Genetic Diversity and Phylogenetic relationship among accessions of Drepanostachyum falcatum ( Nees ) Keng f . from the Garhwal Himalayas

. This study assessed the genetic diversity of 10 accessions of Drepanostachyum falcatum collected from different localities in the Garhwal Himalayas, Uttarakhand, India , in the Hill bamboo germplasm collectionin Khirsu , using isozyme markers with four enzyme system (peroxidase, esterase, malate dehydrogenase and malic enzyme). Isozymatic analyses were performed with polyacrylamide gels (one system), bands were scored as binary data. Cluster analyses were conducted, using Jaccard ́s similarity coefficient and UPGMA method. Very high degree of similarity was reported i.e. 6394% among different accessions. Dendrogram revealed two major clusters with three (A8A10) and seven (A1A7) accessions respectively. The results obtained suggested low genetic diversity in the species and urgent need of the in situ conservation of the natural genetic resources of the D. falcatum species. Key words: Genetic diversity; isozymes; polyacrylamide; Jaccard’s coefficient Introduction: Genetic conservation programmes are directed towards the long-term preservation of genetic resources either in situ or ex situ so that the potential for continuing evolution or improvement could be sustained. In situ conservation includes the organization and/ or servicing of natural supplies where species are permitted to stay in maximum environments with the lowest of management. On the other hand, ex situ conservation includes the use of botanic landscapes, field farms, seeds shops and gene banks and germplasm. The characterization of germplasm is required to maintain identity and purity for proper conservation and management. Various breeding strategies of plants are based on the knowledge of germplasm. Germplasm characterization is thus an important link between the conservation and utilization of plant genetic resources for improvement. Some Bamboos are arborescent grasses belonging to the family Poaceae, but these ones aren't, because they are less than 6m tall, so they are shrubby instead (fruticose), but you don't really need this sentence at all. To study the genetics of bamboo specially, one has to face enormous difficulties such as rare flowering and we cannot make hybridizations as easily as like other plant taxa. Unlike other tropical bamboos, studies on hill bamboos are scarce. Drepanostachyum falcatum, an important hill bamboo, act as soil stabilizer in hilly terrain and contributes significantly to rural livelihoods. Drepanostachyum falcatum, known locally as Gol Ringal, is socioeconomically and ecologically, an important member of hill bamboo, present in Uttarakhand Garhwal Himalayas. Like other bamboo species, it also has erratic and long flowering cycles. Drepanostachyum falcatum flowers irregularly at times, gregarious over large areas, while few culms may be found in flowers almost every year. After seeding the clumps died (Naithani et al. 2003). 10 World Bamboo Congress, Korea 2015 Theme: Biology, Morphology and Taxonomy Due to over usage of genetic resources and heavy extraction of the material from natural forests, the species are depleting at an alarming rate, gregarious flowering in turn intensifying the depletion of Ringal resources since flowering result into death of entire clumps following seeding. If a single regeneration event coincides with unsuitable conditions, the entire population might lose its chance to reproduce. Heavy forest degradation and agricultural encroachment, forest fires, human impact, heavy grazing pressures, etc. narrows the genetic base and eventually degradation of the gene pool of these species. Isozymes are commonly used as biochemical markers as detectably different enzymes, which catalyze the same reaction (Hamrick et al., 1992). Enzymatic analyses are added tools for detecting diversity (Zeidler, 2000). The relationship between observed phenotypes and unobserved genotypes is simpler and better understood for electrophoretic evidence. Allozymes are the biochemical consequence of the substitution, deletion, or addition of amino acids in the polypeptides that comprise the enzymes and they can be distinguished if these changes affect their electrophoretic migration (Gottlieb, 1977). Isozyme electrophoresis is used to describe population structure, breeding structure and gene flow; to know species boundaries, and to document adaptive differences in allozymes; and to investigate phylogenetic relationships, rates of evolution, origin of polyploid plants and ploidy levels (Murphy et. al., 1996). A biochemical study was done using esterase and Peroxidase and phenolics to study the different banding patterns in genera Arundinaria, Pseudosasa, Semiarundinaria, Shibataea, Sinobambusa and Yushania (Chou et al., 1986). Phylogenetic study among 16 species of eight genera were conducted by Li Shengfeng (1989) by using peroxidase and esterase and concluded that isozymes are suitable markers to distinguish among species and genera. The