نشریه بیوتکنولوژی و بیوشیمی غلات
پیاپی 2 (تابستان 1401)

Humans have long sought to select the desirable traits for agriculture and domestication of important and economical crop species around the world. In fact, the human selection is a factor that plays a key role in determining the fate of plant breeding lines, especially cereals. Therefore, the study of genetic diversity and the study of germplasm storage of breeding lines on the one hand and the study of the role and effect of choices made by plant breeders, on the other hand, are key factors in investigating the fate of improved seeds and lines. To conduct such studies, molecular studies using markers that act neutrally and randomly are important. Accordingly, the present study aimed to investigate the effect of selection on seeds of an important crop that has long been under domestication and crop breeding programs. Sixteen pure lines of sorghum grown in the research farm of Agricultural and Natural Resources Research and Training Center of Khorasan Razavi were assessed using retrotransposon-based molecular markers plus desirable morphological traits used in breeding crop sorghums.

A total of 80 individuals belonging to the first to ninth generations of breeding sorghums were randomly selected, and molecular studies were performed using 8 IRAP primer combinations. Morphological studies were also performed using the measurement of traits related to leaf biomass (the number of leaves at 60 days of plant growth).

The observations showed relatively high intergroup genetic diversity (between breeding generations) (63.5%) in the study group. Among the studied generations, the fifth generation and afterward the seventh and eighth generations showed the highest hereditary diversity, the highest heterozygosity, and the highest number of unique alleles. The first and ninth generations with the highest homozygosity, respectively, were the purest lines studied.

The results of dendrogram trees also confirmed the existence of three completely different clusters in the study group. Accordingly, the existence of gene flow between the breeding lines of sorghum and its occurrence among the individuals of the fifth, sixth and seventh generations was confirmed. However, its decline and decrease in the seventh generation onwards indicated the instability of observed recombination. Finally, it was concluded that the selection of superior and desirable phenotypes during the purification process always acts as a selective sweep and as a directional selection eliminates the variations created by gene flow and thus reduces the genetic diversity in the pure lines of crop sorghum.

Assessment of the genetic diversity of crops is vital to plant breeding and heritage conservation programs. Genetic diversity in plant species is important for selecting the right parents for hybridization and producing suitable offspring. The genetic diversity of durum wheat compared to other crops has decreased significantly during the time, initially due to the domestication of the plant and gradually due to the use of uniform and modified germplasm, which has shown this to be a threat.

Genetic diversity and population structure of a set of durum wheat germplasm, including 36 durum wheat landraces and five new cultivars, were evaluated using 15 Dof markers.

The total number of amplified bands was 117, of which 79 were polymorphic with an average polymorphism of 62.32%. The mean polymorphism information content, marker index, and resolving power in the population were 0.34, 1.61 and 1.9, respectively. According to the indices calculated in this study, Dof16, Dof20, Dof31 and Dof35 markers are more suitable for studying the genetic diversity of durum wheat. Population structure analysis divided germplasm into three subgroups (K=3). The molecular analysis of variance based on three subgroups obtained from STRUCTURE for Dof markers showed that the variance within and between subgroups was 85% and 15% of the total variance, respectively. Principal coordinate analysis partly corresponded to the result of population structure and divided the germplasm into three groups.

The results of the present study showed a high level of polymorphism and diversity in Dof markers, indicating the efficiency of these markers in differentiating durum wheat genotypes in this study. Due to the very high conservation of Dof sequences, this specific marker is significant in plants, so this marker can be used to study genetic diversity in different plant species.

Nitrogen is a determining element in nutrition, plant growth, and its quantitative and qualitative performance. Considering the high cultivated area of dryland wheat in the country and the economical importance of this crop in dryland conditions, it is necessary to consider any solution to optimize the quantity and quality of this product.

a strip split plot design based on RCBD with three replicates was conducted under rainfed and supplemental irrigation conditions during two cropping seasons (2016-17 and 2017-18) to evaluate the effect of Nitrogen (urea) applied by different foliar application treatments and top dressing fertilizer on grain yield, grain protein content, Zeleny number, and gluten index of wheat, Experimental treatments were: A: control (without application of N), foliar application of urea during booting, booting + grain filling and grain filling stages as the main plot, B: wheat cultivars as sub-plots, C: top dressing fertilizer including application and non-application (control) in strip factor were considered.

