Plant regeneration from leaf-derived callus cultures of Primrose (Primula vulgaris)

Efficient micropropagation of Primula species is important both for fundamental scientific studies and commercial applications. Primula vulgaris, along with other Primulaceae species, exhibits floral heteromorphy with two distinct forms of hermaphroditic flower. Studies to identify genes that control heteromorphic flower development require propagation of floral mutants, and efficient regeneration is a key requirement for plant transformation. Several species, including P. vulgaris (Huds.) cultivars and P. x polyantha hybrids are important horticultural crops in Europe, USA and Japan and semi-double/double Primula varieties offer a high-end product. Vegetative propagation of sterile double forms, and as a means to increase numbers of inbred parent plants for F1 seed production, is however, slow. Micropropagation offers the most efficient way of increasing these varieties quickly and efficiently. To date most Primula micropropagation protocols require explant material derived from in vitro grown seedlings or use floral parts as donor material with seasonal limitations. Therefore, an effective and efficient protocol was developed for in vitro regeneration of P. vulgaris via indirect organogenesis from adult leaf derived explants. Exposure of leaf explants of P. vulgaris to media containing synthetic cytokinin, thidiazuron (TDZ) and Auxin (NAA or 2,4-D) resulted in undifferentiated cell proliferation and followed by differentiated growth as shoot organogenesis. Silver nitrate improved in vitro callus growth and increased shoot regeneration further, with up to 72% of explants producing shoots. Regenerated plants developed normally and produced normal fertile flowers within 7 months. The system was also successfully applied for the micropropagation of sterile double-flowered P. vulgaris 'Sue Jervis'. The protocol reported here enables propagation of P. vulgaris without seasonal limitation or destruction of valuable parent donor material. The protocol, with further development, has the potential to underpin development of a transformation system for Primula, which would be of value in studies on flower development and disease resistance in laboratory grown plants

ZIP4 is required for normal progression of synapsis and for over 95% of crossovers in wheat meiosis

Tetraploid (AABB) and hexaploid (AABBDD) wheat have multiple sets of similar chromosomes, with successful meiosis and preservation of fertility relying on synapsis and crossover (CO) formation only taking place between homologous chromosomes. In hexaploid wheat, the major meiotic gene TaZIP4-B2 (Ph1) on chromosome 5B, promotes CO formation between homologous chromosomes, whilst suppressing COs between homeologous (related) chromosomes. In other species, ZIP4 mutations eliminate approximately 85% of COs, consistent with loss of the class I CO pathway. Tetraploid wheat has three ZIP4 copies: TtZIP4-A1 on chromosome 3A, TtZIP4-B1 on 3B and TtZIP4-B2 on 5B. Here, we have developed single, double and triple zip4 TILLING mutants and a CRISPR Ttzip4-B2 mutant, to determine the effect of ZIP4 genes on synapsis and CO formation in the tetraploid wheat cultivar ‘Kronos’. We show that disruption of two ZIP4 gene copies in Ttzip4-A1B1 double mutants, results in a 76-78% reduction in COs when compared to wild-type plants. Moreover, when all three copies are disrupted in Ttzip4-A1B1B2 triple mutants, COs are reduced by over 95%, suggesting that the TtZIP4-B2 copy may also affect class II COs. If this is the case, the class I and class II CO pathways may be interlinked in wheat. When ZIP4 duplicated and diverged from chromosome 3B on wheat polyploidization, the new 5B copy, TaZIP4-B2, could have acquired an additional function to stabilize both CO pathways. In tetraploid plants deficient in all three ZIP4 copies, synapsis is delayed and does not complete, consistent with our previous studies in hexaploid wheat, when a similar delay in synapsis was observed in a 59.3 Mb deletion mutant, ph1b, encompassing the TaZIP4-B2 gene on chromosome 5B. These findings confirm the requirement of ZIP4-B2 for efficient synapsis, and suggest that TtZIP4 genes have a stronger effect on synapsis than previously described in Arabidopsis and rice. Thus, ZIP4-B2 in wheat accounts for the two major phenotypes reported for Ph1, promotion of homologous synapsis and suppression of homeologous COs

Speed breeding in growth chambers and glasshouses for crop breeding and model plant research

