Within the tomato MADS-box gene family,
TOMATO AGAMOUS1
(
TAG1
) and
ARLEQUIN/TOMATO AGAMOUS LIKE1
(hereafter referred to as
TAGL1
) are, respectively, members of the euAG and PLE lineages of the ...AGAMOUS clade. They perform crucial functions specifying stamen and carpel development in the flower and controlling late fruit development. To gain insight into the roles of
TAG1
and
TAGL1
genes and to better understand their functional redundancy and diversification, we characterized single and double RNAi silencing lines of these genes and analyzed expression profiles of regulatory genes involved in reproductive development. Double RNAi lines did show cell abnormalities in stamens and carpels and produced extremely small fruit-like organs displaying some sepaloid features. Expression analyses indicated that
TAG1
and
TAGL1
act together to repress fourth whorl sepal development, most likely through the
MACROCALYX
gene. Results also proved that
TAG1
and
TAGL1
have diversified their functions in fruit development: while
TAG1
controls placenta and seed formation,
TAGL1
participates in cuticle development and lignin biosynthesis inhibition. It is noteworthy that both
TAG1
and double RNAi plants lacked seed development due to abnormalities in pollen formation. This seedless phenotype was not associated with changes in the expression of B-class stamen identity genes
Tomato MADS
-
box 6
and
Tomato PISTILLATA
observed in silencing lines, suggesting that other regulatory factors should participate in pollen formation. Taken together, results here reported support the idea that both redundant and divergent functions of
TAG1
and
TAGL1
genes are needed to control tomato reproductive development.
Fruit development and ripening entail key biological and agronomic events, which ensure the appropriate formation and dispersal of seeds and determine productivity and yield quality traits. The MADS ...box gene Arlequin/tomato Agamous-like1 (hereafter referred to as TAGL1) was reported as a key regulator of tomato (Solanum lycopersicum) reproductive development, mainly involved in flower development, early fruit development, and ripening. It is shown here that silencing of the TAGL1 gene (RNA interference lines) promotes significant changes affecting cuticle development, mainly a reduction of thickness and stiffness, as well as a significant decrease in the content of cuticle components (cutin, waxes, polysaccharides, and phenolic compounds). Accordingly, overexpression of TAGL1 significantly increased the amount of cuticle and most of its components while rendering a mechanically weak cuticle. Expression of the genes involved in cuticle biosynthesis agreed with the biochemical and biomechanical features of cuticles isolated from transgenic fruits; it also indicated that TAGL1 participates in the transcriptional control of cuticle development mediating the biosynthesis of cuticle components. Furthermore, cell morphology and the arrangement of epidermal cell layers, on whose activity cuticle formation depends, were altered when TAGL1 was either silenced or constitutively expressed, indicating that this transcription factor regulates cuticle development, probably through the biosynthetic activity of epidermal cells. Our results also support cuticle development as an integrated event in the fruit expansion and ripening processes that characterize fleshy-fruited species such as tomato.
Efficient organogenesis induction in eggplant (Solanum melongena L.) is required for multiple in vitro culture applications. In this work, we aimed at developing a universal protocol for efficient in ...vitro regeneration of eggplant mainly based on the use of zeatin riboside (ZR). We evaluated the effect of seven combinations of ZR with indoleacetic acid (IAA) for organogenic regeneration in five genetically diverse S. melongena and one S. insanum L. accessions using two photoperiod conditions. In addition, the effect of six different concentrations of indolebutyric acid (IBA) in order to promote rooting was assessed to facilitate subsequent acclimatization of plants. The ploidy level of regenerated plants was studied.
In a first experiment with accessions MEL1 and MEL3, significant (p < 0.05) differences were observed for the four factors evaluated for organogenesis from cotyledon, hypocotyl and leaf explants, with the best results obtained (9 and 11 shoots for MEL1 and MEL3, respectively) using cotyledon tissue, 16 h light / 8 h dark photoperiod conditions, and medium E6 (2 mg/L of ZR and 0 mg/L of IAA). The best combination of conditions was tested in the other four accessions and confirmed its high regeneration efficiency per explant when using both cotyledon and hypocotyl tissues. The best rooting media was R2 (1 mg/L IBA). The analysis of ploidy level revealed that between 25 and 50% of the regenerated plantlets were tetraploid.
