All Manihot species so far examined, including cassava (Manihot esculenta), have 2n = 36. Interspecific hybrids between cassava and its wild relatives show fair regular meiosis, and backcrossed generations exhibit high fertility. Electrophoresis shows affinity between species of different sections, as well as between some of them and cassava itself. Polyploidy has apparently contributed to the rapid speciation of this genus, while apomixis has offered a means of perpetuating new hybrid types adapted to different environments. It is assumed that cassava originated by hybridization between two wild Manihot species followed by vegetative reproduction of the hybrid.

Espécies selvagens de Manihot dão origem à mandioca. Elas constituem valioso reservatório genético, com genes mostrando novos caracteres. O exame cuidadoso dessas espécies mostrou que algumas delas têm uma percentagem notavelmente alta de proteína combinada com uma porcentagem baixa de ácido cianídrico. O estudo dos habitats naturais revelou resistência à seca e à toxicidade por alumínio em excesso no solo, assim como adaptação a baixas temperaturas. Alguns dos híbridos obtidos mostraram alta produtividade da raiz e resistência a brocas do caule. A apomixia foi descoberta nas espécies selvagens e transferida com sucesso para as espécies cultivadas.

Wild species of Manihot are progenitors of cassava. They constitute valuable genetic reservoirs presenting genes that show new characters. Screening of these species showed some of them to have a notably high percentage of protein combined with a low percentage of hydrocyanic acid. Study of natural habitats revealed resistance to drought and excessive soil aluminum toxicity as well as adaptation to low temperature. Some of the hybrids obtained showed high root productivity and resistance to stem borers. Apomixis was discovered in the wild and transferred successfully to the cultivate species.

A Apomixia mantém a heterose e evita a transmissão de patógenos sistêmicos que acompanham a propagação vegetativa da mandioca. Um estudo embriônico de ovos clareados de dois clones de mandioca in toto mostrou que eles são de natureza apospórica. A análise citogenética dos 2 clones revelou uma estrutura aneuploide (2n + 1) em indivíduos apomíticos, ao passo que era 2n em plantas reproduzidas sexualmente.

Apomixis maintains heterosis and avoids transmission of systemic pathogens which accompany vegetative propagation of cassava. An embryonic study of cleared ovules of two cassava clones in toto showed them to be of aposporic nature. Cytogenetic analysis of the two clones revealed an aneuploid structure (2n + 1) in apomictic individuals, whereas it was 2n in the sexually reproduced plants.

The use of mentor pollen has enabled successful hybridization between cassava, Manihot esculenta Crantz, and the wild species M. pohlii Warwa. Killed pollen of a cross compatible type produced by freeze-thawing was mixed with incompatible pollen and the mixes were dusted on stigmas. This treatment resulted in production of seed in 4.9% of the total pollinations, compared to 0% in the case of untreated pollinations. The use of a bridge species, M. neusana Nassar, through the hybrid M. pohlii and M. neusana also proved successful in overcoming interspecific barriers between cassava and M. pohlii.