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4 Univ. Montpellier, CIRAD, INRA, Montpellier SupAgro, France. * Corresponding author, gemma.arnau@cirad.fr.

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Academic year: 2021

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Breeding For Improved Tuber Quality in Yam Dioscorea alata L.

Emmanuel Ehounou 1 , Erick Maledon 2,4 , Fabien Cormier 2,4 , Denis Cornet 3,4 , Elie Nudol 2,4 , Amani Kouakou 1 , Hana Chair 3,4 and Gemma Arnau 2,4*

SP02-12

1 CNRA, Bouaké, Cote d’Ivoire. 2 CIRAD, Station de Roujol, Petit Bourg, Guadeloupe, France. 3 CIRAD, Montpellier, France.

4 Univ. Montpellier, CIRAD, INRA, Montpellier SupAgro, France. * Corresponding author, gemma.arnau@cirad.fr.

Introduction

Improving the quality of yams (Dioscorea sp.) is an ongoing challenge for yam breeders. The acceptability of newly developed varieties depends on several tuber traits that are routinely measured in breeding programs (e.g., shape, colour flesh) and on several physico-chemical

characteristics that determine its organoleptic properties (e.g., starch content, dry matter). Breeding for the quality (boiled and pounded yam) is essentially carried out on the basis of phenotypic observations and it’s a difficult and long process. However, the genetic basis of characteristics that determine tuber quality is not known, which limits the efficiency of genetic improvement programs.

Objectives

The objectives are (1) to test the feasibility of use NIRS for predicting different textural and chemical quality attributes, (2) to acquire knowledge about the genetic control of characters that determine the quality, and (3) to identify the genomic regions involved in different quality traits via a meta-QTL analysis in two biparental D. alata populations.

Materials and methods

Two populations were generated by hand pollinations between contrasted diploid genitors. Parents and progenies were genotyped by GBS. A consensus genetic map was constructed using JoinMap 4.1. Phenotyping of progenies (314 hybrids x 2 blocks x 9 replicates x 2 years) is in process.

The measured traits are: flesh color and browning, tuber size (length and width), regularity of shape, hairiness (scored to 0 to 2), skin rough (scored 0-1) and yield.

Twenty seven varieties were used for NIRS calibration. The following characteristics were analyzed: starch content, D.M., amylose, proteins, sugars, hardness, adhesiveness, cohesiveness, springiness and extensibility. Textural evaluation was conducted on pounded samples using texture profile analyses (TPA).

Results

First results of NIRS calibration and validation are

presented. This work shows that it is possible to use this technology for predicting starch content, protein and sugars. We intend to use it to characterize the progenies.

The distribution of tuber shape was close to bimodal. QTL detection identified a locus involved in tuber shape on linkage group LG16 on both populations.

________________________________________________________________________________________________

Parameters Calibration Validation

M SD SEC/SD SD/SECV SEP SD /SEP R

2

Protein

5.06 0.82 0.31 2.47 0.271 2.66 0.865

Starch

79.69 2.75 0.44 1.90 1.144 2.41 0.828

Sugars

3.56 1.72 0.16 4.56 0.478 3.79 0.929

Amylose

60.7 6.17 0.62 1.44 4.338 1.26 0.441 ________________________________________________________________________________________________

Projet Feder CAVALBIO

Figure 1. Hand pollinations (a), seeds (b), male flowers (b) and female flowers (d).

a b c d

Figure 2. NIRS spectra corresponding to 94 flour samples over 400-2500 nm wavelength (absorbance).

Figure 3. Example of double-compression texture profile for pounded yam.

Figure 4. Distribution of tuber shape for the individuals of population B.

Table 1. Statistical parameters of the calibration and validation sets.

Hardness

Adhesiveness

Références

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