Horticultural Plant Species Research Articles

First report of anthracnose caused by Colletotrichum fructicola on winter jasmine (Jasminum nudiflorum) in China.

Winter jasmine (Jasminum nudiflorum Lindl.) is a medium-sized, deciduous shrub native to China that has become a popular choice among gardeners and landscapers. In 2020 to 2021, symptoms of anthracnose including brown necrotic spots, enlarged irregular lesions and leaf blight were observed on leaves of 20 winter jasmine shrubs in a public garden (22°34'58'' N; 113°56'23'' E) in Shenzhen, China, and with an estimated disease incidence of 65%. Tissues samples (6 × 6 mm2) surrounding the necrotic spots were surface sterilized with 75% ethanol for 30 s, followed by 2% NaClO for 1 min, then rinsed with sterile water for three times and dried with sterile filter paper. Tissues were placed on potato dextrose agar (PDA) medium and incubated at 25℃. After 3 to 7 d, pure cultures were obtained by transferring hyphal tips to new plates and 32 isolates producing Colletotrichum-like colonies were obtained from 40 tissues (isolation frequency=32/(4×10)=80%). Three representative isolates YCH09, YCH23 and YCH32 were selected for further study. Three selected isolates were identical in morphological characteristics. Colonies on PDA after 5 d at 25℃ were white to gray with cottony mycelia and grayish-white on the underside of the culture. Conidia (n = 60) measured 15.4 ± 1.1 µm (13.0 to 17.1 µm) in length and 5.4 ± 0.3 µm (4.9 to 6.0 µm) in width and were hyaline, single-celled, cylindrical with rounded ends. Appressoria (n = 15) measured 7.1 ± 0.1 µm (5.3 to 8.9 µm) in length and 5.2 ± 0.2 µm (4.1 to 6.2 µm) in width and were brown to dark brown, ovoid. These morphological features were aligned with those of Colletotrichum spp. (Weir et al. 2012). Sequences of five genetic markers of representative isolates YCH09, YCH23 and YCH32 including the rDNA internal transcribed spacer region, chitin synthase, partial actin, β-tubulin 2 and Apn2-Mat1-2 intergenic spacer and partial mating type (Mat1-2) region were 99.3 to 100% identical to the ex-type isolate of C. fructicola strain ICMP 18581 (Zhang et al., 2020). From the maximum likelihood phylogenetic tree which was constructed based on concatenated sequences, three representative isolates (YCH09, YCH23 and YCH32) were clustered with other isolates of C. fructicola. The above morphological and molecular characteristics suggest that causal agent was C. fructicola. Pathogenicity was tested using a whole-plant assay. Five healthy plants were inoculated by spraying a conidial suspension (1.5×104 conidia/ml; 20 ml per plant) of the isolate YCH23 onto the foliage (Marshall et al., 2023). Three noninoculated control plants were sprayed with sterile water. All plants were placed in a greenhouse at 25±2℃ with approximately 75% relative humidity. Yellow lesions appeared on leaves of inoculated plants as early as 4 days after inoculation (DAI), and irregularly shaped brown spots similar to those observed in the field were formed on 10 DAI. Noninoculated plants remained asymptomatic. Colletotrichum isolates resembling morphological characters of YCH23 were reisolated from all inoculated plants, then identified as C. fructicola by DNA sequence analysis. C. fructicola is a well-known fungus causing anthracnose on more than 63 plant species including agricultural and horticultural plants worldwide (Talhinhas and Baroncelli, 2021). To our knowledge, this is the first report of C. fructicola infecting J. nudiflorum plants in China. Since its potential risk to other horticultural plant species, precautions may be necessary to minimize the spread of this fungi.

Catechin promotes the germination of Pistacia chinensis seeds via GA biosynthesis.

