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the study was undertaken to identify the quantitative trait loci (QtLs) governing yield and its related traits using a recombinant inbred line (RIL) population derived from the popular rice hybrid, KRH-2 (IR58025A/KMR3R). A genetic map spanning 294.2 cM was constructed with 126 simple sequence repeats (SSR) loci uniformly distributed across the rice genome. QTL analysis using phenotyping and genotyping information identified a total of 22 QTLs. Of these, five major effect QTLs were identified for the following traits: total grain yield/plant (qYLD3-1), panicle weight (qPW3-1), plant height (qPH12-1), flag leaf width (qFLW4-1) and panicle length (qPL3-1), explaining 20.23-22.76% of the phenotypic variance with LOD scores range of 6.5-10.59. Few genomic regions controlling several traits (QTL hotspot) were identified on chromosome 3 for total grain yield/plant (qYLD3-1) and panicle length (qPL3-1). Significant epistatic interactions were also observed for total grain yield per plant (YLD) and panicle length (PL). While most of these QTLs were observed to be co-localized with the previously reported QTL regions, a novel, major QTL associated with panicle length (qPL3-1) was also identified. SNP genotyping of selected high and low yielding RILs and their QTL mapping with 1,082 SNPs validated most of the QTLs identified through SSR genotyping. This facilitated the identification of novel major effect QTLs with much better resolution and precision. In-silico analysis of novel QTLs revealed the biological functions of the putative candidate gene (s) associated with selected traits. Most of the high-yielding RILs possessing the major yield related QTLs were identified to be complete restorers, indicating their possible utilization in development of superior rice hybrids.

Nitrogen is the most important macronutrient needed for plant growth and development. The availability of nitrogen in the soil fluctuates greatly in both time and space. Crop plants, except leguminous plants, depend on supply of nitrogen as fertilizers. Large quantities of nitrogen fertilizers are applied to crop plants, but only 33% of it is utilized by the plant. Plants have developed efficient mechanisms to sense the varying levels of nitrogen forms and uptake them. They also have well developed mechanisms to assimilate the incoming nitrogen immediately or translocate to different parts of the plant wherever it is needed. Maintenance of nitrogen homeostasis is essential to avoid toxicity. Apart from translocation and assimilation, plants have developed different mechanisms, nitrogen efflux; vacuolar nitrogen storage and downward transport of nitrogen from aerial parts to roots, for maintaining nitrogen homeostasis. In crop plants the "grain yield per unit of available nitrogen in the soil" is referred as the nitrogen use efficiency (NUE) for which remobilization of nitrogen, mediated by various transporters plays a crucial role. All these processes are tightly regulated by proteins and microRNA in response to both external and internal nitrogen levels, carbon status of the plant and hormones. As most crop plants are non-leguminous and depend on soil nitrogen, more production could be achieved if crop plants can be made to utilize the available nitrogen efficiently. The recent explosion of research information and the mechanisms behind nitrogen sensing, signaling, transport and utilization enables biotechnological interventions for better nitrogen nutrition of crop plants. This review discusses such possibilities in the context of recent understanding of nitrogen nutrition and the genomic revolution sweeping the crop science.

Reduction in fossil fuel consumption by using alternate sources of energy is a major challenge facing mankind in the coming decades. Bioethanol production using lignocellulosic biomass is the most viable option for addressing this challenge. Industrial bioconversion of lignocellulosic biomass, though possible now, is not economically viable due to presence of barriers that escalate the cost of production. As cellulose and hemicellulose are the major constituents of terrestrial biomass, which is available in massive quantities, hydrolysis of cellulose and hemicellulose by the microorganisms are the most prominent biochemical processes happening in the earth. Microorganisms possess different categories of proteins associated with different stages of bioethanol production and a number of them are already found and characterized. Many more of these proteins need to be identified which suit the specificities needed for the bioethanol production process. Discovery of proteins with novel specificities and application of genetic engineering technologies to harvest the synergies existing between them with the aim to develop consolidated bioprocess is the major direction of research in the future. In this review, we discuss the different categories of proteins used for bioethanol production in the context of breaking the barriers existing for the economically feasible lignocellulosic bioethanol production.

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