High genetic diversity and small genetic variation among populations of Magnolia wufengensis (Magnoliaceae), revealed by ISSR and SRAP markers

Genetic diversity and population structure of Euscaphis japonica, a monotypic species

Background

Understanding plant genetic diversity is important for effective conservation and utilization of genetic resources. Euscaphis japonica (Thunb.) Dippel, is a monotypic species with high phenotypic diversity, narrow distribution, and small population size. In this study, we estimated the genetic diversity and population structure of E. japonica using nine natural populations and inter-simple sequence repeat (ISSR) markers. Our results could provide a theoretical reference for future conservation and utilization of E. japonica.

Results

We obtained a total of 122 DNA bands, of which 121 (99.18%) were polymorphic. The average number of effective alleles (Ne = 1.4975), Nei’s gene diversity index (H = 0.3016), and Shannon’s information index (I = 0.4630) revealed that E. japonica possessed a high level of genetic diversity. We observed that E. japonica consisted of both deciduous and evergreen populations. UPGMA tree showed that the evergreen and deciduous E. japonica form a sister group. There is little genetic differentiation among geographic populations based on STRUCTURE analysis. The Dice’s similarity coefficient between the deciduous and evergreen populations was low, and the Fst value was high, indicating that these two types of groups have high degree of differentiation.

Conclusion

Rich genetic diversity has been found in E. japonica, deciduous E. japonica and evergreen E. japonica populations, and genetic variation mainly exists within the population. The low-frequency gene exchange between deciduous and evergreen populations may be the result of the differentiation of deciduous and evergreen populations. We suggest that in-situ protection, seed collection, and vegetative propagation could be the methods for maintenance and conservation of E. japonica populations.

Genetic diversity and population structure assessment using molecular markers and SPAR approach in Illicium griffithii, a medicinally important endangered species of Northeast India

BACKGROUND

Illicium griffithii is an aromatic medicinal tree species that has been listed in the IUCN Red List as an endangered species. Dried seed pods of I. griffithii have a good market potential in the spices and pharmaceutical industries. Fruits are the potential source of shikimic acid and used for the production of oseltamivir (a drug against bird flu). However, in recent years, unscientific harvesting and rampant exploitation of the species has caused a negative and adverse effect on its natural population. Proper knowledge of genetic diversity and population structure is crucial to understand the population dynamics, adaptation, and evolutionary pattern of a particular species for conservation. It was from this view point that the present study was undertaken so as to compare the various types of DNA-based molecular markers namely RAPD, ISSR, DAMD, and SCoT by their efficiency and SPAR approach to evaluate the genetic diversity of I. griffithii as well as to analyze population genetic structure for conservation purpose.

RESULT

A total of 250 discernible bands were generated with 246 bands (98.40 %) being polymorphic in nature. All the primers in combination gave a mean polymorphic information content (PIC) of 0.81 and Rp value (resolving power) of 4.32. Nei's, Gst, and AMOVA analysis showed similar values of genetic differentiation among populations (Gst = 0.396, F_ST = 0.30, respectively), revealing a low level of genetic differentiation among the eight sampled populations. I. griffithii with an estimated gene flow value of Nm = 0.761 was significantly low among populations. Clustering pattern obtained with Bayesian structure and PCoA diagram revealed that intermixing of genetic material across populations is only possible when the populations lie close to each other. This is further validated with UPGMA clustering method where a positive correlation of genetic variability with geographical distance among closely related populations could be clearly seen.

CONCLUSION

The result aids in the identification, collection, and preservation of diverse germplasm of I. griffithii from Arunachal Pradesh and Meghalaya of Northeast India. This would further help in understanding the population structure and genetic diversity among other Illicium species in order to formulate effective conservation strategies for the improvement of this endangered taxa.

Genetic diversity in the candidate trees of Madhuca indica J. F. Gmel. (Mahua) revealed by inter-simple sequence repeats (ISSRs)

Madhuca indica provides livelihood to several tribal people in India, where the flowers are used for extraction of sweet juices having multiple applications. Certain trees have more value as judged by the tribal people mainly based on yield and quality performance of the trees, and these trees were selected for the genetic diversity analyses. Genetic diversity of 48 candidate Mahua trees from Etapalli, Dadagaon, and Jawhar, Maharashtra, India, was assessed using ISSR markers. Fourteen ISSR primers revealed a total of 132 polymorphic bands giving overall 92% polymorphism. Genetic diversity, in terms of expected number of alleles (Ne), the observed number of alleles (Na), Nei's genetic diversity (H), and Shannon's information index (I) was 1.921, 1.333, 0.211, and 0.337, respectively, and suggested lower genetic diversity. Region wise analysis revealed higher genetic diversity for site Etapalli (H = 0.206) and lowest at Dhadgaon (H = 0.140). Etapalli area possesses higher forest cover than Dhadgaon and Jawhar. Additionally, in Dhadgaon and Jawhar M. indica trees are restricted to field bunds; both reasons might contribute to lower genetic diversity in these regions. The dendrogram and the principal coordinate analyses showed no region-specific clustering. The clustering patterns were supported by AMOVA where higher genetic variance was observed within trees and lower variance among regions. Long-distance dispersal and/or higher human interference might be responsible for low diversity and higher genetic variance within the candidate trees.

ISSR Marker Based Population Genetic Study of Melocanna baccifera (Roxb.) Kurz: A Commercially Important Bamboo of Manipur, North-East India

Melocanna baccifera (Roxb.) Kurz is an economically important bamboo of North-East India experiencing population depletion in its natural habitats. Genetic variation studies were conducted in 7 populations sampled from 5 districts of Manipur using ISSR molecular markers. The investigation was carried out as a primary step towards developing effective conservation strategies for the protection of bamboo germplasm. ISSR marker analysis showed significant level of genetic variation within the populations as revealed by moderately high average values of Nei's genetic diversity (H 0.1639), Shannon's diversity index (I 0.2563), percentage of polymorphic bands (PPB 59.18), total genetic variation (H_t 0.1961), and genetic diversity within population (H_s 0.1639). The study also divulged a high genetic variation at species level with Shannon's diversity index (I), Nei's genetic diversity (H), and percentage of polymorphic band (PPB%) recorded at 0.3218, 0.1939, and 88.37, respectively. Genetic differentiation among the populations (G_st) was merely 19.42% leaving 80.58% of genetic variation exhibited within the populations. The low genetic diversity between populations was consistent with AMOVA. The low genetic differentiation among populations coupled with existence of significantly high genetic diversity at species level indicated the urgent necessity of preserving and protecting all the existing natural bamboo populations in the region.