Chinese pistachio (Pistacia chinensis), an important horticultural plant species, holds great ornamental value with beautiful leaves and fruits. Seedling propagation of this tree species is restricted by its erratic seed germination; however, the germination mechanism is ambiguous. The aim of this study was to determine the germination mechanism from a novel perspective based on the multi-omics data. The multi-omics technique combined with hormone content measurement was applied to seed germination of Chinese pistachio. Due to its great accumulation during seed germination, catechin stood out from the identified metabolites in a broadly targeted metabolomic analysis. Exogenous catechin at 10 mg L-1 significantly improved the germination of Chinese pistachio seeds. An interesting result of hormone analysis was that the improving effect of catechin could be attributed to an increase in gibberellic acid 3 (GA3) content rather than a decrease in abscisic acid (ABA) content before germination. Treatments with paclobutrazol (PAC, a GA biosynthesis inhibitor) and PAC + catechin also showed that the promoting effect of catechin on seed germination depends on GA biosynthesis. Transcriptome analysis and qRT‒PCR further revealed that catechin induced the expression of PcGA20ox5 to activate GA biosynthesis. Several transcription factors were induced by catechin and GA treatments, such as TCP, bZIP and C3H, which may play an important regulatory role in GA biosynthesis in a catechin-mediated way. Catechin promotes seed germination via GA biosynthesis in Chinese pistachios. This study proposes a novel mechanism by which catechin promotes seed germination via the GA pathway, which provides new insight into a comprehensive understanding of seed dormancy and germination.

Does Sodium Nitroprusside Alleviate Water Deficit Stress in Impatiens walleriana Shoots Grown In Vitro?

Impatiens walleriana is a decorative horticultural plant species. Commercial production requires that the plants be brought to market, often accompanied by reduced water content during transport. Drought significantly affects metabolic processes in plants. The effects of polyethylene glycol (PEG)-induced water deficit on shoots of I. walleriana were investigated using different mechanisms at the biochemical level. In addition, the potential water deficit-ameliorating effect of sodium nitroprusside (SNP) was tested. Shoots of I. walleriana were initially grown on MS media supplemented with SNP (50, 100 and 250 μM). After pre-treatments, shoots were further transferred to media supplemented with PEG8000 (3%) and/or SNP (50, 100 and 250 μM). Water deficit conditions increased proline, photosynthetic pigments, malondialdehyde (MDA), H2O2, total phenolic content and antioxidant activity. In addition, PEG-induced water deficit increased superoxide dismutase (SOD) and peroxidase (POX) activities but decreased catalase (CAT) activity. SNP did not significantly affect photosynthetic pigments and total phenolic content but increased proline accumulation, MDA and H2O2 content, especially when applied simultaneously with PEG. Moreover, none of the investigated SNP pretreatments significantly altered the activities of SOD, POX, and CAT in I. walleriana. The results indicate that exogenous application of SNP effectively alleviated water deficit stress in shoots of I. walleriana grown in vitro.

Effect of Zinc Excess on Some Physiological Parameters and on the Fatty Acids Profile of Sinapis alba L. and Brassica juncea L. (Czern)

Zinc (Zn) is a vital micronutrient for all living organisms, but in high concentrations, it is a major anthropogenic pollutant. In this study, it was investigated the effect of zinc excess concentrations (50, 100, and 150 mg kg−1) in the substrate on some physiological parameters and the dynamics of fatty acid (FA) content in yellow mustard (Sinapis alba L. cv. Belgia) and oriental mustard (Brassica juncea L. (Czern) cv. Slavanka). The Zn concentration of 50 mg kg−1 did not affect the physiological parameters of yellow mustard, whereas some physiological parameters slightly decreased in oriental mustard. Moreover, this concentration stimulated an increase in total and unsaturated FAs content in leaves of both species, along with high Zn accumulation by both species. The Zn concentrations of 100 and 150 mg kg−1 in substrate had a negative effect on the state of plants as measured by the studied physiological parameters and caused different changes in FAs content in yellow and oriental mustard. Particularly, the total amount of FA increased in comparison to the control, but this increase was due to an elevation in saturated FA (SFA) content. At the same time, the total FA content in oriental mustard slightly decreased while the proportion of unsaturated FAs to SFA kept rising. According to the present data and analysis of the available literature, two strategies of adaptation to heavy metals were suggested through the changes in FAs: height-resistant horticultural plant species on the one side and sensitive species on the other.

The Pengaruh Pemberian Pupuk Bokashi Feses Ayam Broiler Dan NPK Terhadap Pertumbuhan Dan Hasil Tanaman Sawi Caisim (Brassica Juncea L.)

