Kalhaydari is a tall, drought-tolerant and rain-fed cultivar which has been a dominant rain-fed cultivar in Fars and Kohgelouyeh and Boyerahmad provinces for a long time (more than 70 years). However, this superior cultivar is susceptible to yellow rust, caused by Puccinia striiformis f. sp. tritici. Yellow rust causes a severe damage to this cultivar in high rainfall years. The aim of the present study was to transfer two seedling resistance genes (Yr5 and Yr15) and two adult plant resistance genes (Yr18 and Yr29) from standard lines to this cultivar using marker assisted backcrossing. In four separate breeding projects, Kalhaydari was crossed with four donor parents including Yr5/6*Avocet'S', Yr15/6*Avocet'S', Lalbahadur/Pavon and Opata 85 to transfer Yr5, Yr15, Yr18 and Yr29 genes, respectively. The first generation (F1) was backcrossed with Kalhaydari (BC1F1). In the offspring, selection for desirable genotypes was performed using markers assisted selection. Then, offspring carrying the favorable genes were entered the second backcross. The third backcross was performed using the same method. After a few more backcrosses and a selfing generation four yellow rust-resistant lines with the same genetic background, Kalhaydari cultivar, will be created. Durable resistance can be achieved using genes pyramiding.

Introduction: Considering the increasing population growth worldwide, including in Iran, increasing the yield and improving the traits and characteristics of landrace and improved rice varieties are among the most important rice research programs. Crossbreeding between local and improved cultivars is a primary strategy employed by breeders to achieve these goals. This study was conducted to evaluate the performance of different breeding lines that are the result of backcrossing in the previous years.Materials and methods: An experiment was conducted with 36 rice genotypes derived from direct and backcrossing of landrace and improved cultivars, along with four selected control cultivars (Anam, Hashemi, Demsiah, and Hasansarai). The experiment was designed as a randomized complete block with three replications at the Rice Research Institute of Iran in Rasht during the 2022 cropping year. Sixteen morphological, phenological, and yield-related traits were evaluated. Data were recorded, and analysis of variance, mean comparison, and cluster analysis were performed after ensuring the assumptions of variance analysis tests were met.Results: The analysis of variance revealed significant differences among the genotypes for all studied traits, except for the number of spikelets per panicle at the 1% probability level. These differences indicate substantial genetic diversity within the studied collection, necessitating selection within the collection. Based on the mean comparison results, Genotype BC3F4-38-13-1 (line 36) demonstrated a significant yield advantage, averaging 6689 kg/ha compared to the landrace control cultivars. In terms of desirable traits such as short plant stature and early ripening, Genotype BC3F4-15-11-4 (line 23) had the shortest plant height, averaging 84.46 cm. Genotypes BC2F4-37-2 (line 30) and BC2F4-37-3-1 (line 31) exhibited early ripening, with average maturation periods of 102 and 101 days, respectively, significantly earlier than the local control variety Demsiah, which had the longest maturation period of 130 days. According to the cluster analysis results of the third group(includes 19 lines), this group exhibited the highest averages for key traits such as the number of filled grains per panicle, panicle length, Number of total grains, panicle fertility percentage, and grain yield. Additionally, they had the lowest number of unfilled grains per panicle. The average yield of this group was calculated to be 13.81% higher than the overall average, with 20.04% fewer unfilled grains. Given the relative superiority of this group in terms of yield and yield components, the best genotypes from this group can be considered in variety introduction experiments as high-yielding new candidate varieties.Conclusion: Based on the results, several breeding lines had significantly higher grain yield than the control varieties. Additionally, these genotypes exhibited short plant stature and early ripening, which are promising traits. These genotypes can be further investigated in trials to introduce them as new candidate varieties.