The results of a combined analysis of variance and mean comparison showed that foliar spraying of urea fertilizer in all three growth stages significantly increased grain yield, nitrogen content, the percentage of grain protein and grain hardness, Zeleny number and grain gluten index. The application of top dressing fertilizer in both rainfed and supplementary irrigation conditions on grain yield, grain protein and gluten index was also significant. The highest gluten index in rainfed conditions (24.08%) and supplementary irrigation (16.19%) was related to foliar application of urea during the grain filling stage. The highest index of gluten, grain hardness and Zeleny number in both rainfed and supplementary irrigation conditions belonged to Rijaw variety. Rijaw variety had the highest value with 27.3 and Azar-2 variety had the lowest gluten index value with 18.6. Foliar application of urea during the grain filling stage had the most contribution to the increase of grain protein and the control treatment had the least contribution. The highest amount of grain yield in rainfed conditions was 2907 and in supplementary irrigation conditions were 3957 kg, which compared to the control treatment (no application of vinegar fertilizer), increased the grain yield by 19 and 16% in both rainfed and supplementary irrigation conditions, respectively.

The results of this research showed that foliar application treatments and top dressing fertilizer in both rainfed conditions and supplementary irrigation were effective in improving quality traits. In this study, supplementary irrigation led to a significant increase in grain yield compared to rainfed conditions.

Stress is the result of abnormal processes that are formed under the influence of one or a combination of environmental and biological factors. Plants are naturally affected by a wide range of living and non-living stresses. Exposure to stress during the growing season indirectly affects the crop and Gross Domestic Product (GDP). Almost half of all human food needs, especially in Asia, are met directly from cereals. More than a third of the world's population gets their daily calories and protein from wheat products, and It is a cheap source of energy, especially for the people of the Third World. Starch is the most important final product of wheat growth and development, and changes in starch content are indicative of a variety of plant growth processes.

In this study, two bread wheat cultivars named Navid with medium to poor bakery quality and Pishtaz with high bakery quality were selected. Two wheat cultivars were cultivated in the field. Both cultivars had control and drought stress treatment. The design was performed in the form of randomized complete blocks with three replications. Seeds were harvested 35 days after pollination. Morphological parameters, germination percentage, A, B and C granules were separated and the granules were examined by light microscopy. The composition of starch in wheat has a decisive effect on grain quality, flour processing and yield.

Drought caused a significant reduction in thousand seed weight in both Pishtaz and Navid cultivars. However, for spike length and germination percentage, only in Navid cultivar, which had poor bakery quality, the spike length was significantly reduced at the probability level of 1%. Also, drought stress in both cultivars had no significant effect on the amount of starch at the probability level of 1%.

Drought stress caused a significant reduction in thousand seed weight in both wheat cultivars with different qualities, but it did not affect the amount of starch in any of the cultivars. In contrast, the trait of spike length and germination percentage caused a decrease in poor quality cultivars.

Barley is one of the most important crops that is cultivated in many areas and is mainly used in livestock and poultry feed and malt production industry. Some physical and biochemical properties of grain are very effective on the quantity and quality of the grain, malt production, and its nutritional properties.

In this study, seven Iranian and European barley cultivars (Hordeum vulgare subsp. Vulgare) and two wild barley genotypes (Hordeum vulgare subsp. Spontaneum (K. Koch)) were studied for some physicochemical characteristics of the grain.

Based on the results, genotypes were significantly different for all studied traits except moisture content and percentage of soluble sugar, and wild genotypes showed a higher mean for most traits. Cluster analysis divided the genotypes into three groups. The lowest and highest values of genetic variation coefficient were obtained for moisture content and iron content, and the lowest and highest values of phenotypic and environmental variation coefficients were recorded for grain thickness and grain iron content, respectively. Broad-sense heritability was estimated to be high for ash percentage, grain length, width and thickness, and thousand kernel weight. Ash percentage and thousand kernel weight had a higher percentage of mean genetic advance. The coefficient of phenotypic variation of all traits was higher than the coefficient of genetic variation. The small difference between the coefficient of phenotypic and genotypic variations for length, width, thickness, and weight of thousand kernel weight indicates the greater influence of genetic factors on the control of these traits. On the other hand, the genetic and phenotypic correlation coefficients of some traits were significant, which indicates the possibility of simultaneous breeding of the two traits.

