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Drought is a major abiotic stress limiting rice production and yield stability in rainfed ecosystems. Identifying quantitative trait loci (QTL) for rice yield and yield components under water limited environments will help to develop drought resilient cultivars using marker assisted breeding (MAB) strategy. A total of 232 recombinant inbred lines of IR62266/Norungan were used to map QTLs for plant phenology and production traits under rainfed condition in target population of environments. A total of 79 QTLs for plant phenology and production traits with phenotypic variation ranging from 4.4 to 72.8% were detected under non-stress and drought stress conditions across two locations. Consistent QTLs for phenology and production traits were detected across experiments and water regimes. The QTL region, RM204-RM197-RM217 on chromosome 6 was linked to days to 50% flowering and grain yield per plant under both rainfed and irrigated conditions. The same genomic region, RM585-RM204-RM197 was also linked to harvest index under rainfed condition with positive alleles from Norungan, a local landrace. QTLs for plant production and drought resistance traits co-located near RM585-RM204-RM197-RM217 region on chromosome 6 in several rice genotypes. Thus with further fine mapping, this region may be useful as a candidate QTL for MAB, map-based cloning of genes and functional genomics studies for rainfed rice improvement.

Tessellations of kekulenes and cycloarenes are of considerable interest as nanomolecular belts in trapping and transportation of heavy metal ions and chloride ions, as they possess optimal electronic features and pore sizes. A class of cycloarenes called kekulenes have been the focus of several experimental and theoretical studies from the stand point of aromaticity, superaromaticity, chirality, and novel electrical and magnetic properties. In the present study, we investigate the entropies and topological characterization of different tessellations of kekulenes through topological computations of superaromatic structures with pores. We introduce the self-powered vertex degree-based topological indices and then derive the graph entropy measures for three different tessellations (zigzag, armchair, and rectangular) via various molecular descriptors that we derive here. Several applications to computing the molecular properties are pointed out. We demonstrate the existence of isentropic and yet nonisomorphic tessellations of kekulenes for the first time. The two tessellations are predicted to be quite close in energy with comparable energy gaps. Graph theory-based PPP methods with parameters derived from higher levels of theory are proposed to be promising tools for the predictions of relative stabilities of kekulene tessellations. We show that the developed techniques can be applied in the general context of artificial intelligence for the machine generation of nuclear magnetic resonance and electron spin resonance spectroscopic patterns as well as in robust computations of thermochemistry of a large combinatorial libraries of tessellations of kekulenes through the generation of bond-equivalence classes.

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Eucalyptus is an important short rotation pulpy woody plant, grown widely in the tropics. Recently, many genomic programmes are underway leading to the accumulation of voluminous genomic and expressed sequence tag sequences in public databases. These sequences can be utilized for analysis of simple sequence repeats (SSRs) and single nucleotide polymorphism (SNPs) available in the transcribed genes. In this study, in silico analysis of 15,285 sequences representing partial and full-length mRNA from Eucalyptus species for their use in developing SSRs or microsatellites were carried out. A total of 875 EST-SSRs were identified from 772 SSR containing ESTs. Motif size of 6 for dinucleotide and 5 for trinucleotide, tetranucleotide, and pentanucleotides were considered in locating the microsatellites. The average frequency of identified SSRs was 12.9%. The dinucleotide repeats were the most abundant among the dinucleotide, trinucleotide and tetranucleotide motifs and accounted for 50.9% of the Eucalyptus genome. Primer designing analysis showed that 571 sequences with SSRs had sufficient flanking regions for polymerase chain reaction (PCR) primer synthesis. Evaluation of the usefulness of the SSRs showed that EST-derived SSRs can generate polymorphic markers as all the primers showed allelic diversity among the 16 provenances of E. tereticornis.