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Reprogramming of cassava (Manihot esculenta) microspores towards sporophytic development.

Perera PI, Ordoñez CA, Dedicova B, Ortega PE - AoB Plants (2014)

Bottom Line: In two cassava genotypes, different developmental stages of microspores were found to initiate sporophytic cell divisions, that is, with tetrads of TMS 60444 and with mid or late uni-nucleate microspores of SM 1219-9.A low frequency of the reprogramming and the presence of non-responsive microspores among the responsive ones in tetrads were found to be related to the viability and exine formation of the microspores.This paves the way for the development of an efficient technique for the production of homozygous lines in cassava.

View Article: PubMed Central - PubMed

Affiliation: Agrobiodiversity Research Area, International Center for Tropical Agriculture, A.A. 6713, Cali, Colombia Present address: Department of Horticulture and Landscape Gardening, Faculty of Agriculture and Plantation Management, Wayamba University, Gonawila, Makandura, Sri Lanka prasanthi1970@yahoo.com.

No MeSH data available.


Related in: MedlinePlus

Morphological aspects of microspore reprogramming in tetrads of M. esculenta genotype TMS 60444. (A) An immature tetrad containing round-shaped microspores (m) within the callose (c) wall. (B) A tetrad containing two enlarged microspores. Note that the non-responding microspore (nm) remained unchanged. (C) Small vacuole formation upon further enlargement in the responsive microspore. (D) Formation of a large vacuole. (E) A divided small microspore. (F) A divided enlarged microspore. Note that the dividing structure has come out from the callose wall. (G) A four-celled microspore. (H) An eight-celled microspore. (I) Multi-celled structures found in the cultures (A: fresh; B: 2 days; C: 3 days; D: 5 days; E–I: 7 days after culture initiation of the tetrad; scale bar = 20 µm).
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PLU022F2: Morphological aspects of microspore reprogramming in tetrads of M. esculenta genotype TMS 60444. (A) An immature tetrad containing round-shaped microspores (m) within the callose (c) wall. (B) A tetrad containing two enlarged microspores. Note that the non-responding microspore (nm) remained unchanged. (C) Small vacuole formation upon further enlargement in the responsive microspore. (D) Formation of a large vacuole. (E) A divided small microspore. (F) A divided enlarged microspore. Note that the dividing structure has come out from the callose wall. (G) A four-celled microspore. (H) An eight-celled microspore. (I) Multi-celled structures found in the cultures (A: fresh; B: 2 days; C: 3 days; D: 5 days; E–I: 7 days after culture initiation of the tetrad; scale bar = 20 µm).

Mentions: In the cultured tetrads of TMS, the four microspores were morphologically similar in size and shape (Fig. 2A). The first sign of an enlargement of the microspores in tetrads was observed 2 days after culture initiation (Fig. 2B). These microspores enlarged further and formed small vacuoles (Fig. 2C) 3 days after culture initiation, and then the cytoplasm turned into a lighter state (Fig. 2D). By fusion of the small vacuoles 5 days after culture initiation, large vacuoles formed, and the cells acquired oval or oblong shapes (Fig. 2D). At this time, cytoplasmic streaming could be observed in the cells. The tetrads containing at least one enlarged microspore (remaining enclosed or exposed but still attached to the callose wall) were counted as responsive individuals. Seven days after culture initiation, structures with two (Fig. 2E and F), four (Fig. 2G) and eight cells (Fig. 2H) and then multi-cellular structures (MCSs) (Fig. 2I) were observed. The non-responsive microspores of the responsive tetrads remained unchanged whereas the responsive ones either grew larger or divided further. In most cases, only one microspore of the tetrad was reprogrammed, whereas two or three cells were responsive only in rare cases (as in Fig. 2D). The non-responsive microspores in the responsive tetrads and all the microspores in the non-responsive tetrads contained highly dense cytoplasm and, in some cases, escape of cytoplasm out of the cells occurred, indicating cell death. Among the cultured microspores and tetrads captured in the 70 extract, meiocytes were found, which also enlarged and then divided (data not shown).Figure 2.