Mustard plant (Brassica juncea L.) as one of the horticultural plant species from the Brassicaceae family which has great potential to be cultivated in Indonesia. The productivity of mustard greens has decreased due to several factors, one of which is the insufficient nutrients needed by plants during the vegetative and generative stages of the plant. In addition, the factors that affect the cultivation of mustard plants are declining soil quality, uncertain climate change, and attacks by plant-disturbing organisms (OPT). With this problem, it is necessary to add nutrients to the soil, the added nutrients are organic fertilizer bokashi broiler chicken feces and inorganic fertilizer NPK. The purpose of this study was to determine the effect of the interaction between broiler feces bokashi fertilizer and NPK fertilizer on the growth and yield of caisim mustard plants. The research method used a completely randomized design (CRD) which consisted of 2 factors with 3 replications. The first factor of bokashi fertilizer consists of 3 levels, namely B1: 25 grams/polybag; B2: 30grams/poly bag; B3 : 35 gram/poly bag. The second factor is NPK fertilizer which consists of 3 levels, namely N1: 0.63 gram/polybag; N2: 0.47 gram/poly bag; N3: 0.31 gram/poly bag. The data obtained was analyzed using Analysis of Variance (ANOVA), and if it was significantly different, it would be further tested by Duncan's Multiple Range Test or Duncan's Multiple Range Test (DMRT) with a 95% confidence level. The results showed (1) the interaction of broiler feces bokashi fertilizer and NPK fertilizer showed a significant difference in plant height and plant fresh weight variables and other variables showed no significant different effect. (2) Broiler faeces bokashi single fertilizer treatment gave significantly different results on root length and plant fresh weight variables with the best dose being B3 : 35 gram. (3) the single fertilizer treatment gave highly significant different results on the number of leaves variable and not significantly different on the growth rate variable and chlorophyll content variable with the best dosage being N3: 031 gram.

GERDH: an interactive multi-omics database for cross-species data mining in horticultural crops.

Horticultural plants contribute immensely to the quality of humans' life. The rapid development of omics studies on horticultural plants has resulted in large volumes of valuable growth- and development-related data. Genes that are essential for growth and development are highly conserved in evolution. Cross-species data mining reduces the impact of species heterogeneity and has been extensively used for conserved gene identification. Owing to the lack of a comprehensive database for cross-species data mining using multi-omics data from all horticultural plant species, the current resources in this field are far from satisfactory. Here, we introduce GERDH (https://dphdatabase.com), a database platform for cross-species data mining among horticultural plants, based on 12,961 uniformly processed publicly available omics libraries from more than 150 horticultural plant accessions, including fruits, vegetables, and ornamental plants. Important and conserved genes that are essential for a specific biological process can be obtained by cross-species analysis module with interactive web-based data analysis and visualization. Moreover, GERDH is equipped with 7 online analysis tools, including gene expression, in-species analysis, epigenetic regulation, gene co-expression, enrichment/pathway and phylogenetic analysis. By interactive cross-species analysis, we identified key genes contributing to postharvest storage. By gene expression analysis, we explored new functions of CmEIN3 in flower development, which was validated by transgenic chrysanthemum analysis. We believe that GERDH will be a useful resource for key gene identification and will allow for omics big data to be more available and accessible to horticultural plant community members.

The complete chloroplast genome sequence of Chrysojasminum subhumile and its phylogenetic position within Oleaceae

We assembled and characterized the complete chloroplast genome sequence of Chrysojasminum subhumile (W.W.Sm.) Banfi & Galasso 2014, a valuable horticultural and medicinal plant species. The total genome size was 159,918 bp in length and the GC content was 37.4%. It displayed a circular structure and could be divided into a large single-copy region, a small single-copy region, and a pair of inverted repeat regions. The genome encoded a total of 131 unique genes, including 82 protein-coding genes, 41 tRNA genes, and eight rRNA genes. Among these genes, 17 contained a single intron, and two genes had two introns. Phylogenetic analysis results showed that C. subhumile was closely related to Jasminum.

