and Ovule Fertilizability under Red-Light and Plant-Growth-Regulator Treatments

Baguma,

Mukasa,

Ochwo-Ssemakula

et al. 2024

Preprint

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“…It is used in plants such as cassava ( Lentini et al, 2020 ), where hand crossing can lead to under-developed seeds to increase the chances of producing viable plants in the next generation ( Yan et al, 2015 ). Also, for hybridization between species of cassava and castor bean ( Baguma et al, 2019 ) or some Aegilops x Triticum crosses, where hybrid embryos are not naturally viable and must be nurtured to maturity in vitro ( Gill et al, 1981 ; Miller et al, 1987 )].…”

Section: Introductionmentioning

confidence: 99%

Natural and artificial sources of genetic variation used in crop breeding: A baseline comparator for genome editing

2022

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Traditional breeding has successfully selected beneficial traits for food, feed, and fibre crops over the last several thousand years. The last century has seen significant technological advancements particularly in marker assisted selection and the generation of induced genetic variation, including over the last few decades, through mutation breeding, genetic modification, and genome editing. While regulatory frameworks for traditional varietal development and for genetic modification with transgenes are broadly established, those for genome editing are lacking or are still evolving in many regions. In particular, the lack of “foreign” recombinant DNA in genome edited plants and that the resulting SNPs or INDELs are indistinguishable from those seen in traditional breeding has challenged development of new legislation. Where products of genome editing and other novel breeding technologies possess no transgenes and could have been generated via traditional methods, we argue that it is logical and proportionate to apply equivalent legislative oversight that already exists for traditional breeding and novel foods. This review analyses the types and the scale of spontaneous and induced genetic variation that can be selected during traditional plant breeding activities. It provides a base line from which to judge whether genetic changes brought about by techniques of genome editing or other reverse genetic methods are indeed comparable to those routinely found using traditional methods of plant breeding.

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“…In this case, the embryos were advanced in their development (excised 40 DAP), which was supported by the presence of normal endosperm (Akinbo et al, 2010). Embryo rescue was used in interspecific pollination with castor bean (Ricinus communis) in early attempts to produce doubled haploids (Ramos-Abril, 2018;Baguma et al, 2019). Yan et al (2014) suggested to rescue embryos at earlier stages, from 32 to 36 DAP, when most embryos are at cotyledonary stage, the endosperm is already formed, and the embryos are visible and easier to excise from the pollinated ovules without injury.…”

Section: Introductionmentioning

confidence: 99%

“…Similar trends were reported for crosses with Manihot esculenta ssp. flabellifolia (Akinbo et al, 2010) or for wide crosses with R. communis (Ramos-Abril, 2018;Baguma et al, 2019). Therefore, the availability of an embryo rescue protocol in cassava, prior to the 2nd week after pollination, is highly relevant.…”

Section: Introductionmentioning

confidence: 99%

Protocol for Rescuing Young Cassava Embryos

et al. 2020

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Embryo rescue (ER) in cassava breeding has several relevant applications, from the recovery of broad crosses to the recovery of seeds from the standard pollination program. Cassava fruit setting may drop from 100%, during the 1st week after pollination, to less than 40% during the 2nd week after pollination due to the abscission of fruits depending on genotypes. Therefore, the availability of an ER protocol for early stages of embryo development, in particular during the first 2 weeks after pollination (prior the cotyledonary stage), could have practical implications for cassava breeding. Until now, attempts to recover cassava immature embryos at stages of development earlier than the cotyledonary stage failed. The earliest successful rescue reported in cassava is from embryos excised 32-36 days after anthesis (DAA). However, limited information was available regarding embryo development in cassava. This work studied and documented the stage of embryo development in histological sections of handpollinated ovules fixed from 1 to 30 days after anthesis (DAA). At 7 DAA, zygotes were just at the first stages of cell division (pro-embryo stage). At 14 DAA, embryos were at the pre-globular stage. Embryos at the early globular stage were observed in sections fixed at 21 DAA, and at the proper globular stage at 24 DAA. Samples at 30 DAA contained cotyledonary embryos that easily developed after ovule culture into viable plants using existing protocols. A second contribution of this work is the development of a protocol for the recovery of fully developed plants from immature embryos rescued and cultured in vitro as early as 7-14 DAA. Since embryos collected at this age are at the pro-embryo to pre-globular stage, ovary/ovule culture was necessary. A method is described whereby ovules were cultured to allow the development of pro-embryos and pre-globular stage embryos into the cotyledonary stage. Subsequently, these mature embryos were excised from the ovules to induce germination and the recovery of fully developed plants.

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Fruit set and plant regeneration in cassava following interspecific pollination with castor bean

Cited by 5 publications

References 32 publications

Assessment of Cassava Pollen Viability and Ovule Fertilizability under Red-Light and Plant-Growth-Regulator Treatments

Assessment of Cassava Pollen Viability and Ovule Fertilizability under Red-Light and Plant-Growth-Regulator Treatments

Natural and artificial sources of genetic variation used in crop breeding: A baseline comparator for genome editing

Protocol for Rescuing Young Cassava Embryos

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