Reprogramming of cassava (Manihot esculenta) microspores towards sporophytic development.

Perera PI, Ordoñez CA, Dedicova B, Ortega PE - AoB Plants (2014)

Morphological aspects of microspore reprogramming in tetrads of M. esculenta genotype TMS 60444. (A) An immature tetrad containing round-shaped microspores (m) within the callose (c) wall. (B) A tetrad containing two enlarged microspores. Note that the non-responding microspore (nm) remained unchanged. (C) Small vacuole formation upon further enlargement in the responsive microspore. (D) Formation of a large vacuole. (E) A divided small microspore. (F) A divided enlarged microspore. Note that the dividing structure has come out from the callose wall. (G) A four-celled microspore. (H) An eight-celled microspore. (I) Multi-celled structures found in the cultures (A: fresh; B: 2 days; C: 3 days; D: 5 days; E–I: 7 days after culture initiation of the tetrad; scale bar = 20 µm).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4061485&req=5

PLU022F2: Morphological aspects of microspore reprogramming in tetrads of M. esculenta genotype TMS 60444. (A) An immature tetrad containing round-shaped microspores (m) within the callose (c) wall. (B) A tetrad containing two enlarged microspores. Note that the non-responding microspore (nm) remained unchanged. (C) Small vacuole formation upon further enlargement in the responsive microspore. (D) Formation of a large vacuole. (E) A divided small microspore. (F) A divided enlarged microspore. Note that the dividing structure has come out from the callose wall. (G) A four-celled microspore. (H) An eight-celled microspore. (I) Multi-celled structures found in the cultures (A: fresh; B: 2 days; C: 3 days; D: 5 days; E–I: 7 days after culture initiation of the tetrad; scale bar = 20 µm).
Mentions: In the cultured tetrads of TMS, the four microspores were morphologically similar in size and shape (Fig. 2A). The first sign of an enlargement of the microspores in tetrads was observed 2 days after culture initiation (Fig. 2B). These microspores enlarged further and formed small vacuoles (Fig. 2C) 3 days after culture initiation, and then the cytoplasm turned into a lighter state (Fig. 2D). By fusion of the small vacuoles 5 days after culture initiation, large vacuoles formed, and the cells acquired oval or oblong shapes (Fig. 2D). At this time, cytoplasmic streaming could be observed in the cells. The tetrads containing at least one enlarged microspore (remaining enclosed or exposed but still attached to the callose wall) were counted as responsive individuals. Seven days after culture initiation, structures with two (Fig. 2E and F), four (Fig. 2G) and eight cells (Fig. 2H) and then multi-cellular structures (MCSs) (Fig. 2I) were observed. The non-responsive microspores of the responsive tetrads remained unchanged whereas the responsive ones either grew larger or divided further. In most cases, only one microspore of the tetrad was reprogrammed, whereas two or three cells were responsive only in rare cases (as in Fig. 2D). The non-responsive microspores in the responsive tetrads and all the microspores in the non-responsive tetrads contained highly dense cytoplasm and, in some cases, escape of cytoplasm out of the cells occurred, indicating cell death. Among the cultured microspores and tetrads captured in the 70 extract, meiocytes were found, which also enlarged and then divided (data not shown).Figure 2.

Bottom Line: In two cassava genotypes, different developmental stages of microspores were found to initiate sporophytic cell divisions, that is, with tetrads of TMS 60444 and with mid or late uni-nucleate microspores of SM 1219-9.A low frequency of the reprogramming and the presence of non-responsive microspores among the responsive ones in tetrads were found to be related to the viability and exine formation of the microspores.This paves the way for the development of an efficient technique for the production of homozygous lines in cassava.

View Article: PubMed Central - PubMed

Affiliation: Agrobiodiversity Research Area, International Center for Tropical Agriculture, A.A. 6713, Cali, Colombia Present address: Department of Horticulture and Landscape Gardening, Faculty of Agriculture and Plantation Management, Wayamba University, Gonawila, Makandura, Sri Lanka prasanthi1970@yahoo.com.

No MeSH data available.


Related in: MedlinePlus