Dwarf Growth Habit Research Articles

Evaluation of lablab bean [Lablab purpureus (L.) sweet] genotypes: unveiling superior pod yield, nutritional quality, and collar rot resistance.

Malnutrition continues to be a significant concern at unacceptably high levels globally. There is significant potential for addressing malnutrition of human population through the biofortification of climate-resilient vegetables using strategic breeding strategies. Lablab bean [Lablab purpureus (L.) Sweet], a underutilized nutrient-dense crop holds great potential in this aspect. Despite its advantageous nutritional profile, the production, research, and consumption of lablab bean are currently limited. Addressing these limitations and unlock the nutritional benefits of lablab beans needs to prioritized for fighting malnutrition in local inhabitants on a global scale. Twenty five genotypes of lablab bean collected through exploration survey in Eastern India and were evaluated in 2020-2021. Among them, the nine highly diverse well adapted genotypes were again evaluated at the experimental farm of ICAR-Research Complex for Eastern Region, Patna, Bihar, India in 2021-2022. Horticultural important traits of lablab bean were recorded by using the minimum descriptors developed by ICAR-NBPGR in New Delhi and biochemical analysis was done by using standard protocols. Genotypic and phenotypic correlation and path coefficient analysis was done used understand relationships, interdependencies, and causal pathways between different traits. The outcome was revalidated by using principal component analysis (PCA). Descriptive statistics revealed substantial heterogeneity across the traits of lablab bean evaluated. Vitamin A content showed nearly a five-fold variation, Fe ranged from 5.97 to 10.5 mg/100 g, and Vitamin C varied from 4.61 to 9.45 mg/100 g. Earliness and dwarf growth was observed in RCPD-1 (60 cm) and early flowering (41 days). RCPD-3 and RCPD-12 had high pod yield due to their high number of pods and pod weight. Pod yield was significantly correlated with number of pod per plant (NPP) (rg = 0.995) and with average pod weight (APW) (rg = 0.882). A significant positive correlation was also found between protein and Zn content (rg = 0.769). Path coefficient analysis revealed that average pod weight had the most direct positive effect on pod yield, followed by NPP and protein content. The reaction of lablab bean genotypes to collar rot disease was also evaluated and significant differences in disease intensity were observed among the genotypes, with the resistant check RCPD-15 exhibiting the lowest disease intensity. The study highlights the substantial heterogeneity in lablab bean traits, particularly in nutritional components such as vitamin A, iron, and vitamin C concentrations. Early flowering and dwarf growth habit are desirable qualities for lablab bean, and certain genotypes were found to exhibit these traits. Positive correlations, both phenotypic and genotypic, existed among different traits, suggesting the potential for simultaneous improvement. Path coefficient and PCA revealed genotypes with high yield and nutritional traits. Finally, resistant and moderately resistant lablab bean genotypes to collar rot disease were identified. These findings contribute to the selection and breeding strategies for improving lablab bean production and nutritional value.

A single nucleotide substitution in the MATE transporter gene regulates plastochron and the many noded dwarf phenotype in barley (Hordeum vulgare L.)

In higher plants, the shoot apical meristem produces lateral organs in a regular spacing (phyllotaxy) and timing (plastochron). The molecular analysis of mutants associated with phyllotaxy and plastochron would increase our understanding of the mechanism of shoot architecture formation. In this study, we identified mutant mnd8ynp5 that shows an increased rate of leaf emergence and a larger number of nodes in combination with a dwarfed growth habit from an EMS-treated population of the elite barley cultivar Yangnongpi 5. Using a map-based cloning strategy, the mnd8 gene was narrowed down to a 6.7-kb genomic interval on the long arm of chromosome 5H. Sequence analysis revealed that a C to T single-nucleotide mutation occurred at the first exon (position 953) of HORVU5Hr1G118820, leading to an alanine (Ala) to valine (Val) substitution at the 318th amino acid site. Next, HORVU5Hr1G118820 was defined as the candidate gene of MND8 encoding 514 amino acids and containing two multidrug and toxic compound extrusion (MATE) domains. It is highly homologous to maize Bige1 and has a conserved function in the regulation of plant development by controlling the leaf initiation rate. Examination of modern barely varieties showed that Hap-1 was the dominant haplotype and was selected in barley breeding around the world. Collectively, our results indicated that mnd8ynp5 is a novel allele of the HORVU5Hr1G118820 gene that is possibly responsible for the shortened plastochron and many noded dwarf phenotype in barley.

