Development of interspecific hybrids of cassava and paternity analysis with molecular markers

Abstract

The present paper demonstrates the development of interspecific hybrids between Manihot esculenta Crantz ssp. esculenta (Mee) and M. esculenta Crantz ssp. flabellifolia (Mef) and paternity analysis using microsatellite markers [simple sequence repeat (SSR)]. Three Mef accessions (FLA005, FLA025V and FLA029V) were used for crosses with varieties of Mee: Saracura, Aipim Bravo, COL 1725, Aipim Rosa, Abóbora, Paraná and PER334. The paternity of the interspecific hybrids was investigated using 24 SSRs. The observed heterozygosity (Ho), polymorphic information content (PIC), probability of identity (PI) and paternity exclusion (PE) were evaluated. The rate of breeding success varied from 17 to 92%, and an average of two pollinations were required for each generated hybrid plant. The Ho value ranged from 0·11 to 0·92, and the PIC value ranged from 0·12 to 0·59. The uneven distribution of allele frequencies was accompanied by a high PI average (0·56). However, the combined PE for 21 loci was 0·99, which allows for the determination of the paternity of the hybrids with good discriminatory power. Of the 74 hybrids evaluated, 0·82 had their paternity confirmed using microsatellite markers. Discriminant analysis of principal components (DAPC) indicated the presence of eight clusters, of which, one was composed of only Mef varieties and the supposed hybrid Fla52Sar-H7, which was a product of apomixis. The parent Mee and hybrids were allocated in the other seven clusters. The data obtained demonstrate that SSR markers can be routinely used in breeding programmes to verify the paternity of interspecific crosses of cassava.

Obtaining hybrids of cultivars and wild subspecies of cassava

“…The crosses were made during the day, from 10 a.m. to 2 p.m., when the sun is the strongest. This period is related to the anthesis of cassava and wild Manihot species, which occurs during the day when temperatures are the highest and humidity is the lowest, and is also when pistillate flowers open and the stigmas are the most receptive (Vieira et al, 2013).…”

“…esculenta) is the only cultivated species of the genus and is a culture of great importance worldwide, since it is used to feed around 800 million people, especially in countries where food shortages are common (Nhassico et al, 2008). However, despite the great contribution of cassava as a food source to poorer populations, it is necessary to improve the nutritional quality of the root and to obtain varieties resistant to biotic and abiotic factors (Vieira et al, 2013). Cassava is an allogamous species; however, with vegetative propagation, self-fertilization can occur when two plants of the same genotype are crossed (Halsey et al, 2008).…”

“…However, one of the main problems in using wild species of Manihot in genetic improvement programs is the asynchrony in flowering periods, which makes it difficult to propagate and maintain these plants in the field (Vieira et al, 2013). Increasingly, there is a need for studies related to the floral biology of cassava and the hybridization process because they facilitate genetic improvement programs that perform cross-pollination.…”

“…bras., Brasília, v.53, n.2, p.182-188, Feb. 2018 DOI: 10.1590/S0100-204X2018000200006 Normally, crosses made between domesticated cultivars and wild species of Manihot enable the transfer of genes that express undesirable characteristics, such as those related to a lower harvest index and, consequently, to a lower productivity of tuberous roots (Ojulong et al, 2008). To eliminate undesirable characters in possible hybrids, gene introgression based on backcrossing is recommended, using a genotype of a cultivated species with high production potential as the recurrent parent (Vieira et al, 2013). However, the fixation of desirable characteristics from the wild parent of cassava is more difficult as the number of genes that control the characteristic in question increases.…”

Clonal selection ofEucalyptus grandis x Eucalyptus globulusfor productivity, adaptability, and stability, using SNP markers

“…The importance of this analysis should be highlighted as its use can avoid the mislabelling of parentage, and which consequently compromises the certification of breeding programmes that guarantee the identity of a germplasm via genotyping (Torres-Dini et al, 2011;De Vieira et al, 2013;Shanmugapriya and Yasodha, 2014). Incorporating traditional breeding strategies with genotyping increases the level of knowledge about improvement populations, enabling a better selection of clones and preventing common errors, thus improving the effectiveness of decision-making for breeders.…”