Quantitative Trait Loci for Resistance to Potato Dry Rot Caused by Fusarium sambucinum

Tuber dry rot is an important disease of potato caused by soil and seed-borne pathogens of the Fusarium genus leading to losses that may reach 60% of the yield. The goal of this work was to study the inheritance of the dry rot resistance in two diploid potato hybrid populations (11-36 and 12-3) with complex pedigrees, including several wild Solanum spp. We used an aggressive isolate of F. sambucinum for phenotyping both progenies, parents, and standard potato cultivars in laboratory tuber tests, in three subsequent years. The QTL for dry rot resistance were mapped by interval mapping on existing genetic maps of both mapping populations. The most important and reproducible QTL for this trait was mapped on chromosome I and additional year- and population-specific QTL were mapped on chromosomes II, VII, IX, XI, and XII, confirming polygenic control of this resistance. This is the first study mapping the loci affecting tuber dry rot resistance in potato genome that can contribute to better understanding of potato-F. sambucinum interaction and to more efficient breeding of resistant potato cultivars.

Pea Grain Protein Content Across Italian Environments: Genetic Relationship With Grain Yield, and Opportunities for Genome-Enabled Selection for Protein Yield

Wider pea (Pisum sativum L.) cultivation has great interest for European agriculture, owing to its favorable environmental impact and provision of high-protein feedstuff. This work aimed to investigate the extent of genotype × environment interaction (GEI), genetically based trade-offs and polygenic control for crude protein content and grain yield of pea targeted to Italian environments, and to assess the efficiency of genomic selection (GS) as an alternative to phenotypic selection (PS) to increase protein yield per unit area. Some 306 genotypes belonging to three connected recombinant inbred line (RIL) populations derived from paired crosses between elite cultivars were genotyped through genotyping-by-sequencing and phenotyped for grain yield and protein content on a dry matter basis in three autumn-sown environments of northern or central Italy. Line variation for mean protein content ranged from 21.7 to 26.6%. Purely genetic effects, compared with GEI effects, were over two-fold larger for protein content, and over 2-fold smaller for grain and protein yield per unit area. Grain yield and protein content exhibited no inverse genetic correlation. A genome-wide association study revealed a definite polygenic control not only for grain yield but also for protein content, with small amounts of trait variation accounted for by individual loci. On average, the GS predictive ability for individual RIL populations based on the rrBLUP model (which was selected out of four tested models) using by turns two environments for selection and one for validation was moderately high for protein content (0.53) and moderate for grain yield (0.40) and protein yield (0.41). These values were about halved for inter-environment, inter-population predictions using one RIL population for model construction to predict data of the other populations. The comparison between GS and PS for protein yield based on predicted gains per unit time and similar evaluation costs indicated an advantage of GS for model construction including the target RIL population and, in case of multi-year PS, even for model training based on data of a non-target population. In conclusion, protein content is less challenging than grain yield for phenotypic or genome-enabled improvement, and GS is promising for the simultaneous improvement of both traits.

Diversity of lateral line patterns and neuromast numbers in the genus Oryzias

ABSTRACT A remarkable diversity of lateral line patterns exists in adult teleost fishes, the basis of which is largely unknown. By analysing the lateral line patterns and organ numbers in 29 Oryzias species and strains we report a rapid diversification of the lateral line system within this genus. We show a strong dependence of lateral line elaboration (number of neuromasts per cluster, number of parallel lateral lines) on adult species body size irrespective of phylogenetic relationships. In addition, we report that the degree of elaboration of the anterior lateral line, posterior lateral line and caudal neuromast clusters is tightly linked within species, arguing for a globally coordinated mechanism controlling lateral line organ numbers and patterns. We provide evidence for a polygenic control over neuromast numbers and positioning in the genus Oryzias. Our data also indicate that the diversity in lateral lines can arise as a result of differences in patterning both during embryonic development and post-embryonically, where simpler embryonic patterns generate less complex adult patterns and organ numbers, arguing for a linkage between the two processes.