‘Speed breeding’ (SB) shortens the breeding cycle and accelerates crop research through rapid generation advancement. SB can be carried out in numerous ways, one of which involves extending the duration of plants’ daily exposure to light, combined with early seed harvest, to cycle quickly from seed to seed, thereby reducing the generation times for some long-day (LD) or day-neutral crops. In this protocol, we present glasshouse and growth chamber–based SB approaches with supporting data from experimentation with several crops. We describe the conditions that promote the rapid growth of bread wheat, durum wheat, barley, oat, various Brassica species, chickpea, pea, grass pea, quinoa and Brachypodium distachyon. Points of flexibility within the protocols are highlighted, including how plant density can be increased to efficiently scale up plant numbers for single-seed descent (SSD). In addition, instructions are provided on how to perform SB on a small scale in a benchtop growth cabinet, enabling optimization of parameters at a low cost

Agrobacterium-mediated transformation systems of Primula vulgaris

Background: Genetic transformation is a valuable tool and an important procedure in plant functional genomics contributing to gene discovery, allowing powerful insights into gene function and genetically controlled characteristics. Primulaceae species provide one of the best-known examples of heteromorphic flower development, a breeding system which has attracted considerable attention, including that of Charles Darwin. Molecular approaches, including plant transformation give the best opportunity to define and understand the role of genes involved in floral heteromorphy in the common primrose, Primula vulgaris, along with other Primula species. Results: Two transformation systems have been developed in P. vulgaris. The first system, Agrobacterium-mediated vacuum infiltration of seedlings, enables the rapid testing of transgenes, transiently in planta. GUS expression was observed in the cotyledons, true leaves, and roots of Primula seedlings. The second system is based on Agrobacterium tumefaciens infection of pedicel explants with an average transformation efficiency of 4.6%. This transformation system, based on regeneration and selection of transformants within in vitro culture, demonstrates stable transgene integration and transmission to the next generation. Conclusion: The two transformation systems reported here will aid fundamental research into important traits in Primula. Although, stable integration of transgenes is the ultimate goal for such analyses, transient gene expression via Agrobacterium-mediated DNA transfer, offers a simple and fast method to analyse transgene functions. The second system describes, for the first time, stable Agrobacterium-mediated transformation of Primula vulgaris, which will be key to characterising the genes responsible for the control of floral heteromorphy

Aegilops sharonensis genome-assisted identification of stem rust resistance gene Sr62

The wild relatives and progenitors of wheat have been widely used as sources of disease resistance (R) genes. Molecular identification and characterization of these R genes facilitates their manipulation and tracking in breeding programmes. Here, we develop a reference-quality genome assembly of the wild diploid wheat relative Aegilops sharonensis and use positional mapping, mutagenesis, RNA-Seq and transgenesis to identify the stem rust resistance gene Sr62, which has also been transferred to common wheat. This gene encodes a tandem kinase, homologues of which exist across multiple taxa in the plant kingdom. Stable Sr62 transgenic wheat lines show high levels of resistance against diverse isolates of the stem rust pathogen, highlighting the utility of Sr62 for deployment as part of a polygenic stack to maximize the durability of stem rust resistance

Micropropagation of centennial tertiary relict trees of Liquidambar orientalis Miller through meristematic nodules produced by cultures of primordial shoots

WOS: 000356876600004This paper provides an important micropropagation method that might be used for conservation and commercial production of tertiary relict tree Liquidambar orientalis. The Liquidambar orientalis Miller is an important tree as a tertiary relict endemic species in terms of plant biodiversity, and has economic value due to the balsam it produces. In the present study, an efficient micropropagation method was developed for the L. orientalis. Initially, primordial shoot explants isolated from axillary buds were cultured on Murashige and Skoog and Woody Plant Medium (WPM) containing different plant growth regulators (PGRs). The highest number of shoots per explant was obtained on WPM supplemented with 1.0 mg/L 6-benzylaminopurine (BAP) and 1.0 mg/L indole-3-butyric acid (IBA) (shoot proliferation medium: SPM). These shoots were then subcultured continuously on SPM for a period of 18 months. Meristematic nodule clusters were formed at the base of the cultured shoots in SPM, where multiple shoots developed from them. The number of shoots per explant was increased approximately 2.8-fold by applying various strategies such as different explant type (single shoots and shoot clusters) and culture vessels (Glass Tube, 210-cc Glass culture jar, 400-cc Glass culture jar, and Vitro Vent(A (R))). Shoot clusters cultured in ventilated Vitro Vent(A (R)) vessels on SPM gave best result for shoot propagation. In vitro shoots rooted best on WPM containing 30 g/L sucrose, 120 mg/L ethylenediamine di-2-hydroxyphenyl acetate ferric (Fe-EDDHA) and 4.0 mg/L IBA. All plantlets were successfully acclimatized in a glasshouse and then plants were transferred to the field. This methodology has been adapted by a commercial producer

