Uttam Kumar

Ent-kaurenoic acid oxidase genes in wheat

Ent-kaurenoic acid oxidase (KAO) catalysis three steps in the gibberellin (GA) biosynthesis pathway, which yields a large hormone family affecting plant growth and development. In the current study, we performed partial gene cloning and comparative structural and mapping analysis among three Kao genes in bread wheat (Triticum aestivum L.). Molecular-marker-based mapping demonstrated that the Kao loci map to the distal ends of the chromosome arms 7AS, 4AL and 7DS, corresponding to the 7BS/4AL translocation region. Co-linearity of the chromosomal regions carrying the Kao genes was shown. It was concluded that the Kao genes we mapped represent a homoeoloci set, therefore the genes were designated Kao-A1 (chromosome 7AS), Kao-B1 (4AL), and Kao-D1 (7DS). It was found that exonic sequences of the three homoeologues differ from each other mainly by silent mutations, and each homoeologue is expressed.

Molecular approaches for designing heat tolerant wheat

Global warming is causing changes in temperature rapidly for over two decades. The increased temperature during reproductive phase of plant growth has emerged as a serious problem all over the world. Constant or transitory high temperatures may affect the plant growth and development which may lead to diverse morphological, physiological and biochemical changes in plants ultimately decrease in yield. Genetic approaches leading to improved thermo-tolerance can mitigate the reduction in yield. In this backdrop, several indirect traits or parameters have been developed for identification of heat tolerant plants/lines. The traits like stay green/delayed senescence are reported to contribute toward capability of plants to tolerate heat stress. In addition, understanding of biochemical and molecular basis of thermo-tolerance in combination with genetic approaches like identification and mapping of heat tolerant QTLs will not only assist conventional breeders to develop heat tolerant cultivars but also help molecular biologists to clone and characterize genes associated with heat tolerance, which could be used in genetically modified heat tolerant plants. Therefore, overviews of different strategies for developing heat tolerant wheat are discussed in this review.

A Hierarchal Cluster Framework for Wireless Sensor Network

In wireless sensor networks, a cluster algorithm is a good option to reduce redundant data transfer and organize nodes effectively for long life. In this paper we implement and evaluate a new flexible, hierarchical clustering algorithm on the middleware layer based paradigm. The goal of our algorithm is to give the five features, scalability, energy efficiency, fault tolerance, load balancing and multi-level clustering. Our algorithm consists of three protocols. Flat Clustering protocol constructs a 2-level clustering network structure. Function Delegation protocol provides fault tolerance and load balancing features. Multi-Level clustering protocol builds a more than two-level clustering network structure. This paper also examines several popular simulators and clarifies the definition and implementation of our algorithm in NS2 simulator. Then we evaluate the algorithm from different angles. Based on our simulation, we optimize the key parameters for our algorithm and find that performance and energy efficiency of our algorithm is promising, especially in bridge topologies.

Strategic crossing of biomass and harvest index—source and sink—achieves genetic gains in wheat

To accelerate genetic gains in breeding, physiological trait (PT) characterization of candidate parents can help make more strategic crosses, increasing the probability of accumulating favorable alleles compared to crossing relatively uncharacterized lines. In this study, crosses were designed to complement “source” with “sink” traits, where at least one parent was selected for favorable expression of biomass and/or radiation use efficiency—source—and the other for sink-related traits like harvest-index, kernel weight and grains per spike. Female parents were selected from among genetic resources—including landraces and products of wide-crossing (i.e. synthetic wheat)—that had been evaluated in Mexico at high yield potential or under heat stress, while elite lines were used as males. Progeny of crosses were advanced to the F4 generation within Mexico, and F4-derived F5 and F6 generations were yield tested to populate four international nurseries, targeted to high yield environments (2nd and 3rd WYCYT) for yield potential, and heat stressed environments (2nd and 4th SATYN) for climate resilience, respectively. Each nursery was grown as multi-location yield trials. Genetic gains were achieved in both temperate and hot environments, with most new PT-derived lines expressing superior yield and biomass compared to local checks at almost all international sites. Furthermore, the tendency across all four nurseries indicated either the superiority of the best new PT lines compared with the CIMMYT elite checks, or the superiority of all new PT lines as a group compared with all checks, and in some cases, both. Results support—in a realistic breeding context—the hypothesis that yield and radiation use efficiency can be increased by improving source:sink balance, and validate the feasibility of incorporating exotic germplasm into mainstream breeding efforts to accelerate genetic gains for yield potential and climate resilience.

Study of inheritance and allelic relation of resistance to spot blotch (Bipolaris sorokiniana) of wheat

Six varieties viz., Chirya-1, Chirya-3, Chirya-7, Yangmai-6, Ning-8201 and Ning-8319 known for their resistance to spot blotch were crossed with the most susceptible parent i.e., Sonalika for studying inheritance pattern and establishing allelic relationship among different resistance sources. Disease severity of F1 ’s were intermediate to slightly tilted towards resistant parents and thus indicated either no dominance or partial dominance. Progeny rows of these crosses were evaluated in the F3 and F4 generations. Disease severity for each progeny rows was measured at three different growth stages viz., late anthesis (69), late milk (77) and early dough (83) stages. Based on disease severity, the F3, F4 and F5 progenies were grouped into three classes: homozygous dominant, segregating and homozygous susceptible. Based on this ratio, number of effective genes was estimated following χ2 analysis and quantitative approaches. Chirya-1, Chirya-3, Chirya-7, Yangmai-6 and Ning-8201 showed involvement of two genes in resistance while, Ning-8319 showed the presence of three resistance genes to spot blotch. Resistant × resistant crosses were made to establish the allelic relationship of resistance genes. The F3 progeny of all the crosses did not show susceptible plants. This proved that at least one gene was common among parents for resistance. However, the appearance of transgressive segregants was an indication of the non-allelic relationship. The present study also indicated the possibility of achieving enhanced resistance through gene pyramiding.

Harnessing genetic potential of wheat germplasm banks through impact-oriented-prebreeding for future food and nutritional security

The value of exotic wheat genetic resources for accelerating grain yield gains is largely unproven and unrealized. We used next-generation sequencing, together with multi-environment phenotyping, to study the contribution of exotic genomes to 984 three-way-cross-derived (exotic/elite1//elite2) pre-breeding lines (PBLs). Genomic characterization of these lines with haplotype map-based and SNP marker approaches revealed exotic specific imprints of 16.1 to 25.1%, which compares to theoretical expectation of 25%. A rare and favorable haplotype (GT) with 0.4% frequency in gene bank identified on chromosome 6D minimized grain yield (GY) loss under heat stress without GY penalty under irrigated conditions. More specifically, the ‘T’ allele of the haplotype GT originated in Aegilops tauschii and was absent in all elite lines used in study. In silico analysis of the SNP showed hits with a candidate gene coding for isoflavone reductase IRL-like protein in Ae. tauschii. Rare haplotypes were also identified on chromosomes 1A, 6A and 2B effective against abiotic/biotic stresses. Results demonstrate positive contributions of exotic germplasm to PBLs derived from crosses of exotics with CIMMYT’s best elite lines. This is a major impact-oriented pre-breeding effort at CIMMYT, resulting in large-scale development of PBLs for deployment in breeding programs addressing food security under climate change scenarios.

Correction to: Strategic crossing of biomass and harvest index—source and sink—achieves genetic gains in wheat

The original article was corrected. Author Muhammad Kundi should instead read: Muhammad Sohail.