Hybrid Triploid Induced by Megaspore Chromosome Doubling in Jujube (Ziziphus jujuba Mill.) ‘Maya’ and Its Characteristics

Polyploid breeding is an important strategy for tree improvement because polyploid individuals typically show superior traits, such as improved growth, stress resistance, and superior fruit quality. Artificial induction of chromosome doubling of female gametes is an effective approach to obtain triploid progeny. However, no triploid fruit tree cultivars have been developed using this approach. The objective of this study was to explore the utility of chromosome doubling in female gametes of ‘Maya’ jujube to produce triploid individuals. The temporal relationship between flower bud morphology and the megaspore meiotic stage was studied to guide the optimal timing of colchicine treatment. Colchicine solution was applied to bearing shoots of mature ‘Maya’ jujube trees in a field experiment using two treatment methods (improved cotton leaching and injection method) and three concentrations (0.3%, 0.4%, and 0.5%). The water transport rate of ‘Maya’ jujube shoots was studied using dye solution to judge the effectiveness and timing of the colchicine treatment methods. Two triploids were identified among the progenies from the colchicine-treated shoots. The highest efficiency of triploid production was 3.3% when flower buds of diameter 1.76–2.12 mm were treated with 0.3% colchicine solution for 4 h using an improved cotton leaching method. The ground diameter, plant thorn length, leaf width, leaf area, stomatal length, stomatal width, chlorophyll content, and photosynthetic parameters of one triploid individual were significantly higher than those of diploids of identical parentage at 18 months old. Thus, induction of 2n megaspores is an effective approach to generate triploid jujube. These results are expected to promote and accelerate triploid breeding in fruit trees.

Regeneration of plant winter garlic in vitro after colchicine treatment

Relevance. The genetic diversity of winter garlic depends entirely on the natural selection of the best and highest-yielding clones. In unfavorable abiotic factors, physiological and biochemical properties allow polyploidy plants to have greater tolerance and viability than diploid species. Obtaining the source material based on polyploidy in winter garlic (Allium sativum L.) is one of the important alternative approaches to genetic improvement of this crop.Methods. From air garlic bulbs, plants were grown through in vitro culture. Pre-air bulbs were treated with 0.1% colchicine solution for 1 hour, 2 hours, 4 hours. Shoots and roots were regenerated by cultivating explants for 1/2 MS, with 3 mg / l 6-BAP and 0.1 mg/l indole-3-acetic acid and cultured in light with an intensity of 5–8 ths. LC and a photoperiod of 18 hours. Treatment of air bulbs with 0.1% colchicine solution made it possible to obtain winter garlic plants using in vitro culture.Results. In the end, we were not able to get flowering forms from garlic using the polyploidization method. But, thanks to the cultivation of winter garlic in vitro, it became possible to accelerate the selection process by obtaining one generation per year “from clove to clove”. When working on obtaining polyploidy forms, more than one variety should be used, since the reaction of varieties to colchicine treatment is ambiguous, as is their reaction to growing conditions and survival. The most responsive for obtaining plants in vitro culture was the Yubileyny Gribovsky variety.

Use of Flow Cytometry for Producing Tetraploids in Red Clover

Sprouts of diploid red clover ‘Stendes Agrais’ were treated with 0.2% colchicine solution. The ploidy level of plants was detected by flow cytometry. Most of the treated plants were mixoploids and sterile. From progenies of fertile plants, mixoploids were selected that had a proportion of tetraploid cells higher than 60%. In the next generation, stable tetraploid plants were selected, and 49 lines were included in the breeding process.

