Semi-dwarf Wheat Research Articles

Variation of Fusarium Head Blight Attack in Semidwarf Wheat Cultivars and Relationship with Stripe Rust Attack

Fusarium head blight (FHB) is a major threat to wheat production worldwide. We studied the Type 2 resistance of nineteen winter wheat cultivars under artificial inoculation by injecting spores of two Fusarium isolates into central florets of spikes. Weather conditions and Fusarium isolates used for artificial inoculations strongly influenced Fusarium attacks, but we also observed significant differences between cultivars. Six semidwarf wheat cultivars carrying Rht-B1b allele had significantly lower average Area Under Disease Progress Curve (AUDPC) than other cultivars, including two taller cultivars. Three of the six best resistant wheat cultivars carried the 1A-1R translocation, suggesting a beneficial effect of this rye chromatin presence on reducing the Fusarium head blight attack. Presence of stripe rust attacks significantly increased the area under disease development curve for Fusarium head blight, demonstrating the importance of debilitating effects of other biotic stresses.

Attenuation of brassinosteroid signaling enhances grain yield in semi-dwarf wheat varieties.

A recent study identified a natural deletion in the r-e-z haploblock which confers a semi-dwarf trait, higher nitrogen use efficiency, and improved yield in semi-dwarfwheat varietiesby attenuating the brassinosteroid signaling.

CRISPR/Cas9 boosts wheat yield by reducing brassinosteroid signaling

A modern green revolution is needed to ensure global food security. Recently, Song et al. reported a new strategy to create high-yielding, semi-dwarf wheat varieties with improved nitrogen-use efficiency by inhibiting brassinosteroid (BR) signaling through clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein9 (Cas9)-mediated knockout of the ZnF-B gene encoding a zinc-finger RING-type E3 ligase.

Redesigning green revolution trait with increased grain yield and nitrogen utilization efficiency by reducing brassinosteroid signaling in semidwarf wheat.

Redesigning green revolution trait with increased grain yield and nitrogen utilization efficiency by reducing brassinosteroid signaling in semidwarf wheat.

Reducing brassinosteroid signalling enhances grain yield in semi-dwarf wheat

Modern green revolution varieties of wheat (Triticum aestivum L.) confer semi-dwarf and lodging-resistant plant architecture owing to the Reduced height-B1b (Rht-B1b) and Rht-D1b alleles1. However, both Rht-B1b and Rht-D1b are gain-of-function mutant alleles encoding gibberellin signalling repressors that stably repress plant growth and negatively affect nitrogen-use efficiency and grain filling2–5. Therefore, the green revolution varieties of wheat harbouring Rht-B1b or Rht-D1b usually produce smaller grain and require higher nitrogen fertilizer inputs to maintain their grain yields. Here we describe a strategy to design semi-dwarf wheat varieties without the need for Rht-B1b or Rht-D1b alleles. We discovered that absence of Rht-B1 and ZnF-B (encoding a RING-type E3 ligase) through a natural deletion of a haploblock of about 500 kilobases shaped semi-dwarf plants with more compact plant architecture and substantially improved grain yield (up to 15.2%) in field trials. Further genetic analysis confirmed that the deletion of ZnF-B induced the semi-dwarf trait in the absence of the Rht-B1b and Rht-D1b alleles through attenuating brassinosteroid (BR) perception. ZnF acts as a BR signalling activator to facilitate proteasomal destruction of the BR signalling repressor BRI1 kinase inhibitor 1 (TaBKI1), and loss of ZnF stabilizes TaBKI1 to block BR signalling transduction. Our findings not only identified a pivotal BR signalling modulator but also provided a creative strategy to design high-yield semi-dwarf wheat varieties by manipulating the BR signal pathway to sustain wheat production.

Nazareno Strampelli and the first Green Revolution

AbstractThis article describes the wheat‐breeding work of the Italian agronomist Nazareno Strampelli, who was the first agronomist to cross Japanese and western wheat varieties to develop high‐yielding semidwarf wheat. The article describes the environmental and agricultural conditions that motivated Strampelli's breeding, the evolution of his varieties, their role in addressing agricultural and food supply problems in Fascist Italy, some of Strampelli's attitudes about agricultural improvement and the Fascist regime and the influence and heritage of his varieties for later agricultural improvements.

