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Puccinia horiana is the causal agent of chrysanthemum white rust. This microcyclic autoecious rust has a quarantine status and cause major damage in the commercial production of Dendranthema grandiflora. The experiment was carried out to identify genetic resources of chrysanthemum that are resistant/susceptible to white rust disease. A total 20 chrysanthemum genotypes were screened for resistance to P. horiana isolates collected from ICAR-IIHR, Bengaluru. By combing the observation methods without and with optical microscope, we established the identification standards for chrysanthemum white rust. The results showed that out of 20 genotypes screened for white rust, eleven genotypes/lines viz., Sweta Singar, Punjab Gold, Garden Beauty, Red Stone, Punjab Anuradha, Lal Pari, White Dolly, White Andaman, IIHR6-32, IIHR9-3 and IIHR6-41 were determined to be resistant. The use of white rust resistant genotypes will be useful for breeding programs in developing varieties with novel flower quality coupled with resistant to white rust for safe cultivation of chrysanthemum.

Bacterial wilt (causal organism-Ralstonia solanacearum) is one of the most important soil-borne diseases of eggplant (Solanum melongena) worldwide. The best way to control it economically is to develop cultivars resistant to this soil-borne pathogen. Resistance gene (R-gene) cloning and sequencing to obtain resistance gene analogs (RGAs) is one of the most recent approaches for obtaining disease resistant cultivars. Three different types of degenerative PCR based primers were used for isolating RGAs from resistant cultivated/wild species through amplification of the target region of nucleotide binding site-leucine rich repeat (NBS-LRR). Genetic diversity was observed in the sequences isolated, and six sequences showing specific conserved motifs were shortlisted as Solanum melongena RGAs (Sm7RGA1, Sm7RGA2, Sm7RGA4, Sm7RGA8 and Sm7RGA10) and Solanum viarum RGA (SvRGA2). The RGAs isolated in this study belong to both toll interleukin-1 receptors (TIR)-NBS-LRR and non-TIR-NBS-LRR type R-genes and show similarity with other plant resistance genes. This study also confirmed the hypothesis that dicots have both TIR and non-TIR resistance genes. The present study on eggplant RGAs will help develop RGA based markers linked to bacterial wilt in eggplant and other plant species. Further, it will provide information and pave the way for elucidation at the molecular level of wild and cultivated species’ mechanism of resistance to bacterial wilt. This is the first report of NBS-LRR class resistance genes/RGA in resistant eggplant and its wild relatives against bacterial wilt (BW).

SummaryA major disease in garden pea (Pisum sativum var. hortense) is powdery mildew caused by Erysiphe pisi. Homozygous recessive alleles of the er1 and er2 genes, and the dominant allele of Er3 have been found to contribute to powdery mildew resistance in pea. Nine parental genotypes used for pea breeding in India were screened using 12 sequence characterised amplified region (SCAR) markers and five simple sequence repeat (SSR) markers. None of the SCAR markers could differentiate between the resistant or susceptible genotypes, although they amplified at the specific loci previously reported. The SSR marker A5 clearly distinguished the homozygous resistant and susceptible parents and three F2 progeny from crosses of ‘Arka Priya’ × 'IP-3’, ‘Arka Pramod’ × ‘IP-3’, and ‘Arka Ajit’ בAzad-Pea’. Chisquare analysis showed a 1:3 phenotypic segregation pattern and a genotypic ratio of 1:2:1 for the SSR marker A5. Since SSR A5 is a co-dominant marker, it distinguished the clear homozygous (Er1Er1/er1er1) and het...

