Disease-free Planting Material Research Articles

In vitro microrhizome induction in Acorus calamus L., a commercially important aromatic medicinal plant

Acorus calamus L., is a leading aromatic medicinal plant that produces pungent aromatic rhizomes that are valued worldwide as an important herbal medicine and is one of the main ingredients in several polyherbal formulations used for neurological and metabolic disorders. The present investigation aims to develop an efficient protocol for in vitro microrhizome induction in A. calamus for the large-scale production of disease-free planting material for commercial purposes. In vitro derived shoots were initiated on MS medium supplemented with different concentrations of sucrose alone (3–10 %) and different concentrations of sucrose (6 % and 7 %) with varying concentrations of BAP alone (0.5–2 mg/L) and combinations with IAA (0.5 and 1 mg/L) and NAA (0.5 and 1 mg/L) were carried out for the microrhizome induction experiments. In different concentrations of sucrose used, healthy and disease-free microshoots of A. calamus were obtained in MS media supplemented with 7 % sucrose followed by 6 % sucrose. The highest shoot length (24.79 ± 0.03 cm) and microrhizome size (4.98 ± 0.03 cm length and 399.60 ± 0.37 mg fresh weight) were obtained in MS solid medium supplemented with 1 mg/L BAP and 0.5 mg/L NAA with 7 % sucrose followed by the same hormone concentration with 6 % sucrose (shoot length-23.68 ± 0.03 cm, microrhizome length- 4.68 ± 0.03 cm and fresh weight of microrhizome-376.60 ± 0.57 mg). The developed protocol can be used for large-scale production of disease-free propagules without rooting and acclimatization and enhance the production of true-to-type planting material.

In Vitro Microrhizome Production, Genetic Homogeneity Assessment, and Field Performance Evaluation in Ginger

In vitro-induced microrhizomes are promising for producing disease-free planting materials in ginger (Zingiber officinale Rosc.), spice and medicinal crops threatened by several soil-borne diseases. The study examined microrhizome induction, genetic homogeneity, and field performance in ginger. The condition combination of 3.0 mg·L−1 6-benzylaminopurine (BAP), 100 g·L−1 sucrose, and a 12-h photoperiod (the optimal conditions) produced the largest number of microrhizomes among all treatments but resulted in a lower average fresh weight during the 60-day culture period. Larger microrhizomes exhibited greater tolerance to water loss and a higher percentage of sprouting. Therefore, additional efforts were made to increase the size of the microrhizomes. Under the optimal conditions, the fresh weight increased significantly to 280.3 mg and 403.4 mg after 30 days of additional culture and in vitro culture of small-sized microrhizomes, respectively. Flow cytometry analysis and SSR characterization confirmed the genetic homogeneity of the regenerated plants with microrhizomes (MR) and those obtained by directly sowing sprouted microrhizomes into the substrate without acclimatization (FMR). At harvest, the MR had the most robust growth, a significantly higher fresh rhizome weight (206.1 g per plant) than the FMR (121.8 g per plant) and conventional tissue-cultured plants (TC), and similar rhizome finger size (11.5 g and 10.2 cm2) to the FMR. These findings suggest that both the MR and the FMR have advantages over the TC in producing seedling rhizomes of ginger in the first growing season. The established approach may be useful for large-scale production of disease-free ginger rhizomes.

Direct Plant Regeneration from Nodal Explants of Grapefruit (Citrus paradisi Macfad.)

Aims: The present study was undertaken to develop a protocol for in vitro regeneration and multiplication of disease-free quality planting material of Grapefruit (Citrus paradisi Macfad.). Study Design: Completely Randomized Design (CRD) Place and Duration of Study: The study was conducted at the Plant Tissue Culture Laboratory, Department of Horticulture, University of Agricultural Sciences, Gandhi Krishi Vignana Kendra, Bengaluru, from 2020 to 21. Methodology: Nodal segments from the young shoots of field growing plants were used as explants to conduct the experiment. The explants were sterilized and placed on MS medium supplemented with different concentrations and combinations of growth regulators, namely BAP, Kinetin and Gibberellic acid. Results: Among the different combinations of growth regulators, the combination of BAP 1.0 mgL-1 and GA3 3.0 mgL-1 produced maximum number of shoots (7) from nodal segments Conclusion: The use of growth regulators such as BAP and GA3 is reliable for shoot regeneration even when the field explants are used.