Required mowing events of transgenic Kentucky bluegrass cultivars compared with conventional turfgrass cultivar blends and species mixtures

AbstractMowing is a labor‐intensive yet important cultural practice to maximize turfgrass health and performance. Selecting cultivars with a slower vertical growth habit can help reduce mowing frequency and improve turfgrass quality (TQ). New transgenic Kentucky bluegrass (Poa pratensis L.) (KBG) cultivars with a dwarf growth habit have been developed by overexpressing the gibberellin 2‐oxidase pathway. However, the impact of this overexpression on the number of required mowing events and mowing frequency in the field is unknown. Therefore, the primary objective of this research was to quantify the required number of mowing events based on the one‐third rule of four transgenic cultivars (‘ProVista’) (PV) and 16 conventional turfgrass cultivars, blends, and mixtures. Over the 2‐yr research period, four PV cultivars in the top statistical group averaged ≤21 mowing events, whereas all other turfgrasses averaged ≥41 mowing events. For mowing frequency, all PV cultivars required an average mowing frequency of ≥20 d, whereas all other turfgrasses required an average mowing frequency of ≤10 d. Although the PV cultivars required half as many mowing events, two of the PV cultivars were consistently in the top statistical group for TQ. The PV KBG cultivars represent new technology for turfgrass genetics with the novel trait of reduced mowing that can benefit the industry by reducing mower emissions, noise, and use, as well as increased TQ and flexibility for turfgrass practitioners, since mowing frequency can be extended.

Fine Mapping of Cla015407 Controlling Plant Height in Watermelon

The plant compact and dwarf growth habit is an important agronomic trait when breeding watermelon (Citrullus lanatus) cultivars because of their reduced vine length, high-density planting, and better land utilization; however, the genetic basis of the dwarf growth habit is not well-known. In this study, the plant population of six generations, P1, P2, F1, F2, BC1P1, and BC1P2, were studied. A genetic segregation analysis demonstrated that dwarfism is mainly controlled by a single recessive Cldw gene. Furthermore, whole-genome sequencing of two distinct watermelon cultivars, W1-1 (P1) and 812 (P2), was performed and preliminarily mapped through a bulked segregant analysis of F2 individuals that revealed the Cldw gene locus on chromosome 9. Two candidate genes, Cla015407 and Cla015408, were discovered at the delimited region of 43.2 kb by fine mapping, and gene annotation exposed that the Cla015407 gene encodes gibberellic acid 3β-hydroxylase protein. In addition, a comparative analysis of gene sequence and cultivars sequences across the reference genome of watermelon revealed the splice site mutation in the intron region of the Cldw gene in dwarf-type cultivar 812. The quantitative real-time polymerase chain reaction exhibited a significantly higher expression of the Cla015407 gene in cultivar W1-1 compared with 812. There was no significant difference in the vine length of both cultivars after gibberellic acid treatment. In brief, our fine mapping demonstrated that Cla015407 is a candidate gene controlling dwarfism of watermelon plants.

Obtaining new Ruscus products using Gamma radiation

Abstract Ruscus is an evergreen shrub that offers dark-green glossy foliage used as green additions to bouquets and flower arrangements. One of the most significant ways to obtain new varieties of crop and ornamental plants is to induce mutations by radiation. Gamma radiation is most commonly used to obtain mutants in commercial food as well as feed crops and ornamental plants. In this study, we developed tissue culture methods for Ruscus proliferation from rhizomes to obtain rhizomes clusters. These clusters were subsequently irradiated with Gamma rays to obtain unique phenotypes, such as: elongated narrow phylloclades modified stem symmetry and dwarfed growth habit. Such Ruscus types can contribute to the expansion of the floral industry.

