PpSCARECROW1 (PpSCR1) regulates leaf blade and mid-vein development in Physcomitrium patens.

In plants, asymmetric cell divisions result in distinct cell fates forming large and small daughter cells, adding to the cellular diversity in an organ. SCARECROW (SCR), a GRAS domain-containing transcription factor controls asymmetric periclinal cell divisions in flowering plants by governing radial patterning of ground tissue in roots and cell proliferation in leaves. Though SCR homologs are present across land plant lineages, the current understanding of their role in cellular patterning and leaf development is mostly limited to flowering plants. Our phylogenetic analysis identified three SCR homologs in moss Physcomitrium patens, amongst which PpSCR1 showed highest expression in gametophores and its promoter activity was prominent at the mid-vein and the flanking leaf blade cells pointing towards its role in leaf development. Notably, out of the three SCR homologs, only the ppscr1 knock-out lines developed slender leaves with four times narrower leaf blade and three times thicker mid-vein. Detailed histology studies revealed that slender leaf phenotype is either due to the loss of anticlinal cell divisions or failure of periclinal division suppression in the leaf blade. RNA-Seq analyses revealed that genes responsible for cell division and differentiation are expressed differentially in the mutant. PpSCR1 overexpression lines exhibited significantly wider leaf lamina, further reconfirming the role in leaf development. Together, our data suggests that PpSCR1 is involved in the leaf blade and mid-vein development of moss and that its role in the regulation of cell division and proliferation is ancient and conserved among flowering plants and mosses.

Peptides from conserved tandem direct repeats of SHORT-LEAF regulate gametophore development in moss P. patens.

Tandem direct repeat (TDR)-containing proteins, present across all domains of life, play crucial roles in plant development and defense mechanisms. Previously, we identified that disruption of a bryophyte-specific protein family, SHORT-LEAF (SHLF), possessing the longest reported TDRs, is the cause of the shlf mutant phenotype in Physcomitrium patens. shlf exhibits reduced apical dominance, altered auxin distribution, and 2-fold shorter leaves. However, the molecular role of SHLF was unclear due to the absence of known conserved domains. Through a series of protein domain deletion analyses, here, we demonstrate the importance of the signal peptide and the conserved TDRs and report a minimal functional protein (miniSHLF) containing the N-terminal signal peptide and first two TDRs (N-TDR1-2). We also demonstrate that SHLF behaves as a secretory protein and that the TDRs contribute to a pool of secreted peptides essential for SHLF function. Further, we identified that the mutant secretome lacks SHLF peptides, which are abundant in WT and miniSHLF secretomes. Interestingly, shlf mutants supplemented with the secretome or peptidome from WT or miniSHLF showed complete or partial phenotypic recovery. Transcriptomic and metabolomic analyses revealed that shlf displays an elevated stress response, including high ROS activity and differential accumulation of genes and metabolites involved in the phenylpropanoid pathway, which may affect auxin distribution. The TDR-specific synthetic peptide SHLFpep3 (INIINAPLQGFKIA) also rescued the mutant phenotypes, including the altered auxin distribution, in a dosage-dependent manner and restored the mutant's stress levels. Our study shows that secretory SHLF peptides derived from conserved TDRs regulate moss gametophore development.

Conservation of the Restricted Expression of Brassicaceae Bsister-Like Genes in Seeds Requires a Transposable Element in Arabidopsis thaliana.

