So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

Mango malformation is the most important and threatening disease of recent times, primarily because of persistent lacuna in complete understanding of its nature. Diverse Fusarium spp, including F. mangiferae, were found to be associated with the disease. Here, F. mangiferae from mango cv Dashehri was morphologically characterized. Typically, oval-shaped microconidia without septum and crescent-shaped macroconidia with 3-septate were more often observed, whereas not a single chlamydospore was detected. The length and width of micro- and macro-conidia were 7.5, 55, 3.2, and 3.5, respectively. The plant growth regulators such as NAA, GA3, BAP and ethrel were found to induce in vitro germination of conidia of F. mangiferae after 12 h. In contrast, antimalformin silver nitrate (AgNO3) inhibits conidial germination in vitro and none of conidia was germinated beyond 500 ppm, however antimalformin glutathione was highly effective in stimulating conidial germination of F. mangiferae in vitro at > 1000 ppm after 24 h. We observed that the response of F. mangiferae to germinate the conidia in vitro under influence of plant growth regulators and antimalformins is not coincided with earlier findings of reduced disease incidence by exogenous application of these compounds. The present findings do not authenticate the involvement of F. mangiferae in the disease, however hormonal imbalance, most probably ethylene, might be responsible for deformed functional morphology of panicle. Further, a signal transduction mechanism of stress-stimulated ethylene imbalance causing physio-morphological changes in reproductive organs of mango flower and thereby failure of fertilization and fruit set, which needs to be investigated.

In vitro: Response of plant growth regulators and antimalformins on conidia germination of Fusarium mangiferae and incidence of mango malformation

Reactive oxygen species

A reviewer for the Journal of the Royal Statistical Society of England comments \"This is the first book covering in one volume all important topics in genetical statistics.\" Written to provide basic probability ideas in terms of genetic situations, since the theory of genetics is a probability theory; to give a definitive treatment of applications of these ideas to genetic theory; and to describe statistical methods appropriate to the data models that are developed.

An Introduction to Genetic Statistics

Estimates of genetic and environmental variability in soybeans (Glycine max. L.) [Egypt].

Essential oil composition, total phenolic, flavonoid contents, and antioxidant activity of Thymus species collected from different regions of Iran

Wheat improvement for drought tolerance requires reliable assessment of drought tolerance variability among segregating populations. One hundred and fifty-one F3 and F4families of durum wheat derived from a cross between Oste-Gata (as drought tolerance) and Massara-1 (as susceptible) genotypes were evaluated both under moisture stress (E1) and non-stress (E2) field environments using a randomized complete block design for each environment and growing season (2003-04, 2004-05). Entries of E1 were subjected to moisture stress at grain filling period. Five drought tolerance indices comprising: stress tolerance index (STI), stress tolerance (TOL), stress susceptibility index (SSI), mean productivity (MP), and geometric mean productivity (GMP) were used. The indices were adjusted based on grain yield under drought (Ys) and normal (Yp) conditions. Analysis of variance for each individual year showed that there was a significant genetic variation among families for all criteria with the exception of SSI. The combined analysis of variance over seasons indicated the genetic diversity of lines, significant variation of seasons and differential response of genotypes over seasons for all indices with the exception of SSI. The significant and positive correlations of Yp and (MP, GMP and STI) and Ys and (MP, GMP and STI) under both the seasons as well as significant negative correlation of SSI and TOL in E1 revealed that selection could be conducted for high MP, GMP and STI under both environments and low SSI and TOL under E1conditions. The calculated correlation coefficients revealed that STI, MP, and GMP are the superior criteria for selection of high yielding genotypes both under E1 and E2. Cluster analysis of families using Ys, Yp and five other indices categorized genotypes into five groups each of which having 37, 56, 13, 34 and 11 genotypes in year 2003-04 growing season, respectively. Based on 2004-05 growing season data, six groups each of which having 25, 9, 25, 45, 10 and 37 genotypes were obtained, respectively. Cluster analysis distinguished groups contains superior lines for both E1 and E2, superior lines for only E1 conditions and superior lines for E2 conditions, considering their yield performance (Yp and Ys). Results of calculated gain from indirect selection indicated that selection from moisture stress environment would improve yield in moisture stress environment better than selection from non-moisture stress environment. The comparison of the number of families in common within the top 25% families at E1 in year 2004-05 and those selected using various indices indicated that drought tolerant indices could perform comparable with yield performance (Yp and Ys).