The present study was designed to develop an efficient protocol for micro propagation of S. rebaudiana from nodal explants and study the influence of additives on enhancement of shoot proliferation. A two-step protocol has been standardized in which, first step comprising growth hormones concentration is optimized and it was found that MS medium supplemented with 2.0 mg/l BAP + 0.5 mg/l Kin + 0.1 mg/l NAA turned out to be the best treatment for shoot induction. In the second step, the best treatment for shoot induction was fortified with different growth additives for further shoot proliferation. Among the different types of additives used, casein hydrolysate at 0.05% (w/v) was found to be most effective, resulted with maximum of 15.0 shoots. 90% regeneration frequency and shoot length of 6.0 cm were recorded per explant. Thus, the procedure described is a quick and reliable method which could be applied for efficient large scale propagation, genetic transformation assays and secondary metabolite production of Stevia.

The bark-eating caterpillar (Indarbela tetraonis Moore) is one of the two species of insect pests known to infest guava (Psidium guajava). Severe infestation with this pest causes drying up of shoots, which ultimately results in substantial losses in fruit yield and quality. Genetic options are considered most eco-friendly and cost effective to mitigate such losses. DNA marker-assisted breeding of guava for improved resistance to bark-eating caterpillar is expected to increase the efficiency of developing resistant cultivars. As a prelude to this, an investigation was carried out to identify pairs of genotypes contrasting for responses to infestation by bark-eating caterpillar and for a large number of simple sequence repeat (SSR) markers, for use as putative parents to develop mapping populations for chromosomal localization of genomic regions controlling resistance to bark-eating caterpillar in guava. Dendrogram generated by 135 polymorphic SSR markers could separate five morphologically resistant and three morphologically highly susceptible genotypes into two different clusters, barring two exceptions (Bangalore Local and 7–12EC 147036). Four pairs of accessions, viz., Superior Sour Lucidum and Seedless, Portugal and Seedless, Lalit and Seedless, Spear Acid and Seedless, had contrasting response to bark-eating caterpillar and were polymorphic at 111, 103, 101, and 101, SSR loci, respectively. These contrasting pairs of accessions are suggested for use as parents to develop mapping populations to identify DNA markers linked to genomic regions controlling resistance to bark-eating caterpillar, which could help in implementing SSR marker-assisted breeding of guava for resistance to bark-eating caterpillar.

Vitamin C (ascorbic acid) is an essential component for collagen biosynthesis and also for the proper functioning of the cardiovascular system in humans. Unlike most of the animals, humans lack the ability to synthesize ascorbic acid on their own due to a mutation in the gene encoding the last enzyme of ascorbate biosynthesis. As a result, vitamin C must be obtained from dietary sources like plants. In this study, we have developed transgenic potato plants (Solanum tuberosum L. cv. Taedong Valley) over- expressing strawberry GalUR gene under the control of CaMV 35S promoter with increased ascorbic acid levels. Integration of the GalUR gene in the plant genome was confirmed by PCR and Southern blotting. Ascorbic acid (AsA) levels in transgenic tubers were determined by high-performance liquid chromatography (HPLC). The over-expression of GalUR resulted in 1.6-2-fold increase in AsA in transgenic potato and the levels of AsA were positively correlated with increased GalUR activity. The transgenic lines with enhanced vitamin C content showed enhanced tolerance to abiotic stresses induced by methyl viologen (MV), NaCl or mannitol as compared to untransformed control plants. The leaf disc senescence assay showed better tolerance in transgenic lines by retaining higher chlorophyll as compared to the untransformed control plants. Present study demonstrated that the over-expression of GalUR gene enhanced the level of AsA in potato tubers and these transgenics performed better under different abiotic stresses as compared to untransformed control.