Performances of plantlets from selected cassava (Manihot esculenta Crantz) genotypes under Semi - Autotrophic Hydroponics (SAH) using different substrates

The cassava seed system faces challenges due to limited seed stock caused by a slow propagation rate and a lengthy growth period. Conventional methods lacking phytosanitary guarantees further compound these issues. To address these limitations, the Semi-Autotrophic Hydroponics (SAH) technology was adopted for the rapid mass propagation of healthy, disease-free cassava plants. This research aimed to evaluate the performance of cassava planting materials using different substrates for stem-cutting multiplication in the laboratory at the IITA Kalambo research station in DR Congo. The experiment followed a split-plot design of five replications of three consecutive sub-culture periods lasting four weeks each. Four different genotypes: IB961089A, MM060083, Nase14, and Albert28 as the main plots, with four different substrates: KlasmannTS3, Vermiculite, Local Peat, and Sawdust as the sub-plots, were laid out. Cuttings were placed in 500-ml substrate-filled boxes and watered weekly with a 100-ml Miracle-Gro solution. Data were collected on survival, height, leaf and internode numbers, and cutting numbers at the end of each subculture period. The data were analysed using ANOVA in R software. The Fisher's Least Significant Difference (LSD) test was utilised to separate means when significant differences among treatments were present (p <0.05). The results showed that survival was primarily influenced by the substrate used, with KlasmannTS3 demonstrating the highest rate, exceeding 90%. Significant differences (p < 0.05) among genotypes for survival rate and performance parameters mentioned above (p < 0.001) were observed. Similarly, there were significant differences (p < 0.001) among substrates for survival rate and performance parameters. Furthermore, the interaction between genotype and substrate significantly (p < 0.001) affected performance parameters. MM060083 performed the best across all traits. KlasmannTS3 was the superior substrate and had the highest average cutting number regardless of genotype, with a notable increase of 292% from 20 to 58.4 cuttings, representing a ratio of 1:3 within three months. Sawdust had the lowest multiplication rate, with a 5% decrease. The superior performance of KlasmannTS3 was attributed to its rapid growth and favourable properties. The interaction between MM060083 and KlasmannTS3 consistently showed the highest number of cuttings (70.4). Sawdust consistently showed poor growth performance, regardless of genotype. The study concludes that the SAH offers the potential for rapid multiplication of disease-free cassava planting materials in reduced space and time.

Different Preharvest Diseases in Garlic and Their Eco-Friendly Management Strategies.

garlic reproduces mainly through clove planting, as sexual reproduction via seeds is uncommon. Growers encounter challenges with pathogens due to the larger size and vegetative nature of seed cloves, as well as the storage conditions conducive to fungal growth. Some Phyto-pathogenic fungi, previously unrecognized as garlic infections, can remain latent within bulb tissues long after harvest. Although outwardly healthy, these infected bulbs may develop rot under specific conditions. planting diseased seed cloves can contaminate field soil, with some fungal and bacterial infections persisting for extended periods. The substantial size of seed cloves makes complete eradication of deeply ingrained infections difficult, despite the use of systemic fungicides during the preplanting and postharvest phases. Additionally, viruses, resistant to fungicides, persist in vegetative material. They are prevalent in much of the garlic used for planting, and their host vectors are difficult to eliminate. To address these challenges, tissue-culture techniques are increasingly employed to produce disease-free planting stock. Key scientific concepts of the review: garlic faces a concealed spectrum of diseases that pose a global challenge, encompassing fungal threats like Fusarium's vascular wilt and Alternaria's moldy rot, bacterial blights, and the elusive garlic yellow stripe virus. The struggle to eliminate deeply ingrained infections is exacerbated by the substantial size of seed cloves. Moreover, viruses persist in garlic seeds, spreading through carrier vectors, and remain unaffected by fungicides. This review emphasizes eco-friendly strategies to address these challenges, focusing on preventive measures, biocontrol agents, and plant extracts. Tissue-culture techniques emerge as a promising solution for generating disease-free garlic planting material. The review advocates for ongoing research to ensure sustainable garlic cultivation, recognizing the imperative of safeguarding this culinary staple from an array of fungal and viral threats.

