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Sorghum is a self-pollinated crop with multiple economic uses as cereal, forage, and biofuel feedstock. Hybrid breeding is a cornerstone for sorghum improvement strategies that currently relies on cytoplasmic male sterile lines. To engineer genic male sterility, it is imperative to examine the genetic components regulating anther/pollen development in sorghum. To this end, we have performed transcriptomic analysis from three temporal stages of developing anthers that correspond to meiotic, microspore and mature pollen stages. A total of 5286 genes were differentially regulated among the three anther stages with 890 of them exhibiting anther-preferential expression. Differentially expressed genes could be clubbed into seven distinct developmental trajectories using K-means clustering. Pathway mapping revealed that genes involved in cell cycle, DNA repair, regulation of transcription, brassinosteroid and auxin biosynthesis/signalling exhibit peak expression in meiotic anthers, while those regulating abiotic stress, carbohydrate metabolism, and transport were enriched in microspore stage. Conversely, genes associated with protein degradation, post-translational modifications, cell wall biosynthesis/modifications, abscisic acid, ethylene, cytokinin and jasmonic acid biosynthesis/signalling were highly expressed in mature pollen stage. High concurrence in transcriptional dynamics and cis-regulatory elements of differentially expressed genes in rice and sorghum confirmed conserved developmental pathways regulating anther development across species. Comprehensive literature survey in conjunction with orthology analysis and anther-preferential accumulation enabled shortlisting of 21 prospective candidates for in-depth characterization and engineering male fertility in sorghum.

Sorghum is a highly efficient C4 crop, with enormous potential as a biofuel feedstock. Fermentable sugars that accumulate in sorghum stalks, high biomass, drought tolerance and adaptability to diverse climates are some of the key attributes of sorghum. However, sustainable production of renewable fuels through large scale plantation of sorghum needs targeted research efforts at several fronts. One of the promising areas is manipulating gene expression to engineer traits-of-interest. In the recent past, microRNAs have emerged as important targets for engineering complex agronomical traits, including biomass yields, sugar accumulation, flowering time, drought tolerance, disease resistance, micronutrient homeostasis, etc., in several crop plants. Both homology-based bioinformatics, and experimental approaches viz. miRNA microarrays and small RNA sequencing have been utilised to gain insights into the role of miRNAs in regulating bioenergy-related traits in sorghum. Through this review, we provide a comprehensive overview of the information available till date about the miRNA-related research in sorghum and propose the prospective directions for future endeavours in this area.

Seed weight QTL identified in different populations were synthesized into consensus QTL which were shown to harbor candidate genes by in silico mapping. Allelic variation inferred would be useful in breeding B. juncea lines with high seed weight. Seed weight is an important yield influencing trait in oilseed Brassicas and is a multigenic trait. Among the oilseed Brassicas, Brassica juncea harbors the maximum phenotypic variation wherein thousand seed weight varies from around 2.0 g to more than 7.0 g. In this study, we have undertaken quantitative trait locus/quantitative trait loci (QTL) analysis of seed weight in B. juncea using four bi-parental doubled-haploid populations. These four populations were derived from six lines (three Indian and three east European lines) with parental phenotypic values for thousand seed weight ranging from 2.0 to 7.6 g in different environments. Multi-environment QTL analysis of the four populations identified a total of 65 QTL ranging from 10 to 25 in each population. Meta-analysis of these component QTL of the four populations identified six ‘consensus’ QTL (C-QTL) in A3, A7, A10 and B3 by merging 33 of the 65 component Tsw QTL from different bi-parental populations. Allelic diversity analysis of these six C-QTL showed that Indian lines, Pusajaikisan and Varuna, hold the most positive allele in all the six C-QTL. In silico mapping of candidate genes with the consensus QTL localized 11 genes known to influence seed weight in Arabidopsis thaliana and also showed conserved crucifer blocks harboring seed weight QTL between the A subgenomes of B. juncea and B. rapa. These findings pave the way for a better understanding of the genetics of seed weight in the oilseed crop B. juncea and reveal the scope available for improvement of seed weight through marker-assisted breeding.

Scientific Reports 6: Article number: srep38488; published online: 05 December 2016; updated: 06 April 2017 The Acknowledgments section of this Article is incomplete, where: “R.S. and M.K.S. acknowledge the Ramalingaswami fellowship and grant from the Department of Biotechnology, Government of India”.

Teosinte Branched1/Cycloidea/Proliferating cell factors (TCP) genes are key mediators of genetic innovations underlying morphological novelties, stress adaptation, and evolution of immune response in plants. They have a remarkable ability to integrate and translate diverse endogenous, and environmental signals with high fidelity. Compilation of studies, aimed at elucidating the mechanism of TCP functions, shows that it takes an amalgamation and interplay of several different factors, regulatory processes and pathways, instead of individual components, to achieve the incredible functional diversity and specificity, demonstrated by TCP proteins. Through this minireview, we provide a brief description of key structural features and molecular components, known so far, that operate this conglomerate, and highlight the important conceptual challenges and lacunae in TCP research.

Search for genic SSRs from transcriptome sequence data of Brassica juncea and B. nigra and from unigene databank of B. rapa resulted in identification of 20,529 SSRs from 330,827 gene sequences. Identified SSRs (named as unigene microsatellite; UGM) were characterized based on their number of repeats, type of motif and base composition. Primers were designed for 2118 UGMs after in silico polymorphism survey and were tested across 11 different genotypes of B. juncea and B. rapa for PCR amplification and polymorphism. It resulted in clear-cut amplification from 1993 UGMs of which 1319 UGMs showed polymorphism. It was observed that a priori in silico polymorphism survey helped in increasing the polymorphism percentage (6.1–13.2) by PCR amplification. We also report here the development of first SSR-based linkage map of Brassica juncea using a DH mapping population derived from F1 of the cross between the lines EH-2 and Pusajaikisan. The map consisted of 860 markers comprising 462 UGMs, 157 BAC-derived SSRs and 241 intron polymorphic markers and covered a total genetic length of 2073.6 cM. The study also reports an interesting observation of appearance of novel non-parental bands in the mapping population from 18 SSRs and 13 IP markers. Search of Arabidopsis genes orthologous to their primer sequences showed that 11 of such Arabidopsis genes code for proteins involved in various abiotic stresses. The highly transferable genic SSRs developed in the study would serve as valuable resources for comparative genome mapping, mapping of qualitative and quantitative traits, gene cloning and marker-assisted breeding in Brassica species.