ИСХОДНЫЙ МАТЕРИАЛ ДЛЯ СЕЛЕКЦИИ ОЗИМОЙ МЯГКОЙ ПШЕНИЦЫ НА УРОЖАЙНОСТЬ И НИЗКОСТЕБЕЛЬНОСТЬ В УСЛОВИЯХ ЛЕСОСТЕПИ СРЕДНЕГО ПОВОЛЖЬЯ

The research was carried out in order to isolate the initial material of winter soft wheat for crop breeding for high productivity, low stems and their combination in the conditions of the forest-steppe of the Middle Volga region. The work was carried out in 2011-2013 in Ulyanovsk region. The soil of the experimental field is leached chernozem, the predecessor is pure fallow. The material for the study was 102 varieties of winter wheat of various geographical origins. The weather conditions during the experiment were contrasting. Stress factors of the environment, typical for the forest-steppe of the Middle Volga region, did not allow to realize the production potential of most of the winter wheat varieties of the world collection. Varieties from Germany, Hungary, Bulgaria, Serbia, Moldova, China, USA, Japan, Estonia, Latvia formed a yield below the Volzhskaya K standard (in 2011 - 630 g/m2, in 2012 - 367 g/m2, in 2013 - 162 g/m2) by 10 ... 93%. Due to the often developing dry conditions, significant positive correlation-regression dependences of the yield of winter soft wheat on plant height (R2>0.08) were established. High-yielding sources of Poema, Biyskaya ozimaya cultivars, which annually exceeded the standard by 16...205%, were identified and recommended as the starting material for crop breeding. Dwarf and semi-dwarf wheats Donskaya lira, Zamozhnist, Yasnogorka, which have generated yields at or above the Volzhskaya K standard (499 g/m2 on average for 2011–2012 and 264 g/m2 on average for 2012–2013), are breeding value as sources of a combination of low stalks and productivity.

Genetic Effects of GA-Responsive Dwarfing Gene Rht13 on Plant Height, Peduncle Length, Internodal Length and Grain Yield of Wheat under Drought Stress.

Reduction in plant height is generally associated with an increase in lodging resistance, drought tolerance and grain yield of wheat worldwide. Historically, a significant increase in grain yield was observed through the introduction of semi-dwarf wheat varieties utilizing the gibberellic acid-insensitive Rht genes (Rht1 or Rht2). The gibberellic acid sensitive (GA-sensitive) reduced height (Rht) genes are available that are alternatives to gibberellic acid insensitive (GA-insensitive) Rht genes, having a neutral effect on coleoptile length seedling vigor suggesting their potential in using alone or in combination with GA-insensitive Rht genes to improve grain yield and drought tolerance in wheat. This study was conducted to evaluate parents and F1 crosses under drought stress. The crossing was done using line × tester mating design, comprising eight lines and five testers having different GA-sensitive and GA-insensitive Rht genes. Parents and F1 crosses were sown in the field under RCBD with three replications in normal and drought stress. Data were recorded for morpho-physiological traits. The mean comparison showed significant differences among parents and hybrids for most of the studies' traits. The general combining ability showed that line 1 is the good general combiner for days to heading, lodging (%), plant height, peduncle length, internodal length and days to maturity under normal conditions while L5 was the good general cobiner for chlorophyll contents and stomatal conductance both under normal and drought stress. The spcaicfic combing ability estimases showed that the cross L1 × T1 was best for days to heading, lodging (%), plant height and internodal length both under normal and drought stress. F1 hybrids showed a significant reduction in plant height (18-25%), peduncle length (20-28%) and increased grain yield (15-18%) under drought stress. Expression analysis showed upregulation of Rht13 at the middle part of the peduncle internode under drought stress. From the expression analysis, five crosses were selected, and their segregating population was raised and space-plated. Rht13 genes reduced plant height (-30 to -45%), peduncle length (-30 to -53%), peduncle internode length (-28% to -48%), increased spike length (+20% to +50%), number of grains per spike (+17 to +26%) and grain yield per plant (+29% to +50%) compared to Rht1 gene. These results suggested the possibility of using the GA-sensitive Rht13 gene for the development of high-yielding and drought-tolerant wheat varieties.

