A five-point drought stress screening methodology for muskmelon based on visual observation has been standardized by modifying an earlier field screening method. The scale (1 to 5), were categorized into five groups, namely, highly drought tolerant (1), drought tolerant (2), average drought tolerant (3), drought susceptible (4) and highly drought susceptible (5). To validate and standardized the technique, 48 genotypes of muskmelon were evaluated for two successive years. Important physiological parameters, i.e.: relative water content (RWC), electrolyte leakage, photosynthetic efficiency (Fv/Fm), chlorophyll concentration index (CCI), root and shoot length were measured and correlated to make screening results more reliable. Drought tolerance efficiency of genotypes was calculated based on yield, and drought-tolerant genotypes were identified with better yield efficiency and ranking on visual scale. Whereas, yield efficiency of some drought-tolerant genotypes were less, althouth they came under drought-tolerant scale. Being a tolerant genotype, these may not be economical for commercial cultivation. Under water-deficit condition a significant positive correlation was observed between drought tolerance efficiency, and RWC, Fv/Fm, CCI and root length. Out of 48 genotypes, 14 genotypes were came under highly drought-tolerant category based on 5 point scale.

Fe and Zn deficiency are widespread worldwide. As wheat is the primary food for the majority of the world people, producing wheat grains with high mineral content can ameliorate the problem of mineral hunger. However, the genetic variation available for breeders is limited. The aim of this study was to assess the genetic variation in grain Fe and Zn contents in 47 synthetic hexaploid wheats and to identify marker loci associated with Fe and Zn contents. We measured the grain Fe and Zn contents using inductively coupled plasma atomic emission spectroscopy and performed genotyping using SSR markers. The results showed considerable genetic variation for these minerals. We identified three lines with high Fe and Zn contents and six quantitative trait loci of which three were associated with Fe content and the other three with Zn content. The minerals showed positive phenotypic and genotypic correlation and high heritability (>60%). The ratio of the σ2g to the σ2g×e was ≥1 for the two mineral contents indicating that breeding for increasing mineral content within the synthetic lines is possible. The synthetic wheat lines identified in this study are valuable genetic resources, and can be utilized for breeding wheat cultivars with high mineral content.

Among domesticated traits, pre-harvest sprouting (PHS) caused by the early breakage of dormancy leads to severe economic losses. Therefore, regulating PHS is important for cereal crop improvement against changes in climate. In this study, we surveyed naturally occurring variations in seed germination in diverse rice germplasm for the available resources of this trait, and investigated the changes of abscisic acid (ABA) levels during grain development by the distinguished PHS-resistant groups. We discovered wide variations in germination among the 205 rice accessions examined and found that 90 accessions are resistant (germination <20%) to PHS. Tropical and subtropical accessions, which are subjected to long wet periods, are more resistant to PHS than the other accessions. We detected an increase in germination of detached seeds from the panicle compared with intact seeds in panicle at harvesting time. This might be attributed to a weakening of the mechanical barrier that prevents water imbibition and radical emergence. ABA levels were maximal at 10 d after flowering and decreased thereafter. Interestingly, PHS-susceptible accessions maintained higher or similar ABA levels compared with PHS-resistant accessions, suggesting that the key factors for seed dormancy and its breakage are ABA perception and signal transduction rather than total ABA content. The diversity of germination ability detected in this study could be sustainably used for crop improvement and to help unveil the genetic and physiological basis of this quantitative trait.

Focusing on 116 bread wheat landraces, this study investigated high molecular weight glutenin allele polymorphism, gene diversity, genetic variation and linkage disequilibrium (LD) in Glu-1 loci. To identify gluten alleles, sodium dodesyl sulphate-polyacrylamide, gel electrophoresis was used and for statistical analyses POPGENE software was employed. The results indicated that average genetic variation (h) was the highest in Glu-B1 (0.6421) and the lowest in Glu-A1 locus (0.4548); genetic similarity ratio (I) was the highest in Glu-B1 (1.4170); the highest average genetic diversity (Ht) was observed in Glu-B1 (0.6575) and the lowest diversity was observed in Glu-A1 (0.4558). It was also observed that genetic diversity in Glu-1 locus was largely due to intra-population variations. Inter-population gene flow was also calculated as 4.0051. Marmara and Southeastern Anatolia regions, the results further indicated, had the highest (2.8691) and lowest (0.1694) heterozygosity. Genetic erosion risk for Turkish bread wheat landraces was also seen to be high. Considering the mutual analyses of subunits of nationwide wheat landraces, it is possible to speculate about a limited migration between the landraces. LD of the landraces was largely because of this limited migration and/or epistatic natural selection. Since Turkey is known as the gene centre for major cereals including wheat, barley, rye and oat, where they diversified and spread throughout the world, studying the gluten allele diversity of Turkish bread wheat landraces is important. In addition, this study has revealed the applicability of LD, and neutrality tests to gluten protein diversity for the first time.

