Fine mapping a QTL qCTB7 for cold tolerance at the booting stage on rice chromosome 7 using a near-isogenic line

Low temperature at the booting stage is a serious abiotic stress in rice, and cold tolerance is a complex trait controlled by many quantitative trait loci (QTL). A QTL for cold tolerance at the booting stage in cold-tolerant near-isogenic rice line ZL1929-4 was analyzed. A total of 647 simple sequence repeat (SSR) markers distributed across 12 chromosomes were used to survey for polymorphisms between ZL1929-4 and the cold-sensitive japonica cultivar Towada, and nine were polymorphic. Single marker analysis revealed that markers on chromosome 7 were associated with cold tolerance. By interval mapping using an F₂ population from ZL1929-4 × Towada, a QTL for cold tolerance was detected on the long arm of chromosome 7. The QTL explained 9 and 21% of the phenotypic variances in the F₂ and F₃ generations, respectively. Recombinant plants were screened for two flanking markers, RM182 and RM1132, in an F₂ population with 2,810 plants. Two-step substitution mapping suggested that the QTL was located in a 92-kb interval between markers RI02905 and RM21862. This interval was present in BAC clone AP003804. We designated the QTL as qCTB7 (quantitative trait locus for cold tolerance at the booting stage on chromosome 7), and identified 12 putative candidate genes.     

Heterologous expression of <Emphasis Type="Italic">PDH47</Emphasis> confers drought tolerance in <Emphasis Type="Italic">indica</Emphasis> rice

Jerusalem artichoke (Helianthus tuberosus L.) cultivars are conserved in genebanks for use in breeding and horticultural research programs. Jerusalem artichoke collections are particularly vulnerable to environmental and biological threats because they are often maintained in the field. These field collections could be securely conserved in genebanks if improved cryopreservation methods were available. This work used four Jersualem artichoke cultivars (‘Shudi’, ‘M6’, ‘Stampede’, and ‘Relikt’) to improve upon an existing procedure. Four steps were optimized and the resulting procedure is as follows: preculture excised shoot tips (2–3 mm) in liquid MS medium supplemented with 0.4 M sucrose for 3 days, osmoprotect shoot tips in loading solution for 30 min, dehydrate with plant vitrification solution 2 for 15 min before rapid cooling in liquid nitrogen, store in liquid nitrogen, rapidly rewarm in MS liquid medium containing 1.2 M sucrose, and recover on MS medium supplemented with 0.1 mg L^?1 GA₃ for 3–5 days in the dark and then on the same medium for 4–6 weeks in the light (14 h light/10 h dark). After cryopreservation, Jerusalem artichoke cultivar ‘Shudi’ had the highest survival (93%) and regrowth (83%) percentages. Cultivars ‘M6’, ‘Stampede’, and ‘Relikt’ achieved survival and regrowth percentages ranging from 44 to 72%, and 37–53%, respectively. No genetic changes, as assessed by using simple sequence repeat markers, were detected in plants regenerated after LN exposure in Jerusalem artichoke cultivar ‘Shudi’. Differential scanning calorimetry analyses were used to investigate the thermal activities of the tissues during the cryopreservation process and it was determined that loading with 2.0 M sucrose and 0.4 M sucrose dehydrated the shoot tips prior to treatment with PVS2. Histological observations revealed that the optimized droplet vitrification protocol caused minimal cellular damage within the meristem cells of the shoot tips.     

Overexpression of ethylene response factor <Emphasis Type="Italic">TERF2</Emphasis> confers cold tolerance in rice seedlings

Rice (Oryza sativa L.) is a warm-season plant exposed to various stresses. Low temperature is an important factor limiting extension of rice cultivation areas and productivity. Previously, we have demonstrated that tomato ERF protein TERF2 enhances freezing tolerance of transgenic tobacco and tomato plants. Herein, we report that overexpression of TERF2 enhances transgenic rice tolerance to cold without affecting growth or agronomic traits. Physiological assays revealed that TERF2 could not only increase accumulation of osmotic substances and chlorophyll, but also reduce reactive oxygen species (ROS) and malondialdehyde (MDA) content and decrease electrolyte leakage in rice under cold stress. Further analysis of gene expression showed that TERF2 could activate expression of cold-related genes, including OsMyb, OsICE1, OsCDPK7, OsSODB, OsFer1, OsTrx23, and OsLti6, in transgenic rice plants under natural condition or cold stress. Thus, our findings demonstrated that TERF2 modulated expression of stress-related genes and a series of physiological adjustments under cold stress, indicating that TERF2 might have important regulatory roles in response to abiotic stress in rice and possess potential utility in improving crop cold tolerance.     