Deletion in the Promoter of PcPIN-L Affects the Polar Auxin Transport in Dwarf Pear (Pyrus communis L.)

Dwarf cultivars or dwarfing rootstocks enable high-density planting and are therefore highly desirable in modern pear production. Previously, we found that the dwarf growth habit of pear is controlled by a single dominant gene PcDw. In this study, PcPIN-L (PCP021016) was cloned from dwarf-type and standard-type pears. PcPIN-L expression was significantly lower in the dwarf-type pears than in standard-type pears, which was caused by the CT repeat deletion in the promoter of dwarf-type pears. PcPIN-L overexpression in tobacco plants enhanced the growth of the stems and the roots. Notably, the indole acetic acid (IAA) content decreased in the shoot tips and increased in the stems of transgenic lines compared with wild type, which is consistent with the greater IAA content in the shoot tips and lower IAA content in the stems of dwarf-type pears than in standard-type pears. The CT repeat deletion in the promoter that causes a decrease in promoter activity is associated with lower PcPIN-L expression in the dwarf-type pears, which might limit the polar auxin transport and in turn result in the dwarf phenotype. Taken together, the results provide a novel dwarfing molecular mechanism in perennial woody plants.

Development of molecular markers for genetic and physical mapping of the PcDw locus in pear (Pyrus communis L.)

ABSTRACTDwarf tree architecture is an important agronomic trait for modern fruit breeding and cultivation. The dwarf growth habit of pear (Pyrus communis L.), inherited from the pear cultivar ‘Nain Vert’, is controlled by a single dominant gene PcDw. To fine map the PcDw locus at higher resolution, 14 primer pairs for recently reported simple sequence repeat (SSR) markers mapped to the top region of linkage group 16 (LG16) in the apple and pear linkage maps, as well as 43 and 50 new primer pairs based on apple and European pear genome sequences for identifying SSR markers and single nucleotide polymorphism (SNP) markers, respectively, were analysed in the F1 progeny of an ‘Aihuali’ × ‘Chili’ cross by bulked segregant analysis. Eight new PcDw-linked markers, consisting of six SSR markers and two SNP markers detected by high resolution melting analysis, were obtained. Linkage analysis showed that the PcDw locus was flanked by the SSR markers CN993875 and QauSSR36, and that PcDw was mapped to scaffold00074: 137126–163908 in the European pear genome. Six gene transcripts have been predicted in this region. Several closely linked markers were also tested in the F1 progeny of a ‘7-34’ × ‘Zhongxiang’ cross. In this case, the PcDw locus co-segregated with SSR markers CN993875 and QauSSR36. Our findings should facilitate the identification of PcDw in the pear genome and thereby help elucidate the molecular mechanism of the dwarf habit in pear.

Gamma-ray Irradiation Induces Useful Morphological Variation in Bermudagrass

Bermudagrass, Cynodon dactylon (L.) Pers. is a widely used warm-season turfgrass species in warmer regions of the world. Gamma (ɣ) irradiation has been used to generate useful variations in turfgrass breeding for various morphological traits. The objective of the present study was to measure and determine variations in morphology and turfgrass characteristics of a native drought resistant bermudagrass germplasm irradiated with 70, 90 or 110 Gy using a 60Co source. The stolons containing a single node were irradiated and immediately planted for regeneration in a greenhouse at the Akdeniz University, Antalya, Turkey. Selected mutants regenerated from the irradiated stolons were clonally propagated and transplanted into plastic pots for further observations of turfgrass characteristics. Survival rates of stolons exposed to 70, 90 and 110 Gy were 76%, 43% and 17% respectively, 6 weeks after treatment. Dosages of 85 and 57 Gy were determined as LD50 and LD20 for the cuttings, respectively. The linear reduction of survival rate with increasing gamma-rays was highly correlated (r2=0.99). A total of four mutant lines (0.3 % of the irradiated plants) showed a distinct dwarfed growth habit. Three of these lines were originated from 70 Gy and one from 110 Gy. These mutant lines exhibited more dwarf growth habit, higher shoot density, finer leaf texture than parental genotype. Mutant lines developed in this study can be used for the development of improved bermudagrass cultivars for landscaping and sports turf.