Transgenic lines of creeping bent grass were generated by Agrobacterium-mediated transformation with the VuNCED1 which was cloned from cow pea has a homology to 9-cis-epoxycarotenoid dioxygenase, which is supposed to be involved in abscisic acid (ABA) biosynthesis. ABA, a cleavage product of carotenoids, is involved in stress responses in plants. The limiting step of ABA biosynthesis in plants is presumably the cleavage of 9-cis-epoxycarotenoids, the first committed step of ABA biosynthesis. Molecular analyses of transgenic lines as performed by Southern hybridization genomic DNA-PCR revealed integration of the VuNCED1. Challenge studies performed with transgenic plants by exposure to salt stress (up to 10 dS m−1) and water stress (up to 75%) for 10 weeks, revealed that more than 50% of the transgenic plants could survive NaCl and drought stress whereas wild-type was not. ABA levels were measured under drought and normal conditions, endogenous ABA was dramatically increased by drought and NaCl stress in transgenic plants. These results indicate that it is possible to manipulate ABA levels in plants by over expressing the key regulatory gene in ABA biosynthesis and that stress tolerance can be improved by increasing ABA levels.

A new selection system for onion transformation that does not require the use of antibiotics or herbicides was developed. The selection system used the Escherichia coli gene that encodes phosphomannose isomerase (pmi). Transgenic plants carrying the manA gene that codes for pmi can detoxify mannose-6-phosphate by conversion to fructose-6-phosphate, an intermediate of glycolysis, via the pmi activity. Six-week-old embryogenic callus initiated from seedling radicle was used for transformation. Transgenic plants were produced efficiently with transformation rates of 27 and 23% using Agrobacterium and biolistic system, respectively. Untransformed shoots were eliminated by a stepwise increase from 10 g l(-1) sucrose with 10 g l(-1) mannose in the first selection to only 10 g l(-1) mannose in the second selection. Integrative transformation was confirmed by PCR, RT-PCR and Southern hybridization.

MADS-box genes encode a family of transcription factors, which control developmental processes in flowering plants ranging from flower to root development. During the last few years increasing evidence point to more general roles of these factors not only in the control of flowering time, but also in other reproductive processes. However, they are also expressed in roots, stems and leaves. These results suggest that their function may be much more diverse than those involved in flowering, and the possibility of uncovering new roles for MADS-box genes in plant development. Here, we specifically explore the role of the STMADS subfamily in development of vegetative structures. This subfamily continues to grow, providing new insight into the vegetative development of other plant species and how it is distinct from the one in Arabidopsis is investigated.

A new MADS-box gene, IbMADS4, had been cloned in Ipomoea batatas (L.) Lam. that is expressed in all vegetative tissues of the plant, mainly in the root tissues, but not in flower organs. Sequence similarity besides the spatial and temporal expression patterns allows defining a novel MADS-box subfamily comprising STMADS16 and the other MADS-box genes expressed specifically in vegetative tissues. Expression of the IbMADS4 sense cDNA under the control of the 35S cauliflower mosaic virus promoter modifies dramatic changes in the phenotype, such as axillary shoot formation in chrysanthemum. Leaf and axillary shoot number of sense transgenic plants showed a three- and four-fold increase in shoot regeneration compared with the wild-type, respectively. The results presented here are aimed at understanding the molecular mechanisms involved in shoot morphogenesis.

Different types of ventilation of the culture vessel with and without the ethylene inhibitor KMnO 4 in the culture media were investigated in terms of their effect on hyperhydricity of in vitro cultured potato shoots. The shoots grown in a completely sealed vessel (CSV) were severely vitrified, but the shoots cultured in a gas permeable vessel (GPV) showed normal shoot proliferation. Dry weight percentage and chlorophyll content were lower in the vitrified shoots than in the normal shoots. The levels of ethylene and CO 2 were significantly higher in the CSV, but little ethylene was detected in the GPV system. When an ethylene scrubber (perlite treated with KMnO 4 ) was applied to the CSV, the shoots exhibited normal growth without any sign of vitrification. In addition, no ethylene was found in CSV with the ethylene scrubber (CSVE). These results indicate that hyperhydricity is related to the ethylene accumulated in the culture vessel during the in vitro culture of potato shoots. It is suggested to use CSVE to reduce the ethylene level and overcome hyperhydricity.