Micropropagation and prevention of hyperhydricity in olive (Olea europaea L.) cultivar 'Gemlik'

Gurel, Aynur/0000-0002-7002-9752WOS: 000506413200032Olive (Olea europaea L.) is an economically important crop because of its fruit and oil. Successful olive micropropagation is highly dependence on cultivar, shoot proliferation rate, which is generally low, the rooting of micropropagated olive plantlets is difficult, and the rate of post-transplanting losses is high. in addition, hyperhydricity, a common problem in vitro culture was found to be prevalent. the aim of this study was to establish a micropropagation system for the Turkish O. europaea L. cv. Gemlik. Initially, five different basal media were tested to determine appropriate medium for establishment of in vitro culture and Woody Plant Medium (WPM) was the most efficient. Nodal explants were cultured on WPM containing different plant growth regulators (PGRs) for shoot regeneration. Maximum regeneration frequency and number of shoots per explant were achieved from nodal explants cultured on WPM supplemented with 4.0 mg/L 6-benzyladenine (BA). However, all cultures showed high hyperhydricity and an experimentation was also conducted to resolve the hyperhydricity problem. Hyperhydricity was prevented by changing the gelling agent to Agar-Agar. the shoots regenerated from nodal explants and still attached to initial woody nodal explant were transferred to four different medium formulations each containing 2.0 mg/L zeatin (ZEA) for shoot elongation. Modified Olive Medium (MOM2: OM with three times the concentrations of KNO3) fortified with 2.0 mg/L ZEA was found to be the best for shoot elongation. the elongated shoots were rooted on Olive medium (OM) containing 160 mg/L Putrescine, 1.5 mg/L naphthaleneacetic acid (NAA), 30 g/L mannitol and solidified with 0.65% (w/v) Agar-Agar. Finally, all plantlets were successfully acclimatized in a climate chamber and the plants were transferred to greenhouse conditions. (C) 2019 SAAB. Published by Elsevier B.V. All rights reserved.Ege University Scientific Research Projects Coordination UnitEge University [09-MUH-010]This work was supported by Ege University Scientific Research Projects Coordination Unit [grant number: 09-MUH-010]. All of the experiments were carried out at the Bioengineering Department of Ege University. the authors are grateful to Mark Smedley for critically reviewing the manuscript

Shoot proliferation and HPLC-determination of iridoid glycosides in clones of Gentiana cruciata L

WOS: 000294910600018Gentiana cruciata L. (Cross gentian) is a medicinal and ornamental plant, threatened in its natural habitats. The wild root extracts of this species are known to exhibit many curative properties. In the present study, an efficient protocol for in vitro propagation of G. cruciata L. was developed from node culture. A semi-solidified Murashige and Skoog (MS) basal medium supplemented with 2.22 mu M 6-benzyladenine (BA), 2.46 mu M indole-3-butyric acid (IBA) and sucrose (3% w/v) improved the production of multiple shoots directly from nodal segments, providing 3.9 shoots per explants on average. The highest rooting (81.7%) was observed with half-strength MS medium supplemented with 2.46 mu M IBA. Plants with well-developed roots were transferred to pots containing turf/vermiculite mixtures and acclimatized in plant growth chamber conditions. Acclimatized plants showed 100% survival and remained healthy. The content of secondary metabolites in the clones was determined by HPLC, and the presence of gentiopicroside, loganic acid, swertiamarin, and sweroside in the samples was confirmed. Gentiopicroside was found to be the major compound.Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [TUBITAK-TOVAG 106O111]; Ege University Scientific Research Projects CommissionEge University [05MUH016]This research is sponsored by The Scientific and Technological Research Council of Turkey (TUBITAK-TOVAG 106O111) and Ege University Scientific Research Projects Commission (05MUH016). The authors are also grateful to Dr. Serdar Gokhan SENOL for providing wild plant material