Cultivated beets, including leaf beets, garden beets, fodder beets, and sugar beets, which belong to the species Beta vulgaris L., are economically important edible crops that have been originated from a halophytic wild ancestor, Beta maritima L. (sea beet or wild beet). Salt and drought are major abiotic stresses, which limit crop growth and production and have been most studied in beets compared to other environmental stresses. Characteristically, beets are salt- and drought-tolerant crops; however, prolonged and persistent exposure to salt and drought stress results in a significant drop in beet productivity and yield. Hence, to harness the best benefits of beet cultivation, knowledge of stress-coping strategies, and stress-tolerant beet varieties, are prerequisites. In the current review, we have summarized morpho-physiological, biochemical, and molecular responses of sugar beet, fodder beet, red beet, chard (B. vulgaris L.), and their ancestor, wild beet (B. maritima L.) under salt and drought stresses. We have also described the beet genes and noncoding RNAs previously reported for their roles in salt and drought response/tolerance. The plant biologists and breeders can potentiate the utilization of these resources as prospective targets for developing crops with abiotic stress tolerance.

Both genomes in chloroplasts and mitochondria of plant cell are usually inherited from maternal parent, with rare exceptions. To characterize the inheritance patterns of the organelle genomes in cucumber (Cucumis sativus var. sativus), two inbred lines and their reciprocal F₁ hybrids were analyzed using an next generation whole genome sequencing data. Their complete chloroplast genome sequences were de novo assembled, and a single SNP was identified between the parental lines. Two reciprocal F₁ hybrids have the same chloroplast genomes with their maternal parents. Meanwhile, 292 polymorphic sites were identified between mitochondrial genomes of the two parental lines, which showed the same genotypes with their paternal parents in the two reciprocal F₁ hybrids, without any recombination. The inheritance patterns of the chloroplast and mitochondria genomes were also confirmed in four additional cucumber accessions and their six reciprocal F₁ hybrids using molecular markers derived from the identified polymorphic sites. Taken together, our results indicate that the cucumber chloroplast genome is maternally inherited, as is typically observed in other plant species, whereas the large cucumber mitochondrial genome is paternally inherited. The combination of DNA markers derived from the chloroplast and mitochondrial genomes will provide a convenient system for purity test of F₁ hybrid seeds in cucumber breeding.

Cultivated beets (sugar beets, fodder beets, leaf beets, and garden beets) belonging to the species Beta vulgaris L. are important sources for many products such as sugar, bioethanol, animal feed, human nutrition, pulp residue, pectin extract, and molasses. Beta maritima L. (sea beet or wild beet) is a halophytic wild ancestor of all cultivated beets. With a requirement of less water and having shorter growth period than sugarcane, cultivated beets are preferentially spreading from temperate regions to subtropical countries. The beet cultivars display tolerance to several abiotic stresses such as salt, drought, cold, heat, and heavy metals. However, many environmental factors adversely influence growth, yield, and quality of beets. Hence, selection of stress-tolerant beet varieties and knowledge on the response mechanisms of beet cultivars to different abiotic stress factors are most required. The present review discusses morpho-physiological, biochemical, and molecular responses of cultivated beets (B. vulgaris L.) to different abiotic stresses including alkaline, cold, heat, heavy metals, and UV radiation. Additionally, we describe the beet genes reported for their involvement in response to these stress conditions.