Methods of Blackberry Propagation in vitro Condition

Blackberry, one of the most important fruit species belonging to the Rosaceae family, can be grown in different environments due to having wide adaptation ability. Although it originated in Europe, today most of the common cultivars have North American origin. Also, expansion of its production last 25 years especially in Europe and the USA, the blackberry has become the fourth berry in the fresh berry market after strawberries, blueberries, and raspberries. Blackberry fruits are rich in vitamins, polyphenols, minerals, and antioxidants, especially gallic acid and routine. Many studies have proven that high nutritional composition has a positive effect on human health in preventing various diseases. It has an important place in the fresh and processed market. Frozen fruits can be used processed such as an ice cream, juice, jam, marmalade, cake, and sweet products. Blackberry breeding studies have been ongoing for over 100 years to increase yield and fruit quality, thornless cane, to improve disease insect resistance, and cane management and primocane fruiting. In vitro propagation is an alternative method to introduce new cultivars quickly into the market and to provide disease-free planting material compared with traditional methods. The purpose of this study was to summarize blackberry propagation methods in vitro conditions.

Decoding Huanglongbing: Understanding the Origins, Impacts, and Remedies for Citrus Greening

Citrus cultivation is a vital component of the agricultural sector, offering significant nutritional and economic benefits. However, citrus plants face numerous disorders, including Huanglongbing (HLB), also known as citrus greening disease. HLB is a devastating disease caused by the bacterial species Candidatus Liberibacter asiaticus (Las), primarily transmitted by the citrus psyllid and grafting. Investigating the distribution and molecular characterization of HLB in various citrus varieties and psyllid populations is crucial. Molecular techniques and iodine starch staining have been used to detect HLB symptoms. Several studies have been designed to determine the incidence and severity of HLB symptoms in different citrus varieties and locations and estimate the psyllid population density in different citrus varieties. Furthermore, these studies established a correlation between the population of psyllids and the incidence and severity of HLB in different locations and these findings suggest a potential link between psyllid infestation and the prevalence of HLB. This study highlights the prevalence of HLB in various locations and varieties, providing insights into the distribution, severity, and correlation between psyllid populations and HLB incidence. The reliability of PCR testing for Las infection confirms its effectiveness. Such findings suggest implementing integrated pest management strategies, including monitoring and controlling psyllid populations, removing infected plants, and using certified disease-free planting materials to prevent HLB spread.

Somatic Embryogenesis and Plant Regeneration of Farmer-Preferred Passion Fruit Varieties Grown in Kenya

In vitro regeneration of passion fruit has great prospects for mass production of disease-free planting materials. The objective of this study was to develop an in vitro regeneration system through somatic embryogenesis for farmer-preferred genotypes grown in Kenya. Callus induction and somatic embryogenesis were carried out using leaf and immature seed explants. The explants were cultured on Murashige and Skoog medium augmented with different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) alone and 2,4-D combined with 1.0 mg L−1 thidiazuron (TDZ). Data were recorded and subjected to analysis of variance. The highest number of somatic embryos was obtained from KPF4 genotype using MS medium supplemented with 8 mg L−1 2,4-D and 1 mgL−1 TDZ. The embryos were converted to plants on germination medium comprising of MS augmented with 0.5 mg L−1 6-benzyl amino purine (BAP). The plantlets were hardened for 4 weeks in plastic pots. The survival rate during hardening of in vitro regenerated plants was 77.8%. The present study reports a regeneration system through somatic embryogenesis for KPF4 passion fruit grown in Kenya. The in vitro regeneration system can be utilized for mass propagation and genetic improvement of KPF4 variety grown in Kenya.

Induction of micro-rhizomes for in vitro ginger (Zingiber officinale Rosco) disease-free planting materials regeneration

Ginger has been a leading spice crop in Ethiopia until ginger bacterial wilt disease interrupted its production. The disease transmission is mainly through infected planting materials and products. Regeneration of healthy planting materials is among the best option to minimize the disease impact. This research aimed to induce and produce disease-free in vitro micro-rhizome in a combination of sucrose, BAP, ammonium nitrate, and silver nitrate. The results from observations indicated that sucrose and BAP were best combinations for induction of disease free micro-rhizomes. Ammonium nitrate and silver nitrate showed lower induction than sucrose and BAP combinations alone. The maximum viable number of micro-rhizome (5.67) and shoot number (10.33) were from 80.0 g/l sucrose and 6.0 mg/l BAP contained medium. Viability test indicated 80 % of the micro-rhizomes were sprouted after one month in soil. The micro-rhizome production potential observed in this experiment can enhance disease-free ginger production.