According to the results and the significant differences in physicochemical characteristics, the selection of a wild genotype and a cultivated variety with a suitable genetic distance based on ash percentage, iron and zinc content, grain protein and high thousand kernel weight was found to be suitable for creating a segregating population.

One of the primary challenges that exist all over the world is the reduction of plant yield due to soil salinity. 5.97% of the world's water is saline, and also many areas have saline land. Human activities exacerbate this challenge. Salinity is one of the main issues affecting the yield of crops worldwide, and more than 7% of flat land is salty. The nutritional superiority of quinoa has been known since ancient times in the Inca Empire. The importance that quinoa can play in nutrition is emphasized not only in developing countries but also in developed countries. Quinoa seeds have a higher nutritional value than most grains and contain high-quality protein and large amounts of carbohydrates, fat, vitamins, and minerals. Quinoa shows high levels of resistance to prevailing adverse factors such as soil salinity, drought, cold, diseases, and pests.

In this study, the physiological effects of salinity stress on two quinoa genotypes in the germination stage were investigated. The studied genotypes were Sajama and Titicaca. The salinity stress (NaCl) was applied at 0, 4, 6, 8, 10, and 12 decisions per meter. This experiment was carried out using a factorial design based on the completely randomized design in the laboratory of Guilan University in 2015. The measured traits were germination percentage, root length, shoot length, plant weight, Malondialdehyde (MDA) concentration, catalase, and peroxidase.

The results obtained from the analysis of variance showed that the effects of genotype, salinity, and interactions were significant for different traits. According to the results, germination percentage, root length, shoot length, and plant weight decreased with increasing salinity levels. The germination percentage of the Sajama genotype showed a response at 10 and 12 decimes/m salinity, while the germination percentage of the Titicaca genotype decreased at the salinity level of 6 decimes/m. Increasing the level of salinity stress resulted in increasing the accumulation of malondialdehyde, peroxidase, and catalase activity in the examined genotypes. At salinity levels of 6 and 4 dS/m, the highest amount of catalase was obtained for Sajama genotype in comparison with other genotypes.

Sajama is introduced as a salinity tolerant genotype for further studies due to the superiority of indicators such as the activity of antioxidant enzymes. It can be said that the Sajama genotype under the effect of salt stress can reduce the harmful effects of salt stress by removing oxygen-free radicals and cleaning the cell environment from them.

Sweet corn, Zea mays Var. Saccharata is the youngest form of corn that arose after an accidental mutation in the common corn, and the Native Americans and Indian tribes began to cultivate it after becoming aware of the differences. The first registered variety of sweet corn was named Black Iroquois by European settlers in 1779. In the 19th century, white OP (open pollination) cultivars became popular in the United States. Two varieties of this type that are still cultivated and consumed are the Country Gentleman variety (with elongated and small seeds and irregular rows, also called Shoepeg corn) and the 'Stowell's Evergreen' variety. Scientific developments in the field of plant breeding, including the hybridization technology by inducing traits such as ripening at the same time and improving the quality of cobs and resistance to diseases, created tremendous changes in the production of sweet corn in the 20th century. This article with an overview of the successes achieved in creating new cultivars and improving the quality and marketability traits of sweet corn, its genetic differences from common corn, and the role of hybridization as one of the common tools of classical breeding to achieve superior genotype qualities are emphasized in sweet corn. Classification of sweet corn hybrid cultivars based on factors such as genes affecting carbohydrate metabolism and endosperm sugar percentage, planting time until harvest, seed color (yellow, white, pink, purple, and black), cob shape, and type of consumption (freshly eaten, Freezing, canning and exporting) forms another part of this article. Examining sweet corn breeding methods shows that despite the use of a number of specific techniques and theories, due to the different results of each method, the effect of external pollination, and the high perishability of the final product, Sweet corn breeding is very different in practice. The most important methods in sweet corn breeding have been reviewed in another part of this article. These methods include pedigree breeding, production of synthetic and composite masses, backcrossing and breeding with the help of molecular markers, as well as selection for some special traits such as edible quality, seed production, improved germination in Sh2 seeds, and resistance to pests and pathogens. In the final part, all kinds of sweet corn varieties, including commercial hybrids for fresh consumption and hybrids suitable for processing, have been introduced according to the genetic changes that have taken place in sweet corn cultivars since long ago.