Incorporation of stay-green Quantitative Trait Loci (QTL) in elite sorghum (Sorghum bicolor L. Moench) variety through marker-assisted selection at early generation

Incorporation of stay-green Quantitative Trait Loci (QTL) in elite sorghum (Sorghum bicolor L. Moench) variety through marker-assisted selection at early generation.Objective: The present investigation was undertaken to develop drought tolerant varieties through introgression of stay-green QTLs in order to improve sorghum yield in semi-arid areas of Burkina Faso.Methodology and Result: Marker-assisted selection was carried out to introgress stay-green QTLs into elite sorghum variety. A stay-green donor source, BTx642 (B35), was crossed to the elite variety (Sariaso09) to obtain F1 progenies that were backcrossed to their recurrent parents to obtain the BC1F1 progenies. Seventeen flanking Simple Sequence Repeat (SSRs) polymorphic markers were used for foreground selection and 18 were used for background selection. Eighteen BC1F1 were heterozygous at all target loci for stay-green (stg1, stg2, stg3, stg4 and stgB), 5 progenies (S9B37, S9B43, S9B46 S9B85 and S9B13) had incorporated 3 of these QTLs. 4 plants (S9B34, S9B38, S9B73 and S9B16) incorporated double QTLs (Stg3 and StgB) and three plants (S9B44, S9B48 and S9B20) were heterozygous for Stg1.Conclusions and applications of findings: Among BC1F1 generation, 30 progenies had incorporated at least one stay-green QTL. Two of the introgression lines had high levels of the recurrent parents’ genomes and constitute some promising lines to develop drought tolerant varieties that will ensure sorghum production in semi-arid tropics areas and therefore, contribute to ensure food security in Burkina Faso. Despite the small number of genotypes obtained, the results showed the efficiency of Marker Assisted Back Crossing (MABC) versus the conventional backcross procedure.Keywords: sorghum, stay-green, drought, post-flowering, QTL, MAB

Confirmation de QTL et validation de marqueurs SNPs associés à la résistance du niébé à Colletotrichum capsici, agent responsable de la maladie des taches brunes

Le niébé (Vigna unguiculata (L.) Walp.) est une légumineuse à graine très importante et constitue la principale source de protéines végétales pour l’alimentation des populations d’Afrique Subsaharienne. Sa production au Burkina Faso est entravée par la maladie des taches brunes provoquée par un champignon, Colletotrichum capsici (Syd.) Butler et Bisby. C’est dans la perspective d’accroître la productivité du niébé que nous avons entrepris de renforcer la lutte variétale contre cet agent pathogène. L’identification de marqueurs SNPs (Single Nucleotide Polymorphism) et QTL liés à la résistance à la maladie des taches brunes a été entrepris à partir d’une population biparentale F2 issus du croisement entre la variété sensible Tiligré et celle résistante KN-1. L’analyse QTL de la résistance du niébé à C. capsici à partir de la méthode ICIM add. a permis de confirmer et de valider respectivement un QTL majeur dénommé qBBDR2.1 et 9 marqueurs SNPs convertis, lesquels ont été cartographiés sur le chromosome Vu02 du niébé. Ce QTL dominant a présenté des effets additifs élevés liés aux allèles favorables de KN-1 et des valeurs de PVE de l’ordre de 51,50% et 55,33%, respectivement aux 21ème et 28ème JAI. English title: Confirmation of QTL mapping and validation of SNPs markers associated to cowpea resistance to Colletotrichum capsici, causal agent of brown blotch disease Cowpea (Vigna unguiculata (L.)Walp.) is one of the most important grain legume crops and constitutes the main source of plant protein for people food in sub-Saharan Africa. Cowpea production in Burkina Faso is constrained by brown blotch disease caused by a fungal,  Colletotrichum capsici (Syd.) Butler and Bisby. In order to increase cowpea productivity we initiated a project to enhance host plant resistance to control the pathogen. The identification of SNP (Single Nucleotide Polymorphism) markers and QTL associated with brown blotch disease resistance was undertaken from a bi-parental F2 population resulting from a cross between the sensitive variety Tiligre and the resistant KN-1 to the disease. QTL analysis of cowpea resistance to C. capsici using the ICIM add method. Allowed to confirm and validate respectively a major QTL named qBBDR2.1 and 9 converted SNP markers, which were mapped on cowpea chromosome Vu02. This dominant QTL showed higher additive effects associated to alleles from KN-1 and PVE values of 51.50% and 55.33% respectively at 21 and 28 days after inoculatio

THE IMPACT OF CLIMATE VARIABILITY ON OCCURRENCE OF SESAME PHYLLODY AND SYMPTOMATOLOGY OF THE DISEASE IN A MEDITERRANEAN ENVIRONMENT

Although climate change and variability is considered as an alerting situation and a big challenge to food security, we describe here a positive impact of it regarding disappearance of sesame phyllody in an unusually cool and rainy growing season of 2010 at West Mediterranean region of Turkey where the disease has been devastating last five years and it would occur at any rate in the same field since the start of sesame cultivation in 1995. Phyllody symptomatology and incidence were studied in three groups of plant material; i.e., (1) in a 2-year agronomic performance trial, (2) in the breeding nurseries (on the regenerated branches in the stubbles and unselected left-plants), and (3) in the M-1 plant progenies (grown as M-2 families beyond the commercial growing season for a training purpose). Unexpectedly, in 2010, there was no any single phyllody incidence (0%) in the first and second group material in comparison to the previous years, e.g., 6.0% in 2009). Although the incidence was nil in the third group material of M2 families until onset of capsules (sown very late), phyllody symptoms started to appear as capsules grew and reached at 3% at the physiologic maturity. Also, stubbles of cut plants and unselected-left plants in the field after harvest (especially of F(1)s with heterosis) grew new late branches like ratoon crop and developed phyllody in them, providing a good match between vectors and plant growth. Much of the impact of climate change and variability on sesame phyllody may be through the vectors of the disease and, thus, subject to the effects of fluctuating climate variables on their biology and population dynamics. To reveal the uniqueness of the year 2010 and its effect on the disappearance of the disease, the climate data clearly indicated a cool and rainy season and possibly a mismatch for the cycle of the vectors and crop growth. Three types of main symptoms which specify the phyllody disease were observed, i.e., 'virescence', 'phyllody', and 'ploriferation (witches' broom)', but the latter was less-frequent. Also among several indirect symptoms such as stunted habitus, exudates, vivipary, and yellowing, we described here a new effect of the disease causing short filament, and thus pin-type flower. Finally climate change and variability may also offer some positive impact to exploit for the benefit of food security and such cases should be considered in the crop management tactics and strategies as well as in modeling studies aiming to forecast impact of climate variability