Role of phytohormone on in vitro regeneration of tea [Camellia sinensis (L.) O. Kuntze

Phytohormones are small molecules present in very low concentrations in plants and provide a promising strategy to improve mass culture biotechnology due to their intrinsic role in growth, development, and survival. This study is aimed at evaluating the effect of different plant growth regulators on in vitro callus induction and shoot regeneration in tea. The experiment was conducted at Complete Randomize Design (CRD) with three replications. Callus induction and shoot regeneration was done by using Murashige & Skoog (MS) media supplemented with various concentrations and combinations of Naphthalene Acetic Acid (NAA), Benzyl Adenine (BA), and 2,4-Dichlorophenoxyacetic Acid (2,4-D). Shoot tips and nodal segments were used as explant. The highest percentage (86.51%) of callus induction was observed in the combined treatment of 2.00 milligram per litre (mg/L) BA + 1.50 mg/L 2, 4-D in 2.12 weeks. The same treatment produced the highest weight of calli, which was 0.18, 0.56, and 1.11 grams (g) for 6, 10, and 14 weeks after inoculation (WAI), respectively. The highest percentage (84.39%) of shoot induction was recorded with 2.00 mg/L BA + 2.00 mg/L NAA in 32.43 days. The maximum number (1.42, 2.46, and 4.49) and the highest length of the shoot (1.41, 3.28, and 4.61 cm) at 60, 90, and 120 DAI (days after inoculation) were also recorded from the same treatment. No callus or shoot induction was recorded in the controlled treatment. The protocol developed from the present study might be useful for the large-scale production of healthy, disease-free planting material for tea.

Constraints faced under open and protected cultivation of vegetables- A case studyof tomatoes and capsicum in Karnataka

The present study aimed to analyze the constraints faced by farmers in the production and marketing oftomatoes and capsicum under open and protected cultivation practices in Karnataka. The study was conducted in majortwo vegetable producing districts of Karnataka. Kolar from South Karnataka and Belagavi from North Karnataka were thetwo districts selected for the study. Rank Based Quotient (RBQ) was adopted for the analysis. The results indicated thatheavy incidence of pests and diseases (RBQ value 69.44) and severe incidence of blossom end rot due to calcium deficiency(RBQ value 85.19) were the major production constraints under open and protected cultivation practices, respectively.Lack of quality planting material and requirement of intensive management practices were the other serious productionproblems under open field cultivation of tomatoes. While, incidence of fruit borer and requirement of high cost forestablishment were the production problems faced by the farmers under protected cultivation of tomatoes. Heavy drop ofimmature fruits under open cultivation and high cost of establishment under protected cultivation were the other seriousproblems faced by farmers in production of capsicum. Lower market price during peak harvesting season and high fluctuationin prices for capsicum were the serious marketing problems. Use of disease-free quality planting material, self-raising ofseedlings, utilization of calcium fertilizers and adoption of cost-effective management practices and proper portfolio managementwere the measures suggested to the farmers to overcome these problems. These findings will be helpful to the policy makersand farmers for developing policy framework and relevant guidance for promoting vegetable production in the state.

An Efficient Protocol for In vitro Regeneration and Acclimatization of Banana (Musa spp.) cv. Grand Naine