Pumpkins (Cucurbita moschata) are one of the most important economic crops in genus Cucurbita worldwide. They are a popular food resource and an important rootstock resource for various Cucurbitaceae. Especially, C. moschata is widely used as a rootstock for the commercial production of bloomless cucumbers in East Asia. Since the genetic diversity of the commercial rootstock varieties is narrow, there has been an increasing demand for the trait development of abiotic and biotic stress tolerance breeding. In this study, 2071 high-quality SNPs that were distributed evenly across 20 chromosomes of pumpkins were discovered through the genotyping-by-sequencing (GBS) analysis of 610 accessions of C. moschata germplasm with a global origin. Using these SNPs, various analyses of the genetic diversity and the population structure were performed. Three subgroups were clustered from the germplasm collection, which included East Asia, Africa, and America, and these areas were included the most in each subgroup. Among those groups, accessions from Africa and South Asia showed the highest genetic diversity, which was followed by the Mexico accessions. This result reflected that large gene pools that consist of various native landraces have been conserved in those of countries. Based on the genetic diversity, we finally constructed the C. moschata core collection, which included 67 representative accessions from the 610 germplasms. Five morphological traits that are important in commercial grafting and rootstock seed production, which include the cotyledon length, the cotyledon width, the hypocotyl length, the internode length, and the number of female flowers, were investigated for three years and used to confirm the validity of the core collection selection. The results are expected to provide valuable information about the genetic structure of the worldwide C. moschata germplasm and help to create new gene pools to develop genetically diverse rootstock breeding materials.

This study aimed to establish a rapid in vitro plant regeneration method from rhizome buds of Kaempferia parviflora to obtain the valuable secondary metabolites with antioxidant and enzyme inhibition properties. The disinfection effect of silver oxide nanoparticles (AgO NPs) on rhizome and effects of plant growth regulators on shoot multiplication and subsequent rooting were investigated. Surface sterilization of rhizome buds with sodium hypochlorite was insufficient to control contamination. However, immersing rhizome buds in 100 mg L⁻¹ AgO NPs for 60 min eliminated contamination without affecting the survival of explants. The number of shoots (12.2) produced per rhizome bud was higher in Murashige and Skoog (MS) medium containing 8 µM of 6-Benzyladenine (6-BA) and 0.5 µM of Thidiazuron (TDZ) than other treatments. The highest number of roots (24), with a mean root length of 7.8 cm and the maximum shoot length (9.8 cm), were obtained on medium MS with 2 µM of Indole-3-butyric acid (IBA). A survival rate of 98% was attained when plantlets of K. parviflora were acclimatized in a growth room. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) was used to determine the chemical profile of K. parviflora leaf extracts. Results showed that several biologically active flavonoids reported in rhizomes were also present in leaf tissues of both in vitro cultured and ex vitro (greenhouse-grown) plantlets of K. parviflora. We found 40 and 36 compounds in in vitro cultured and ex vitro grown leaf samples, respectively. Greenhouse leaves exhibited more potent antioxidant activities than leaves from in vitro cultures. A higher acetylcholinesterase inhibitory ability was obtained for greenhouse leaves (1.07 mg/mL). However, leaves from in vitro cultures exhibited stronger butyrylcholinesterase inhibitory abilities. These results suggest that leaves of K. parviflora, as major byproducts of black ginger cultivation, could be used as valuable alternative sources for extracting bioactive compounds.

Cucumbers are an important economic vegetable crop that is used for fresh or processing purposes worldwide. In this study, we used 264 accessions that consisted of world-wide wild germplasms and advanced breeding lines in order to understand the genetic diversity and the genetic correlation among the germplasm collection. A genotyping-by-sequencing (GBS) approach was applied to obtain dense genome-wide markers coverage (>12,082 SNPs) to construct a high-density haplotype map. Various population stratification methods were performed, and three subgroups were divided based on the genetic diversity, which reflected their geographic regions. According to the phylogenetic analysis, the breeding lines were separated from wild germplasms, and the two distinct groups were divided within the breeding lines. One of the groups mainly consisted of East-Asian varieties, which showed the unique homogenous genotype patterns. Using this germplasm collection, three important horticultural traits of cucumbers—powdery mildew resistance, spine color, and fruit stalk-end color—were evaluated and used to conduct the genome-wide association study (GWAS). All of the significant SNPs and two novel candidate genes (Csa5G453160 and Csa5G471070) for the powdery mildew were identified in chromosome 5 from the natural population, which is where reported major QTLs from various bi-parental population are located. Furthermore, two candidate genes, Csa1G006300 and Csa3G824850, and four candidate genes, Csa2G368270, Csa3G236570, Csa5G175680, and Csa6G448170, were identified for the spine color and the fruit stalk-end color, respectively. These results are expected to be helpful to develop molecular markers of the horticultural traits in cucumbers.