Biochar, but not soil microbial additives, increase the resilience of urban plant species to low water availability

Impervious surfaces that characterise urban areas can make them harsh, water-limited places for plants to grow. To help alleviate plant stress under these challenging drought conditions, a range of soil additives can be utilised. Although well-studied individually, our understanding of the interaction between different soil additives in alleviating drought stress in urban areas is rudimentary. The aim of this study was to (1) assess the growth of urban horticultural plant species under drought stress and (2) determine whether drought stress in these species is alleviated by the use of soil additives, both individually and in combination. We grew six plant species (three trees, three graminoids) commonly planted in Australian urban areas under two watering regimes (drought-stressed, well-watered) and four soil additive treatments (no additive, microbial additive only, biochar only, microbial additive and biochar), and assessed their performance. We found that drought stress significantly reduced the growth of the six study species. Surprisingly, this decrease in growth was not reduced with the use of soil additives, despite biochar increasing soil water content and mycorrhizal colonisation when used in combination with the microbial additive. However, the addition of biochar significantly delayed the visual onset of drought stress across all species. Our results show that soil additives can be used as a cost-effective management strategy to increase plant resilience to drought stress in urban areas.

Aqueous Extracts of Four Medicinal Plants and Their Allelopathic Effects on Germination and Seedlings: Their Morphometric Characteristics of Three Horticultural Plant Species

Allelopathy is a biological phenomenon of synthesizing and excreting compounds that can affect the growth of various organisms, i.e., plant species. The aim of this work was to investigate the possible allelopathic influence of aqueous extracts, obtained from plant species chia (Salvia hispanica L.), black cumin (Nigella sativa L.), wormwood (Artemisia absinthium L.), and nettle (Urtica dioica L.), on the seed germination growth and morphometric characteristics of pepper (Capsicum annuum L.), spinach (Spinacia oleracea L.) and lettuce (Lactuca sativa L.) seedlings in laboratory conditions. Pepper, spinach, and lettuce seedlings were treated with aqueous extracts of chia, nettle, wormwood, and black cumin of different concentrations (2.5, 5 and 10%, respectively). The aqueous extracts were prepared according to the method developed by Norsworthy and the qualitative and quantitative analysis of phenolic compounds in aqueous extracts were performed using ultra-performance liquid chromatography electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). Phytochemical composition of chia aqueous extracts showed the highest content (above the 1 mg L−1) of epicatechin, quinic acid, caffeic acid, esculetin and cinnamic acid in the comparison with others from the total of 19 detected chemical compounds. In aqueous extracts of black cumin, there were six compounds detected in content above 1 mg L−1, i.e., epicatechin, quinic acid, caffeic acid, esculetin, cinnamic acid, and kaempferol. The same compounds were the most abundant in wormwood extracts, along with gallic acid. Epicatechin and esculetin were only two compounds detected in aqueous extract of nettle in concentration higher than 1 mg L−1. According to the results of this study, only the treatment of spinach seeds with chia aqueous extract in concentration of 2.5% before germination stimulates the germination of spinach seeds, and wormwood herbs and chia extracts in concentrations of 2.5 and 5% stimulate the germination of lettuce seeds and the growth of hypocotyl and radicle length of developed seedlings. The treatment of pepper and lettuce seeds with aqueous extract of nettle in concentration of 10% completely inhibited seed germination.

Study on morphological characterization of Citrus macroptera Mont collected from garo hills district Meghalaya, India

The work was undertaken to study the variability in Citrus macroptera from five Garo hills district. Many important horticultural plant species, viz. Citrus are known to have originated from this region. Citrus macroptera Mont. is one of the endangered, semi-wild species which have found to exist in various parts of NE region, including Meghalaya. Thirty accession of Citrus macroptera from five different districts of Garo Hills, Meghalaya were collected to study its variability in quantity and quality parameters. In the study significant to highly significant differences were observed among the genotypes. The analysis of variance for different parameters such as tree height, tree girth, leaf length, leaf width, fruit width, fruit length, fruit weight, number of fruit segment, rind thickness, number of seeds per segment, seed length, and seed width varied significantly among accession. Variability among accession collected from different location shows the great scope for genetically potential genotypes for cultivation and also for their exploitation in plant breeding programme.