Changes in transcription factor binding sites (TFBSs) can alter the spatiotemporal expression pattern and transcript abundance of genes. Loss and gain of TFBSs were shown to cause shifts in expression patterns in numerous cases. However, we know little about the evolution of extended regulatory sequences incorporating many TFBSs. We compare, across the crucifers (Brassicaceae, cabbage family), the sequences between the translated regions of Arabidopsis Bsister (ABS)-like MADS-box genes (including paralogous GOA-like genes) and the next gene upstream, as an example of family-wide evolution of putative upstream regulatory regions (PURRs). ABS-like genes are essential for integument development of ovules and endothelium formation in seeds of Arabidopsis thaliana. A combination of motif-based gene ontology enrichment and reporter gene analysis using A. thaliana as common trans-regulatory environment allows analysis of selected Brassicaceae Bsister gene PURRs. Comparison of TFBS of transcriptionally active ABS-like genes with those of transcriptionally largely inactive GOA-like genes shows that the number of in silico predicted TFBS) is similar between paralogs, emphasizing the importance of experimental verification for in silico characterization of TFBS activity and analysis of their evolution. Further, our data show highly conserved expression of Brassicaceae ABS-like genes almost exclusively in the chalazal region of ovules. The Arabidopsis-specific insertion of a transposable element (TE) into the ABS PURRs is required for stabilizing this spatially restricted expression, while other Brassicaceae achieve chalaza-specific expression without TE insertion. We hypothesize that the chalaza-specific expression of ABS is regulated by cis-regulatory elements provided by the TE.

AUXIN RESPONSE FACTOR 16 (StARF16) regulates defense gene StNPR1 upon infection with necrotrophic pathogen in potato.

KEY MESSAGE: We demonstrate a new regulatory mechanism in the jasmonic acid (JA) and salicylic acid (SA) mediated crosstalk in potato defense response, wherein, miR160 target StARF16 (a gene involved in growth and development) binds to the promoter of StNPR1 (a defense gene) and negatively regulates its expression to suppress the SA pathway. Overall, our study establishes the importance of StARF16 in regulation of StNPR1 during JA mediated defense response upon necrotrophic pathogen interaction. Plants employ antagonistic crosstalk between salicylic acid (SA) and jasmonic acid (JA) to effectively defend them from pathogens. During biotrophic pathogen attack, SA pathway activates and suppresses the JA pathway via NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1). However, upon necrotrophic pathogen attack, how JA-mediated defense response suppresses the SA pathway, is still not well-understood. Recently StARF10 (AUXIN RESPONSE FACTOR), a miR160 target, has been shown to regulate SA and binds to the promoter of StGH3.6 (GRETCHEN HAGEN3), a gene proposed to maintain the balance between the free SA and auxin in plants. In the current study, we investigated the role of StARF16 (a miR160 target) in the regulation of the defense gene StNPR1 in potato upon activation of the JA pathway. We observed that a negative correlation exists between StNPR1 and StARF16 upon infection with the pathogen. The results were further confirmed through the exogenous application of SA and JA. Using yeast one-hybrid assay, we demonstrated that StARF16 binds to the StNPR1 promoter through putative ARF binding sites. Additionally, through protoplast transfection and chromatin immunoprecipitation experiments, we showed that StARF16 could bind to the StNPR1 promoter and regulate its expression. Co-transfection assays using promoter deletion constructs established that ARF binding sites are present in the 2.6 kb sequence upstream to the StNPR1 gene and play a key role in its regulation during infection. In summary, we demonstrate the importance of StARF16 in the regulation of StNPR1, and thus SA pathway, during JA-mediated defense response upon necrotrophic pathogen interaction.

The unique bryophyte-specific repeat-containing protein SHORT-LEAF regulates gametophore development in moss.

Convergent evolution of shoot development across plant lineages has prompted numerous comparative genetic studies. Though functional conservation of gene networks governing flowering plant shoot development has been explored in bryophyte gametophore development, the role of bryophyte-specific genes remains unknown. Previously, we have reported Tnt1 insertional mutants of moss defective in gametophore development. Here, we report a mutant (short-leaf; shlf) having two-fold shorter leaves, reduced apical dominance, and low plasmodesmata frequency. UHPLC-MS/MS-based auxin quantification and analysis of soybean (Glycine max) auxin-responsive promoter (GH3:GUS) lines exhibited a striking differential auxin distribution pattern in the mutant gametophore. Whole-genome sequencing and functional characterization of candidate genes revealed that a novel bryophyte-specific gene (SHORT-LEAF; SHLF) is responsible for the shlf phenotype. SHLF represents a unique family of near-perfect tandem direct repeat (TDR)-containing proteins conserved only among mosses and liverworts, as evident from our phylogenetic analysis. Cross-complementation with a Marchantia homolog partially recovered the shlf phenotype, indicating possible functional specialization. The distinctive structure (longest known TDRs), absence of any known conserved domain, localization in the endoplasmic reticulum, and proteolytic cleavage pattern of SHLF imply its function in bryophyte-specific cellular mechanisms. This makes SHLF a potential candidate to study gametophore development and evolutionary adaptations of early land plants.