Expression of IPT in Asakura-sanshoo (Zanthoxylum piperitum (L.) DC. f. inerme Makino) Alters Tree Architecture, Delays Leaf Senescence, and Changes Leaf Essential Oil Composition.

The IPT gene encodes isopentenyl pyrophosphate transferase, a key enzyme in cytokinin biosynthesis. We introduced IPT under the control of the CaMV35S promoter into Asakura-sanshoo (Zanthoxylum piperitum (L.) DC. f. inerme Makino) via stable Agrobacterium tumefaciens-mediated transformation. Three of 3-year-old transgenic Asakura-sanshoo lines Y5, Y16, and Y17 were used to evaluate the effects of IPT expression on the morphological characteristics, leaf senescence, and essential oil composition. Introduced IPT into Asakura-sanshoo stimulated an increase in cytokinin content and a decrease in auxin level. The increase in the cytokinin/auxin ratio affected the tree architecture in 3-year-old transgenic lines. The phenotypes of transgenic lines included reduced stem elongation, decreased leaf surface area, increased branching, and delayed leaf senescence. The expression of IPT in Asakura-sanshoo also affected the leaf essential oil composition. The amount of oxygenated sesquiterpenoid compounds in Y5 and Y16 was 21.1 and 15.8 % higher, respectively, than that in wild type (WT). The amount of aromatic compounds in Y5 and Y16 was 2.9 and 24.6 % lower, respectively, than that in WT. These results show that ipt expression in Asakura-sanshoo conferred desirable traits, including a dwarf growth habit, delayed senescence, and increased concentrations of some sesquiterpenoid compounds.Electronic supplementary materialThe online version of this article (doi:10.1007/s11105-015-0948-9) contains supplementary material, which is available to authorized users.

Activation tagging library construction and mutant phenotype analysis

AbstractActivation tagging plays an important role in plant genomics studies. In this paper, an activation tagging library containing 50 000 Basta-resistant lines was constructed by mediated transformation of the mutantbzr1-DofAribidopsis thaliana. Among these transformants, 47 lines showed obvious phenotypes, including late flowering time, dwarf growth habit, changed leaf shape, longer leaf petiole, leaves lacking trichomes, sterility and no kink between stem/leaf. Some T-DNA flanking sequences were obtained by TAIL (thermal asymmetric interlaced) and nested PCR. Results showed that the mutants contained one to three T-DNA insertions. The insertions were distributed in the first, fourth and fifth chromosomes of the genome.

Dual function of Arabidopsis glucan synthase‐like genes GSL8 and GSL10 in male gametophyte development and plant growth

Members of the glucan synthase-like (GSL) family are believed to be involved in synthesis of the cell-wall component callose in specialized locations throughout the plant. We identified two members of the Arabidopsis GSL gene family, GSL8 and GSL10, that are independently required for male gametophyte development and plant growth. Analysis of gsl8 and gsl10 mutant pollen during development revealed specific malfunctions associated with asymmetric microspore division. GSL8 and GSL10 are not essential for normal microspore growth and polarity, but play a role in entry of microspores into mitosis. Impaired function of GSL10 also leads to perturbation of microspore division symmetry, irregular callose deposition and failure of generative-cell engulfment by the cytoplasm of the vegetative cell. Silencing of GSL8 or GSL10 in transgenic lines expressing gene-specific dsRNAi constructs resulted in a dwarfed growth habit, thereby revealing additional and independent wild-type gene functions for normal plant growth.

