African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12269

Full Length Research Paper

In vitro embryo rescue and plant regeneration following self-pollination with irradiated pollen in cassava (Manihot esculenta Crantz)

Mary Buttibwa
  • Mary Buttibwa
  • National Crops Resources Research Institute (NaCRRI), Namulonge, P. O. Box 7084, Kampala, Uganda.
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Robert S. Kawuki
  • Robert S. Kawuki
  • National Crops Resources Research Institute (NaCRRI), Namulonge, P. O. Box 7084, Kampala, Uganda.
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Arthur K. Tugume*
  • Arthur K. Tugume*
  • Department of Biological Sciences, College of Natural Sciences, Makerere University, P. O. Box 7062, Kampala, Uganda.
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Jacinta Akol
  • Jacinta Akol
  • National Crops Resources Research Institute (NaCRRI), Namulonge, P. O. Box 7084, Kampala, Uganda.
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Stephen Magambo
  • Stephen Magambo
  • National Crops Resources Research Institute (NaCRRI), Namulonge, P. O. Box 7084, Kampala, Uganda.
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Hellen Apio
  • Hellen Apio
  • National Crops Resources Research Institute (NaCRRI), Namulonge, P. O. Box 7084, Kampala, Uganda.
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Erwin Heberle-Bors
  • Erwin Heberle-Bors
  • Max-F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9, 1030 Vienna, Austria.
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Maria Wedzony
  • Maria Wedzony
  • Institute of Biology, Pedagogical University of Krakow, Podchorazych, 30-084, Krakow, Poland.
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Hernan Ceballos
  • Hernan Ceballos
  • International Center for Tropical Agriculture (CIAT), Apartado, Aereo, 6713, Cali, Colombia.
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Clair Hershey
  • Clair Hershey
  • International Center for Tropical Agriculture (CIAT), Apartado, Aereo, 6713, Cali, Colombia.
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Yona Baguma
  • Yona Baguma
  • National Crops Resources Research Institute (NaCRRI), Namulonge, P. O. Box 7084, Kampala, Uganda.
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  •  Received: 19 March 2015
  •  Accepted: 17 June 2015
  •  Published: 14 July 2015

Abstract

Cassava is a highly heterozygous species; hence, current methods used in classical cassava breeding cannot match the urgent need to high yielding varieties. Recently, progress was made through androgenesis and gynogenesis as pathways for raising doubled cassava haploid lines to overcome problems associated with cassava’s inherent reproductive biology, but these efforts were limited (no candidate cassava plantlets were regenerated). For the first time, this study shows that pollen irradiation coupled with self-pollination and embryo rescue regenerated 62 candidate cassava plantlets. Plants of an elite cassava variety, Nase14, served as a mother plant and as the pollen donor for the irradiation. Irradiation dosages of 50 to 250 Gray studied across five pollination events and 300 or 500 Gray in one pollination event caused a reduction in pollen germination up to 67.0%. By 15 days after pollination (DAP) with irradiated pollen, up to 89.7% of the pollinated flowers had aborted. By embryo rescue time (42 DAP), significant differences were observed in number of fruits, seeds and embryos generated, with the non-irradiated pollen treatments having significantly higher numbers. Sixteen (16) heterozygous SSR markers in the parent and ploidy analysis showed that none of the regenerated plants was haploid or homozygous. However, the plantlets resulting from pollination with non-irradiated pollen had 56.2% homozygous loci, while progeny derived from irradiated treatments had frequencies of homozygous loci between 28.1 and 55.0%. This is the first time to use irradiated pollen in cassava as a pathway to generate candidate plantlets as an initial step in double haploid production. 
 
Key words: Cassava, doubled haploids, embryo rescue, plant regeneration, pollen germination, pollen irradiation.