A potent chitin-hydrolyzing enzyme from Myrothecium verrucaria affects growth and development of Helicoverpa armigera and plant fungal pathogens.

Chitin, a crucial structural and functional component of insects and fungi, serves as a target for pest management by utilizing novel chitinases. Here, we report the biocontrol potential of recombinant Myrothecium verrucaria endochitinase (rMvEChi) against insect pest and fungal pathogens. A complete ORF of MvEChi (1185 bp) was cloned and heterologously expressed in Escherichia coli. Structure based sequence alignment of MvEChi revealed the presence of conserved domains SXGG and DXXDXDXE specific for GH-18 family, involved in substrate binding and catalysis, respectively. rMvEChi (46.6 kDa) showed optimum pH and temperature as 7.0 and 30 °C, respectively. Furthermore, rMvEChi remained stable within the pH range of 6.0 to 8.0 and up to 40 °C. rMvEChi exhibited kcat/Km values of 129.83 × 103 [(g/L)-1 s-1] towards 4MU chitotrioside. Hydrolysis of chitooligosaccharides with various degrees of polymerization (DP) using rMvEChi indicated the release of DP2 as main end product with order of reaction as DP6 > DP5 > DP4 > DP3. Bioassay of rMvEChi against Helicoverpa armigera displayed potent anti-feedant activity and induced mortality. In vitro antifungal activity against plant pathogenic fungi (Ustilago maydis and Bipolaris sorokiniana) exhibited significant inhibition of mycelium growth. These results suggest that MvEChi has significant potential in enzyme-based pest and pathogen management.

Agrobacterium-mediated Tnt1 mutagenesis of moss protonemal filaments and generation of stable mutants with impaired gametophyte.

The gametophyte of moss exhibits a simple body plan, yet its growth is regulated by complex developmental phenomena similar to angiosperms. Because moss can be easily maintained under laboratory conditions, amenable for gene targeting and the availability of genome sequence, P. patens has become an attractive model system for studying evolutionary traits. Until date, there has been no Agrobacterium-mediated Tnt1 mutagenesis protocol for haploid protonemal filaments of moss. Hence, we attempted to use the intact tobacco Tnt1 retrotransposon as a mutagen for P. patens. Bioinformatic analysis of initiator methionyl-tRNA (Met-tRNAi), a critical host factor for Tnt1 transposition process, suggested that it can be explored as a mutagen for bryophytes. Using protonemal filaments and Agrobacterium-mediated transformation, 75 Tnt1 mutants have been generated and cryopreserved. SSAP analysis and TAIL-PCR revealed that Tnt1 is functional in P. patens and has a high-preference for gene and GC-rich regions. In addition, LTR::GUS lines exhibited a basal but tissue-specific inducible expression pattern. Forward genetic screen resulted in 5 novel phenotypes related to hormonal and gravity response, phyllid, and gamete development. SSAP analysis suggests that the Tnt1 insertion pattern is stable under normal growth conditions and the high-frequency phenotypic deviations are possibly due to the combination of haploid explant (protonema) and the choice of mutagen (Tnt1). We demonstrate that Agrobacterium-mediated Tnt1 insertional mutagenesis could generate stable P. patens mutant populations for future forward genetic studies.

Mechanistic insights into enzymatic catalysis by trehalase from the insect gut endosymbiont Enterobacter cloacae.