Axillary Bud Fate Shapes Plant Architecture in Horticultural Crops

Above-ground plant architecture is dictated to a large extent by the fates and growth rates of aerial plant meristems. Shoot apical meristem gives rise to the fundamental plant form by generating new leaves. However, the fates of axillary meristems located in leaf axils have a great influence on plant architecture and affect the harvest index, yield potential and cultural practices. Improving plant architecture by breeding facilitates denser plantations, better resource use efficiency and even mechanical harvesting. Knowledge of the genetic mechanisms regulating plant architecture is needed for precision breeding, especially for determining feasible breeding targets. Fortunately, research in many crop species has demonstrated that a relatively small number of genes has a large effect on axillary meristem fates. In this review, we select a number of important horticultural and agricultural plant species as examples of how changes in plant architecture affect the cultivation practices of the species. We focus specifically on the determination of the axillary meristem fate and review how plant architecture may change even drastically because of altered axillary meristem fate. We also explain what is known about the genetic and environmental control of plant architecture in these species, and how further changes in plant architectural traits could benefit the horticultural sector.

Combined Biostimulant Applications of Trichoderma spp. with Fatty Acid Mixtures Improve Biocontrol Activity, Horticultural Crop Yield and Nutritional Quality

The growing demand for safer foods reflects the public perception of the adverse consequences of chemicals used in agriculture. This research aimed at developing new biological formulations based on the combination of small microbial consortia containing two Trichoderma spp., with a medium–long chain fatty acids mixture (FAm). The bioactivity of these formulations was investigated on different vegetable crops in terms of biocontrol, growth promotion, yield and quality improvements. FAm application reduced Botrytis cinerea necrosis by up to 90% compared to the infected control plants and some of the assayed Trichoderma spp. + FAm combinations contained Rhizoctonia disease, reaching more than 90% reduction of tomato and lettuce plant mortality. An increasing yield, ranging to 25 and 90%, was recorded on treated tomato, lettuce and kohlrabi compared to untreated plants. A significant enrichment in carotenoids (+60%) and glucosinolates (+39%) was measured on biotreated plants compared to controls. Untargeted LC-MS analysis revealed a higher content of tomatine and dehydro-phytosphingosine, glycoalkaloids involved in defense responses, in Trichoderma spp. + FAm combination-treated plants. The combined biostimulant applications of Trichoderma spp. with FAm were able to improve the performances of different horticultural plant species, producing a premium quality marketable vegetable with higher antioxidant content.

Feature Papers in Horticulturae

The presented Feature Papers reflect the diversity of the types of research performed on horticultural plant species, spanning from the basic to the applied, production systems, and postharvest studies, in addition to highlighting some critical issues facing horticultural plant species [...]

Population and Conservation Status of the Flying Fox Pteropus dasymallus in Taiwan.

Pteropus dasymallus is widely distributed on islands throughout the western edge of the Pacific Ocean. The Formosan flying fox, P. d. formosus, is an endemic subspecies in Taiwan found mainly on Lyudao; it was previously thought to have been extirpated. Since 2005, intensive surveys have been conducted to investigate the residency, population size and plant resource utilization of P. dasymallus in Taiwan. Interviews were carried out to investigate its former abundance and the causes of population decline. In Taiwan, P. dasymallus is in a state of ongoing oceanic dispersal and colonization and has considerably expanded its geographic range. In addition to remaining in its historic habitat on Lyudao, P. dasymallus has also established colonies on Gueishan Island and in Hualien on Taiwan's main island in the past few decades. The total population size is estimated to be 240 individuals, and this number is on the rise. Approximately three-quarters of the entire population (73.64%) was found on Gueishan Island. The sex ratio was strongly skewed toward males. A total of 40 plant species were recorded as being used by the flying fox for food, roosts or perches. More agricultural and horticultural plant species were used by the flying fox in urban Hualien. According to the interviews, flying foxes were abundant on Lyudao, but their number dramatically declined from the 1970s to the mid-1980s, mainly due to commercial hunting. Maintaining a sufficient population size and genetic variability is fundamental to the long-term survival of the flying fox. Enforcing conservation laws, restoring habitats, controlling invasive species and improving public awareness are the main steps in the recovery and sustainability of the flying fox population.