Aim: The study was undertaken with a view to standardize a protocol for in vitro regeneration of Banana cv. Grand naine using shoot tip of sucker as an explant
 Methodology: In present study, explants sterilized with different sterilizing agents such as Tween-20 (1%), Bavistin (0.5-1%), Streptomycin sulphate (250 mg/L), Ascorbic acid (150 mg/L) + Citric acid (100 mg/L), HgCl2 (0.1%) and 70% ethanol.Sterilized explants were cultured on Murashige and Skoog (MS) medium supplemented with different concentrations of plant growth hormones for shoot initiation BAP alone (1.5, 2.0, 4.0, 6.0 mg/L) and BAP (3.0 mg/L) in combination with IAA and IBA (2.0 mg/L), elongation BAP (3.0 mg/L) and NAA (1.0, 1.5, 2.0 mg/L) and rooting IAA (1.0, 1.5 mg/L) and IBA (1.0, 1.5 mg/L). Primary and secondaryhardening was done in potting mixture containing autoclaved black soil: vermicompost: cocopeat (1:1:1) and garden black soil, cocopeat and red soil (1:1:1) respectively.
 Results: In present investigation 1% Bavistin (fungicide) showed maximum respond to prevent fungal contamination. Highest shoot initiation (100%) was observed on a MS medium fortified with BAP (1.5 mg/L). Maximum shoot length (10.7 cm) was recorded on a MS medium supplemented with BAP (3.0 mg/L) + NAA (2.0 mg/L) + Activated charcoal. Maximum root initiation was observed on half strength MS medium supplemented with IAA (1.5 mg/L). In vitro regenerated plantlets hardened on the mixture of autoclaved black soil: vermicompost: cocopeat (1:1:1). After 14 weeks In vitro plantlets transferred in green house for acclimatization where, 80% survival rate was recorded.
 Conclusion: Regeneration protocol was successfully standardized. Therefore, itcan be used for large scale propagation of healthy, disease and virus free planting material and In vitro propagation helps to meet higher demand of healthy planting material within shorter period.

Features of obtaining an aseptic culture of Prunus dulcis (Mill.) D.A. Webb.

The purpose of the presented article is to establish the features of obtaining an aseptic culture of regenerants of Prunus dulcis in vitro. Since the impact of climate change is becoming increasingly large-scale in Ukraine, one of the urgent problems that hinders humanity, both in terms of agro-ecology and food, is the need to diversify traditional agriculture. Mydal is one of the valuable promising nut crops in Ukraine, thanks to which it is possible to diversify the climatic risks listed above. The varieties of domestic selection were taken for experiments, since foreign selection with low winter resistance and a long growing season are not suitable for our zone. Four intensive new varieties of almonds E5 Borozan, M41 Alex, Georgia, Louise, which were bred by breeder V.M. Babanskyi and entered into the State Register of Plant Varieties, and allowed in Ukraine for cultivation. One of the reliable methods of reproduction is microclonal reproduction, with the help of which it is possible to quickly obtain high-quality, disease-free planting material. Therefore, for the production of planting material, modern nurseries are switching to biotechnological methods. It was established that the preparation of explant donors reduces the number of primary explants that released phenolic substances. In addition to the preparation of donors, nutrients, which were present in different amounts in nutrient media with different composition, had a significant impact. The fewest explants with phenol-like exudate were on NAM and NRM media.Common to these two environments is a relatively low content of nitrogen in both ammonium and nitrate forms, and the DKW environment contains the highest amount of sulfur. The release of phenol-like exudate also depended on the biological characteristics of almond varieties. The highest number of primary explants was in the high-growing variety E5 Borozan, and the least in the variety Louise with medium growth intensity. Depending on the variety, 81–91 % were free from contaminants in the depository, while 59–70 % were in control. Morphogenic and at the same time without signs of contamination were found from 69 % among the explants of the Louise variety and up to 73 % of the E5 Borozan variety, compared to 35 and 51 %, respectively, in the control. Based on the results of the research, it was established that the influence of the time of isolation of the primary explants and the features of the interaction of the plant and its surrounding microbiota in different seasons are different. This is manifested in the features of contamination by these objects of primary explants and, accordingly, the success of decontamination (E1) and the appearance of microbiological contamination on the nutrient medium. Key words: microclonal propagation, nut crops, multiplication, morphogenesis, contaminants, decontamination.

Control of Bacterial Wilt (Ralstonia solanacearum) and Reduction of Ginger Yield Loss through Integrated Management Methods in Southwestern Ethiopia