Energy metabolism in the diamondback moth Plutella xylostella is facilitated by trehalase, an enzyme which assists in trehalose hydrolysis, from the predominant gut bacterium Enterobacter cloacae. We report the biochemical and structural characterization of recombinant trehalase from E. cloacae (Px_EclTre). Px_EclTre showed KM of 1.47 (±0.05) mm, kcat of 6254.72 min-1 and Vmax 0.2 (±0.002) mm·min-1 at 55 °C and acidic pH. Crystal structures of Px_EclTre were determined in the ligand-free form and bound to the inhibitor Validoxylamine A. The crystal structure of the ligand-free form, unavailable until now for any other bacterial trehalases, enabled us to delineate the conformational changes accompanying ligand binding in trehalases. Multiple salt bridges were identified that potentially facilitated closure of a hood over the substrate-binding site. A cluster of five tryptophans lined the -1 substrate-binding subsite, interacted with crucial active site residues and contributed to both trehalase activity and stability. The importance of these residues in enzyme activity was further validated by mutagenesis studies. Many of these identified residues form part of signature motifs and other conserved sequences in trehalases. The structure analysis thus led to the assignment of the functional role to these conserved residues. This information can be further explored for the design of effective inhibitors against trehalases.

A Dead Gene Walking: Convergent Degeneration of a Clade of MADS-Box Genes in Crucifers.

Genes are "born," and eventually they "die." These processes shape the phenotypic evolution of organisms and are hence of great biological interest. If genes die in plants, they generally do so quite rapidly. Here, we describe the fate of GOA-like genes that evolve in a dramatically different manner. GOA-like genes belong to the subfamily of Bsister genes of MIKC-type MADS-box genes. Typical MIKC-type genes encode conserved transcription factors controlling plant development. We show that ABS-like genes, a clade of Bsister genes, are indeed highly conserved in crucifers (Brassicaceae) maintaining the ancestral function of Bsister genes in ovule and seed development. In contrast, their closest paralogs, the GOA-like genes, have been undergoing convergent gene death in Brassicaceae. Intriguingly, erosion of GOA-like genes occurred after millions of years of coexistence with ABS-like genes. We thus describe Delayed Convergent Asymmetric Degeneration, a so far neglected but possibly frequent pattern of duplicate gene evolution that does not fit classical scenarios. Delayed Convergent Asymmetric Degeneration of GOA-like genes may have been initiated by a reduction in the expression of an ancestral GOA-like gene in the stem group of Brassicaceae and driven by dosage subfunctionalization. Our findings have profound implications for gene annotations in genomics, interpreting patterns of gene evolution and using genes in phylogeny reconstructions of species.

Genomic and functional characterization of coleopteran insect-specific α-amylase inhibitor gene from Amaranthus species.

The smallest 32 amino acid α-amylase inhibitor from Amaranthus hypochondriacus (AAI) is reported. The complete gene of pre-protein (AhAI) encoding a 26 amino acid (aa) signal peptide followed by the 43 aa region and the previously identified 32 aa peptide was cloned successfully. Three cysteine residues and one disulfide bond conserved within known α-amylase inhibitors were present in AhAI. Identical genomic and open reading frame was found to be present in close relatives of A. hypochondriacus namely Amaranthus paniculatus, Achyranthes aspera and Celosia argentea. Interestingly, the 3'UTR of AhAI varied in these species. The highest expression of AhAI was observed in A. hypochondriacus inflorescence; however, it was not detected in the seed. We hypothesized that the inhibitor expressed in leaves and inflorescence might be transported to the seeds. Sub-cellular localization studies clearly indicated the involvement of AhAI signal peptide in extracellular secretion. Full length rAhAI showed differential inhibition against α-amylases from human, insects, fungi and bacteria. Particularly, α-amylases from Helicoverpa armigera (Lepidoptera) were not inhibited by AhAI while Tribolium castaneum and Callosobruchus chinensis (Coleoptera) α-amylases were completely inhibited. Molecular docking of AhAI revealed tighter interactions with active site residues of T. castaneum α-amylase compared to C. chinensis α-amylase, which could be the rationale behind the disparity in their IC50. Normal growth, development and adult emergence of C. chinensis were hampered after feeding on rAhAI. Altogether, the ability of AhAI to affect the growth of C. chinensis demonstrated its potential as an efficient bio-control agent, especially against stored grain pests.