RECENT USDA–ARS BLUEBERRY CULTIVAR RELEASES

Two new southern highbush blueberry cultivars, `Dixieblue' and `Gupton', will provide growers with new blueberry cultivars having excellent fruit quality that ripen relatively early in the season, during the profitable early fresh-market window. Berries of `Dixieblue' are light blue, medium in size, and their flat shape makes them most attractive. `Gupton' is very productive and berry quality is also excellent. The performance of these cultivars represent an improvement over most currently available southern highbush blueberry cultivars due to 1) their durability and performance on both upland and sandy soils endemic to the Gulf Coast and 2) consistent production of high quality fruit that will meet the demand for early ripening fresh-market blueberries. The new rabbiteye blueberry cultivar, `DeSoto', represents an improvement over currently available rabbiteye blueberry cultivars for late-season production. `DeSoto' produces medium-to-large fruit having excellent color, flavor, and firmness Plants of `DeSoto' are productive, vigorous but semi-dwarf, upright and spreading. It's semi-dwarf growth habit, which is unique among currently grown rabbiteye blueberries, results in bushes that attain a maximum height of about 2 meters upon maturity, reducing the necessity of top-pruning that is required for all other cultivars. `DeSoto' blooms two to three weeks later than early-to-mid season cultivars such as `Climax' and `Tifblue', providing insurance against late-spring freezes. Similarly, its fruit mature 21 to 14 days or more, respectively after these same cultivars. `DeSoto' will provide niche market blueberry growers with a new cultivar having productivity, plant vigor, fruit quality, and very late ripening period that will extend their marketing season. The new evergreen ornamental blueberry, `Native Blue', is low growing, compact and finely branched with small glaucous leaves, traits that are quite typical of V. darowii. `Native Blue' has beautiful foliage that changes color in different seasons. Mature leaves are darker green while newer growth exhibits a light pinkish hue that changes to a bluish green. Other desirable characteristics of `Native Blue' are its dwarf growth habit, hardy and vigorous growth, and its capacity for a high level of fruit production that serves as an attractant to birds and other wildlife. `Native Blue' will provide southeastern U.S. nurserymen, landscapers, and homeowners with a novel and beautiful new ornamental shrub that will complement plantings of azaleas, camellias, crepe myrtles, etc.

Association of phytoplasmas and viruses with malformed clovers.

Plants of Trifolium spp. exhibiting two different kinds of symptoms--phyllody associated with yellowing/reddening, and dwarf growth habit without floral abnormalities--were observed in several areas of the Czechia. Nested polymerase chain reaction (PCR) with phytoplasma specific primers, and restriction fragment length polymorphism (RFLP) analyses of 16SrDNA revealed that phyllody of T. repens was associated with phytoplasmas belonging to the 16SrI-C subgroup. Similar symptoms in T. hybridum and T. pratense plants revealed the presence of phytoplasmas belonging to two subgroups: 16SrI-C and 16SrIII-B. Dwarf disease of cultivated T. pratense plants was associated with more than one agent: 11 of 20 plants examined by PCR/RFLP analysis revealed the presence of phytoplasmas belonging to four distinct subgroups: 16SrI-B, 16SrI-C, 16SrIII-B and 16SrX-A. Moreover, two kinds of bacilliform virions were observed in ultrathin sections of 15 T. pratense plants. Particles occurred mostly in the parenchymatous cells of vascular bundles and were located in the cytoplasm as aggregates within an extended network of membranous cisternae. Phytoplasmas and rhabdoviruses occurred singly, and both together or in co-presence with filamentous virus-like particles.

The mur2 mutant of Arabidopsis thaliana lacks fucosylated xyloglucan because of a lesion in fucosyltransferase AtFUT1.

Cell walls of the Arabidopsis mutant mur2 contain less than 2% of the wild-type amount of fucosylated xyloglucan because of a point mutation in the fucosyltransferase AtFUT1. The mur2 mutation eliminates xyloglucan fucosylation in all major plant organs, indicating that Arabidopsis thaliana fucosyltransferase 1 (AtFUT1) accounts for all of the xyloglucan fucosyltransferase activity in Arabidopsis. Despite this alteration in structure, mur2 plants show a normal growth habit and wall strength. In contrast, Arabidopsis mur1 mutants that are defective in the de novo synthesis of l-fucose exhibit a dwarfed growth habit and decreased wall strength [Reiter, W. D., Chapple, C. & Somerville, C. R. (1993) Science 261, 1032-1035]. Because the mur1 mutation affects several cell wall polysaccharides, whereas the mur2 mutation is specific to xyloglucan, the phenotypes of mur1 plants appear to be caused by structural changes in fucosylated pectic components such as rhamnogalacturonan-II. The normal growth habit and wall strength of mur2 plants casts doubt on hypotheses regarding roles of xyloglucan fucosylation in facilitating xyloglucan-cellulose interactions or in modulating growth regulator activity.