Agronomic Trait Analysis and Genetic Mapping of a New Wheat Semidwarf Gene Rht-SN33d.

Plant height is a key agronomic trait that is closely to the plant morphology and lodging resistance in wheat. However, at present, the few dwarf genes widely used in wheat breeding have narrowed wheat genetic diversity. In this study, we selected a semi-dwarf wheat mutant dwarf33 that exhibits decreased plant height with little serious negative impact on other agronomic traits. Genetic analysis and mutant gene mapping indicated that dwarf33 contains a new recessive semi-dwarf gene Rht-SN33d, which was mapped into ~1.3 Mb interval on the 3DL chromosome. The gibberellin metabolism-related gene TraesCS3D02G542800, which encodes gibberellin 2-beta-dioxygenase, is considered a potential candidate gene of Rht-SN33d. Rht-SN33d reduced plant height by approximately 22.4% in mutant dwarf33. Further study revealed that shorter stem cell length may be the main factor causing plant height decrease. In addition, the coleoptile length of dwarf33 was just 9.3% shorter than that of wild-type Shaannong33. These results will help to expand our understanding of new mechanisms of wheat height regulation, and obtain new germplasm for wheat improvement.

A Global Green Revolution: Semidwarf Genes from Asia, Agrónomos, and the Environmental Laboratory of Mexico, 1953-1970

In 1943, the Rockefeller Foundation (RF) and Mexican government collaborated in the creation of the Mexican Agricultural Program (MAP) to boost the production of hybrid corn and wheat in Mexico. The MAP utilized a top down strategy in which it sought to provide largescale, affluent farmers with new seed technology to boost staple crop production intended for urban consumers that underpinned industrialization, principally in the middle- and upper-classes. The MAP’s wheat program served as the model for the Green Revolution in the Global South beginning in the 1960s, and policymakers and philanthropists continue to evoke it today as a successful effort to combat rural poverty despite mixed results. During the Green Revolution, farmers produced millions more tons of food using semidwarf wheat seed technology which possessed short, stiff straw that allowed farmers to transcend the biological constraints of conventional wheat. In particular, this wheat prevented a problem called lodging which meant farmers could now apply massive amounts of inorganic fertilizers, the byproduct of natural gas and oil production, to wheat fields. While the historiography of the Green Revolution credits the U.S. and RF with this innovation, the semidwarf characteristic derived from a Korean wheat seed technology that underwent protracted testing in Japan in the early twentieth century. Moreover, agrónomos, Mexican agricultural scientists, also played a prominent role in the MAP’s wheat breeding program which gave rise to the Green Revolution. In particular, the treatment of Mexico as an environmental laboratory gave rise to an innovative practice called shuttle breeding which revealed unique characteristics in wheat and allowed MAP scientists to produce universal wheat. Mexico’s environmental diversity meant a wheat that could grow widely in Mexico was easily adaptable around the world, especially the Global South.

Comparative study of photosynthetic capacity in lower leaves in the canopy of dwarf and semidwarf wheat

Semidwarf wheat contributes to significant yield increase worldwide, however, few dwarf cultivars of wheat are cultivated due to grain yield penalty. In this study, a new dwarf wheat Triticum aestivum L., cv. Xiaoyan 101, was investigated to explore its photosynthetic performance and yield potential. In the comparison of the semidwarf wheat cultivars, Jing 411 and Xiaoyan 101, although the first three leaves (including flag leaves) did not differ significantly in both genotypes, Xiaoyan 101 conferred a higher content of photosynthetic pigments and higher photochemical efficiency but had lower contents of hydrogen peroxide and malondialdehyde in lower leaves in the canopy. In addition, the antioxidant enzymes-encoding genes were upregulated while the senescence-associated genes (TaSAG3, TaSAG5, TaSAG7, and TaSAG12) were downregulated in lower leaves in the canopy of Xiaoyan 101. Ultimately, Xiaoyan 101 produced approximate or even higher grain yield than the local semidwarf wheat varieties. Therefore, it is possible to breed dwarf wheat with enhanced photosynthetic activity but without yield sacrifice.

Population structure and genetic diversity of U.S. wheat varieties.