French bean ( Phaseolus vulgaris L.) 2n=14 is an important legume vegetable grown for its tender green pods which are rich in proteins, minerals and dietary fibre. Though it is a short duration crop, it is prone to several biotic and abiotic stresses. Among the biotic stresses, rust caused by Uromyces phaseoli (Reben Wint) has become epidemic in bean growing areas and the yield loss to the tune of 80% is reported. Rust fungi have wide variability in pathogenicity and also demonstrate frequent sexual recombination and more than 150 physiological races of the pathogen are reported. Hence, the induction of genetic resistance is always preferred because it is least expensive and has no adverse environmental effects. Inheritance of rust resistance was studied in F 2 generation by using molecular markers. Resistance was confirmed in parent genotype IC525236 by using SK 14. In IC525236 resistance to rust is controlled by single dominant gene.

Lilies are one of the most valuable bulbous ornamental cut flower crops and are commercially propagated by conventional scaling, which results in varied bulb quality. This article demonstrates the effectiveness of using specific organ sources in conjunction with the thin cell layer (TCL) system to establish successful organogenic and somatic embryogenic pathways in Lilium longiflorum. TCLs derived from different explant sources, such as receptacle, leaf, young stem, stem node, bulblets, pseudo-bulblets, shoot and somatic embryos, respectively, can be manipulated to form different organs. Furthermore, the choice of plant growth regulator and medium additives such as activated charcoal and sucrose strongly affect the success of the process. This article further highlights that transient transgene expression derived from either particle bombardment or Agro-infection is both strong and repeatable, as a result of the direct exposure of competent cells to the gene introduction method, resulting in a reduction of escapes. The ability to manipulate and control organogenesis through a TCL system, coupled with repeatable, efficient transformation opens up the possibility of micropropagating members of this genus with new and available characteristics, producing superior plants of high quality.

Micropropagation of Phalaenopsis through flower stalk culture was investigated. Bracts of flower stalks were removed before or after sterilization. Decontamination rate of nodal sections was higher when they were sterilized with bract. Subsequent growth of lateral buds was affected by the timing of bract removal. Much lateral bud developed flower stalk secondary when bracts were removed after sterilization, but much of them developed vegetative shoots when bract was removed before sterilization. Propagation from a plantlet was investigated using in vitro clone plantlets. Base part of a plantlet, 1.5 cm was cut into 2.5 mm or 5 mm slice segments, and they were cultured on NP medium with or without coconut water (CW) and/or 6-benzylaminopurine (BA). Regeneration of shoot(s) and callus like body (CLB) was dominant in the slice segments derived from 5-10 mm part from the base of the shoot and was promoted by addition of CW and/or BA.

Potato microtubers produced in vitro of the cultivar ‘Superior’ were assessed to decide up to what size it can be used for the seed potato with respect to storability, dormancy period, and sprouting vigor. The larger microtubers lost moisture content more slowly and retained firmness longer when stored at 4 °C. In the sprouting test, the larger ones had less period of dormancy and showed more vigorous sprouting ability. The starch increased with increasing size of the microtuber and showed the distribution of about 70–80% of dry matter content. The amounts of sugars were positively co-related with the size of the potato. The internal factors such as dry matter and carbohydrate content reveal that potato microtuber follows the field-grown potatoes in all aspects. The results suggest that the size of microtubers can be used as an index for grading their quality as seed potatoes, and the size of the microtuber should be at least 0.5 g to be used as seed potato.

As the world population continues to show an explosive increase, so the demand for crops and vegetables increases. To satisfy this demand, increased productivity comes about through advanced plant breeding and selection techniques. Modern plant breeding addresses this demand by production of desired end products (cultivar, variety or hybrid) with desired/useful characteristics or traits, which may be controlled by one or a few genes (qualitative traits) or may be under the control of many interacting genes with small individual effects (quantitative traits). To better allow the breeder to reliably select for genes controlling desirable traits, genetic markers can be used to create linkage or plant genome maps.