Single and Mixed Phytoplasma Infections in Phyllody- and Dwarf-Diseased Clover Plants in Lithuania.

Naturally diseased plants of clover (Trifolium spp.) exhibiting symptoms of clover phyllody (virescence and phyllody of flowers) or of clover dwarf (abnormally small leaves, shortened internodes, proliferation of shoots, and dwarf growth habit) were observed in fields in Lithuania. Phytoplasma group-specific polymerase chain reactions (PCRs) and restriction fragment length polymorphism (RFLP) analysis of 16S rDNA revealed that the plants were infected by two mutually distinct phytoplasmas. Clover phyllody-diseased plants were infected by a subgroup 16SrI-C (subgroup I-C) phytoplasma (CPh-L) related to clover phyllody (CPh-C) phytoplasma in Canada. Clover dwarf-diseased plants were infected by both CPh-L and a phytoplasma (CYE-L) related to clover yellow edge (CYE-C) phytoplasma (subgroup 16SrIII-B = III-B) in Canada. A 1.8-kbp fragment of rRNA operon from CYE-L was amplified, cloned, and sequenced, and putative restriction sites mapped. This sequence shared high similarity (99.7%) with that of CYE-C and exhibited no differences from CYE-C in RFLP patterns of 16S rDNA; therefore, we tentatively classified CYE-L in subgroup 16SrIII-B (type strain, CYE = CYE-C phytoplasma) of the X-disease phytoplasma group. These findings extend the known geographical ranges of subgroup I-C and subgroup III-B taxa to the region of northern Europe including Lithuania and suggest a role of the subgroup III-B phytoplasma in clover dwarf disease.

Inheritance of Pod Type, Stem Color, and Dwarf Growth Habit in Medicago polymorpha

Identification of marker traits in annual Medicago species (medics) would assist plant breeders in cultivar development. The objective of this research was to determine the inheritance of pod type, stem color, and dwarf growth habit in Medicago polymorpha L., a diploid species. Progeny from each of three crosses were evaluated in the F1, F2, and F3 generations. Results indicate that pod type was controlled by a single gene with a dominant allele for spiny pods. We propose the gene symbol Sp1 for the pod type trait. Stem color also was controlled by a single gene, with a dominant allele for red stems. We propose Rs1 as the gene symbol for this trait. The dwarf trait was not present in the parents or the F1 generation, but was observed in the F2 generation of one of the crosses. Dwarf plants had much shorter stems, internodes, and leaf petioles than normal plants, and they also had smaller, puckered leaves. The trait appeared to be controlled by two genes with partial recessive epistasis. We propose the gene symbols Dwl and Dw2 for this trait. Results indicated that the genes for pod type and stem color segregated independently and were not linked.

Intraspecific reproductive variation in Gelidium pusillum (Stackh.) Le Jol. (Gelidiales, Rhodophyta) from Europe

Interfertility has been demonstrated in vitro between isolates of G. pusillum from Norway, France and the British Isles, but anomalies in reproductive behaviour were observed in the two Norwegian isolates. In one of the latter (Fedje), female gametophytes were sterile. Carpogonia and nutritive filaments were differentiated, but further development was always disrupted and carposporangia never formed. On one occasion, bilocular ‘pseudo-cystocarps’ were formed in a self-cross, but no carpospores were produced. Male reproductive structures were functional and used in crossability tests. In the other Norwegian isolate (Solund), only a small percentage of the released tetraspores survived, and most of these had an aberrant dwarfed growth habit. Only a few of several thousand spores produced functional male and female gametophytes of normal appearance. In quantitative experiments, significantly higher sporeling survival was found in one of the French isolates (Cancale) than in the Solund isolate. Stages of the first meiotic division were observed and a haploid chromosome number of approximately n =15 − 20 was counted for the Solund isolate. During the second meiotic division, failure was frequently observed in that cytokinesis took place without completion of nuclear divison. In the French isolates of the same species (Cancale and Wimereux isolates), a haploid chromosome number of n = 20 or 21 was determined during meiosis in tetrasporocytes.