Fine mapping of the <Emphasis Type="Italic">qCTS4</Emphasis> locus associated with seedling cold tolerance in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Rice seedlings are sensitive to low temperatures (≤15°C) and under prolonged or repeated exposure, yellowing and stunting are commonly observed. Damage to seedlings results in poor stand establishment and delayed maturation, which can cause significant reductions in yield. In general, japonica rice varieties exhibit more cold tolerance than indica varieties. Earlier genetic analysis of the California rice variety M202 revealed several quantitative trait loci (QTL) that contribute to its tolerance to low temperatures in comparison to the indica rice variety IR50. Among these QTL, qCTS4 is associated with tolerance to yellowing and stunting of rice seedlings and accounts for 40% of the phenotypic variation. Here we report on the fine mapping of qCTS4 to a 128 kb region of chromosome 4, which is highly suppressed for recombination in our mapping populations. Our results provide the necessary foundation for identifying the gene(s) underlying qCTS4 and the markers developed here may be used to introgress this region into indica varieties to improve seedling tolerance to low temperatures. The mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

Characterization of the new human pleomorphic undifferentiated sarcoma <Emphasis Type="Italic">TP53</Emphasis>-<Emphasis Type="Italic">null</Emphasis> cell line <Emphasis Type="Italic">mfh</Emphasis>-<Emphasis Type="Italic">val2</Emphasis>

Pleomorphic undifferentiated sarcoma (PUS), also called malignant fibrous histiocytoma, is a soft tissue sarcoma which occurs predominantly in the extremities. Its origin is a poorly defined mesenchymal cell, which derives to histiocytic and fibroblastic cells. The patient, a 58 year-old man, presented a lesion located in the forearm composed by spindle cells and multinucleated giant cells, which expressed vimentin and adopted a histological pattern formed by irregular-swirling fascicles. Cells were cultured in vitro and a new cell line was established. We characterized this new cell line by histological analyses, cytogenetics (using G-bands and spectral karyotype technique) and cytometric analyses. Cells were grown in culture for more than 100 passages. They had elongated or polygonal morphology. The cells presented a saturation rate of 70,980 cells/cm², a plating efficiency of 21.5% and a mitotic index of 21 mitoses per field. The cell line was tumorigenic in nude mice. The ploidy study using flow cytometry revealed an aneuploid peak with a DNA index of 1.43. A side population was detected, demonstrating the presence of stem and progenitor cells. Cytogenetics showed a hypotriploid range with many clonal unbalanced rearrangements. Loss of p53 gene was evidenced by MLPA. We describe, for the first time, the characterization of a new human PUS TP53-null cell line called mfh-val2. Mfh-val2 presents a wide number of applications as a TP53-null cell line and a great interest in order to characterize genetic alterations influencing the oncogenesis or progression of PUS and to advance in the biological investigation of this tumor.     

Physical mapping and putative candidate gene identification of a quantitative trait locus <Emphasis Type="Italic">Ctb1</Emphasis> for cold tolerance at the booting stage of rice

Norin-PL8 is a cold-tolerant variety of rice (Oryza sativa L.) that was developed by introgressing chromosomal segments from a cold-tolerant tropical japonica variety, Silewah, into a template japonica variety, Hokkai241. We previously identified two closely linked quantitative trait loci, Ctb1 and Ctb2, for cold tolerance at the booting stage of Norin-PL8 in the long arm of chromosome 4. We report here the physical mapping of Ctb1 and the identification of the candidate genes. A total of 2,008 segregating individuals were screened for recombination in the Ctb1 region by a PCR-based screening, and a series of near-isogenic lines (NILs) were developed from progenies of recombinants. A comparison of the degrees of cold tolerance of the NILs indicated that Ctb1 is located in the 56-kb region covered by a bacterial artificial chromosome clone, OSJNBa0058 K23, that had been sequenced by the International Rice Genome Sequence Project. We found seven open reading frames (ORFs) in the 56-kb region. Two ORFs encoded receptor-like protein kinases that are possibly involved in signal transduction pathways. Proteins that may be associated with a ubiquitin-proteasome pathway were encoded by three ORFs, two of which encoded F-box proteins and one of which encoded a protein with a BAG domain. The other two ORFs encoded a protein with an OTU domain and an unknown protein. We were also able to show that Ctb1 is likely to be associated with anther length, which is one of major factors in cold tolerance at the booting stage.     

