RECENT ADVANCES IN ANDROGENESIS INDUCTION OF CASSAVA (MANIHOT ESCULENTA CRANTZ)
Cassava is the fourth most important source of energy and the sixth most important source of calories in the human diet. It is a highly heterozygous plant. Availability of homozygous lines would have a great impact on crop improvement. Attempts were made to induce androgenesis in anthers and microspores. Two genotypes, SM 1219-9 and TMS 60444, were used. Male flower buds were categorized into four size groups, 2.0-2.3, 2.3-2.6, 2.6-2.9 and 2.9-3.2 mm, to identify the optimum flower size for androgenesis. Modified MS liquid medium supplemented with 8 mg/L 2,4-D and 9% sucrose was used as the basal medium. After blending the male flowers, the mixture was filtered with 213, 149, 104, 88 and 41 µm meshes; microspores were collected from the 88 and 41 meshes for further sequential purification with 30, 20 and 10% sucrose solutions at 40.88 or 163.52 g centrifugation. A high response was obtained from the cultured anthers after 4 months of inoculation. 54 and 36% callus induction was observed in SM 1219-9 anthers from 2.3-2.6 and 2.9-3.2 mm size categories, respectively. In TMS 60444 the greatest response (17%) was observed from the anthers in the 2.3-2.6 category. Callus breaking through the anther wall indicated androgenesis from the microspores within the anther. Response from the microspores was comparable to the anther culture results. The greatest percentage of microcallus was observed in microspores isolated from the flower category of 2.3-2.6 mm. Microcallus formation was observed in tetrads, microspores and mature pollen grains, and different stages of microcalli development were identified. As confirmed by cytological studies, mature pollen grains induced callus through a connector like structure. This is the first successful report of androgenesis in cassava.
Perera, P.I.P., Dedicova, B., Ordoňez, C., Kularatne, J.D.J.S., Quintero, M. and Ceballos, H. (2012). RECENT ADVANCES IN ANDROGENESIS INDUCTION OF CASSAVA (MANIHOT ESCULENTA CRANTZ). Acta Hortic. 961, 319-325
microspore culture, anther culture, cytology, callus, multicellular structures, haploid