The United States is a major wheat producer with more than a century of wheat (Triticum aestivum L.) research and breeding. Using a panel of 753 historical and modern wheat varieties grown in the United States from the early 1800s to present day, we examined population structure and changes in genetic diversity. We used previously mapped high-quality single-nucleotide polymorphism (SNP) markers from the wheat 90K SNP array for genotyping. The wheat varieties had a slight hierarchical population structure based on growth habit and then by kernel color within spring varieties and by kernel hardness within winter varieties, which corresponds with geographical distribution of the varieties. Classifying varieties by market class, which is a combination of habit, hardness, and color, accounted for the greatest amount of variation (13.3%). We did not find evidence of decreased genetic diversity of either spring or winter varieties after the release of the first semidwarf wheat variety in 1961. On the contrary, northern and Pacific spring varieties, hard red spring (HRS), hard white spring (HWS), and soft white winter (SWW) had increases in both SNP and haplotype genetic diversity after 1961. The soft white spring (SWS) and soft red winter (SRW) market classes already had high genetic diversity in varieties before 1961 and showed some evidence of decreased diversity after 1961. Examination of temporal trends in genetic diversity also did not indicate long-term decline in diversity despite occasional fluctuations.

Mutation Breeding and Its Importance in Modern Plant Breeding

Mutations occur as a result of alterations in DNA or during the replication/cell division process. For agricultural development, plant breeding necessitates genetic variety of valuable features. Multiple mutant alleles, on the other hand, constitute a source of genetic variety for crop breeding and, in many cases, functional investigation of the targeted gene. Plant breeding can only improve when the breeder has access to enough variation for a particular trait. Any change in an organism's DNA that is not caused by normal recombination and segregation is referred to as a mutation. Exposure to mutagenic agents such as radiation or certain chemicals, as well as faults made during normal cell division and replication, are all possible causes. The first breeding successes were achieved by utilizing spontaneous (naturally occurring) mutations. The most well-known example is the use of semi-dwarf wheat and rice mutants during the 'Green Revolution.' Induced mutagenesis is becoming increasingly popular in plant molecular biology as a method for identifying and isolating genes, as well as studying their structure and function. Molecular mutation breeding is ushering in a new era of crop enhancement mutation breeding. In the coming years and decades, mutation breeding will play a vital role in crop improvement and resolving concerns related to global food security. As a result, the goal of this review paper is to evaluate the function of mutant breeding in crop development and how it might be used.

Some aspects of winter wheat productivity

The article presents studies carried out in 2018–2019 and 2019–2020 in the southern foothill zone of the North-West Caucasus in the fields of the selection and primary seed produc- tion department of the Adygh Research Institute of Agriculture. The aim was to study the actual, biological or potential yield of winter soft wheat varieties cultivated in the region, as well as the ratio of the mass of the grain part and the harvested straw - the yield index. The studied varieties were divided into groups according to plant height: semi-dwarfs (up to 90 cm), short-stemmed (up to 105 cm), medium-sized (up to 120 cm). According to the results of the studies carried out, differences in the studied characteristics were revealed. In the group of semi-dwarf varieties, the grain yield varied from 7,25 to 8,05 t/ha, short-stemmed 7,78–8,91 t/ha, medium-sized 7,34–9,60 t/ha. The highest grain yield was shown by the Vekha variety (9,60 t/ha) belonging to the group of medium-sized varieties, from the short-stemmed Maikopchanka varieties (8,91 t/ha) stood out, Kalym semi-dwarf varieties (8,05 t/ha). The biological yield in the experiment varied from 9,37 to 15,29 t/ha. From semi-dwarf varieties, Grom stood out (14,06 t/ha), short-stemmed varieties – Mafe (10,8 t/ha), medium-sized varieties – Vekha (15,29 t/ha). The difference between the actual and biological grain yield of varieties belonging to the short-stem group was the smallest in comparison with the varieties of the semi-dwarf and medium-grown group. On average, over two years of research, the harvesting index was 46,9–53,2%. Semi-dwarf winter wheat varieties had the maximum value of this indicator. In the group of short-stemmed Grom and Graf varieties, the ratio of the mass of the grain part to the harvested straw varied from 46,8% (Velena) to 50,5% (Alekseich). The harvesting index for medium-sized varieties was at the level of 46,9–51,8%. The Vekha variety, which showed the maximum value, stood out from this group.