The performance of paludiculture commodities at different peat depths in Central Kalimantan

Paludiculture is one of the alternative efforts to restore degraded peatland. It involves rewetting, revegetation and revitalization of local livelihood. This research evaluated three paludiculture demonstration plots at Central Kalimantan, one in the shallow peat of Pilang village and two plots in the deep peat of Tumbang Nusa village. The plots were evaluated in terms of the plant’s growth, productivity, commodities introduced and environmental monitoring, including water table, soil physical and chemical properties, carbon stocks and CO2 emission. The results showed that the three plots were categorized as “compromised” paludiculture plots because some of the commodities were not local peatland species. Belangeran (Shorea balangeran) and horticultural plant species such as rambutan (Nephelium lappaceum) and pineapple (Ananas comosus) showed good growth performance. Liberica coffee (Coffea liberica) was not suitable for deep peat due to its low survival rate and poor growth. The result also showed that soil peat characteristics of the sites were still in good condition; however, the impact of peatland utilization should have been monitored to support land-use sustainability. Moreover, stingless bee cultivation and vegetables could become potential commodities to be developed in shallow and deep peatland.

Isoleucine Enhances Plant Resistance Against Botrytis cinerea via Jasmonate Signaling Pathway.

Amino acids are the building blocks of biomacromolecules in organisms, among which isoleucine (Ile) is the precursor of JA-Ile, an active molecule of phytohormone jasmonate (JA). JA is essential for diverse plant defense responses against biotic and abiotic stresses. Botrytis cinerea is a necrotrophic nutritional fungal pathogen that causes the second most severe plant fungal disease worldwide and infects more than 200 kinds of monocot and dicot plant species. In this study, we demonstrated that Ile application enhances plant resistance against B. cinerea in Arabidopsis, which is dependent on the JA receptor COI1 and the jasmonic acid-amido synthetase JAR1. The mutant lib with higher Ile content in leaves exhibits enhanced resistance to B. cinerea infection. Furthermore, we found that the exogenous Ile application moderately enhanced plant resistance to B. cinerea in various horticultural plant species, including lettuce, rose, and strawberry, suggesting a practical and effective strategy to control B. cinerea disease in agriculture. These results together showed that the increase of Ile could positively regulate the resistance of various plants to B. cinerea by enhancing JA signaling, which would offer potential applications for crop protection.

Susceptibility of Garden Plants to Phytophthora Root Rot.

Phytophthora root rot (PRR) is a serious disease of horticultural, forest, and ornamental plant species caused by species of the oomycete genus Phytophthora. Their wide host range makes the choice of resistant plants in the management of the disease difficult. We used the Royal Horticultural Society diagnostic dataset of PRR records from U.K. gardens to compare the susceptibility of different host genera to the disease. The dataset was compared with existing reports of plants recorded as notably resistant or notably susceptible to PRR. An index-based approach was used to separate 177 genera of woody plants into three categories: 85 were low index (<0.10: rarely affected), 34 were medium index (0.10 to 0.20: sometimes affected) and 58 were high index (>0.20: frequently affected). Similarly, genera of nonwoody plants were separated into: 45 low index (<0.22), 16 medium index (0.22 to 0.44), and 18 high index (>0.44). Taxus was the genus with the highest index, while most genera in the Malvales and Ericales were in the high-index group. Most genera in the Myrtales, Fabales, and Monocotyledons were low index. While 30 Phytophthora species were recorded in our study, the wide host range spp., P. plurivora, P. cryptogea, and P. cinnamomi, represented 63% of identifications. P. plurivora was the most common species on woody plants and P. cryptogea on nonwoody plants. These results provide confidence in the use of host resistance as part of the integrated management of PRR.