present work was therefore, undertaken to assess variability among accessions of D. falcatum growing in a Germplasm at Khirsu (Pauri) through genetic tools with the objective i.e. to study the genetic polymorphism on the basis of biochemical i.e. isozyme analysis. Material and Method: Sample Collection: The young leaves of selected accessions (Table.1)were collected from Hill Bamboo Germplasm, Khirsu (India), tagged properly in polybags and stored in ice bucket till they were brought to Plant Physiology Laboratory (FRI, Dehradun). The leaves were stored at -20°C in freezer (vest frost DFS 345) till use. Extraction of Enzymes: Two grams of young leaves were macerated to powder with liquid Nitrogen in a mortar – pestle and then 0.1 gm PVP and 5ml of extraction buffer was added. The extraction buffer consisted of 1 M Sucrose, 0.2 M Tris and 0.056 M β Marcaptoethanol. The volume was made up to 100 ml with distilled water and pH was adjusted at 8.5. The macerates were centrifuged at 1500 rpm for 20 minutes at 4 C to collect the supernatants (Das and Mukherjee, 1997). Electrophoresis of the Enzyme Extracts: Each sample was applied to a native discontinuous polyacrylamide gel (4% stacking, 10% separating gel) and the runs were performed on a mini gel apparatus in TrisGlycine (pH 8.3) buffer. Four enzyme systems were examined in this study. They are peroxidase (PRX, E.C.1.11.1.7), esterase (EST, E.C. 3.1.1.1), malate dehydrogenase (MDH, E.C.1.1.1.37) and Malic enzyme (ME, EC 1.1.1.40). Fixation and Storage of the Gel: After appearance of the bands, the gel was transferred to a fixative solution that contained 100 ml of 50% methanol, 20 ml of 10% acetic acid and 40ml of distilled water. The gel was stored at 4C in refrigerator. 10 World Bamboo Congress, Korea 2015 Theme: Biology, Morphology and Taxonomy Statistical analysis of isozyme profile data: Each accession was considered a taxonomical operational unit (OTU) and isozyme bands were analysed as binary characteristics. The presence (coded as 1)/ absence (coded as 0) data matrix was prepared by scoring the gel. Relationships among the taxa were inferred with UPGMA clustering from Jaccard's similarity matrix of the bands. Data were analysed using the SAHN (Sequential Agglomerative Hierarchical and Nested) module of NTSYS-PC 2.11 (Numerical Taxonomy and Multivariate Analysis System) software program (Sharifi et al., 2006) and dendrogram with bootstrap values was constructed by Darwin (version 5.0) software program. Results: A total of 31 bands were recovered for esterases (EST), in 10 accessions with six loci viz. EST-1, EST-2, EST-3, EST-4, EST-5 and EST-6. Esterase loci (E1-E6) were numbered in sequence from the anode according to their decrease in negative charge. The locus EST-4 was monomorphic for all OTU’s whereas EST5 was present in only accession A8. Locus EST-3 was present in three accessions viz. A2, A8 and A9. With Peroxidase (PRX) resolution, a total of twenty two bands were resolved with maximum (three) loci viz. PRX-1, PRX-2 and PRX-3 for accessions A3 and A5. Loci PRX-1 and PRX-2 were monomorphic for all accessions. Locus PRX3 was found to be polymorphic and represented by the accessions A3 and A5. Malate dehydrogenase (MDH) enzyme system was monomorphic for all the accessions showing single locus for each. Overall, 10 bands were recovered in all the accessions. Malic enzyme was represented with thirty seven bands with four loci viz. ME1, ME2, ME3 and ME4. Locus ME-2 was found to be polymorphic whereas remaining three loci i.e. ME-1, ME-2 and ME-3 were monomorphic for all accessions of A. falcata. A total of 100 bands with fourteen putative loci in the four different enzyme assays were resolved with sufficient consistency and clarity. The number of polymorphic loci was 7. The polymorphism ranged from 25 83.33%. Maximum polymorphism (83.33%) was achieved through Esterase followed by Peroxidase (33.33%). and minimum for Malic enzyme (25%). MDH revealed only monomorphic bands (Table.2). Overall 50% polymorphism was depicted by ten accessions of D. falcatum with four enzyme systems. (Table.2) Cluster analysis: Data scored for 10 accessions of D. falcatum with four enzyme systems, were used to generate similarity coefficients. The genetic relatedness among the accessions revealed by unweighted pair group methods with arithmetic mean (UPGMA) cluster analysis is presented in dendrogram as below. Cluster analysis was performed using isozyme data and it produced stable and consistent patterns. At 73% similarity level, the dendrogram revealed two major clusters; First cluster consisted of seven accessions (A1 to A7) representing different localities. The second cluster consisted of only three accessions viz. A8, A9 and A10 with overall similarity of 82%, which was further sub divided into two sub clusters at overall similarity of 88%, consisting of A10 and A9 as one sub cluster and A8 as second sub cluster. Similarity between different accessions was laid between 63 to 94%. Maximum of 94 % similarity was found between accessions A