ISSR markers for gender identification and genetic diagnosis of Hippophae rhamnoides ssp. turkestanica growing at high altitudes in Ladakh region (Jammu and Kashmir)

The Systematics, Reproductive Biology, Biochemistry, and Breeding of Sea Buckthorn-A Review

Both the fruit flesh and seeds of sea buckthorn have multiple uses for medicinal and culinary purposes, including the valuable market for supplementary health foods. Bioactive compounds, such as essential amino acids, vitamins B, C, and E, carotenoids, polyphenols, ursolic acid, unsaturated fatty acids, and other active substances, are now being analyzed in detail for their medicinal properties. Domestication with commercial orchards and processing plants is undertaken in many countries, but there is a large need for improved plant material with high yield, tolerance to environmental stress, diseases, and pests, suitability for efficient harvesting methods, and high contents of compounds that have medicinal and/or culinary values. Applied breeding is based mainly on directed crosses between different subspecies of Hippophae rhamnoides. DNA markers have been applied to analyses of systematics and population genetics as well as for the discrimination of cultivars, but very few DNA markers have as yet been developed for use in selection and breeding. Several key genes in important metabolic pathways have, however, been identified, and four genomes have recently been sequenced.

Authentication of Hippophae rhamnoides ssp. sinensis and ssp. mongolica Based on Single Nucleotide Polymorphism at Ribosomal DNA and Their Vitamin Content Analysis

Hippophae rhamnoides widely known as sea buckthorn berries (SB) are rich in vitamins and phytonutrients. The subspecies ssp. sinensis and ssp. mongolica are highly valued for their medicinal properties and vitamin contents, hence domesticated widely across Eurasia and Southeast Asia. Due to the frequent usage of these two subspecies, accurate identification is required to prevent economically motivated adulteration. In this study, we report the single nucleotide polymorphism (SNP) based molecular markers to easily distinguish these two subspecies at 45S nrDNA region. From the determined 45S rDNA region, we designed two primers (5′ sinensis and 5′ mongolica) and developed a multiplex PCR profile. The developed primers effectively distinguished the sea buckthorn subspecies in commercial products as well. Along with the development of subspecies specific primers, we have profiled vitamin contents from H. rhamnoides ssp. sinensis and ssp. mongolica and found ascorbic acid and riboflavin contents were high in both ssp. sinensis and spp. mongolica, yet the content of folic acid was high only in ssp. mongolica. Thus, we provide species specific primers and vitamin profile as an effective authentication of H. rhamnoides.

Oligo-FISH Can Identify Chromosomes and Distinguish Hippophaë rhamnoides L. Taxa

Oligo-fluorescence in situ hybridization (FISH) facilitates precise chromosome identification and comparative cytogenetic analysis. Detection of autosomal chromosomes of Hippophaë rhamnoides has not been achieved using oligonucleotide sequences. Here, the chromosomes of five H. rhamnoides taxa in the mitotic metaphase and mitotic metaphase to anaphase were detected using the oligo-FISH probes (AG3T3)3, 5S rDNA, and (TTG)6. In total, 24 small chromosomes were clearly observed in the mitotic metaphase (0.89–3.03 μm), whereas 24–48 small chromosomes were observed in the mitotic metaphase to anaphase (0.94–3.10 μm). The signal number and intensity of (AG3T3)3, 5S rDNA, and (TTG)6 in the mitotic metaphase to anaphase chromosomes were nearly consistent with those in the mitotic metaphase chromosomes when the two split chromosomes were integrated as one unit. Of note, 14 chromosomes (there is a high chance that sex chromosomes are included) were exclusively identified by (AG3T3)3, 5S rDNA, and (TTG)6. The other 10 also showed a terminal signal with (AG3T3)3. Moreover, these oligo-probes were able to distinguish one wild H. rhamnoides taxon from four H. rhamnoides taxa. These chromosome identification and taxa differentiation data will help in elucidating visual and elaborate physical mapping and guide breeders’ utilization of wild resources of H. rhamnoides.

Spectroscopic and Molecular Methods to Differentiate Gender in Immature Date Palm (Phoenix dactylifera L.)