A glycoprotein α-amylase inhibitor from Withania somnifera differentially inhibits various α-amylases and affects the growth and development of Tribolium castaneum.

BACKGROUND: Identification and characterisation of plant defensive molecules enrich our resources to design crop protection strategies. In particular, plant-derived proteinaceous inhibitor(s) of insect digestive enzymes appear to be a safe, sustainable and attractive option. RESULTS: A glycoprotein having non-competitive α-amylase inhibitory activity with a molecular weight of 8.3 kDa was isolated and purified from seeds of Withania somnifera α-amylase inhibitor (WSAI). Its mass spectrometry analysis revealed 59% sequence coverage with Wrightide II-type α-amylase inhibitor from Wrightia religiosa. A dose-dependent inhibition of α-amylases from Aspergillus oryzae, Bacillus subtilis, Helicoverpa armigera and Tribolium castaneum was recorded. Interestingly, WSAI did not inhibit human salivary α-amylase significantly. When adults of T. castaneum were fed with WSAI (1.6 mg g-1 ), decrease in consumption, growth and efficiency of conversion of ingested food was evident, along with over fourfold increases in feeding deterrence index. A decline in larval residual α-amylase activity after feeding of WSAI resulted in a reduction in longevity of T. castaneum. CONCLUSION: The study reflects the significance of WSAI in affecting the overall growth and development of T. castaneum. Pre- and post-harvest pest resistive capability makes WSAI a potential candidate for insect pest management. Further, the effectiveness of this inhibitor could be explored either in formulations or through a transgenic approach. © 2016 Society of Chemical Industry.

The MADS Box Genes ABS, SHP1, and SHP2 Are Essential for the Coordination of Cell Divisions in Ovule and Seed Coat Development and for Endosperm Formation in Arabidopsis thaliana.

Seed formation is a pivotal process in plant reproduction and dispersal. It begins with megagametophyte development in the ovule, followed by fertilization and subsequently coordinated development of embryo, endosperm, and maternal seed coat. Two closely related MADS-box genes, SHATTERPROOF 1 and 2 (SHP1 and SHP2) are involved in specifying ovule integument identity in Arabidopsis thaliana. The MADS box gene ARABIDOPSIS BSISTER (ABS or TT16) is required, together with SEEDSTICK (STK) for the formation of endothelium, part of the seed coat and innermost tissue layer formed by the maternal plant. Little is known about the genetic interaction of SHP1 and SHP2 with ABS and the coordination of endosperm and seed coat development. In this work, mutant and expression analysis shed light on this aspect of concerted development. Triple tt16 shp1 shp2 mutants produce malformed seedlings, seed coat formation defects, fewer seeds, and mucilage reduction. While shp1 shp2 mutants fail to coordinate the timely development of ovules, tt16 mutants show less peripheral endosperm after fertilization. Failure in coordinated division of the innermost integument layer in early ovule stages leads to inner seed coat defects in tt16 and tt16 shp1 shp2 triple mutant seeds. An antagonistic action of ABS and SHP1/SHP2 is observed in inner seed coat layer formation. Expression analysis also indicates that ABS represses SHP1, SHP2, and FRUITFUL expression. Our work shows that the evolutionary conserved Bsister genes are required not only for endothelium but also for endosperm development and genetically interact with SHP1 and SHP2 in a partially antagonistic manner.

Characterization of two coleopteran α-amylases and molecular insights into their differential inhibition by synthetic α-amylase inhibitor, acarbose.

