Genetic analysis of field and physiological indicators of drought tolerance in bread wheat (Triticum aestivum L.) using diallel mating design

In order to study the inheritance of field, physiological and metabolite indicators of drought tolerance in wheat, an eight-parental diallel cross, excluding reciprocals, was grown in a randomized complete block design (RCBD) with three replications under two different water regimes (irrigated and rainfed). Significant differences were found for yield potential (Yp), stress yield (Ys), stress tolerance index (STI), leaf water potential (LWP), relative water content (RWC), water use efficiency (WUE) and evapotranspiration efficiency (ETE). Yp, RWC and evapotranspiration efficiency (ETE) showed highly significant differences for both general combining ability (GCA) and specific combining ability (SCA), indicating the involvement of both additive and non-additive gene action in their inheritance. Ys, STI and WUE revealed highly significant differences for SCA, hence non-additive gene action was predominant for these traits. The best general combiners with positive effects, for improvement of Yp, Ys, STI, LWP, RWC, WUE and ETE under drought conditions were parents 5, 1, 6, 2, 7, 1 and 2, respectively. The best specific combination with heterobeltiosis over the best parents for improvement of Yp, Ys, STI, LWP, RWC, WUE and ETE were crosses 3 × 6, 2 × 4, 2 × 6, 5 × 8, 2 × 6, 2 × 4 and 1 × 7, respectively indicating that parents of these crosses are genetically diverse. High broad-sense heritability observed for all the traits confirmed that all the traits are more genetic, but because of low narrow-sense heritability the rule of additive part was low.Key words: Drought tolerance, physiological indicators, diallel mating design, genetic analysis

Genetic Analysis of Grain Yield Related Traits in Rice

To determine gene action and heritability of grain yield related traits in rice, six rice varieties including Hashemi, Vandana, Kadous, Hassani, Shahpasand and IR36 were crossed in a diallel design in 2010. The parents and seeds of F1 generation (36 genotypes) were grown in a completely randomized block design with three replications at the Research Field of the Rice Research Institute of Iran-Rasht in 2011. In this experiment, the yield related traits including grain yield, number of panicles per plant, number of spikelet’s per panicle, 1000-grain weight, plant height, panicle length and flag leaf area were measured in each experimental unit. Evaluation of the gene action based on the Hayman graphical method indicated that 1000-grain weight was controlled by partial dominance effect and the other attributes were controlled by complete dominance to over-dominance effects. Broad-sense heritability varied from 54.91% to 99.84% for flag leaf area and plant height, respectively and narrow-sense heritability ranged from 26.04% to 88.68% for panicle length and 1000-grain weight, respectively. Results of this research showed that the additive gene effect can be used to improve several traits including 1000-grain weight, but utilizing the heterosis phenomenon and hybrid production is recommended to improve the remaining traits in the studied population

A Role for the Bone Marrow Microenvironment in Drug Resistance of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease with a poor prognosis and remarkable resistance to chemotherapeutic agents. Understanding resistance mechanisms against currently available drugs helps to recognize the therapeutic obstacles. Various mechanisms of resistance to chemotherapy or targeted inhibitors have been described for AML cells, including a role for the bone marrow niche in both the initiation and persistence of the disease, and in drug resistance of the leukemic stem cell (LSC) population. The BM niche supports LSC survival through direct and indirect interactions among the stromal cells, hematopoietic stem/progenitor cells, and leukemic cells. Additionally, the BM niche mediates changes in metabolic and signal pathway activation due to the acquisition of new mutations or selection and expansion of a minor clone. This review briefly discusses the role of the BM microenvironment and metabolic pathways in resistance to therapy, as discovered through AML clinical studies or cell line and animal models

Genomics and molecular markers for rice grain quality: a review

Rice grain quality is a benchmark of rice breeding success. Current rice breeding programs consider grain characteristics that are preferred by consumers in the rice value chain. Specific traits of quality that suit the demands of stakeholders must be targeted before, during and after breeding of new varieties. Therefore, screening tools that are environmentally independent, cheap, robust and easy to use, such as molecular markers, are needed to facilitate timely and accurate selection of traits. As a multifaceted overall phenotype and consisting of several parameters ranging from physical, textural, aroma and increasingly nutritional properties, the selection for quality has not only become about which trait(s) to focus on but is rather an issue of the combination of traits that can be incorporated into a dream variety. The more traits that are available, the more markers we need to capture these traits and feed them into the breeding and selection pipelines. This chapter reviews progress made on genomics and the molecular markers developed for quality traits of rice grains. In addition, this chapter presents the increasing need for novel phenotypes in the form of metabolites that can be traced back to the genome of rice