An efficient protocol for organogenesis of both cultivated and wild accessions of eggplant, based on the use of ZR, is proposed. The universal protocol developed may be useful for fostering in vitro culture applications in eggplant requiring regeneration of plants and, in addition, allows developing tetraploid plants without the need of antimitotic chemicals.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Fruit of tomato (Solarium lycopersicum), like those from many species, have been characterized to undergo a shift from partially photosynthetic to truly heterotrophic metabolism. While there is ...plentiful evidence for functional photosynthesis in young tomato fruit, the rates of carbon assimilation rarely exceed those of carbon dioxide release, raising the question of its role in this tissue. Here, we describe the generation and characterization of lines exhibiting a fruit-specific reduction in the expression of glutamate 1-semialdehyde aminotransferase (GSA). Despite the fact that these plants contained less GSA protein and lowered chlorophyll levels and photosynthetic activity, they were characterized by few other differences. Indeed, they displayed almost no differences in fruit size, weight, or ripening capacity and furthermore displayed few alterations in other primary or intermediary metabolites. Although GSA antisense lines were characterized by significant alterations in the expression of genes associated with photosynthesis, as well as with cell wall and amino acid metabolism, these changes were not manifested at the phenotypic level. One striking feature of the antisense plants was their seed phenotype: the transformants displayed a reduced seed set and altered morphology and metabolism at early stages of fruit development, although these differences did not affect the final seed number or fecundity. Taken together, these results suggest that fruit photosynthesis is, at least under ambient conditions, not necessary for fruit energy metabolism or development but is essential for properly timed seed development and therefore may confer an advantage under conditions of stress.
Reproductive development of higher plants comprises successive events of organ differentiation and growth which finally lead to the formation of a mature fruit. However, most of the genetic and ...molecular mechanisms which coordinate such developmental events are yet to be identified and characterized. Arlequin (Alq), a semi-dominant T-DNA tomato mutant showed developmental changes affecting flower and fruit ripening. Sepals were converted into fleshy organs which ripened as normal fruit organs and fruits displayed altered ripening features. Molecular characterization of the tagged gene demonstrated that it corresponded to the previously reported tomato Agamous-like 1 (TAGL1) gene, the tomato ortholog of shatterproof MADS-box genes of Arabidopsis thaliana, and that the Alq mutation promoted a gain-of-function phenotype caused by the ectopic expression of TAGL1. Ectopic overexpression of TAGL1 resulted in homeotic alterations affecting floral organ identity that were similar to but stronger than those observed in Alq mutant plants. Interestingly, TAGL1 RNAi plants yielded tomato fruits which were unable to ripen. They displayed a yellow-orange color and stiffness appearance which are in accordance with reduced lycopene and ethylene levels, respectively. Moreover, pericarp cells of TAGL1 RNAi fruits showed altered cellular and structural properties which correlated to both decreased expression of genes regulating cell division and lignin biosynthesis. Over-expression of TAGL1 is able to rescue the non-ripening phenotype of rin and nor mutants, which is mediated by the transcriptional activation of several ripening genes. Our results demonstrated that TAGL1 participates in the genetic control of flower and fruit development of tomato plants. Furthermore, gene silencing and over-expression experiments demonstrated that the fruit ripening process requires the regulatory activity of TAGL1. Therefore, TAGL1 could act as a linking factor connecting successive stages of reproductive development, from flower development to fruit maturation, allowing this complex process to be carried out successfully.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Coronilla viminalis Salisb. is a fodder leguminous plant from the Canary Islands and Northwestern Africa with adaptation to drought. Its conservation status is critical. Its low germination capacity ...and intense loss of viability of the seeds over time complicate its conservation, limiting its long-term maintenance in germplasm banks and hampering its potential use as a resilient fodder crop. Therefore, in this work, two alternative propagation methods have been addressed. The first was based on facilitating seed germination under aseptic conditions, supplementing the media with gibberellic acid (GA3). The latter consisted of creating a micropropagation method from nodal segments and testing different media and pretreatments with indole-3-acetic acid (IAA). The quantity and quality of the roots were assessed, and the plant acclimation rate was measured. The results showed that the optimum concentration of GA3 for germination, up to 98%, was 250 PPM. The experiments showed that using IAA in the micropropagation media is critical for in vitro rooting in this species. A hormonal pretreatment with IAA significantly improved the rooting efficiency compared to supplementing it into the culture media. One hundred percent of acclimated plants survived the process. These new protocols will help conserve the species and explore its possibilities as fodder crops.
Tomato mutants altered in leaf morphology are usually identified in the greenhouse, which demands considerable time and space and can only be performed in adequate periods. For a faster but equally ...reliable scrutiny method we addressed the screening in vitro of 971 T-DNA lines. Leaf development was evaluated in vitro in seedlings and shoot-derived axenic plants. New mutants were characterized in the greenhouse to establish the relationship between in vitro and in vivo leaf morphology, and to shed light on possible links between leaf development and agronomic traits, a promising field in which much remains to be discovered.
Following the screening in vitro of tomato T-DNA lines, putative mutants altered in leaf morphology were evaluated in the greenhouse. The comparison of results in both conditions indicated a general phenotypic correspondence, showing that in vitro culture is a reliable system for finding mutants altered in leaf development. Apart from providing homogeneous conditions, the main advantage of screening in vitro lies in the enormous time and space saving. Studies on the association between phenotype and nptII gene expression showed co-segregation in two lines (P > 99%). The use of an enhancer trap also allowed identifying gain-of-function mutants through reporter expression analysis. These studies suggested that genes altered in three other mutants were T-DNA tagged. New mutants putatively altered in brassinosteroid synthesis or perception, mutations determining multiple pleiotropic effects, lines affected in organ curvature, and the first tomato mutant with helical growth were discovered. Results also revealed new possible links between leaf development and agronomic traits, such as axillary branching, flower abscission, fruit development and fruit cracking. Furthermore, we found that the gene tagged in mutant 2635-MM encodes a Sterol 3-beta-glucosyltransferase. Expression analysis suggested that abnormal leaf development might be due to the lack-off-function of this gene.