Post-harvest insect infestation of stored grains makes them unfit for human consumption and leads to severe economic loss. Here, we report functional and structural characterization of two coleopteran α-amylases viz. Callosobruchus chinensis α-amylase (CcAmy) and Tribolium castaneum α-amylase (TcAmy) along with their interactions with proteinaceous and non-proteinaceous α-amylase inhibitors. Secondary structural alignment of CcAmy and TcAmy with other coleopteran α-amylases revealed conserved motifs, active sites, di-sulfide bonds and two point mutations at spatially conserved substrate or inhibitor-binding sites. Homology modeling and molecular docking showed structural differences between these two enzymes. Both the enzymes had similar optimum pH values but differed in their optimum temperature. Overall, pattern of enzyme stabilities were similar under various temperature and pH conditions. Further, CcAmy and TcAmy differed in their substrate affinity and catalytic efficiency towards starch and amylopectin. HPLC analysis detected common amylolytic products like maltose and malto-triose while glucose and malto-tetrose were unique in CcAmy and TcAmy catalyzed reactions respectively. At very low concentrations, wheat α-amylase inhibitor was found to be superior over the acarbose as far as complete inhibition of amylolytic activities of CcAmy and TcAmy was concerned. Mechanism underlying differential amylolytic reaction inhibition by acarbose was discussed.

Biochemical, structural and functional diversity between two digestive α-amylases from Helicoverpa armigera.

BACKGROUND: Helicoverpa armigera (Lepidoptera) feeds on various plants using diverse digestive enzymes as one of the survival tool-kit. The aim of the present study was to understand biochemical properties of recombinant α-amylases of H. armigera viz., HaAmy1 and HaAmy2. METHODS: The open reading frames of HaAmy1 and HaAmy2 were cloned in Pichia pastoris and expressed heterologously. Purified recombinant enzymes were characterized for their biochemical and biophysical attributes using established methods. RESULTS: Sequence alignment and homology modeling showed that HaAmy1 and HaAmy2 were conserved in their amino acid sequences and structures. HaAmy1 and HaAmy2 showed optimum activity at 60°C; however, they differed in their optimum pH. Furthermore, HaAmy2 showed higher affinity for starch and amylopectin whereas HaAmy1 had higher catalytic efficiency. HaAmy1 and HaAmy2 were inhibited to the same magnitude by a synthetic amylase inhibitor (acarbose) while wheat amylase inhibitor showed about 2-fold higher inhibition of HaAmy1 than HaAmy2 at pH7 while 6-fold difference at pH11. Interactions of HaAmy1 and HaAmy2 with wheat amylase inhibitor revealed 2:1 stoichiometric ratio and much more complex interaction with HaAmy1. CONCLUSIONS: The diversity of amylases in perspective of their biochemical and biophysical properties, and their differential interactions with amylase inhibitors signify the potential role of these enzymes in adaptation of H. armigera on diverse plant diets. GENERAL SIGNIFICANCE: Characterization of digestive enzymes of H. armigera provides the molecular basis for the polyphagous nature and thus could assist in designing future strategies for the insect control.

Analysis of the floral transcriptome of Tarenaya hassleriana (Cleomaceae), a member of the sister group to the Brassicaceae: towards understanding the base of morphological diversity in Brassicales.

BACKGROUND: Arabidopsis thaliana, a member of the Brassicaceae family is the dominant genetic model plant. However, while the flowers within the Brassicaceae members are rather uniform, mainly radially symmetrical, mostly white with fixed organ numbers, species within the Cleomaceae, the sister family to the Brassicaceae show a more variable floral morphology. We were interested in understanding the molecular basis for these morphological differences. To this end, the floral transcriptome of a hybrid Tarenaya hassleriana, a Cleomaceae with monosymmetric, bright purple flowers was sequenced, annotated and analyzed in respect to floral regulators. RESULTS: We obtained a comprehensive floral transcriptome with high depth and coverage close to saturation analyzed using rarefaction analysis a method well known in biodiversity studies. Gene expression was analyzed by calculating reads per kilobase gene model per million reads (RPKM) and for selected genes in silico expression data was corroborated by qRT-PCR analysis. Candidate transcription factors were identified based on differences in expression pattern between A. thaliana and T. hassleriana, which are likely key regulators of the T. hassleriana specific floral characters such as coloration and male sterility in the hybrid plant used. Analysis of lineage specific genes was carried out with members of the fabids and malvids. CONCLUSIONS: The floral transcriptome of T. hassleriana provides insights into key pathways involved in the regulation of late anthocyanin biosynthesis, male fertility, flowering time and organ growth regulation which are unique traits compared the model organism A. thaliana. Analysis of lineage specific genes carried out with members of the fabids and malvids suggests an extensive gene birth rate in the lineage leading to core Brassicales while only few genes were potentially lost during core Brassicales evolution, which possibly reflects the result of the At-ß whole genome duplication. Our analysis should facilitate further analyses into the molecular mechanisms of floral morphogenesis and pigmentation and the mechanisms underlying the rather diverse floral morphologies in the Cleomaceae.