Isolation,fine mapping and expression profiling of a lesion mimic genotype, <Emphasis Type="Italic">spl</Emphasis><Superscript><Emphasis Type="Italic">NF4050</Emphasis>-<Emphasis Type="Italic">8</Emphasis></Superscript> that confers blast resistance in rice

We evaluated a large collection of Tos17 mutant panel lines for their reaction to three different races of Magnaporthe oryzae and identified a lesion mimic mutant, NF4050-8, that showed lesions similar to naturally occurring spl5 mutant and enhanced resistance to all the three blast races tested. Nested modified-AFLP using Tos17-specific primers and southern hybridization experiments of segregating individuals indicated that the lesion mimic phenotype in NF4050-8 is most likely due to a nucleotide change acquired during the culturing process and not due to Tos17 insertion per se. Inheritance and genetic analyses in two japonica × indica populations identified an overlapping genomic region of 13 cM on short arm of chromosome 7 that was linked with the lesion mimic phenotype. High-resolution genetic mapping using 950 F₃ and 3,821 F₄ plants of NF4050-8 × CO39 delimited a 35 kb region flanked by NBARC1 (5.262 Mb) and RM8262 (5.297 Mb), which contained 6 ORFs; 3 of them were ‘resistance gene related’ with typical NBS–LRR signatures. One of them harbored a NB–ARC domain, which had been previously demonstrated to be associated with cell death in animals. Microarray analysis of NF4050-8 revealed significant up-regulation of numerous defense/pathogenesis-related genes and down-regulation of heme peroxidase genes. Real-time PCR analysis of WRKY45 and PR1b genes suggested possible constitutive activation of a defense signaling pathway downstream of salicylic acid but independent of NH1 in these mutant lines of rice.     

Biological synthesis of quercetin 3-<Emphasis Type="Italic">O</Emphasis>-<Emphasis Type="Italic">N</Emphasis>-acetylglucosamine conjugate using engineered <Emphasis Type="Italic">Escherichia coli</Emphasis> expressing <Emphasis Type="Italic">UGT78D2</Emphasis>

Biotransformation of flavonoids using Escherichia coli harboring nucleotide sugar-dependent uridine diphosphate-dependent glycosyltransferases (UGTs) commonly results in the production of a glucose conjugate because most UGTs are specific for UDP-glucose. The Arabidopsis enzyme AtUGT78D2 prefers UDP-glucose as a sugar donor and quercetin as a sugar acceptor. However, in vitro, AtUGT78D2 could use UDP-N-acetylglucosamine as a sugar donor, and whole cell biotransformation of quercetin using E. coli harboring AtUGT78D2 produced quercetin 3-O-N-acetylglucosamine. In order to increase the production of quercetin 3-O-N-acetylglucosamine via biotransformation, two E. coli mutant strains deleted in phosphoglucomutase (pgm) or glucose-1-phosphate uridylyltransferase (galU) were created. The galU mutant produced up to threefold more quercetin 3-O-N-acetylglucosamine than wild type, resulting in the production of 380-mg/l quercetin 3-O-N-acetylglucosamine and a negligible amount of quercetin 3-O-glucoside. These results show that construction of bacterial strains for the synthesis of unnatural flavonoid glycosides is possible through rational selection of the nucleotide sugar-dependent glycosyltransferase and engineering of the nucleotide sugar metabolic pathway in the host strain.     

Fine mapping of <Emphasis Type="Italic">qSTV11</Emphasis><Superscript><Emphasis Type="Italic">KAS</Emphasis></Superscript>, a major QTL for rice stripe disease resistance

