Salt stress responses and alleviation strategies in legumes: a review of the current knowledge.

Salinity is one of the most significant environmental factors limiting legumes development and productivity. Salt stress disturbs all developmental stages of legumes and affects their hormonal regulation, photosynthesis and biological nitrogen fixation, causing nutritional imbalance, plant growth inhibition and yield losses. At the molecular level, salt stress exposure involves large number of factors that are implicated in stress perception, transduction, and regulation of salt responsive genes' expression through the intervention of transcription factors. Along with the complex gene network, epigenetic regulation mediated by non-coding RNAs, and DNA methylation events are also involved in legumes' response to salinity. Different alleviation strategies can increase salt tolerance in legume plants. The most promising ones are Plant Growth Promoting Rhizobia, Arbuscular Mycorrhizal Fungi, seed and plant's priming. Genetic manipulation offers an effective approach for improving salt tolerance. In this review, we present a detailed overview of the adverse effect of salt stress on legumes and their molecular responses. We also provide an overview of various ameliorative strategies that have been implemented to mitigate/overcome the harmful effects of salt stress on legumes.

Allelic variation at high-molecular weight and low-molecular weight glutenin subunit genes in Moroccan bread wheat and durum wheat cultivars.

Glutenin is a major protein fraction contributing to the functional properties of gluten and dough. The glutenin constitutes 30-40% of the protein in wheat flour and about half of that in gluten. It is essential to identify correct glutenin alleles and to improve wheat quality by selecting alleles that exert favorable effects. Moroccan wheat cultivars are unique in West Asia and North Africa region, since many of them possess resistance to Hessian fly, a pest, which is becoming important in other countries in the region. Hence, these cultivars are being used as donor for the resistance in the breeding program. Here, we determine the allelic variation in high-molecular weight glutenin subunits (HMW-GS) and low-molecular weight glutenin subunits (LMW-GS) in Moroccan cultivars of bread and durum wheat using the gene-specific PCR markers. In 20 cultivars of bread wheat, 9 different allele variants were detected at HMW-GS and 13 different allele variants were detected at LMW-GS, in which the alleles Glu-A1b (2*), Glu-B1i (17 + 18), Glu-B1c (7*/7 + 9), Glu-D1d (5 + 10), Glu-A3c, Glu-B3 h, and Glu-D3b were the most frequents. In 26 cultivars of durum wheat, less allelic variation was found: seven different allele variants at HMW-GS and six different allele variants at LMW-GS were identified, in which the major alleles were Glu-A1c (null), Glu-B1b (7 + 8), Glu-B1e (20), Glu-A3c, and Glu-B3d. The mean value of the genetic diversity for the glutenin loci was 0.502 in bread wheat and 0.449 in durum wheat. Most of the glutenin alleles carried by Moroccan bread wheat cultivars impart good bread-making quality. Most of the durum wheat glutenin alleles were related to low strength dough or poor quality and need to be improved. To improve quality of Moroccan durum wheat, essentially, Glu-A1c and Glu-B3d alleles of the genes should be replaced with the better alleles through breeding.

Genetic characterization of Moroccan and the exotic bread wheat cultivars using functional and random DNA markers linked to the agronomic traits for genomics-assisted improvement.

Genetic characterization, diversity analysis and estimate of the genetic relationship among varieties using functional and random DNA markers linked to agronomic traits can provide relevant guidelines in selecting parents and designing new breeding strategies for marker-assisted wheat cultivar improvement. Here, we characterize 20 Moroccan and 19 exotic bread wheat (Triticum aestivum L.) cultivars using 47 functional and 7 linked random DNA markers associated with 21 loci of the most important traits for wheat breeding. The functional marker analysis revealed that 35, 45, and 10 % of the Moroccan cultivars, respectively have the rust resistance genes (Lr34/Yr18/Pm38), dwarfing genes (Rht1b or Rht2b alleles) and the leaf rust resistance gene (Lr68). The marker alleles for genes Lr37/Yr17/Sr38, Sr24 and Yr36 were present only in the exotic cultivars and absent in Moroccan cultivars. 25 % of cultivars had 1BL.1RS translocation. 70 % of the wheat cultivars had Ppo-D1a and Ppo-A1b associated with low polyphenol oxidase activity. 10 % of cultivars showed presence of a random DNA marker allele (175 bp) linked to Hessian fly resistance gene H22. The majority of the Moroccan cultivars were carrying alleles that impart good bread making quality. Neighbor joining (NJ) and principal coordinate analysis based on the marker data revealed a clear differentiation between elite Moroccan and exotic wheat cultivars. The results of this study are useful for selecting suitable parents for making targeted crosses in marker-assisted wheat breeding and enhancing genetic diversity in the wheat cultivars.

Genetic diversity in algerian durum wheat varieties (Triticum turgidum L var. durum) using microsatellite markers / Diversidade genética em variedades de trigo duro argelino (Triticum turgidum L var. durum) usando marcadores microssatélites

Characterization of germplasm by DNA-markers provides powerful tool to precise germplasm identification. This study aimed to quantify the genetic diversity and to estimate the phylogenetic relationship among genotypes in many crop species. The results of the present study realized between Nov and Dec 2016 in biotechnologie unit (ICARDA, Morocco) which aimed to characterize a subset of 14 Algerian selected durum wheat cultivars (Triticum turgidum L. var. durum), using 13 SSR (Single Sequence Repeat) indicated the presence of a total of 39 alleles. The genetic diversity at the 13 microsatellites loci varied from 0,142 for Xgwm337 to 0.735 for Xgwm213 with a mean of 0.444. Polymorphic information content (PIC) values ranged from 0.13 to 0.70 and the genetic distance among the cultivars from 0.15 to 0.77. Clustering analysis showed that the studied varieties were grouped according to their population of origin, suggesting a provenance effect in their ordination. In fact the most similar varieties were those introduced from CIMMYT-ICARDA breeding program, which may have common parents in their pedigree. Selections from local landraces were more similar to each other and dissimilar to CIMMYT-ICARDA material, showing an agro-ecological adaptation.

A caracterização de germoplasma por marcadores de DNA fornece uma ferramenta poderosa para a identificação precisa de germoplasma, quantificar a diversidade genética e estimar a relação filogenética entre genótipos em muitas espécies de culturas. Os resultados do presente estudo foram realizados entre novembro e dezembro de 2016 na unidade de biotecnologia (ICARDA, Marrocos) que objetivou caracterizar um subconjunto de 14 cultivares de trigo duro argelinos selecionados (Triticum turgidum L. var. durum), utilizando 13 SSR (Single Sequence Repeat ) indicou a presença de um total de 39 alelos. A diversidade genética nos 13 locos de microssatélites variou de 0,142 para Xgwm337 a 0,735 para Xgwm213 com uma média de 0,444. Os valores do conteúdo de informação polimórfica (PIC) variaram de 0,13 a 0,70 e a distância genética entre as cultivares de 0,15 a 0,77. A análise de agrupamento mostrou que as variedades estudadas foram agrupadas de acordo com sua população de origem, sugerindo um efeito de proveniência em sua ordenação. De fato, as variedades mais similares foram aquelas introduzidas no programa de criação CIMMYT-ICARDA, que podem ter pais comuns em seu pedigree. Seleções de variedades locais foram mais similares entre si e diferentes do material CIMMYT-ICARDA, mostrando uma adaptação agroecológica.