The valorization of genetic diversities of major crops like wheat may help substantially to feed the world Population. Durum wheat genotypes consisting of 265 farmers’ varieties (FVs), which have been cultivated for many centuries in Ethiopia, as well as 24 improved varieties (IMVs) have been recently evaluated in northern Ethiopia. The evaluation has been carried out at two different locations for 2 consecutive years to verify the inherited diversity in FVs for important phenological and agronomic traits; with the intention to provide refined information to breeders and genebank managers. As a result of a careful evaluation, a very significant variation was observed between the FVs and IMVs. A large number of the former have demonstrated superior performance to the latter in terms of mean values of the major traits within the stipulated years and locations. The best performing FV has shown a gain of 20% grain yield over the best IMV. Multivariate analyses revealed that FVs displayed larger genetic diversity than in those IMVs. FVs could therefore be used as donor of useful alleles in durum wheat breeding for improvement of yield per se and other traits of agronomic and phenological importance. The identified stable superior FVs include: 8208, 226834A, 238567, 222426, 226282 could be best candidates for farmers in marginal environments. Genotypes that have shown stable performance for spatial variation such as 204493A, 214357 and 238567; and temporal variation such as 8208, 208479, 214357 and 226834A could be the best candidates for exploitation in future breeding programs.

Heterosis is a main force underlying the hybrid seed industry in maize. Our experimental approach consists of a correlation study between retrotransposon-related genetic distances between parental inbred lines and hybrid performance. The assumption is that, at least for certain traits, heterosis results from genome rearrangements, largely related to retrotransposon insertions and/or removals. Fifteen maize inbred lines and one F1 hybrid, representative of the genetic diversity among sweet corn and field corn lines were screened for polymorphism by retrotransposon microsatellite amplified polymorphism markers. DNA fingerprints served as row data for estimating genetic diversity of maize inbred lines and its correlation with the heterotic effect in their hybrids. A correlation between phenotypic and molecular distances was evident only at the level of individual inbred lines. Weak correlation between genetic distances and heterosis effect was observed for the average of all inbred lines. Phenotypic distances negatively correlated with heterosis for insertion height, diameter of the ear and number of kernel rows per ear. The relative contribution of each inbred line to heterosis in its derived hybrids was also estimated. Accordingly, we identified inbred lines with increased genetic distances that mostly add to the heterosis effect in their hybrids and that we recommend as prospective to be used in maize breeding programmes.

A blueberry (Vaccinium sp.) germplasm collection was screened for allelic variation in TERMINAL FLOWER 1 (TFL1) that could be used in breeding flowering or architecture traits. TFL1 has been found to repress the transition from vegetative to reproductive growth in diverse plant species, with mutations leading to altered flowering and form. The VcTFL1 gene sequence was determined from the draft genome sequence of diploid V. corymbosum line W8520. VcTFL1 is a member of a PEBP gene family and it could be distinguished from its family members by sequence comparison with PEBP family genes from other plants. High-resolution DNA melting analysis of 160 Vaccinium accessions detected VcTFL1 exons that differed in sequence from the W8520 control. DNA sequence analysis confirmed the presence of single nucleotide polymorphisms (SNPs) and identified haplotypes of tetraploid accessions. A total of 18 SNP sites were detected in VcTFL1 coding sequences of the Vaccinium germplasm screened. A SNP causing an alanine-to-valine change in exon 4 (A159V) was determined by multiple bioinformatic tools to be deleterious to VcTFL1 function. A diploid V. corymbosum accession heterozygous for the VcTFL1 mutation was identified as a candidate for breeding novel traits for blueberry.

