Leaves, not roots or floral tissue, are the main site of rapid, external pressure-induced ABA biosynthesis in angiosperms

Rapid biosynthesis of abscisic acid (ABA) in the leaf, triggered by a decrease in cell volume, is essential for a functional stomatal response to vapour pressure deficit (VPD) in angiosperms. However, it is not known whether rapid biosynthesis of ABA is triggered in other plant tissues as well. Through the application of external pressure to flower, root and leaf tissues, we test whether a reduction in cell volume can trigger rapid increases in ABA levels across plant body in two species Solanum lycopersicum and Passiflora tarminiana. Our results show that, in contrast to rapid ABA synthesis in the leaf, flower and root tissue did not show a significant, rapid increase in ABA level in response to a drop in cell volume over a short time-frame, suggesting that fast ABA biosynthesis occurs only in leaf, not in flower or root tissues. A gene encoding the key, rate-limiting carotenoid cleavage enzyme (9`-cis-epoxycarotenoid dioxygenase, NCED) in ABA biosynthetic pathway in S. lycopersicum, NCED1, was unregulated to lesser degree in flowers and roots compared to leaves in response to applied pressure. In both species, floral tissues contained substantially lower levels of NCED substrate 9`-cis-neoxanthin than leaves, and this ABA precursor could not be detected in roots. Slow and minimal ABA biosynthesis was detected after 2 h in petals, indicating that floral tissue is capable of synthesising ABA in response to sustained water deficit. Our results indicate that rapid ABA biosynthesis predominantly occurs in the leaves, and not in other tissues

A genome-scale integrated approach aids in genetic dissection of complex flowering time trait in chickpea

A combinatorial approach of candidate gene-based association analysis and genome-wide association study (GWAS) integrated with QTL mapping, differential gene expression profiling and molecular haplotyping was deployed in the present study for quantitative dissection of complex flowering time trait in chickpea. Candidate gene-based association mapping in a flowering time association panel (92 diverse desi and kabuli accessions) was performed by employing the genotyping information of 5724 SNPs discovered from 82 known flowering chickpea gene orthologs of Arabidopsis and legumes as well as 832 gene-encoding transcripts that are differentially expressed during flower development in chickpea. GWAS using both genome-wide GBS- and candidate gene-based genotyping data of 30,129 SNPs in a structured population of 92 sequenced accessions (with 200–250 kb LD decay) detected eight maximum effect genomic SNP loci (genes) associated (34 % combined PVE) with flowering time. Six flowering time-associated major genomic loci harbouring five robust QTLs mapped on a high-resolution intra-specific genetic linkage map were validated (11.6–27.3 % PVE at 5.4–11.7 LOD) further by traditional QTL mapping. The flower-specific expression, including differential up- and down-regulation (>three folds) of eight flowering time-associated genes (including six genes validated by QTL mapping) especially in early flowering than late flowering contrasting chickpea accessions/mapping individuals during flower development was evident. The gene haplotype-based LD mapping discovered diverse novel natural allelic variants and haplotypes in eight genes with high trait association potential (41 % combined PVE) for flowering time differentiation in cultivated and wild chickpea. Taken together, eight potential known/candidate flowering time-regulating genes [efl1 (early flowering 1), FLD (Flowering locus D), GI (GIGANTEA), Myb (Myeloblastosis), SFH3 (SEC14-like 3), bZIP (basic-leucine zipper), bHLH (basic helix-loop-helix) and SBP (SQUAMOSA promoter binding protein)], including novel markers, QTLs, alleles and haplotypes delineated by aforesaid genome-wide integrated approach have potential for marker-assisted genetic improvement and unravelling the domestication pattern of flowering time in chickpea

The Pea Photoperiod Response Gene STERILE NODES Is an Ortholog of LUX ARRHYTHMO

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Identification and phylogenetic analysis of FT genes in common bean (Phaseolus vulgaris L.)

1 página.-Resumen del póster presentado en el Simposio que bajo el título "Plant proteins for the future" se celebró en Pontevedra entre el 4 y el 7 de mayo de 2015.Flowering in many plant species is controlled by photoperiod, which represents the most reliable seasonal change in nature. The availability of crops with different photoperiod responses made it possible to extend their distribution range. The gene network controlling flowering is well studied in the model plant Arabidopsis thaliana, where the FLOWERING LOCUS T (FT) gene is crucial for the acceleration of flowering. FT is part of a gene family that also includes the TERMINAL FLOWER 1 (TFL1) gene, which inhibits flowering. Constitutive FT expression or loss of TFL1 function causes early flowering and transition of the shoot apex from vegetative to reproductive identity. FT proteins have a conserved role as mobile flowering signals in several different species and promote flowering in long or short days depending on the species. The induction of flowering by FT family members has been investigated in legumes such as pea, soybean and Medicago but the FT family has not yet been characterized in common bean. Increasing knowledge of the identity and regulation of FT genes in common bean will be helpful to select variants that are better adapted to changing photoperiod conditions. BLAST searching revealed ten genes with homology to FT/TFL1 in the common bean genome. The inferred phylogenetic tree from the identified common bean FT/TFL1 amino acid sequences and sequences of soybean (Glycine max), chickpea (Cicer arietinum), Medicago truncatula, Lotus japonica, and pea (Pisum sativum) indicated that common bean contains MFT-like, BFT-like and FT/TFL1-like genes. Phylogenetic analyses also revealed substantial levels of microsynteny between Medicago, chickpea and pea, and between soybean and common bean, as expected from their proximity within the legume family. These results indicate that the expansion of the FT family occurred relatively early in legume evolution.This work was financially supported by the Ministerio de Economía y Competitividad (AGL2011-25562) and UE-FEDER Program. The authors would also like to thank Junta de Andalucía (grant number P10-AGR-06931), Campus de Excelencia Internacional Agroalimentario-CeiA3 and Xunta de Galicia (GAIN37/2014) for partially supporting this work financially.Peer reviewe

The homologues of Arabidopsis FLOWERING LOCUS T and GIGANTEA genes are involved in the control of photoperiod response of flowering in common bean

Resumen y póster del trabajo presentado en la Conferencia internacional que bajo el lema "Legumes for a sustainable world" tuvo lugar en Troia, Portugal, entre el 11 y el 14 de octubre de 2016.In the common bean short-day (SD) plant, seasonal flowering is a crucial aspect of maximizing reproductive fitness. Expansion to higher latitudes or changes in day length has been accompanied by earlier flowering under long-day (LD) and a reduction in photoperiod responsiveness that enables plants to anticipate approaching seasonal variation in the surrounding environment. In the model species Arabidopsis thaliana, flowering time is determined by day-length¿dependent induction of the FLOWERING LOCUS T (FT) gene, which encodes a floral-inductive mobile signal, and GIGANTEA (GI) gene acting upstream of FT. The characterization of common bean homologues of Arabidopsis photoperiodic flowering pathway genes is reported with the end goal of accelerating common bean breeding by understanding the genetic basis of day-length adaptation.This work was financially supported by the Ministerio de Economía y Competitividad (AGL2014-51809-R), Investigación y Tecnología Agraria y Alimentaria (RF2012-C00026-C02-01 and RF2012-C00026-C02-02) and UE-FEDER Program.Peer reviewe