Genetic Architecture and QTL Selection Response For Kernza Perennial Grain Domestication Traits

Perennial grains have the potential to provide food for humans as well as decrease the negative impacts of annual agriculture. Intermediate wheatgrass (IWG, Thinopyrum intermedium, Kernza®) is a promising perennial grain candidate that The Land Institute has been breeding since 2001. We evaluated four consecutive breeding cycles of IWG from 2016-2020 with each cycle containing approximately 1100 unique genets. Using genotyping-by-sequencing markers, quantitative trait loci (QTL) were mapped for 34 different traits using genome-wide association analysis Combining data across cycles and years, we found 93 marker-trait associations (MTA) for 16 different traits, with each association explaining 0.8-5.2% of the observed phenotypic variance. Across the four cycles, only three QTL showed an FST differentiation > 0.15 with two corresponding to a decrease in floret shattering. Additionally, one marker associated with brittle rachis was 216 bp from an ortholog of the btr2 gene. Power analysis and quantitative genetic theory was used to estimate the effective number of QTL, which ranged from a minimum of 33 up to 558 QTL for individual traits. This study suggests that key agronomic and domestication traits are under polygenic control, and that molecular methods like genomic selection are needed to accelerate domestication and improvement of this new crop.

QTL analysis of seed germination traits in tobacco (Nicotiana tabacum L.)

Genetic mapping of seed germination traits has been performed with many plant species. In tobacco, however, investigations are rare. In the present study, a bi-parental mapping population consisting of 118 doubled haploid lines and derived from a cross between ‘Beinhart-1000’ and ‘Hicks’ was investigated. Four germination-related traits, total germination (TG), normal germination (NG), time to reach 50% of total germination (T50), and the area under the curve after 200 h of germination (AUC) were considered by examining seeds either untreated or after a moderate controlled deterioration (CD). Quantitative trait loci were found for all traits distributed on 11 out of the 24 linkage groups. It was demonstrated that, as in many other species, germination-related traits are very complex and under polygenic control.

Genetic markers for the resistance of honey bee to Varroa destructor

In the mid-20th century, the first case of infection of European bees Apis mellifera L. with the ectoparasite mite Varroa destructor was recorded. The original host of this mite is the Asian bee Apis cerana. The mite V. destructor was widespread throughout Europe, North and South America, and Australia remained the only continent free from this parasite. Without acaricide treatment any honeybee colony dies within 1–4 years. The use of synthetic acaricides has not justified itself – they make beekeeping products unsuitable and mites develop resistance to them, which forces the use of even greater concentrations that can be toxic to the bees. Therefore, the only safe measure to combat the mite is the use of biological control methods. One of these methods is the selection of bee colonies with natural mite resistance. In this article we summarize publications devoted to the search for genetic markers associated with resistance to V. destructor. The first part discusses the basic mechanisms of bee resistance (Varroa sensitive hygienic behavior and grooming) and methods for their assessment. The second part focuses on research aimed at searching for loci and candidate genes associated with resistance to varroosis by mapping quantitative traits loci and genome-wide association studies. The third part summarizes studies of the transcriptome profile of Varroa resistant bees. The last part discusses the most likely candidate genes – potential markers for breeding Varroa resistant bees. Resistance to the mite is manifested in a variety of phenotypes and is under polygenic control. The establishing of gene pathways involved in resistance to Varroa will help create a methodological basis for the selection of Varroa resistant honeybee colonies.

Наследование формы клубней в гибридных популяциях картофеля различного генетического происхождения