Introduction: Fusarium wilt (FW) caused by F. oxysporum f. sp. ciceris causes extensive damage to chickpea in many parts of the Iran. The technique of Marker-assisted backcrossing (MABC) is one of the effective and accurate methods in transferring specific genes such as disease resistance genes in a short time in self-pollination plants. Hashem is one of Iranian chickpea cultivars with high yield, plant height and tall stems which its cultivation is limited due to susceptibility to the fusarium wilt. Therefore, Purpose of this study was to introgression resistance to fusarium wilt from Ana cultivar, as a donor, to Hashem as a recurrent and susceptible cultivar using molecular marker-assisted backcrossing. Methodology: This research was conducted during five cropping seasons (2018-2023). Crossing was done between the selected parents of chickpea cultivar Ana (as a donor parent) and Hashem (as a recurrent parent) and the F1 progeny was backcrossed with Hashem to produce the BC1F1 generation. By using three backcrosses and one rounds of selfing, BC3F2 progeny was obtained. Foreground selection (FGS) was conducted with four markers (TA59, TA96, TR19, and CaM1402) linked to FW resistance genes. Background selection (BGS) was employed with evenly distributed 16 (Ana × Hashem) SSR markers in the chickpea genome to select plant(s) with higher recurrent parent genome (RPG) recovery. Finally, the selected lines of BC3F2 generation were phenotypically evaluated in terms of Fusarium disease resistance. Research findings: In first year, from the crossing of two parents, 20 real F1 plants were obtained and backcrossed with Hashem to produce BC1F1 plants. Based on results of foreground selection (FGS), was undertaken using four markers (TA59, TA96, TR19, and CaM1402) linked to resistance genes, 6 BC1F1 plants contained 4 resistant alleles and participated in the second backcrossing to produce BC2F1 plants. In the following, from a total of 52 BC2F1 plants 12 BC2F1 plants contained 4 resistant alleles, for background selection (BGS) to observe the recovery of recurrent parent genome using 16 SSRs, At this stage based on the BGS results 5 plant, with the highest background recovery, selected and backcrossed with recurrent parent to produce BC3F1 plants. Followed by cycles of, 6 plants in BC3F1 containing resistant genes and most similar to the recurrent parent were selected. The identified plants were selfed to obtain 6 BC3F2 lines which were screened phenotypically for resistance to fusarium wilt. Finally, 12 BC3F2 lines were obtained which led to identification of 3 highly resistant lines of Hashem with FWR gene introgressed in them. Also, in this study using Meta-QTL analysis region associated with genetic resistance to different race of fusarium wilt were identified on chromosomes 2, 4, 5 and 6.

Stripe (yellow) rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most important diseases of wheat in many parts of the world. Genetic resistance is the best way to deal with this disease. This disease evolves very quickly, and for this reason, the resistance of many major-effect resistance genes has been overcome. In this study, the Yr5 and Yr15 genes, which are among the most effective resistance genes in a full-grown plant stage, were introduced to the Iranian cultivars, including Baharan, Rakhshan, Setareh, Sivand, Parsi, and Amin using the marker-assisted backcrossing method. These genes were intrroduced to the mentioned cultivars in six distinct breeding projects. Cultivars were crosses with the donor parents Yr5/6*Avocet‘S’and Yr15/6*Avocet‘S’. The progeny of F1 generation, were backcrossed with the Iranian cultivars (recurrent parent) to obtain BC1F1 progeny in each population. By genotyping 30 random plants in each project, the heterozygous genotypes carrying the resistance genes were identified using specific markers, and the second backcrossing was performed. Overall, the results of this studuy demonstrated that within each population, a stripe rust-resistant line can be developed through repeated generations of backcrossing followed by one generation of selfing. The introduction and pyramiding of yellow rust resistance genes into the Iranian cultivars not only enhance durable resistance and mitigate yield losses during epidemic years but also can contribute to benefits to the environment.

Vernalization genes (Vrn) control wheat growth habit (spring and winter habit). These genes play a key role in flowering time and earliness of bread wheat and are of great interest in wheat drought tolerance studies. In a research that was designed to develop isogenic lines for Vrn-B1 and Vrn-D1 genes, in the BC5F5 generation of Roshan (recipient parent) and Excalibur (donor parent), some isogenic lines were awned. Since the recurrent parent was awnless and the genetic background of the isogenic lines were similar with a probability of 99.99%, the possibility that the awn controlling gene is independent of the Vrn-B1 and Vrn-D1genes was rejected. Results showed that the awned and awnless isogenic lines carry Vrn-D1 and Vrn-D1a alleles, respectively. Therefore, the evidence can confirm the association of a gene controlling awn and Vrn-D1. The hypotheses of genetic linkage and pleiotropic effect were proposed to explain this association. To find the genetic reason for this relationship, in addition to Roshan and Excalibur, Rakhshan, Shahpasand, Mahdavi and Kalhaydari cultivars were also genetically evaluated. The results showed that Shahpasand, Mahdavi and Kalhaydari cultivars had Vrn-D1/Vrn-D1 genotype while Rakhshan had Vrn-D1a/Vrn-D1a genotype. Therefore, the hypothesis of pleiotropic effect was rejected and it was determined that the gene which is located at a close distance from Vrn-D1 is controlling the awns. The distance between these two genes is so tight that no crossing over has been occurred between them in 14 generations of sexual reproduction. Three known genes on chromosomes 4A, 5A and 6B are controlling awns. Yet, there is not known gene on chromosome 5D controlling awns. Therefore, the gene that is located at a short distance of Vrn-D1 and controls the awns has remained unknown till now. In this research, it was found that the awned phenotype is linked with the Vrn-D1a allele. Since awnless phenotype is not a desirable trait, the genetic linkage of these two genes reduces the agronomic value of cultivar.