Improving the Efficiency of Colchicine-Based Chromosomal Doubling of Maize Haploids

Production and use of doubled haploids (DH) is becoming an essential part of maize breeding programs worldwide as DH lines offer several advantages in line development and evaluation. One of the critical steps in maize DH line production is doubling the chromosomes of in vivo-derived haploids so that naturally sterile haploids become reproductively fertile diploids (DH) to produce seed. This step of artificially doubling the chromosomes is labor-intensive and costly; hence, optimizing protocols to improve the doubling success is critical for achieving efficiencies in the DH production pipelines. Immersion of 3–4-day old germinating haploid seedlings in colchicine solution is commonly used for chromosome doubling in large-scale maize DH line production. This manuscript presents a new method of colchicine application to haploid seedlings that showed superior doubling rates compared to other methods like standard seedling immersion, seed immersion, root immersion, and direct application of colchicine solution to the seedlings at V2 stage in the greenhouse trays. The new method involves immersing the crown region of the haploid seedlings along with all the seedling roots at V2 stage in the colchicine solution. Further experiments to optimize this method indicated that increasing colchicine concentration had a very positive effect on overall success rate in chromosomal doubling, while not drastically affecting survival rate. The optimized method showed on average 5.6 times higher overall success rate (OSR) compared to the standard haploid seedling immersion method which was the second-best method in our experiments. This improved method of colchicine application saves resources by reducing the number of haploids to be generated and handled in a maize DH production pipeline.

Abnormal Development of Hyalomma Marginatum Ticks (Acari: Ixodidae) Induced by Plant Cytotoxic Substances

The increasing application of toxic plant substances to deter and fight ticks proves the need for investigations focused on the elucidation of their impact on the developmental stages and populations of these arthropods. We examined the course of embryogenesis and egg hatch in Hyalomma marginatum ticks under the effect of cytotoxic plant substances. The investigations demonstrated that the length of embryonic development of egg batches treated with 20 μL of a 0.1875% colchicine solution did not differ significantly from that in the control group. Colchicine caused the high mortality of eggs (16.3%) and embryos (9.7%), disturbances in larval hatch (8.1%), and lower numbers of normal larval hatches (65.6%). In 0.2% of the larvae, colchicine induced anomalies in the idiosoma (67.6%) and gnathosoma (22.5%) as well as composite anomalies (8.5%). The study demonstrates that cytotoxic compounds with an effect similar to that of colchicine can reduce tick populations and cause teratological changes, which were observed in the specimens found during field studies. Since there are no data on the toxic effects of active plant substances on other organisms and the risk of development of tick resistance, a strategy for the use of such compounds in tick control and the management of plant products should be developed.

Comparison of the number and distribution of chromosomes of three varieties of Nile tilapia (Oreochromis niloticus)

The aims of this study is to determine the number and distribution of the chromosomes of three Nile tilapia (Oreochromis niloticus) varieties as basic information in the process of identifying the characteristics of varieties in tilapia. This research was conducted in August-October 2016, at the Unair Banyuwangi PSDKU laboratory. The research procedures included rearing of test fish, immersion of test fish with colchicine solution and tissue preservation, preparation of preparations and staining, and observation. Based on the results of the study, it was found that each variety of tilapia (black, red, and white) showed a difference in the spread of chromosomes, while the number of chromosomes was the same, namely 44 pieces.

Megaspore Chromosome Doubling in Eucalyptus urophylla S.T. Blake Induced by Colchicine Treatment to Produce Triploids

Triploids generally provide an advantage in vegetative growth in forest trees. However, the technique of triploid breeding is still an open field in the Eucalyptus tree species. This study aims to explore the colchicine treatment technique for megaspore chromosome doubling to establish triploids in this tree species. Cytological observation on microsporogenesis and megasporogenesis was carried out to guide megaspore chromosome doubling induced by colchicine treatment. Ploidy level in progenies was detected by flow cytometry and somatic chromosome counting. A relationship between microsporogenesis and megasporogenesis was established to guide the colchicine treatment. Seven triploids were obtained in the progenies, and the highest efficiency of triploid production was 6.25% when the flower buds underwent a 0.25% colchicine solution treatment for 6 h using an aspiration method seven days after the first observation of leptotene during microsporogenesis on the floral branch. Cytological analysis showed that the megasporocyte from leptotene to diakinesis may be the optimal period for megaspore chromosome doubling by colchicine treatment. Plant height, ground diameter, leaf area, and the photosynthetic parameter of triploid eucalypt were significantly higher than those of the diploid plant at 6 months old. Hybridization with 2n megaspores induced by colchicine treatment is an effective way for Eucalyptus triploid breeding. These results should accelerate the development of advanced germplasms in this tree species.