Rice stripe disease, caused by rice stripe virus (RSV), is one of the most serious diseases in temperate rice-growing areas. In the present study, we performed quantitative trait locus (QTL) analysis for RSV resistance using 98 backcross inbred lines derived from the cross between the highly resistant variety, Kasalath, and the highly susceptible variety, Nipponbare. Under artificial inoculation in the greenhouse, two QTLs for RSV resistance, designated qSTV7 and qSTV11 ^KAS , were detected on chromosomes 7 and 11 respectively, whereas only one QTL was detected in the same location of chromosome 11 under natural inoculation in the field. The stability of qSTV11 ^KAS was validated using 39 established chromosome segment substitution lines. Fine mapping of qSTV11 ^KAS was carried out using 372 BC₃F_2:3 recombinants and 399 BC₃F_3:4 lines selected from 7,018 BC₃F₂ plants of the cross SL-234/Koshihikari. The qSTV11 ^KAS was localized to a 39.2 kb region containing seven annotated genes. The most likely candidate gene, LOC_Os11g30910, is predicted to encode a sulfotransferase domain-containing protein. The predicted protein encoded by the Kasalath allele differs from Nipponbare by a single amino acid substitution and the deletion of two amino acids within the sulfotransferase domain. Marker-resistance association analysis revealed that the markers L104-155 bp and R48-194 bp were highly correlated with RSV resistance in the 148 landrace varieties. These results provide a basis for the cloning of qSTV11 ^KAS , and the markers may be used for molecular breeding of RSV resistant rice varieties.     

Thai jasmine rice cultivar KDML105 carrying <Emphasis Type="Italic">Saltol</Emphasis> QTL exhibiting salinity tolerance at seedling stage

Saltol, the major salinity tolerance quantitative trait loci (QTL) in rice, was introgressed from IR66946-3R-230-1-1 (FL530) into Khao Dawk Mali 105 (KDMl105) by two rounds of marker-assisted backcrossing (MAB). Twenty-eight BC₂F₂ introgression lines (BILs) with positive Saltol allele (BIL^+Saltol) and 19 BILs with negative Saltol allele (BIL^?Saltol) were validated for the effect of Saltol as key salinity tolerant trait at seedling stage. A hydrophonic system with salt stress of 12 dS m^?1 (130 mM Na⁺) was conducted, and significant differences between BILs^+Saltol and BILs^?Saltol were observed for the period of plant survival (PPS), total K⁺ (T-K⁺) and Na⁺ (T-Na⁺) concentration, whole plant Na⁺-K⁺ ratio (T-Na⁺/K⁺), shoot Na⁺ (S-Na⁺) and K⁺ (S-K⁺) concentration, and shoot Na⁺-K⁺ ratio (S-Na⁺/K⁺). BILs^+Saltol displayed higher PPS, uptake less Na⁺ (T-Na⁺; 43.4 ppm), and more K⁺ (T-K⁺; 30.9 ppm), while the BILs^?Saltol uptake more Na⁺ (T-Na⁺; 45.7 ppm) and less K⁺ (T-K⁺; 28.2 ppm). Direct effects on PPS and salt injury score (SIS) were observed, indicating Na⁺/K⁺ homeostasis mechanism by the Saltol under hydrophonic salt stress. All BILs^+Saltol recovered KDML105 cooking quality profile such as low apparent amylose content (AAC), high score of alkaline spreading value (ASV), intermediate gel consistency (GC), and strong fragrance. However, variation in agronomic traits was observed. The possibility of lowering S-Na⁺/K⁺ ratio under salt stress at seedling stage in KDML105 by introgression of the Saltol was demonstrated. Currently, BC₂F₇ of the BIL^+Saltol selected lines are being tested for salinity tolerance in the salt-affected areas in the northeast of Thailand.     

Fine mapping of a male sterility gene <Emphasis Type="Italic">ms</Emphasis>-<Emphasis Type="Italic">3</Emphasis> in a novel cucumber (<Emphasis Type="Italic">Cucumis sativus</Emphasis> L.) mutant

Key message

The cucumber male sterility gene ms - 3 was fine mapped in a 76 kb region harboring an MMD1 -like gene Csa3M006660 that may be responsible for the male sterile in cucumber.

Abstract

A cucumber (Cucumis sativus L.) male sterile mutant (ms-3) in an advanced-generation inbred line was identified, and genetic analysis revealed that the male sterility trait was controlled by a recessive nuclear gene, ms-3, which was stably inherited. Histological studies suggested that the main cause of the male sterility was defective microsporogenesis, resulting in no tetrad or microspores being formed. Bulked segregant analysis (BSA) and genotyping of an F₂ population of 2553 individuals were employed used to fine map ms-3, which was delimited to a 76 Kb region. In this region, a single non-synonymous SNP was found in the Csa3M006660 gene locus, which was predicted to result in an amino acid change. Quantitative RT-PCR analysis of Csa3M006660 was consistent with the fact that it plays a role in the early development of cucumber pollen. The protein encoded by Csa3M006660 is predicted to be homeodomain (PHD) finger protein, and the high degree of sequence conservation with homologs from a range of plant species further suggested the importance of the ms-3 non-synonymous mutation. The data presented here provide support for Csa3M006660 as the most likely candidate gene for Ms-3.