Sensitivity of alfalfa to acidity and aluminium (Al) toxicity in soil is the major limiting factor in broadening of its growing area. Due to lack of Al tolerance in primary alfalfa germplasm, there is a need for transfer of genes for Al tolerance from other Medicago germplasm. One of the identified sources of Al tolerance is M. sativa ssp. caerulea accession PI 464724, which was used as a female parent in our study. The objectives of this study were: (i) obtaining the tetraploid offspring from 2x–4x M. sativa ssp. caerulea – M. sativa ssp. sativa spontaneous crosses, and (ii) development of a breeding strategy for Al/acid tolerance in alfalfa, using M. sativa ssp. caerulea as a source of Al tolerance. Out of eleven fully developed plants, five were morphologically similar to M. sativa ssp. caerulae, while six plants were similar to M. sativa ssp. sativa. All tested plants were fertile, with the pollen viability ranging from 21.45 to 97.09% and the average number of ovules per plant from 8.80 to 12.29. Eleven SSR primer pairs confirmed the hybrid nature of M. sativa ssp. caerulae × M. sativa ssp. sativa offspring. Both the Cluster Analysis and the Principal Coordinates Analysis separated plants in the caerulae type from plants in the sativa type, with one exception. Strategies based on conventional and molecular marker breeding efforts could lead towards development of tolerant alfalfa cultivars and successful crop production on acidic, Al-contaminated soils.

The dwarfing wheat (Triticum aestivum L.) breeding has promoted a dramatic increase in yields. Since the utilized dwarfing genes in wheat are very limited, identification of novel dwarfing genes is necessary for improving the genetic diversity of wheat. In this study, more than 300 dwarfing wheat lines from induced mutation were screened by kompetitive allele-specific PCR and gibberellin (GA) treatment. The 17.49% of Rht-D1b and 1.37% of Rht-B1b dwarfing mutants were identified in this mutant group. Additionally, Rht-D1b mutants showed more effective in reduction of plant height and higher 1000-grain weight comparing with that of Rht-B1b mutants. By combing with comparison of yield components and expression profile of GA biosynthetic genes with wild-type, the GA-responsive mutant dm15 without directly involvement in GA metabolism, significantly increased 1000-grain weight but no change of other yield components in two locations of field experiments. Meanwhile, another elite mutant dm11 with change of GA biosynthetic genes expression was also identified. These mutants will be promising candidates for dwarfing wheat breeding.

Aegilops tauschii, the D genome donor of wheat, is an invaluable source of genetic variability, which can be utilized for broadening the wheat gene pool. Linked leaf rust resistance and non-glaucousness genes transferred from Ae. tauschii to cultivated wheat variety WH542 were mapped in the present study. Genetic analysis in an F2 population from a BC3 plant derived from the cross Triticum durum cv. PBW114/Ae. tauschii acc. pau14195//4*T. aestivum cv. WH542 revealed monogenic dominant inheritance for both the traits. The leaf rust resistance and the non-glaucousness gene were tentatively named LrT and IwT, respectively. Leaf rust resistance gene exhibited all stage resistance. SSR markers Xbarc124, Xgdm5, Xgdm35, Xcfd51 and EST-derived markers Xcau96 and Xte6 on chromosome 2DS were linked with both genes. Chromosomal assignments of the genes were confirmed by testing linked SSR markers on Chinese Spring nulli-tetrasomics lines. SSR markers Xcau96 (1.6 cM) and Xbarc124 (0.6 cM) flanked LrT and Xgdm35 (4.1 cM) and Xte6 (2.5 cM) flanked non-glaucousness gene. LrT and IwT showed a recombination distance of 3.4 cM. Hence, IwT can be used as an easy to score morphological marker of LrT during its transfer to other glaucous backgrounds.

Hybrid rice development, a major advance in rice breeding, has demonstrated its immense potential in enhancing the rice productivity. In the three line system of hybrid rice, the restoration of fertility of the widely used wild-abortive type of cytoplasmic male sterility is controlled by Rf3 and Rf4, two fertility restoration genes. Exploration for restorers in diverse genetic backgrounds is a critical step in hybrid rice breeding. As genetic resources constitute the major source of new genes/alleles, an attempt was made to assess the distribution of these two restorer genes in the native populations collected from the geographic regions known to be the primary and secondary centres of origin of rice. In addition, assays were performed on the populations of Oryza rufipogon and Oryza nivara, the wild progenitors of rice. The results suggest that the Rf genes are well distributed in the wild forms at a higher frequency, more in O. rufipogon, while in cultivated forms, their frequency is low, particularly for the Rf3 gene. The genes and the alleles identified in the genetically divergent, low-performing land races and wild relatives can be successfully employed for the development of new hybrid rice cultivars.