Fouad Maalouf

Quantitative Trait Loci for Grain Yield and Adaptation of Durum Wheat (Triticum durum Desf.) Across a Wide Range of Water Availability

Grain yield is a major goal for the improvement of durum wheat, particularly in drought-prone areas. In this study, the genetic basis of grain yield (GY), heading date (HD), and plant height (PH) was investigated in a durum wheat population of 249 recombinant inbred lines evaluated in 16 environments (10 rainfed and 6 irrigated) characterized by a broad range of water availability and GY (from 5.6 to 58.8 q ha−1). Among the 16 quantitative trait loci (QTL) that affected GY, two major QTL on chromosomes 2BL and 3BS showed significant effects in 8 and 7 environments, with R2 values of 21.5 and 13.8% (mean data of all 16 environments), respectively. In both cases, extensive overlap was observed between the LOD profiles of GY and PH, but not with those for HD. QTL specific for PH were identified on chromosomes 1BS, 3AL, and 7AS. Additionally, three major QTL for HD on chromosomes 2AS, 2BL, and 7BS showed limited or no effects on GY. For both PH and GY, notable epistasis between the chromosome 2BL and 3BS QTL was detected across several environments.

Association mapping in durum wheat grown across a broad range of water regimes

Association mapping was used to dissect the genetic basis of drought-adaptive traits and grain yield (GY) in a collection of 189 elite durum wheat accessions evaluated in 15 environments highly different for water availability during the crop cycle (from 146 to 711 mm) and GY (from 9.9 to 67.3 q ha(-1)). For highly heritable traits (e.g. heading date, kernel weight, etc.) several significant experiment-wise marker-trait associations were detected across five or more (up to 13 for kernel weight) environments, with R(2) values ranging from ca. 5 to 10%. As to GY, significant associations (R(2) from 2.5 to 4.2%) were mostly detected in one environment only (56 markers), while decreasing rapidly from two to five environments (from 20 to three markers, respectively) and with only one marker (Xbarc197 on chr. 5A) found significant in six environments (ranging from low- to high-yielding). These results are probably due to the complex genetic basis of GY and its interaction with environmental conditions. The number of markers significantly affecting GY decreased considerably under drought conditions, suggesting a limited effectiveness of association mapping to identify loci for GY under low-moisture conditions, most likely because different genotypes can attain similar phenotypes via different morpho-physiological traits and corresponding gene networks. Our study confirmed the role of major loci for phenology previously described in biparental mapping populations, highlighted a novel set of loci for drought-adaptive traits, and provided information on the agronomic value of the alleles at such loci across a broad range of soil moisture conditions.

A panel of elite accessions of durum wheat (Triticum durum Desf.) suitable for association mapping studies

The effectiveness of association mapping (AM) based on linkage disequilibrium (LD) is currently beingtestedinanumberofcrops.AnimportantprerequisitefortheapplicationofAMistheavailabilityofcollectionsofaccessionswithasuitablelevelofgeneticvariationfortargettraitsandwith limited spurious LD due to the presence of population structure. Herein, the results of a genomewide molecular characterization of a collection of elite durum wheat accessions well-adapted to Mediterranean environments are presented. Ninety-seven highly polymorphic simple sequence repeats and 166 amplified fragment length polymorphism markers were used to characterize 189 durum accessions, mainly cultivars and advanced breeding lines. Genome-wide significant and sizeable LD indices at a centimorgan scale were observed, while LD mainly decayed within 10cM. On the other hand, effects due to spurious LD were notably lower than those previously observed in a durum wheat collection sampling durum gene pools of more diverse origin.

The role of crop-pollinator relationships in breeding for pollinator-friendly legumes: from a breeding perspective

Breeders are encouraged to develop breeding approaches that strive to integrate food production into the healthy functioning of agro-ecosystems. In the case of legumes, this approach should preserve bee fauna by providing suitable floral resources within the crops themselves. In parallel, legume breeding for sustainable agriculture is linked to the development of environmental services. Foraging places and nesting sites for solitary and social bees are some of the ecological services provided for legumes. Crops with floral attractiveness and rewards for insects can be used to enhance pollinator conservation as well as crop yield and yield stability. We analyze how understanding crop-pollinator relationships (CPR) can contribute to the production of high-yielding and pollinator-friendly varieties by examining: (1) The status of knowledge on mating systems and floral traits; (2) The contribution of CPR understanding to plant breeding for both hybrid-seed production and open-pollinated population improvement.

A SNP-based consensus genetic map for synteny-based trait targeting in faba bean (Vicia faba L.)