Semidwarf winter wheat roots contain fewer organic acids than wild‐type varieties under phosphorus stress

AbstractOrganic acids are exuded by plant roots into the rhizosphere for a variety of reasons, including nutrient acquisition. The most frequently reported organic acids are those involved in the Krebs cycle and other important biochemical pathways that are responsible for the production of important plant metabolites, including oxalic, malic, and citric acid. Many studies report increased citric and malic acid exudation when plants are P‐deficient. Because plant breeding is typically carried out under heavily fertilized conditions, it is possible that wheat (Triticum aestivum L.) breeders have unintentionally selected for varieties with decreased nutrient acquisition capability from soil organic matter and soil colloids. In this study, we evaluated a diverse panel of 10 winter wheat cultivars, which included wild‐type (tall) and semidwarf varieties, for organic acid content. Plants were grown in solution culture with and without P for 24 d. Thirty 1‐cm root tips were bulked per sample and the extracts were analyzed by high‐performance liquid chromatography for citric, malic, and oxalic acid content. Under P deficiency, total organic acid content differed between wild‐type and semidwarf varieties, with wild‐type cultivars containing more organic acids in the root tips. This difference in total production was driven by oxalic acid, whereas citric and malic acid concentrations were conserved. Unlike citric and malic acid, oxalic acid is not necessary for major metabolic processes and therefore may be expendable. Breeding for semidwarf wheat corresponds with unintentional changes to root system function that could impact nutrient acquisition and other rhizosphere processes.

Coleoptile length comparison of three winter small grain cereals adapted to the Great Plains

Successful crop stand establishment is critical to realize high yield potential, which is dependent on depth of seed placement to access soil moisture. The coleoptile determines sowing depth by its length and ability to emerge from depth. This study was conducted to assess coleoptile length among three sets of three Great Plains winter small grain cereals—wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and triticale (X triticosecale Wittm.)—and to evaluate the effect of the Rht-B1b dwarfing allele on coleoptile length in wheat and triticale. Fifty seeds of each genotype were sown in wet germination paper in two replications utilizing a randomized complete block design, which were placed in dark growth chambers at 25°C. Measurements were conducted after 7 d, and analysis of variance and comparison of least square means for coleoptile length among and within each set of genotypes were performed in Statistix 8.1 software using Fisher’s protected least significance difference at the α = 0.05 significance level. Results revealed that triticale had the longest coleoptiles, which were significantly longer (P < 0.05) than those measured in both barley and wheat. Additionally, significant variation in coleoptile length (P < 0.05) was also found within each set of wheat (3.52–6.41 cm), barley (4.32–6.63 cm) and triticale (4.05–6.92 cm) genotypes, respectively. These findings confirm other reports that the presence of the Rht-B1b allele was pleiotropic for coleoptile length, but development of semi-dwarf wheats with longer coleoptiles is possible if breeders deploy concurrent selection strategies.

Characterizing reduced height wheat mutants for traits affecting abiotic stress and photosynthesis during seedling growth.

Most high-yielding, semidwarf wheat (Triticum aestivum L.) grown around the world contains either Rht1 or Rht2 genes. The success of these high-yielding cultivars is greatest in the most productive farming environments but provide marginal benefits in less favorable growing conditions such as shallow soils and low-precipitation dryland farming. Further, growing evidence suggests semidwarf genes not only affect early seedling growth but limit grain yield, especially under abiotic stress conditions. There are 23 other reduced-height mutants reported in wheat, most of which have not been functionally characterized. We evaluated these mutants along with their parents for several traits affecting seedling emergence, early seedling growth, and photosynthetic efficiency. Two- to seven-fold differences in coleoptile length, first leaf length, root length, and root angle were observed among the genotypes. Most of the mutations had a positive effect on root length, while the root angle narrowed. Coleoptile and first leaf lengths were strongly correlated with emergence. A specialized deep planting experiment identified Rht5, Rht6, Rht8, and Rht13 with significantly improved seedling emergence compared to the parent. Among the mutants, Rht4, Rht19, and Rht12 ranked highest for photosynthetic traits while Rht9, Rht16, and Rht15 performed best for early seedling growth parameters. Considering all traits collectively, Rht15 showed the most promise for utilization in marginal environments followed by Rht19 and Rht16. These wheat mutants may be useful for deciphering the underlying molecular mechanisms of understudied traits and breeding programs in arid and semiarid regions where deep planting is practiced.