Phoenix dactylifera (date palm) is a well-known nutritious and economically important fruit tree found in arid regions of the Middle East and North Africa. Being diploid, it has extremely high divergence in gender, where sex differentiation in immature date palms (Phoenix dactylifera L.) has remained an enigma in recent years. Herein, new robust infrared (near-infrared reflectance spectroscopy (NIRS) and Fourier transform infrared attenuated total reflectance (FTIR/ATR)) and nuclear magnetic resonance (NMR) spectroscopy methods coupled with extensive chemometric analysis were used to identify the sex differentiation in immature date palm leaves. NIRS/FTIR reflectance and 1H-NMR profiling suggested that the signals of monosaccharides (glucose and fructose) and/or disaccharides (maltose and sucrose) play key roles in sex differentiation. The three kinds of spectroscopic data were clearly differentiated among known and unknown male and female leaves via principal component and partial least square discriminant analyses. Furthermore, sex-specific genes and molecular markers obtained from the lower halves of LG12 chromosomes showed enhanced transcript accumulation of mPdIRDP52, mPdIRDP50, and PDK101 in females compared with in males. The phylogeny showed that the mPdIRD033, mPdIRD031, and mPdCIR032 markers formed distinctive clades with more than 70% similarity in gender differentiation. The three robust analyses provide an alternative tool to differentiate sex in date palm trees, which offers a solution to the long-standing challenge of dioecism and could enhance in situ tree propagation programs.

Occurrence of subdioecy and scarcity of gender-specific markers reveal an ongoing transition to dioecy in Himalayan seabuckthorn (Hippophae rhamnoides ssp. turkestanica)

Dioecy and the dynamics of its evolution are intensely investigated aspects of plant reproduction. Seabuckthorn (Hippophae rhamnoides ssp. turkestanica) is an alpine shrub growing wild in certain parts of western Himalaya. The previous studies have reported heteromorphic sex chromosomes in the species and yet marker-based studies indicate high similarity between the male and female genomes. Lack of information on sexual system in the species has further complicated the situation. A systematic study was thus undertaken to understand the sexual system in seabuckthorn and to discern the extent of similarity/dissimilarity between the male and female genomes by generating a large number of markers using amplified fragment length polymorphism and representational difference analysis. Floral biology and regular monitoring of species revealed the presence of polygamomonoecious (PGM) plants in most populations at a low percentage (~2-4%). PGM plants showed low pollen production and overall low fertility, suggesting a monoecy-paradioecy pathway at function. The results of the marker study demonstrated that there are limited differences between male and female genomes and these differences were not uniform across the populations in the Leh-Ladakh region, especially when the geographical distance increases. Results also suggest that a dynamic partitioning of genomes is operational between the two genders of seabuckthorn and differences are not homogenized across the populations. Both reproductive biology-based and DNA marker-based studies indicate that genders have separated recently. The present study proposes seabuckthorn as a promising model system to study evolution of dioecy and sex determination.

Genetic diversity and variation of Chinese fir from Fujian province and Taiwan, China, based on ISSR markers

Genetic diversity and variation among 11 populations of Chinese fir from Fujian province and Taiwan were assessed using inter-simple sequence repeat (ISSR) markers to reveal the evolutionary relationship in their distribution range in this report. Analysis of genetic parameters of the different populations showed that populations in Fujian province exhibited a greater level of genetic diversity than did the populations in Taiwan. Compared to Taiwan populations, significant limited gene flow were observed among Fujian populations. An UPGMA cluster analysis showed that the most individuals of Taiwan populations formed a single cluster, whereas 6 discrete clusters were formed by each population from Fujian. All populations were divided into 3 main groups and that all 5 populations from Taiwan were gathered into a subgroup combined with 2 populations, Dehua and Liancheng, formed one of the 3 main groups, which indicated relative stronger relatedness. It is supported by a genetic structure analysis. All those results are suggesting different levels of genetic diversity and variation of Chinese fir between Fujian and Taiwan, and indicating different patterns of evolutionary process and local environmental adaption.