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.

IntroductionGreen Revolution which occurred by introducing dwarfing genes into bread wheat varieties had a great impact on the global wheat production. Nevertheless, these genes decrease grain yield under rain-fed conditions. In general, semi-dwarf genes may not have any advantage in heat and drought stress conditions. In rain-fed conditions, the combination of Rht-D1b and Rht-B1b genes causes a decrease in the grain yield and coleoptile length. It should be noted that the genes Rht4, Rht5, Rht7, Rht8, Rht9, Rht12, Rht13 and Rht14, which are sensitive to gibberellic acid, do not affect coleoptile length.Materials and methodsIn the present research, wild type genes which cause higher plant height were transferred from Roshan to Excalibur variety using backcrossing. Similarly, in the F3 generation of a cross between Roshan and Mahdavi, a semi-dwarf plant was observed. This plant was backcrossed with Roshan to have semi-dwarf isogenic lines of this cultivar. Development of isogenic lines for plant height in two genetic backgrounds made it possible to study the effect of the plant height on yield and yield components. Isogenic lines and their parents were evaluated in two successive years (2020-2021 and 2021-2022) under Sepidan rain-fed conditions.Results and discussionOn average, plant height of Roshan and its semi-dwarf isogenic lines were 90.84 and 51.22 cm, respectively. Also, the average plant height of Excalibur and its tall isogenic line were 47.61 and 65.36 cm, respectively. Results showed that breeding for higher plant height had a positive and significant effect on wheat grain yield under rain-fed conditions. On average, tallness increased grain yield by 375.43 and 177.94 kg.ha in Roshan and Excalibur genetic backgrounds, respectively. In addition, the effect of plant height on yield components under rain-fed conditions was investigated. The findings of this research show that breeding for higher plant height indirectly increase grains number per spike and 1000 grain weight to improve grain yield. While, spikes number per meter square was not affected with plant height. Considering the high heritability of plant height and its significant correlation with grain yield, it is suggested that this trait be considered in breeding programs under rain-fed conditions.ConclusionIn the present research, it was found that tallness improve grains yield of bread wheat under rain-fed conditions via increasing grains number per spike. Two other yield components were also investigated and it was found that the plant height had no effect on spikes number per meter square. 1000-grains weight did not affected by plant height in the first year, although in the second year, the taller genotypes had higher 1000-grains weight. Considering that plant height has high heritability and response to selection, it is recommended to pay special attention to this trait in breeding programs for rain-fed conditions. It should be mentioned that as narrow sense heritability of plant height is very high, selection for this trait based on single plant is very effective. Consequently, selection for plant height in backcrossing and pedigree breeding methods could be extremely successful.

Objective Early heading as an adaptation mechanism for end season heat and drought stress is an important goal in wheat breeding programs. Photoperiod (Ppd) and vernalization (Vrn) are the most important genes controlling early heading in bread wheat. The aim of the present study was to investigate the effect of Ppd and Vrn genes on early heading, grain yield and important agronomic traits in BC4F2 generation of Roshan (recurrent parent) and Excalibur backcross. Materials and methods A BC4F2 population resulted from backcross of Roshan and Excalibur was generated in Shahid Bahonar University of Kerman. In this breeding program, early heading was transferred from Excalibur cultivar to Roshan (recurrent parent). This population, including 175 BC4F2 progenies, and their parents were cultivated in the research field of Shahid Bahonar University of Kerman in the 2019-2020 growing season. The progenies were genotyping using specific markers Vrn B1, Vrn-D1 and Ppd-D1. In this population, early heading, grain yield and important agronomic traits were evaluated. Results Excalibur and Roshan had Ppd-D1a, and Ppd-D1b alleles, respectively. The frequency of Ppd-D1a/Ppd-D1a and heterozygous genotypes in the evaluated population were 27. 33% and 415%, respectively. In this population, Ppd-D1a/Ppd-D1a, which is photoperiod insensitive genotype, was 6 and 4 days earlier heading than Ppd-D1b/Ppd-D1b and Ppd-D1a/Ppd-D1b genotypes, respectively. There was no allelic diversity between progeny for Vrn-1 locus. Early heading had a significant negative correlation with grain yield, 1000-grain weight, spikes number and grains number per spike. Conclusions The results confirm the importance of Ppd-D1a gene in the early heading, grain yield and yield components. Selection for early heading increased grain yield, 1000-grain weight, spikes number, biological yield, stover biomass at harvest and spikes dry weight. Due to the large and significant effect of Ppd-D1a gene on grain yield and yield components, we recommend marker assisted selection of this gene in wheat breeding programs. Phenotypic selection was performed before BC4F2 generation and Vrn gene diversity was established in the population.

