Dissection of Gene Loci Underlying Pasting Temperature Property in Cassava

Cassava (Manihot esculenta Crantz) genetic linkage maps have been developed and applied for identification of Quantitative trait loci (QTL) underlying several traits including pasting temperature (PT). PT is an important trait in starch properties that showed most significant of broad sense heritabilities when analyzed in an F₁ population of ‘Huay Bong60’ (HB) x ‘Hanatee’ (HN). Although, QTL associated with the PT trait have been initially identified, but molecular markers tightly linked to this trait have not yet been found. In order to identify linked markers and genes controlling the PT properties, saturation of markers within the QTL regions has been performed. Simple Sequence Repeats (SSR) primers were designed based on two scaffolds (S4043 and S11341) of the cassava genome sequence which covered the selected QTL region. Total of 55 and 61 SSR primer pairs from the two scaffolds were screened with the parental lines, HB and HN.  The polymorphic markers were identified in 24 (43.6%) and 25 (41%) primer pairs derived from S11341 and S4043, respectively, whereas that rest were monomorphism, non-specific amplification and no PCR product. Of these, 23 (95.8%) of 24 and 19 (76%) of 25 were informative polymorphic markers when screened with an F₁ population. All informative makers will be further genotype with 100 samples of the F₁population. Finally, QTL will be analyze in order to identify linked markers and genes controlling the PT trait.