Identification of Quantitative Trait Loci (QTLs) Conferring Dry Matter Content and Starch Content in Cassava (<i>Manihot esculenta</i> Crantz)

Abstract

Cassava tubers are an excellent source of carbohydrate and a competitive source of starch most traded internationally. It is a highly desirable raw material for food and industrial purpose due to its high dietary carbohydrate content. The economic value of cassava products lies in the DMC (dry matter content). Cassava roots contain up to 80-90 per cent of carbohydrate by dry weight and 80 per cent of carbohydrate is starch. Increasing world population, limited land area, changing climatic condition and food scarcity demanded the need for improved cassava starch. Yield of cassava tubers is related to both tuber volume and DMC and thus DMC can be improved by cassava breeding. Thus QTL mapping of DMC is very much relevant to understand the genetic effects controlling the traits. The current study focused on QTL mapping for DMC and SC (starch content) to identify and study the favourite alleles using Windows cartographer version 2.5. Single marker analysis (SMA) identified seven marker alleles associated with DMC and eight marker alleles associated with SC. Using interval mapping, a single QTL for DMC was identified in chrom21 flanked by SSRY110 b and SSRY182 b . On the other hand, five QTLs for SC were identified by simple interval mapping (SIM) and a single QTL in chrom17 with R 2 value of 12% and at a LOD value 5 using composite interval mapping (CIM). The exact position of the QTLs and its interactions were studied using MIM and the genetic effect of QTLs controlling DMC was found to be over-dominance. But in the case of SC, the QTL interaction was identified and found to be additive x additive epistatic interaction.

Breeding Cassava for End-User Needs

“…For the acceptance of cassava for value chain actors, dry matter content (DMC) is an important character for variety acceptance. DMC is referred to as true biological yield or economic yield which is controlled by many genes [39,40]. Majority of cassava accessions have DMC between 20 and 40% [39].…”

Advances in Genetic Analysis and Breeding of Cassava (Manihot esculenta Crantz): A Review

“…Dry matter content is an important character for the acceptance of cassava by producer, consumer, and processor. It is considered as the economic or true biological yield, which is controlled by polygenes [58]. The proportion of dry matter in cassava storage roots ranges from 17 to 47%, with the majority of the accessions lying between 20% and 40% [59] and values above 30% are considered to be high.…”

Genotypic variability and genetic parameters for root yield, dry matter and related traits of cassava in the Guinea Savannah ecological zone of Ghana

“…However, certain cassava varieties have high dry matter content which makes them ideal for industrial processing. Dry matter content is highly polygenic trait in cassava and is very useful for the acceptance or rejection of cassava varieties by most end-users including processors (Prasannakumari et al, 2021). High dry matter cassava varieties have been useful in starch production since high dry matter content has been found to be positively associated with high starch content (Maraphum et al, 2021;Teye et al, 2011).…”