In vitro culture is a quick, efficient and reliable tool for identifying tomato mutants altered in leaf morphology. The characterization of new mutants in vivo revealed new links between leaf development and some agronomic traits. Moreover, the possible implication of a gene encoding a Sterol 3-beta-glucosyltransferase in tomato leaf development is reported.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Since membranes play essential roles in all living beings, all cells have developed mechanisms for efficient and fast repair of membrane damage. In
Escherichia coli
, the Phage shock stress A (PspA) ...protein is involved in the maintenance of the integrity of its inner membrane in response to the damage produced by exposure to stress conditions. A role in thylakoid membrane maintenance and reorganization has been proposed for Vesicle Inducing Protein in Plastid 1 (VIPP1), the putative PspA ortholog in
Arabidopsis thaliana
. While some membranes of plant cells have been extensively studied, the biosynthesis and maintenance of chloroplast thylakoid membrane remains poorly known. Here, we report the cloning and functional characterization of the tomato (
Solanum lycopersicum
L.) ortholog of
Escherichia coli PspA
and
Arabidopsis thaliana VIPP1
, which we dubbed
SlVIPP1
. Our genetic and molecular characterization of
slvipp1
, an insertional mutant, allowed us to conclude that the tomato
SlVIPP1
gene is needed for development, as Arabidopsis
VIPP1
, but not
Escherichia coli PspA
. Homozygous
slvipp1
tomato plants are albino and exhibit early lethality and highly aberrant chloroplast development with almost complete absence of thylakoids. The phenotype of tomato RNAi lines and that of additional
slvipp1
alleles generated by CRISPR/Cas9 gene editing technology confirmed that the morphological and histological aberrations shown by
slvipp1
homozygotes are caused by
VIPP1
lack of function. We also found that tomato
SlVIPP1
overexpression does not cause any visible effect on plant morphology and viability. Our work with
slvipp1
plants evidences that
SlVIPP1
is an essential gene required for tomato survival, since its function is crucial for the proper formation and/or maintenance of thylakoid membranes.
Pelargonium is one of the most popular garden plants in the world. Moreover, it has a considerable economic importance in the ornamental plant market. Conventional cross-breeding strategies have ...generated a range of cultivars with excellent traits. However, gene transfer via Agrobacterium tumefaciens could be a helpful tool to further improve Pelargonium by enabling the introduction of new genes/traits. We report a simple and reliable protocol for the genetic transformation of Pelargonium spp. and the production of engineered long-life and male sterile Pelargonium zonale plants, using the pSAG12::ipt and PsEND1::barnase chimaeric genes respectively.
The pSAG12::ipt transgenic plants showed delayed leaf senescence, increased branching and reduced internodal length, as compared to control plants. Leaves and flowers of the pSAG12::ipt plants were reduced in size and displayed a more intense coloration. In the transgenic lines carrying the PsEND1::barnase construct no pollen grains were observed in the modified anther structures, which developed instead of normal anthers. The locules of sterile anthers collapsed 3-4 days prior to floral anthesis and, in most cases, the undeveloped anther tissues underwent necrosis.
The chimaeric construct pSAG12::ipt can be useful in Pelargonium spp. to delay the senescence process and to modify plant architecture. In addition, the use of engineered male sterile plants would be especially useful to produce environmentally friendly transgenic plants carrying new traits by preventing gene flow between the genetically modified ornamentals and related plant species. These characteristics could be of interest, from a commercial point of view, both for pelargonium producers and consumers.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Summary
Fruit set and fruit development in tomato is largely affected by changes in environmental conditions, therefore autonomous fruit set independent of fertilization is a highly desirable trait ...in tomato. Here, we report the production and characterization of male‐sterile transgenic plants that produce parthenocarpic fruits in two tomato cultivars (Micro‐Tom and Moneymaker). We generated male‐sterility using the cytotoxic gene barnase targeted to the anthers with the PsEND1 anther‐specific promoter. The ovaries of these plants grew in the absence of fertilization producing seedless, parthenocarpic fruits. Early anther ablation is essential to trigger the developing of the transgenic ovaries into fruits, in the absence of the signals usually generated during pollination and fertilization. Ovaries are fully functional and can be manually pollinated to obtain seeds. The transgenic plants obtained in the commercial cultivar Moneymaker show that the parthenocarpic development of the fruit does not have negative consequences in fruit quality. Throughout metabolomic analyses of the tomato fruits, we have identified two elite lines which showed increased levels of several health promoting metabolites and volatile compounds. Thus, early anther ablation can be considered a useful tool to promote fruit set and to obtain seedless and good quality fruits in tomato plants. These plants are also useful parental lines to be used in hybrid breeding approaches.
PDF