Background: Bacterial wilt incited by Ralstonia solanacearum is the most important disease affecting ginger production in southwestern Ethiopia. The unavailability of disease-free planting materials, resistant cultivars, and effective chemical compounds are the key constraints in managing the disease. Objective: The study was initiated to determine the effect of integrated management methods on bacterial wilt disease and yield loss of ginger through combining hot water, bio-fumigation, soil-solarization and chemical pesticides. Methods: A total of seven treatment combinations comprising hot water, bio-fumigation, soil-solarization, Mancozeb, and bleaching powder were tested in a randomized complete block design in three replications. Data on disease incidence, growth, yield, and yield components were recorded from randomly selected plants. Results: The use of Mancozeb for seed socking and soil drenching combined with bio-fumigation and soil-solarization reduced the incidence of bacterial wilt by 63.3% and enhanced the rhizome yield by 66.8%. Rhizome and soil treatment using bleaching powder along with soil bio-fumigation also reduced the disease incidence by 38.9% and increased ginger yield by 61.5%. It also provided the highest (6678.7%) marginal rate of return of any treatment combination tested in the experiment. Disease incidence was highly significantly and inversely (r= -0.98**) correlated with rhizome yield. The regression slope estimated that 83.4% of ginger yield loss was associated with bacterial wilt disease. Conclusion: A combined application of Mancozeb, bio-fumigation and soil-solarization can be used to control ginger bacterial wilt. Alternatively, bleaching powder for rhizome and soil treatment in conjunction with bio-fumigation can be employed as an integrated management system against the disease.

Control of Bacterial Wilt (Ralstonia solanacearum) and Reduction of Ginger Yield Loss through Integrated Management Methods in Southwestern Ethiopia

Background: Bacterial wilt incited by Ralstonia solanacearum is the most important disease affecting ginger production in southwestern Ethiopia. Unavailability of disease-free planting materials, resistant cultivars, and effective chemical compounds are the key constraints in managing the disease. Objective: The study was initiated to determine the effect of integrated management methods on bacterial wilt disease and yield loss of ginger through combining hot water, bio-fumigation, soil-solarization and chemical pesticides. Methods: A total of seven treatment combinations comprising hot water, bio-fumigation, soil-solarization, Mancozeb, and bleaching powder were tested in a randomized complete block design in three replications. Data on disease incidence, growth, yield, and yield components were recorded from randomly selected plants. Results: The use of Mancozeb for seed socking and soil drenching combined with bio-fumigation and soil-solarization reduced the incidence of bacterial wilt by 63.3% and enhanced the rhizome yield by 66.8%. Rhizome and soil treatment using bleaching powder along with soil bio-fumigation also reduced the disease incidence by 38.9% and increased ginger yield by 61.5%. It also provided the highest (6678.7%) marginal rate of return of any treatment combination tested in the experiment. Disease incidence was highly significantly and inversely (r= -0.98**) correlated with rhizome yield. The regression slope estimated that 83.4% of ginger yield loss was associated with the bacterial wilt disease. Conclusion: A combined application of Mancozeb, bio-fumigation and soil-solarization can be used to control ginger bacterial wilt. Alternatively, bleaching powder for rhizome and soil treatment in conjunction with bio-fumigation can be employed as an integrated management system against the disease.

Occurrence, Characterization and management of Sri Lankan Cassava Mosaic Virus (SLCMV) in cassava growing Namakkal district of Tamil Nadu, India

Cassava mosaic disease caused by begomoviruses of Geminiviridae family is one of the major constraints for the Cassava production in many Cassava growing states of India. The disease is known to be transmitted by whiteflies Bemisia tabaci and spread though the infected Cassava planting material. In India the Cassava mosaic disease (CMD) is caused by both Indian cassava mosaic virus (ICMV) and Sri Lankan cassava mosaic virus (SLCMV). However, Sri Lankan cassava mosaic virus was the most predominant virus species in the study area. To assess the severity of CMD, a survey was conducted during 2021-2022 in different blocks of the Namakkal district, Tamil Nadu state. The incidence was ranging from 34-95 percent, highest 95 % was recorded in Venandur and lowest 34 % was recorded in Elachipalayam block. The disease prevalence was ranging from 36-85 percent, highest 85 % was recorded in in Paramathi and lowest 36 percent recorded in the Elachipalayam block respectively. Variety Sree Padmanabha was found to be resistant for the Cassava mosaic virus in a trial conducted in a farmers’ field in Venandur block. Growing of CMD resistant varieties and use of disease-free Cassava planting material are the most important and economically feasible practices in the management of the Cassava mosaic Disease.