Цель работы: изучение характера наследования формы клубней в гибридных популяциях картофеля от скрещивания специально подобранных родительских форм, охватывающих широкий ряд изменчивости этого морфологического признака. Материал исследований: селекционные сорта, различающиеся формой клубня от округлой до удлиненной и гибридные популяции от скрещивания по диаллельной схеме. Исследования проводили в 2017-2018 годах на экспериментальных базах ВНИИКХ Коренево и Пышлицы Московской области. В результате изучения характера наследования формы клубней 35 гибридных популяций, полученных от диаллельных скрещиваний родительских компонентов, характеризующихся значительным различием данного признака, установлена широкая вариабельность формы клубней как у селекционных сортов (7,8-16,8), так и гибридного потомства (10,5-22,2) картофеля. В гибридном потомстве изученных родительских форм отмечено расщепление по признаку формы клубней с преобладанием удлиненных клубней и увеличение вариабельности признака по отдельным популяциям. Корреляционная связь индексов формы клубней исходных родительских форм и их потомства варьировала от слабоположительной до слабоотрицательной, что указывает на полигенное контролирование этого признака. Установлена отрицательная корреляция между формой клубней двух материнских форм с удлиненными клубнями и формой клубней их гибридного потомства, уровень которой составляет -0,17 и -0,60 соответственно. В гибридных популяциях с участием материнских форм с удлиненными клубнями под влиянием опылителей с округло-овальными клубнями формировались генотипы с овальными клубнями. Лучшим опылителем, хорошо передающим форму клубней потомству, оказался сорт ВР 808, средний коэффициент наследуемости признака у которого составил 0,36. Остальные отцовские формы по мере снижения коэффициента наследуемости ранжированы в следующем порядке: Голубка (0,33), Инноватор (0,24), Вымпел (0,12), Крепыш (0,01). Среди материнских форм выделились только сорта Ноктюрн (0,29) и Винета (0,29). Использование в скрещиваниях сортов-опылителей, отличающихся повышенным коэффициентом наследуемости формы клубней, позволяет с большей долей вероятности передавать этот признак гибридному потомству.The aim of the work is to study the nature of inheritance of tubers in hybrid potato populations from crossing specially selected parent forms, covering a wide range of variability of this morphological feature. Research material: breeding varieties that differ in tuber shape from rounded to elongated and hybrid populations from crossing according to the diallel scheme. The research was conducted in 2017-2018 at the experimental bases of VNIIKH Korenevo and Pyshlitsy in the Moscow region. As a result of studying the nature of the inheritance of tubers in 35 hybrid populations obtained from diallel crosses of parent components characterized by a significant difference in this characteristic, a wide variability in the shape of tubers was established in both breeding varieties (7.8-16.8) and hybrid offspring (10.5-22.2) of potatoes. In the hybrid offspring of the studied parent forms, there was a cleavage based on the shape of tubers with a predominance of elongated tubers and an increase in the variability of the trait for individual populations. The correlation between the tuber shape indices of the original parent forms and their offspring varied from weakly positive to weakly negative, indicating polygenic control of this trait. A negative correlation was established between the tuber shape of two maternal forms with elongated tubers and the tuber shape of their hybrid offspring, the level of which is -0.17 and -0.60, respectively. In hybrid populations with the participation of mother forms with elongated tubers, genotypes with oval tubers are formed under the influence of round-oval pollinators. The best pollinator, well transmitting the shape of tubers to offspring, was the variety BP 808, which had an average heritability coefficient of 0.36. The rest of the paternal forms are ranked in the following order according to the number of decrease in the heritability coefficient: Golubka (0.33), Innovator (0.24), Vimpel (0.12), Krepish (0.01). Only Nocturne (0.29) and Vineta (0.29) varieties were distinguished among the mother forms. The use of pollinator varieties in crosses that differ in an increased heritability coefficient of the tuber shape makes it possible to pass this trait to hybrid offspring with a greater probability.

Delayed Puberty—Phenotypic Diversity, Molecular Genetic Mechanisms, and Recent Discoveries

This review presents a comprehensive discussion of the clinical condition of delayed puberty, a common presentation to the pediatric endocrinologist, which may present both diagnostic and prognostic challenges. Our understanding of the genetic control of pubertal timing has advanced thanks to active investigation in this field over the last two decades, but it remains in large part a fascinating and mysterious conundrum. The phenotype of delayed puberty is associated with adult health risks and common etiologies, and there is evidence for polygenic control of pubertal timing in the general population, sex-specificity, and epigenetic modulation. Moreover, much has been learned from comprehension of monogenic and digenic etiologies of pubertal delay and associated disorders and, in recent years, knowledge of oligogenic inheritance in conditions of GnRH deficiency. Recently there have been several novel discoveries in the field of self-limited delayed puberty, encompassing exciting developments linking this condition to both GnRH neuronal biology and metabolism and body mass. These data together highlight the fascinating heterogeneity of disorders underlying this phenotype and point to areas of future research where impactful developments can be made.

Study of Variability and Genetic Diversity of 50% Heading Date and Seed Yield in Blackgram (Vigna mungo L.)

The present investigation involves study of variability and genetic diversity of few developmental characters such as date of maximum flower per plant (DMF), number of seeds per plant (NSPP) and seed weight per plant (SWPP) in blackgram (Vigna mungo L.). These three quantitative characters were studied in 24 lines and three years under different environmental conditions. The model proposed by Perkins and Jinks was followed in this study. In the analysis, greater portion of total phenotypic variation (s2p) appeared to be due to the environmental variations (s2e). The highest heritability (h2 b) (0.8181) was found for SWPP, while the highest genetic advance (G.A.=172.5508), high genetic advance of percentage (G.A.%=332.5627) and high genetic co-efficient of variability (G.C.V.=161.4381) were estimated in NSPP. The present investigation deals with the analysis of phenotypic, genotypic and environmental co-efficient of variability, range, mean with standard error, heritability (in broad sense), genetic advance and genetic advance of percentage. Genetic co-efficient of variability was very much pronounced and varied from treatment to treatment, year to year and lines to lines for all the characters, which indicates that the characters were quantitative in nature and under polygenic control. Therefore, further research would be undertaken for improving the characters of this pulse. South Asian J. Agric., 7(1&2): 1-5