Assessing the relationship between trait-based and horticultural classifications of plant responses to drought

Water availability can be a major abiotic constraint for plant success in urban areas. To ensure resilient green spaces, understanding which species are able to cope with low water availability is paramount for plant selection. However, in the horticultural industry, descriptions of species’ responses to low water availability are oftentimes poorly defined, inconsistent across sources, and informed from the natural habitat of species, personal experience, or both. Therefore, a method to objectively assess tolerances of species to low water availability is needed. Using a multivariate approach, we characterised the drought strategies of 113 horticultural plant species spanning five different growth forms (graminoids, herbs, climbers, shrubs and trees) by using five leaf-level traits (leaf mass per area (LMA), leaf thickness, unit leaf area, leaf dry matter content (LDMC) and leaf water potential at turgor loss point (TLP)). Based on this approach, we found that species clustered into three distinct groups, which correspond to fundamental drought strategies based on previous ecological literature (i.e., ‘dehydration avoiders’ (species with high LMA and LDMC, thick leaves and low (more negative) TLP), ‘dehydration tolerators’ (species with low LMA and LDMC and high (less negative) TLP) and an ‘intermediate’ mixture of the two strategies). We found that the majority of species that were considered as ‘drought tolerant’ by the horticultural industry were classified as either ‘dehydration tolerators’ (31.9 %) or ‘dehydration avoiders’ (42.5 %) using our trait-based approach. We did not find any strong connections between the climate of origin of our species and our trait-based classifications. Distinguishing between dehydration avoidance and dehydration tolerance may help to enhance horticultural guidelines by better informing which species are suitable for particular biophysical and landscape contexts. This trait-based approach allows for evidence-based evaluation of drought strategies of new and emerging species and cultivars that may be suitable for urban landscapes.

Carbon sequestration by horticultural plants in East Calcutta Wetlands ecosystem, a Ramsar Site in India

East Calcutta Wetlands (ECW) located at the eastern fringe of Kolkata metropolitan, India designated as a Ramsar Site (No. 1208). ECW receives municipal solid wastes and composite wastewater from the city and local artisans use this for horticulture, agriculture and pisciculture practices. Horticulture designated as ‘green industry’ sequester significant amount of carbon (C) in plant biomass and in soil, therefore, helps to mitigate greenhouse gases and combat against global climate change. Six horticultural plant species commonly cultivated in ECW ecosystems were selected for present study. C sequestration potential of horticultural plants depends on plant biomass and plant density in cultivation fields. Highest amount of C was sequestered (40.76±6.73 ton ha-1) by ixora, a perennial plant in plant biomass. In case of basil, also a perennial plant, significant portion of the living plant biomass was exported from ECW as economically important parts which constitute 5.79±0.96 ton ha-1 C. Highest amount of soil organic carbon (SOC) was recorded from marigold fields (50.36±24.88 ton ha-1) which also constitute highest amount of C (34.37±5.67 ton ha-1) in residual parts (RP). Horticulture practices can sequester more amount of C in the ecosystem either by residual parts or remaining living plant biomass than agricultural practices.

A case study of using an efficient CRISPR/Cas9 system to develop variegated lettuce

The clustered, regularly interspaced, short palindromic repeat associated endonuclease 9 (CRISPR/Cas9) system has emerged as a powerful approach for precision breeding to create plants with desirable traits. However, the CRISPR/Cas9 system relies heavily on an efficient plant transformation system that is usually time-consuming and costly. Here, we have constructed a CRISPR-Cas9 vector with neomycin phosphotransferase II and green fluorescent protein (eGFP-NPTII), where the high expression of GFP during plant regeneration allowed us to minimize the positional effect on T-DNA expression and facilitate screening T-DNA-free mutants. Successful gene editing using CRISPR/Cas9 has been illustrated in different plant species, but an important aesthetic characteristic of leaf variegation remained unexplored. With the newly designed construct, we have targeted the variegation gene <i>LsVAR2</i> in lettuce. Our results indicated that <i>LsVAR2</i> is closely related to both <i>AtFtsH2</i> and <i>AtFtsH8</i>, in which homozygous mutations lead to an albino phenotype while a variegated phenotype was induced by CRISPR/Cas9 <i>de novo</i> gene editing. In conclusion, the unique design of our CRISPR/Cas9 construct could efficiently edit the target gene and ease the screening of non-TDNA mutants through detecting GFP signals during plant regeneration and progeny segregation. Additionally, the success of gene-editing of <i>LsVAR2</i> in lettuce demonstrates proof in this method to develop novel plant breeding materials for valuable horticultural plant species.