Conservation, Rearrangement, and Deletion of Gene Pairs During the Evolution of Four Grass Genomes

Gene order and content differ among homologous regions of closely related genomes. Similarities in the expression profiles of physically adjacent genes suggest that the proper functioning of these genes depends on maintaining a specific position relative to each other. To better understand the results of the interaction of these two genomic forces, convergent, divergent, and tandem gene pairs in rice and sorghum, as well as their homologs in rice, sorghum, maize, and Brachypodium were analyzed. The status of each pair in all four species: whether it was conserved, inverted, rearranged, or missing homologs was determined. We observed that divergent gene pairs had lower rates of conservation than convergent or tandem pairs, but higher rates of rearranged pairs and missing homologs in maize than in any other species. We also discovered species-specific gene pairs in rice and sorghum. In rice, gene pairs with strongly correlated expression levels were conserved significantly more often than those with little or no correlation. We assigned three types of gene pair to one of 14 possible evolutionary history categories to uncover their evolutionary dynamics during the evolution of grass genomes

Metabolomics, biomass and lignocellulosic total sugars analysis in foxtail millet (setaria italica) inoculated with different combinations of plant growth promoting bacteria and mycorrhiza

Foxtail millet (Setaria italica) is the second most widely produced millet with potential as a biofuel source. Employment of plant growth promoting bacteria (PGPB) and mycorrhiza could serve as environment-friendly alternatives for the use of excessive NPK fertilizers and producing biofuel. The highest increase of biomass was associated with endomycorrhiza combined with PGPB in comparison to control. Nuclear magnetic resonance (NMR) analysis detected 28 metabolites in foxtail shoot with most of them upregulated in ecto/endomycorrhiza group and combined with PGPB. The upregulation of metabolites associated with synthesis of amino acids correlated positively with biomass. The inoculation with both PGPB and endomycorrhiza gave the best results with reference to total sugar yield. Our study indicates that PGPB and endomycorrhiza combination is well suited for enhancing biomass and boosting sugar yield, which are useful attributes for utilizing foxtail millet as a biofuel source

Anticancer Activities of Plant Secondary Metabolites: Rice Callus Suspension Culture as a New Paradigm

Plant natural products including alkaloids, polyphenols, terpenoids and flavonoids have been reported to exert anticancer activity by targeting various metabolic pathways. The biological pathways regulated by plant products can serve as novel drug targets. Plant natural compounds or their derivatives used for cancer treatment and some novel plant-based compounds which are used in clinical trials were discussed. Callus suspension culture with secondary metabolites can provide a continuous source of plant pharmaceuticals without time and space limitations. Previous research has shown that rice callus suspension culture can kill \u3e95% cancer cells with no significant effect on the growth of normal cells. The role of candidate genes and metabolites which are likely to be involved in the process and their potential to serve as anticancer and anti-inflammatory agents were discussed. Large scale production of plant callus suspension culture and its constituents can be achieved using elicitors which enhance specific secondary metabolites combined with bioprocess technology

On the Tetraploid Origin of the Maize Genome

Data from cytological and genetic mapping studies suggest that maize arose as a tetraploid. Two previous studies investigating the most likely mode of maize origin arrived at different conclusions. Gaut and Doebley [7] proposed a segmental allotetraploid origin of the maize genome and estimated that the two maize progenitors diverged at 20.5 million years ago (mya). In a similar study, using larger data set, Brendel and colleagues (quoted in [8]) suggested a single genome duplication at 16 mya. One of the key components of such analyses is to examine sequence divergence among strictly orthologous genes. In order to identify such genes, Lai and colleagues [10] sequenced five duplicated chromosomal regions from the maize genome and the orthologous counterparts from the sorghum genome. They also identified the orthologous regions in rice. Using positional information of genetic components, they identified 11 orthologous genes across the two duplicated regions of maize, and the sorghum and rice regions. Swigonova et al. [12] analyzed the 11 orthologues, and showed that all five maize chromosomal regions duplicated at the same time, supporting a tetraploid origin of maize, and that the two maize progenitors diverged from each other at about the same time as each of them diverged from sorghum, about 11.9 mya

Synergistic Effect of Azotobacter nigricans and Nitrogen Phosphorus Potassium Fertilizer on Agronomic and Yieldtraits of Maize (Zea mays L.)

Peer reviewe

Identification of stress-responsive genes in an indica rice (Oryza sativa L.) using ESTs generated from drought-stressed seedlings

The impacts of drought on plant growth and development limit cereal crop production worldwide. Rice (Oryza sativa) productivity and production is severely affected due to recurrent droughts in almost all agroecological zones. With the advent of molecular and genomic technologies, emphasis is now placed on understanding the mechanisms of genetic control of the drought-stress response. In order to identify genes associated with water-stress response in rice, ESTs generated from a normalized cDNA library, constructed from drought-stressed leaf tissue of an indica cultivar, Nagina 22 were used. Analysis of 7794 cDNA sequences led to the identification of 5815 rice ESTs. Of these, 334 exhibited no significant sequence homology with any rice ESTs or full-length cDNAs in public databases, indicating that these transcripts are enriched during drought stress. Analysis of these 5815 ESTs led to the identification of 1677 unique sequences. To characterize this drought transcriptome further and to identify candidate genes associated with the drought-stress response, the rice data were compared with those for abiotic stress-induced sequences obtained from expression profiling studies in Arabidopsis, barley, maize, and rice. This comparative analysis identified 589 putative stress-responsive genes (SRGs) that are shared by these diverse plant species. Further, the identified leaf SRGs were compared to expression profiles for a drought-stressed rice panicle library to identify common sequences. Significantly, 125 genes were found to be expressed under drought stress in both tissues. The functional classification of these 125 genes showed that a majority of them are associated with cellular metabolism, signal transduction, and transcriptional regulation

Conference Review On the tetraploid origin of the maize genome

Abstract Data from cytological and genetic mapping studies suggest that maize arose as a tetraploid. Two previous studies investigating the most likely mode of maize origin arrived at different conclusions. Gaut and Doebley [12] analyzed the 11 orthologues, and showed that all five maize chromosomal regions duplicated at the same time, supporting a tetraploid origin of maize, and that the two maize progenitors diverged from each other at about the same time as each of them diverged from sorghum, about 11.9 mya

Retrotransposon insertions in rice gene pairs associated with reduced conservation of gene pairs in grass genomes

Small-scale changes in gene order and orientation are common in plant genomes, even across relatively short evolutionary distances. We investigated the association of retrotransposons in and near rice gene pairs with gene pair conservation, inversion, rearrangement, and deletion in sorghum, maize, and . Brachypodium. . Copia and . Gypsy LTR-retrotransposon insertions were found to be primarily associated with reduced frequency of gene pair conservation and an increase in both gene pair rearrangement and gene deletions. SINEs are associated with gene pair rearrangement, while LINEs are associated with gene deletions. Despite being more frequently associated with retrotransposons than convergent and tandem pairs, divergent gene pairs showed the least effects from that association. In contrast, convergent pairs were least frequently associated with retrotransposons yet showed the greatest effects. Insertions between genes were associated with the greatest effects on gene pair arrangement, while insertions flanking gene pairs had significant effects only on divergent pairs. © 2012