Summary Faba bean (Vicia faba L.) is a globally important nitrogen‐fixing legume, which is widely grown in a diverse range of environments. In this work, we mine and validate a set of 845 SNPs from the aligned transcriptomes of two contrasting inbred lines. Each V. faba SNP is assigned by BLAST analysis to a single Medicago orthologue. This set of syntenically anchored polymorphisms were then validated as individual KASP assays, classified according to their informativeness and performance on a panel of 37 inbred lines, and the best performing 757 markers used to genotype six mapping populations. The six resulting linkage maps were merged into a single consensus map on which 687 SNPs were placed on six linkage groups, each presumed to correspond to one of the six V. faba chromosomes. This sequence‐based consensus map was used to explore synteny with the most closely related crop species, lentil and the most closely related fully sequenced genome, Medicago. Large tracts of uninterrupted colinearity were found between faba bean and Medicago, making it relatively straightforward to predict gene content and order in mapped genetic interval. As a demonstration of this, we mapped a flower colour gene to a 2‐cM interval of Vf chromosome 2 which was highly colinear with Mt3. The obvious candidate gene from 78 gene models in the collinear Medicago chromosome segment was the previously characterized MtWD40‐1 gene controlling anthocyanin production in Medicago and resequencing of the Vf orthologue showed a putative causative deletion of the entire 5′ end of the gene.

Evaluation of faba bean breeding lines for spectral indices, yield traits and yield stability under diverse environments

Abstract. Drought is a major limiting factor in faba bean (Vicia faba L.) production in the Mediterranean region, which is known for its irregular water distribution and moderate moisture levels (∼500 mm rainfall). In this study, faba bean genotypes were evaluated for spectral indices, yield traits, rhizobium nodulation and yield stability under diverse environments, and their relationships. Eleven faba bean genotypes were evaluated under two water regimes, rainfed and supplemental irrigation (SI), in 2008–09; and under three water regimes (rainfed, 50% and 100% soil water capacity irrigation) for three consecutive growing seasons (2009–10, 2010–11, 2011–12), at Tel Hadya in Syria. They were also evaluated at Terbol in Lebanon for one season (2011–12) in a split-plot experiment with three irrigation treatments and at Kfardan in Lebanon for two seasons, 2008–09 (rainfed) and 2010–11 (rainfed and SI). The genotypes included three cultivars and eight drought-tolerant breeding lines selected at <300 mm annual rainfall. Phenological and morphological traits were recorded, as well as nodule weight per plant, grain yield, biological yield and spectral reflectance indices. Data were statistically analysed for each year. There were significant genotypic differences for seed yield under SI and rainfed conditions in 2008–09, and full irrigation in 2009–10 and 2011–12. Days to flowering and maturity were significantly different among genotypes for rainfed and irrigated conditions. There were significant differences between water regimes and genotypes, but their interactions were not significant. FLIP06-010FB was the highest yielding and most stable among the tested genotypes across different environments. Days to flowering and days to maturity were positively correlated with grain yield. The spectral indices structure-insensitive pigment index and normalised pheophytinisation index were found to correlate positively with grain yield and could therefore be used for selection under drought-prone environments.

New faba bean germplasm with multiple resistances to Ascochyta blight, chocolate spot and rust diseases

Faba bean is one of the oldest crops that originated in the Fertile Crescent and is now distributed around the world and produced under different agro-climatic conditions. It is mainly cultivated in high rainfall and irrigated areas which are favorable for the development of foliar diseases causing severe crop losses. The purpose of this study was to identify new sources of resistance to the three key foliar diseases. A total of 2000 accessions, breeding lines and populations were screened for resistance to chocolate spot, Ascochyta blight and rust diseases from 2005 to 2012, at Lattakia Station, Syria. A total of 30 lines combining Ascochyta blight, chocolate spot and rust resistance were identified from accessions collected from China, Italy, Jordan, Lebanon and Spain. These new sources of resistance will enhance the development of faba bean breeding lines with combined resistance to the three foliar diseases.

Genetic enhancement of food legumes for nutritional security and sustainable cereal-based cropping systems

Food legume crops are cultivated since the earliest days of agriculture for human food and animal feed. Today these crops are grown globally, providing food and nutritional security. In particular, they are the main source of protein, macro and micronutrients in the diets of medium to lowincome people in most developing countries. Besides their nutritional value, food legumes are important nitrogen fixers, contributing to soil health improvement and thus providing sustainable cropping system. However, global food legume production of about 67 million tons per year is insufficient to meet demand from ever-increasing populations, particularly in Africa and Asia. Food legumes are grown mainly by small and marginal farmers under rainfed conditions in marginal areas, leading to low and unstable yields. Moreover, they have long been ‘orphan crops’, receiving very little attention from researchers and policy makers. To attain a sustainable increased production in food legumes, several international research centers are working closely with national institutions to address these issues. The International Center for Agricultural Research in the Dry Areas (ICARDA), located in the center of origin of many food legume species, is engaged in research to develop and deliver improved food legume technologies to farmers. The research covers multiple crops (lentil, faba bean, Kabuli chickpea, grasspea) and involves a multidisciplinary team comprising breeders, biotechnologists, pathologists, entomologists, and seed specialists, To date, a total of 368 improved varieties of these crops have been released for cultivation in various countries, jointly developed by ICARDA and national partners.