	 

	Key words: Durum wheat, Moisture stress, Drought tolerance index, grain yield.

https://www.academicjournals.org/article/article1380784635_Golabadi et al.pdf

Assessment of Drought Tolerance in Segregating Populations in Durum Wheat

Salinity limits the production capabilities of agricultural soils in large areas of the world. Both breeding and screening germplasm for salt tolerance encounter the following limitations: (a) different phenotypic responses of plants at different growth stages, (b) different physiological mechanisms, (c) complicated genotype × environment interactions, and (d) variability of the salt-affected field in its chemical and physical soil composition. Plant molecular and physiological traits provide the bases for efficient germplasm screening procedures through traditional breeding, molecular breeding, and transgenic approaches. However, the quantitative nature of salinity stress tolerance and the problems associated with developing appropriate and replicable testing environments make it difficult to distinguish salt-tolerant lines from sensitive lines. In order to develop more efficient screening procedures for germplasm evaluation and improvement of salt tolerance, implementation of a rapid and reliable screening procedure is essential. Field selection for salinity tolerance is a laborious task; therefore, plant breeders are seeking reliable ways to assess the salt tolerance of plant germplasm. Salt tolerance in several plant species may operate at the cellular level, and glycophytes are believed to have special cellular mechanisms for salt tolerance. Ion exclusion, ion sequestration, osmotic adjustment, macromolecule protection, and membrane transport system adaptation to saline environments are important strategies that may confer salt tolerance to plants. Cell and tissue culture techniques have been used to obtain salt tolerant plants employing two in vitro culture approaches. The first approach is selection of mutant cell lines from cultured cells and plant regeneration from such cells (somaclones). In vitro screening of plant germplasm for salt tolerance is the second approach, and a successful employment of this method in durum wheat is presented here. Doubled haploid lines derived from pollen culture of F1 hybrids of salt-tolerant parents are promising tools to further improve salt tolerance of plant cultivars. Enhancement of resistance against both hyper-osmotic stress and ion toxicity may also be achieved via molecular breeding of salt-tolerant plants using either molecular markers or genetic engineering.

Improving salinity tolerance in crop plants: a biotechnological view

Salinity is a consistent factor of crop productivity loss in the world and in particular arid and semi-arid areas where the soil salinity and saline water are major problems. Plants employ various mechanisms to cope with salinity stress and activate an array of stress-responsive genes to counteract the salinity-induced osmotic and ionic stresses. Genetic improvement for salinity tolerance is challenging, and thus progress attained over the several decades has been far less than anticipated. The generation of an explosion of knowledge and technology related to genetics and genomics over the last few decades is promising in providing powerful tools for future development of salinity-tolerant cultivars. Despite a major progress in defining the underlying mechanisms of salinity tolerance, there are still major challenges to be overcome in translating and integrating the resultant information at the molecular level into plant-breeding practices. Various approaches have been suggested to improve the eff...

Smart Engineering of Genetic Resources for Enhanced Salinity Tolerance in Crop Plants

A sustainable and wholesome food supply is the most important incentive that has led to an increasing interest in ancient wheats over the past few decades. Domestication of wheat, followed by breeding efforts, largely over the past 2 centuries, has resulted in yield increases but with grain quality deterioration due to the reduction of protein, vitamins, and minerals in grains. It has also resulted in a decrease in food diversity due to the loss of genetic variation in the cultivated wheat gene pool. Ancient hulled wheats, einkorn, emmer, and spelt are among the early cereals that were domesticated in their places of origin in the Fertile Crescent of the Middle East where their wild predecessors still grow. The ancient wheats had a long history as part of human diet, and played an important role as a major source of food for the early civilizations in that region. The risks of genetic erosion of crop plants and the associated likely consequences for agriculture now call for revitalization of the unrealized potentials of ancestral species like einkorn, emmer, and spelt wheat, the domesticated ancestors of modern durum and bread wheats. These ancestors need to be exploited to maximize the sustainable supply of grain protein, fiber, minerals, and phytochemicals. In addition, ancient wheat biodiversity can be utilized to ensure sustainable wheat production in the context of climate change and low-input organic farming systems. This review provides a holistic synthesis of the information on ancient wheats to facilitate a greater exploitation of their potential benefits.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/1541-4337.12262

Ahmad Arzani

Papers

Essential oil composition, total phenolic, flavonoid contents, and antioxidant activity of Thymus species collected from different regions of Iran

Assessment of Drought Tolerance in Segregating Populations in Durum Wheat

Improving salinity tolerance in crop plants: a biotechnological view

Smart Engineering of Genetic Resources for Enhanced Salinity Tolerance in Crop Plants

Cultivated Ancient Wheats (Triticum spp.): A Potential Source of Health‐Beneficial Food Products