     

<Emphasis Type="Italic">egl</Emphasis>-<Emphasis Type="Italic">4</Emphasis> modulates electroconvulsive seizure duration in <Emphasis Type="Italic">C. elegans</Emphasis>

Increased neuronal excitability causes seizures with debilitating symptoms. Effective and noninvasive treatments are limited for easing symptoms, partially due to the complexity of the disorder and lack of knowledge of specific molecular faults. An unexplored, novel target for seizure therapeutics is the cGMP/protein kinase G (PKG) pathway, which targets downstream K⁺ channels, a mechanism similar to Retigabine, a recently FDA-approved antiepileptic drug. Our results demonstrate that increased PKG activity decreased seizure duration in C. elegans utilizing a recently developed electroconvulsive seizure assay. While the fly is a well-established seizure model, C. elegans are an ideal yet unexploited model which easily uptakes drugs and can be utilized for high-throughput screens. In this study, we show that treating the worms with either a potassium channel opener, Retigabine or published pharmaceuticals that increase PKG activity, significantly reduces seizure recovery times. Our results suggest that PKG signaling modulates downstream K⁺ channel conductance to control seizure recovery time in C. elegans. Hence, we provide powerful evidence, suggesting that pharmacological manipulation of the PKG signaling cascade may control seizure duration across phyla.     

Mechanisms of thaxtomin A-induced root toxicity revealed by a thaxtomin A sensitive <Emphasis Type="Italic">Arabidopsis</Emphasis> mutant (<Emphasis Type="Italic">ucu2</Emphasis>-<Emphasis Type="Italic">2/gi</Emphasis>-<Emphasis Type="Italic">2</Emphasis>)

Key message

The Arabidopsis mutant ( ucu2 - 2/gi - 2 ) is thaxtomin A, isoxaben and NPA-sensitive indicated by root growth and ion flux responses providing new insights into these compounds mode of action and interactions.

Abstract

Thaxtomin A (TA) is a cellulose biosynthetic inhibitor (CBI) that promotes plant cell hypertrophy and cell death. Electrophysiological analysis of steady-state K⁺ and Ca²⁺ fluxes in Arabidopsis thaliana roots pretreated with TA for 24 h indicated a disturbance in the regulation of ion movement across the plant cell membrane. The observed inability to control solute movement, recorded in rapidly growing meristematic and elongation root zones, may partly explain typical root toxicity responses to TA treatment. Of note, the TA-sensitive mutant (ucu2-2/gi-2) was more susceptible with K⁺ and Ca²⁺ fluxes altered between 1.3 and eightfold compared to the wild-type control where fluxes altered between 1.2 and threefold. Root growth inhibition assays showed that the ucu2-2/gi-2 mutant had an increased sensitivity to the auxin 2,4-D, but not IAA or NAA; it also had increased sensitivity to the auxin efflux transport inhibitor, 1-naphthylphthalamic acid (NPA), but not 2,3,5- Triiodobenzoic acid (TIBA), when compared to the WT. The NPA sensitivity data were supported by electrophysiological analysis of H⁺ fluxes in the mature (but not elongation) root zone. Increased sensitivity to the CBI, isoxaben (IXB), but not dichlobenil was recorded. Increased sensitivity to both TA and IXB corresponded with higher levels of accumulation of these toxins in the root tissue, compared to the WT. Further root growth inhibition assays showed no altered sensitivity of ucu2-2/gi-2 to two other plant pathogen toxins, alternariol and fusaric acid. Identification of a TA-sensitive Arabidopsis mutant provides further insight into how this CBI toxin interacts with plant cells.

     

Overexpression of <Emphasis Type="Italic">MeDREB1D</Emphasis> confers tolerance to both drought and cold stresses in transgenic <Emphasis Type="Italic">Arabidopsis</Emphasis>

Cassava (Manihot esculenta) is an important tropical crop with extraordinary tolerance to drought stress but few reports on it. In this study, MeDREB1D was significantly and positively induced by drought stress. Two allelic variants of the gene named MeDREB1D(R-2) and MeDREB1D(Y-3) were identified. Overexpressing MeDREB1D(R-2) and MeDREB1D(Y-3) in Arabidopsis resulted in stronger tolerance to drought and cold stresses. Under drought stress, transgenic plants had more biomass, higher survival rates and less MDA content than wild-type plants. Under cold stress, transgenic plants also had higher survival rates than wild-type plants. To further characterize the molecular function of MeDREB1D, we conducted an RNA-Seq analysis of transgenic and wild-type Arabidopsis plants. The results showed that the Arabidopsis plants overexpressing MeDREB1D led to changes in downstream genes. Several POD genes, which may play a vital role in drought and cold tolerance, were up-regulated in transgenic plants. In brief, these results suggest that MeDREB1D can simultaneously improve plant tolerance to drought and cold stresses.     