Potential Changes in Watermelon (Citrullus lannatus) Ploidy Treated By Colchicine

The purpose of this study was to determine the effect of colchicine on changes in ploidy watermelon. The research was conducted in Agroecotechnology laboratory Universitas Malikussaleh, Microtechnique laboratory Agronomy and Horticulture Departement, Bogor Agricultural University, and Beuringen, Murah Mulia subdistrict, North Aceh. This research used Completely Randomized Design (CRD) two factors. The first factor was watermelon seed soaking time in colchicines 0,02% ie.0, 24,36, and 48 hours. The second factor was the concentration of the colchicine solution on the sprout growth point i.e. 0, 0,1, and 0,2 %. The results showed that plants were given colchicine became to shorter and fewer number of leaves than plants without any treatment. Colchicine could increase the size of the stomata, but it did not change the shape of stomata. Plants that were given colchicine had the potential to ploidy multiplication.

Fertility recovery of anther-derived haploid plants in Cape gooseberry (Physalis peruviana L.)

The cape gooseberry (Physalis peruviana L.) is one of the most important Colombian exotic fruits. Chromosome doubling of anther-derived plants is a key factor in the application of double haploid technology for the genetic improvement of crops. In the present study, axillary buds from four haploid cape gooseberry genotypes were used to evaluate artificial chromosome doubling induced by colchicine and its effects on ploidy level and pollen fertility. Three concentrations of colchicine (5, 10 and 15 mM) and three exposure times (2, 4 and 6 h) were used to determine the best treatment for the generation of fertileB plants from axillary buds of haploid genotypes. The colchicine increased both the number of chromosomes, from 36 to 129, and the average chloroplasts in stomata guard cell, from 4.5 to 23.8. The optimal chromosome doubling of the haploids was obtained with the 5 mM colchicine solution and 2 h exposure time. This protocol produced chromosome doubling in over 60% of the regenerants of the four haploid genotypes, with a high level of fertility. Morphologically, the fertile mixoploid plants showed variation in the vegetative, flowering and fruit characteristics, as compared to the haploid plants.

Development and Evaluation of Diploid and Polyploid Hibiscus moscheutos

Hibiscus moscheutos L. is an herbaceous hibiscus native to eastern North America that has been a popular landscape and container plant exhibiting large and colorful flowers in the summer. However, unsightly fruit develop and remain on the stalks at the end of the blooming season, which greatly decreases the ornamental value. Thus, breeding for sterility was attempted through ploidy level manipulation to reduce formation and growth of seed stalks, and to improve blooming vigor and longevity. Colchicine and oryzalin were used as mitotic inhibitors to induce tetraploid breeding lines that could be used to develop sterile triploids. Germinated seedlings of ‘Luna Red’ were soaked in three concentrations of each doubling agent for three different durations. Exposure to a low concentration of colchicine solution for a long time or to a low concentration of oryzalin for a short period was found to be effective in yielding a high number of tetraploids with a low rate of mortality. Triploids were obtained from the traditional method of crossing tetraploids with diploids. Triploid and tetraploid plants showed a decrease in height with a more compact form. Leaves of tetraploid plants were more ruffled, with an increase in overall leaf thickness, but were not different from leaves of diploids and triploids in regard to leaf mass per area (LMA). Triploid plants bloomed longer but had smaller flowers than diploid plants. Although the whole planting was infected by aerial phytophthora, diploid, tetraploid, and triploid plants were significantly different in their tolerances: all diploid branches were infected, but only a minor infection occurred on one triploid branch, and the transmission remained slow. Flowers of tetraploid plants failed to produce pollen, whereas flowers of triploid plants produced only nonviable pollen grains and fruits aborted after pollination, which led to infertility of induced triploids.