Triploids and Haploid Progenies Derived from Small Seeds of 'Banpeiyu', a Pummelo, Crossed with 'Ruby Red' Grapefruit.

In order to establish a triploid grapefruit-like cultivar adaptable to the citrus area of Japan, 'Banpeiyu' (Citrus grandis Osbek) was crossed with 'Ruby Red' grapefruit (C. para-disi Macf.). Out of 2, 049 seeds, 82 were selected as small seeds. Among the seedlings obtained from the small seeds, one haploid, 18 diploids, and 51 triploids segregated. The haploid seedling has a dwarf growth habit with a roseate leaf type. When grafted onto trifoliate orange (Poncirus trifoliata Raf.) rootstock, however, it grew normally. The tri-ploids grew poorly immediately after germination, but after one year they grew as vigor-ously and as well as the diploid seedlings derived from the normal large seeds.

Comparison ofEnt-kaurene synthetase A and B activities in cell-free extracts from young tomato fruits of wild-type andgib-1, gib-2, andgib-3 tomato plants

The nonallelicgib-1 andgib-3 tomato (Lycopersion esculentum Mill.) mutants are gibberellin deficient and exhibit a dwarfed growth habit. Previous work has shown that this dwarfed growth pattern can be reversed by the application of a number of gibberellins and their precursors, includingent-kaurene (ent-kaur-16-ene). This indicates that they are blocked in gibberellin biosynthesis at a step prior toent-kaurene metabolism. The normal accumulation of carotenoids observed in these mutants suggests a functionally normal isoprenoid pathway.Ent-kaurene is synthesized from geranylgeranyl pyrophosphate in a two-step process with copalyl pyrophosphate as an intermediate.In vitro assays using young fruit extracts from wild-type andgib-2 plants resulted in the conversion of geranylgeranyl pyrophosphate to copalyl pyrophosphate, and the conversion of copalyl pyrophosphate toentkaurene. Similar assays usinggib-1 plants indicated a reduced ability for synthesis of copalyl pyrophosphate from geranylgeranyl pyrophosphate, and thus a reducedent-kaurene synthetase A activity. Furthermore,gib-3 extracts demonstrated a reduced ability to synthesizeent-kaurene from copalyl pyrophosphate, and thus a reducedent-kaurene synthetase B activity. These results establish the enzymatic conversion of geranylgeranyl pyrophosphate to copalyl pyrophosphate, and copalyl pyrophosphate toent-kaurene, as the sites of the mutations ingib-1 andgib-3 tomatoes, respectively. We also note that tomato fruit extracts contain components which are inhibitory toent-kaurene synthesis.

`Caddo' and `Tonto' Lugerstroemia

EgoIf, 1986), ‘Biloxi’ (NA 54974), ‘Miami’ (NA 52714), and ‘Wichita’ (NA 54973; Egolf, 1987) are the tree types. The six intermediate cultivars are ‘Apalachee’ (NA 54879), ‘Comanche’ (NA 54976), ‘Lipan’ (NA 54978), ‘Osage’ (NA 54980), ‘Sioux’ (NA 54971), and ‘Yuma’ (NA 54975; Egolf, 1987). The four semi-dwarf cultivars are ‘Acoma’ (NA 48472), ‘Hopi’ (NA 52711), ‘Pecos’ (NA 54977), and ‘Zuni’ (NA 54982; Egolf, 1986). ‘Caddo’ and ‘Tonto’ extend the landscape attributes and raise the total U.S. National Arboretum Lagerstroemia (indica × fauriei) cultivar releases to nineteen. hybridization in an attempt to intensify flower color and mildew resistance, and to refine the dwarf-growth habit. A cross made in 1974 of [(L. indica ‘Pink Lace’ × L. fauriei) × L. indica ‘Catawba’] x L. indica ‘Tuscarora’ produced seedlings with deeper-pigmented flowers. One seedling selection with compact growth habit and deep fuchsia flowers has been designated as the cultivar Tonto.