Cultivar and Crop Management Effects on Test Weight in Winter Wheat (Triticum aestivum)

Test weight or volumetric (hectolitre) weight is an important trait of wheat grain, being an important predictor of flour extraction rate and a determinant factor of the efficiency of wheat transport and storage. It is included in most standards for cereal grading and as such can influence the price received by farmers. Test weight was measured in yield trials with winter wheat cultivars grown with several crop management practices at the National Agricultural Research and Development Institute Fundulea - Romania (44º27’45’’ N latitude and 26º31’35” E longitude, 68 m above sea level) in three seasons. Years were the main factor of test weight variation and this was associated with differences between years in maximum temperatures during the second half of grain filling period. Cultivars also had a very significant effect, while the influence of mangements and of interaction between cultivars and managements with years was not significant. On average most cultivars fulfilled the requirements for Grade 1 and 2, but the percentage of cases below the 75 kg hl-1 limit varied from 0 to 66.7%. Only two of the Romanian cultivars had half or more cases in Grade 3, while most Western European cultivars had more than 50% samples below 75% kg hl-1 . Variances of the test weight values suggest that cultivars are different in stability of test weight, with most of the Romanian cultivars being less affected by the weather conditions than most Western European varieties. Two of the shortest Romanian cultivars (Voinic and Izvor) had highest average test weight and lowest frequency of lower grades, which is a progress but at the same time suggesting large possibilities of improving this trait in semidwarf wheat.

Grain Size and Plant Height Correlation in Doubled-Haploid (DH) Progenies of a Cross Between Contrasting Winter Wheat (Triticum aestivum L.) Parents

Grain size is an important yield component in wheat. Knowing its relationship with plant height can facilitate breeding for increased thousand kernels weight in optimum plant height cultivars. A set of 85 doubled-haploid obtained from the F1`s of G.603-86 (large grains and tall plants) and F.132 (normal size grains and semidwarf with plants) was tested along with the parents during three seasons. DH lines showed near normal distributions for plant height and thousand kernels weight, suggesting that many genes were involved in the control of both traits. Strong correlations were found between plant height and thousand kernels weight on average for the three years of testing, but also for each year. This suggests that transferring the favorable alleles from the high thousand kernels weight parent to semidwarf wheat is not an easy breeding task.

RELACIÓN ENTRE EL GEN Lr67 DE RESISTENCIA A ROYA DE LA HOJA Y EL GEN Rht-D1 DE ENANISMO DEL TRIGO

El gen Lr67, localizado en el cromosoma 4D, confiere resistencia a la roya de la hoja causada por Puccinia triticina E. Este gen fue común en las variedades de trigo (Triticum spp.) de porte alto liberadas en México hasta antes de 1960, no así en las variedades semienanas liberadas desde esa fecha hasta el presente. Las variedades semienanas de trigo liberadas en México poseen ya sea el gen de enanismo Rht-B1 localizado en el cromosoma 4B o el gen Rht-D1 localizado en el cromosoma 4D. Con el fin de investigar si existe algún impedimento genético para conjuntar los genes Lr67 y Rht-D1 en la misma variedad de trigo, se caracterizó genotípicamente la F3 de la cruza entre la variedad Nasma que posee el gen Rht-D1 con la variedad Marroqui 588 poseedora del gen Lr67. Mediante pruebas de ji-cuadrada y marcadores moleculares de diagnóstico, se encontró que la distancia genética entre ambos genes es de 23.6 cM con análisis de ligamiento y de 27.6 cM con análisis molecular. Estas distancias son suficientemente grandes para que exista recombinación genética, por lo que no hay ningún impedimento genético para obtener genotipos recombinantes que combinen el gen de resistencia a roya de la hoja (Lr67) con el gen de porte bajo de planta (Rht-D1), mismos que en los progenitores se encuentran en fase de repulsión.