The Tarenaya hassleriana genome provides insight into reproductive trait and genome evolution of crucifers.

The Brassicaceae, including Arabidopsis thaliana and Brassica crops, is unmatched among plants in its wealth of genomic and functional molecular data and has long served as a model for understanding gene, genome, and trait evolution. However, genome information from a phylogenetic outgroup that is essential for inferring directionality of evolutionary change has been lacking. We therefore sequenced the genome of the spider flower (Tarenaya hassleriana) from the Brassicaceae sister family, the Cleomaceae. By comparative analysis of the two lineages, we show that genome evolution following ancient polyploidy and gene duplication events affect reproductively important traits. We found an ancient genome triplication in Tarenaya (Th-α) that is independent of the Brassicaceae-specific duplication (At-α) and nested Brassica (Br-α) triplication. To showcase the potential of sister lineage genome analysis, we investigated the state of floral developmental genes and show Brassica retains twice as many floral MADS (for minichromosome maintenance1, AGAMOUS, DEFICIENS and serum response factor) genes as Tarenaya that likely contribute to morphological diversity in Brassica. We also performed synteny analysis of gene families that confer self-incompatibility in Brassicaceae and found that the critical serine receptor kinase receptor gene is derived from a lineage-specific tandem duplication. The T. hassleriana genome will facilitate future research toward elucidating the evolutionary history of Brassicaceae genomes.

Amylase gene expression patterns in Helicoverpa armigera upon feeding on a range of host plants.

Expression of two amylase genes (HaAmy1 and HaAmy2) was studied in Helicoverpa armigera (Hübner; Lepidoptera: Noctuidae) feeding on different host plants and during larval development. Alignment of HaAmy1 and HaAmy2 with other insect amylases shows similarities with known Lepidopteran amylase transcripts. H. armigera amylase gene expression is influenced by the availability of reducing sugars, sucrose and starch content of host plants and further correlates to the pool of reducing sugars in the gut and haemolymph of larvae. HaAmy1 and HaAmy2 during larval development on two host plants viz., maize (cereal) and marigold (ornamental) showed their relative difference. Results support the view that when host plants differ in their macronutrients, relationships of enzymes and substrates are flexible. The present work highlights the distribution of HaAmy1 and HaAmy2 (i) during various stages of insect development (second, fourth and sixth instar, pupa, adult and egg), (ii) in various tissues viz., head, haemolymph, fat body, integument and whole larval body of H. armigera feeding on artificial diet and (iii) in three gut regions of larvae fed on various diets. Complexity in expression of amylase genes suggests existence of mechanisms involved to detect nutrient balance required for avoiding fitness costs and focus their importance in insect nutrition.

Mannitol production from glycerol by resting cells of Candida magnoliae.

Production of mannitol from glycerol by resting cells of Candida magnoliae under aerobic condition was investigated. The resting cells were suspended in aqueous solution of glycerol in Erlenmeyer flasks and incubated on rotary shaker. The samples were analyzed by ion exclusion-HPLC equipped with refractive index and UV detector. The resting cells of C. magnoliae produced mannitol from fructose, sucrose and glycerol but not from glucose. Addition of yeast extract and/or potassium phosphate to the glycerol solution adversely affected its conversion to mannitol. The conversion of glycerol to mannitol was dependent on oxygen availability. Using resting cells, the yield of mannitol was as high as 45%. This is probably the first report of conversion of glycerol to mannitol by osmophilic yeast.