Diagnostics for production of disease free planting material of potato

Diagnostics for production of disease free planting material of potato

Micropropagation of fruit crops: a review

In vitro culture has the greatest commercial value in the extremely quick creation of clonal plants compared to conventional techniques of propagation. It has also proven to be of tremendous practical utility as assistance to the development and maintenance of disease-free planting material, germplasm conservation, and supplements to the regular methods of plant progress, such as plant genetic engineering. The discovery and implementation of current tissue culture techniques are thought to be paving the way for a second green revolution. Here, the standardization of techniques for the in vitro clonal propagation of fruit crops is highlighted. In addition, we summarize the effects of several surface sterilizing agents, plant growth regulators (PGRs), and anti-phenolic chemicals on culture establishment, shoot proliferation, in vitro rooting, hardening and economics of in vitro generation of true-to-type plants.

‘Priming’ protects Piper nigrum L. from Phytophthora capsici through reinforcement of phenylpropanoid pathway and possible enhancement of Piperine biosynthesis

Piper nigrum L. (black pepper), a woody perennial spice crop indigenous to India is positioned at the phylogenetically unique basal lineage of angiosperms. Cultivation of this major spice crop is constrained by rampant fungal and viral infections leading to a lack of disease-free planting material. The major disease that poses severe threat to P. nigrum plantations and nurseries is ‘quick wilt’ caused by the oomycete Phytophthora capsici, which affects the leaf, stem, spike, collar and root. In this paper, we report the consequence of priming in modulating Piper nigrum defense against Phytophthora capsici. Glycol Chitosan (GC) was used to infiltrate detached leaves of mature P. nigrum plants. It was observed that pre-treatment of GC for 24 hours resulted in significant reduction of disease symptoms in infected leaves, as evidenced by the marked decrease in the size of lesions, and also delayed the appearance of symptoms up to 72 hpi. Experiments repeated in P. nigrum seedlings under controlled growth conditions indicate that delayed disease symptoms of GC pre-treated leaves do not spread to healthy uninfiltrated leaves suggesting a priming-associated systemic defense response. An ROS-mediated manifestation of Hypersensitive Response (HR) induced by Chitosan was also evident in pre-treated leaves. A corresponding visual indication of increased lignification was observed, which correlated with an enhanced lignin content of GC-treated leaves. Enhanced callose deposition was also apparent in GC infiltrated leaves, establishing a stimulatory effect of GC in triggering HR through ROS production, enhanced lignification and callose deposition. Key genes of the core phenylpropanoid and isoprenoid pathways along with major defense signalling pathway genes of P. nigrum, including pathogenesis-related genes and hormone signalling genes showed significant transcript enrichment consequential to GC treatment. A significant quantitative enhancement in Piperine content was evident in GC-infiltrated leaves. The systemic nature of priming on disease protection was established through experiments conducted in rooted cuttings monitored for 30 days after disease infection. This is the first report that provides strong molecular evidence endorsing the twofold advantage of defense priming in P. nigrum by improving crop protection with a concomitant enhancement in Piperine biosynthesis.

Biology and biotechnological aspect of sweet potato (Ipomoea batatas L.): a commercially important tuber crop

This review highlights the economic importance of sweet potato and discusses new varieties, agronomic and cultivation practices, pest and disease control efforts, plant tissue culture protocols, and unexplored research areas involving this plant. Abstract Sweet potato is widely consumed in many countries around the world, including India, South Africa and China. Due to its valuable nutritional composition and highly beneficial bioactive compounds, sweet potato is considered a major tuber crop in India. Based on the volume of production, this plant ranks seventh in the world among all food crops. Sweet potato is considered a "Superfood" by the 'Centre for Science in the Public Interest' (CSPI), USA. This plant is mostly propagated through vegetative propagation using vine cuttings or tubers. However, this process is costly, labour-intensive, and comparatively slow. Conventional propagation methods are not able to supply sufficient disease-free planting materials to farmers to sustain steady tuber production. Therefore, there is an urgent need to use various biotechnological approaches, such as cell, tissue, and organ culture, for the large-scale production of healthy and disease-free planting material for commercial purposes throughout the year. In the last five decades, a number of tissue culture protocols have been developed for the production of in vitro plants through meristem culture, direct adventitious organogenesis, callus culture and somatic embryogenesis. Moreover, little research has been done on synthetic seed technology for the in vitro conservation and propagation of sweet potato. The current review comprehensively describes the biology, i.e., plant phenotypic description, vegetative growth, agronomy and cultivation, pests and diseases, varieties, and conventional methods of propagation, as well as biotechnological implementation, of this tuber crop. Furthermore, the explored and unexplored areas of research in sweet potato using biotechnological approaches have been reviewed.