Molecular evolution of the clustered <Emphasis Type="Italic">MIC</Emphasis>-<Emphasis Type="Italic">3</Emphasis> multigene family of <Emphasis Type="Italic">Gossypium</Emphasis> species

The Gossypium MIC-3 (Meloidogyne Induced Cotton-3) gene family is of great interest for molecular evolutionary studies because of its uniqueness to Gossypium species, multi-gene content, clustered localization, and root-knot nematode resistance-associated features. Molecular evolution of the MIC-3 gene family was studied in 15 tetraploid and diploid Gossypium genotypes that collectively represent seven phylogenetically distinct genomes. Synonymous (d_S) and non-synonymous (d_N) nucleotide substitution rates suggest that the second of the two exons of the MIC-3 genes has been under strong positive selection pressure, while the first exon has been under strong purifying selection to preserve function. Based on nucleotide substitution rates, we conclude that MIC-3 genes are evolving by a birth-and-death process and that a ‘gene amplification’ mechanism has helped to retain all duplicate copies, which best fits with the “bait and switch” model of R-gene evolution. The data indicate MIC-3 gene duplication events occurred at various rates, once per 1 million years (MY) in the allotetraploids, once per ~2 MY in the A/F genome clade, and once per ~8 MY in the D-genome clade. Variations in the MIC-3 gene family seem to reflect evolutionary selection for increased functional stability, while also expanding the capacity to develop novel “switch” pockets for responding to diverse pests and pathogens. Such evolutionary roles are congruent with the hypothesis that members of this unique resistance gene family provide fitness advantages in Gossypium.     

Fine genetic mapping of <Emphasis Type="Italic">xa24</Emphasis>, a recessive gene for resistance against <Emphasis Type="Italic">Xanthomonas oryzae</Emphasis> pv. <Emphasis Type="Italic">oryzae</Emphasis> in rice

Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is the most devastating plant bacterial disease worldwide. Different bacterial blight resistance (R) genes confer race-specific resistance to different strains of Xoo. We fine mapped a fully recessive gene, xa24, for bacterial blight resistance to a 71-kb DNA fragment in the long arm of rice chromosome 2 using polymerase chain reaction-based molecular markers. The xa24 gene confers disease resistance at the seedling and adult stages. It mediates resistance to at least the Philippine Xoo races 4, 6 and 10 and Chinese Xoo strains Zhe173, JL691 and KS-1-21. Sequence analysis of the DNA fragment harboring the dominant (susceptible) allele of xa24 suggests that this gene should encode a novel protein that is not homologous to any known R proteins. These results will greatly facilitate the isolation and characterization of xa24. The markers will be convenient tools for marker-assisted selection of xa24 in breeding programs. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Regulation of stipule development by <Emphasis Type="Italic">COCHLEATA</Emphasis> and <Emphasis Type="Italic">STIPULE</Emphasis>-<Emphasis Type="Italic">REDUCED</Emphasis> genes in pea <Emphasis Type="Italic">Pisum sativum</Emphasis>

Pisum sativum L., the garden pea crop plant, is serving as the unique model for genetic analyses of morphogenetic development of stipule, the lateral organ formed on either side of the junction of leafblade petiole and stem at nodes. The stipule reduced (st) and cochleata (coch) stipule mutations and afila (af), tendril-less (tl), multifoliate-pinna (mfp) and unifoliata-tendrilled acacia (uni-tac) leafblade mutations were variously combined and the recombinant genotypes were quantitatively phenotyped for stipule morphology at both vegetative and reproductive nodes. The observations suggest a role of master regulator to COCH in stipule development. COCH is essential for initiation, growth and development of stipule, represses the UNI-TAC, AF, TL and MFP led leafblade-like morphogenetic pathway for compound stipule and together with ST mediates the developmental pathway for peltate-shaped simple wild-type stipule. It is also shown that stipule is an autonomous lateral organ, like a leafblade and secondary inflorescence.