In hybrid seed production program based on three-line system, the use of fertility restorer line with desirable specific combining ability carrying fertility restoration (Rf) genes is indispensible. In this research, fertility restoration locus Rf3 was transferred into CMS line ‘Neda-A’ using marker-assisted backcrossing (MAB) method and simultaneously its effect on pollen and panicle fertility of recipient line was evaluated in each generation. For transferring the locus, a single F2 plant (derived from ‘Neda-A’ x ‘IR36’ cross) was selected based on Rf3- linked three markers (RM1, RM3233 and RM3873) and backcrossed to ‘Neda-A’ (as the recurrent parent). The BC1 progenies were screened for Rf3-linked markers and also phenotyped and subsequently screened for 15 background SSR markers. Only two BC1 plants with donor dominant allele at all three loci showed high panicle fertility (65% and 50%). BC2 progenies were developed after backcrossing these two plants to recurrent parent. Among BC2 progenies, a single plant having a higher fertility was self-pollinated and 170 resultant BC2F2 plants were screened with 3 foreground Rf3-linked markers (RM1, RM3233 and RM3873) and also evaluated in terms of seed setting. Seven plants were identified with a higher rate of recurrent parent genome (91.1% to 98.5%) and in complete homozygote state at three Rf3- linked markers. These plants had a high pollen and panicle fertility (75% to 97%), indicating that with increasing homozygosity of Rf3 locus, fertility restoration to WA cytoplasmic male sterility in the genetic background of CMS recipient line was further enhanced. Therefore, it can be concluded that Rf3 locus has an interaction to WA cytoplasmic male sterility in favor of increasing the rice pollen and panicle fertility, and hence it can be utilized along with other restoring fertility genes in hybrid seed production program of rice.

Objective Flowering time in bread wheat is controlled by three groups of genes including photoperiod (Ppd), vernalization (Vrn) and earliness per se (Eps). The objective of the present study was to assess the effect of photoperiod and vernalization genes on phenology of bread wheat using near-isogenic lines (NILs) in three genetic backgrounds. Materials and methods Genomic DNA was extracted from parents, the earliest and the latest heading genotypes of each BC5F2 population obtained from backcrossing three Iranian cultivars including Roshan, Mahdavi and Kalheydari (recurrent parents) with Australian cultivar, Excalibur (donor parent). PCR was performed using specific primers for Ppd and Vrn genes. Results Excalibur and Mahdavi had Ppd-D1a allele whereas Kalheydari and Roshan were carrying Ppd-D1b allele. As it was expected, early and late heading progeny of Mahdavi were similar to parents. Late heading progeny of Roshan was homozygote and similar to recurrent parent whereas early heading progeny was heterozygote. Early and late heading progeny of Kalheydari were heterozygote. The reason for this could be the presence of modifier genes that are influenced by genetic background. Excalibur, Kalheydari and Mahdavi were possessed Vrn-B1a and vrn-D1 alleles, while Roshan carried vrn-B1 and Vrn-D1a alleles in Vrn-B1 and Vrn-D1 loci, respectively. Since Excalibur, Kolhaydari and Mahdavi did not show genetic diversity, as it was expected, early and late heading progeny were similar to their parents. In Roshan background, since vrn-B1 and Vrn-D1a improve earliness, early and late heading progeny were similar to recurrent parent. Conclusions The Ppd-D1a allele discriminated early and late heading progeny of Roshan genetic background. This result showed the importance and role of this gene on earliness. Early and late heading progeny of Roshan were similar to Vrn-B1 and Vrn-D1 loci. The reason is phenotypic selection for earliness in backcrossing program, where genes controlling late maturity have not selected during phenotypic selection.