STUDIES ON THE ARBUSCULAR MYCORRHIZAL FUNGAL BIODIVERSITY IN THE PLANT SPECIES OF YELLANAHALLI HILLS, VALLEY VIEW OF NILGIRIS, UDHAGAMANDALAM, TAMIL NADU, INDIA

The present study to investigated that the arbuscular mycorrhizal fungal root colonization and spore population in some medicinal at Yellanahalli hills, valley view of Nilgiris, Udhagamandalam, Tamilnadu, India. Root and rhizosphere soil samples were collected during the month of August, 2017 March, 2018 Soil pH was to be recorded. From the study results revealed that totally 25 plant species belonging to 13 families were recorded root colonization and rhizosphere spore population. A totally 12 Arbuscular mycorrhizal fungal species belonging to 7 genera and 2 different Orders were isolated and identified. The maximum spore population was found in the rhizosphere soil samples of Justicia procumbens (380 /100 g of soil) which belongs to the family Acanthaceae and the lowest spore population was observed in the Crotalarieae juncea (102 / 100 g of soil) belongs to Fabaceae. Among these plant species the highest 81% AM fungal infection was found in roots of Solanum nigrum belongs to the family Solanaceae While the lowest 23 % AM fungal association was found in the root of Verbascum thapsus belongs to Scrophulariaceae.


INTRODUCTION
As the world population continues to increase, the demands placed on agriculture to supply future food and fiber needs will be one of the greatest challenges facing the agricultural community. In particularly soil is one of the most important along with various microorganisms colonizing the rhizosphere soil surface, mycorrhizae, the mutualistic symbiotic, play an important role in mobilizing phosphorus from the deeper layers of the soil and supplying it to the host plants. Among the mycorrhizae, Arbuscular mycorrhizae (AM) is the most prevalent type (1).
In recently, considerable importance is being given to AM fungi, because of awareness of environmental pollution and health hazards by the use of chemicals. The responsibility of AM fungi and PGPR's, in improving crop plants growth is well documented (2, 3). Arbuscular Mycorrhizal fungi are also known to several benefits of the hosts by improving the uptake of other nutrients such as nitrogen (4), copper (5), sulphur, potassium and calcium (6) and by limiting uptake of toxic heavy metals such as Zn and Cd from soil (5) and they also increase drought tolerance (7), disease resistance (8). Hence in this present research work, the arbuscular mycorrhizal fungal root colonization and spore population in the rhizosphere soil samples were invesigated in Yellanahalli hills, valley view of Nilgiris, Udhagamandalam, Tamilnadu.

Study area
The present study area of Yellanahalli valley Coonoor (taluk) located in the Nilgiris District of Tamil Nadu State, India. The hill is located 11.404457°N 76. 712843°E (Fig. 1). The elevation of valley view ranges 2,400 msl (7,900ft). Near Yellanahalli are another two villages called Ketti and Aruvankadu. The Ketti is located to the south-west of Yellanahalli and is also sometimes referred to as the Switzerland of Southern India due to the yearround climatic conditions. The maximum annual rainfall 991mm and maximum temperature 24.3°C and minimum were 4.8°C.

Sample collection
The present study root and rhizosphere soils samples were collected from 25 plant species during the year August, 2017 to March, 2018. All the samples were placed in the polyethylene bags, labeled and then transported to the laboratory. The root samples were freshly processed, whereas rhizosphere soil samples were analyzed for mycorrhizal spore population and AM fungal root colonization.

Estimation of AM fungal root colonization
The fresh root samples were cleared and stained in tryphan blue following method of (9). Root samples of each plant species were washed gently under tap water and cleared in 2.5% KOH, acidified in 5 N HCL and stained in lacto glycerol with 0.05% Trypan blue. The stained roots were examined under a compound microscope (40x-100x). Hundred root segments for each sample were randomly selected for microscopic observation and the degree of colonization was estimated using the slide method (10).
The percentage of AM fungal infect ion was calculated using the formula: No. of root segments colonized Percentage of colonization = ×100 Total no of root segments of observed 2.4. AMF spore identification AM fungal spores were extracted from 100 g rhizosphere soil by wet-sieving and decanting method (11) through a series of 710 to 37μm size sieve filter. For the identification and nomenclature of these AM fungal spore synoptic keys developed by (12,13,14) were used. The classification was based upon the color, shape, hyphae, structure, size, and cell wall thickness and spore diameter.

Soil pH
The pH of the rhizosphere soil samples was determined (soil-water suspensions 1:5) with the help of pH meter (Elico) and values were recorded.

RESULTS AND DISCUSSION
In the present research, revealed that AM fungal colonization and spore population totally 25 plant species belongs to 13 families and pH of rhizosphere soil samples ranges between 4.8 to 6.6 were recorded from the study region . The detailed information about the plant species and their family habit, parts used and medicinal uses presented in (Table-1 In this study, analysis of life forms indicates that 72% of them are herbs and 28% of them are shrubs (Fig. 3). As far as the plant part used is concerned, it was noted that the local people especially in Badagas employed almost all part of plant used as ethnomedicine. The leaf is most predominantly used 44 % followed by whole plant 32%, seed 8 %, flower 8%, fruit 4% and root 4% (Fig.4) respectively. Based on the present study, it has been found that the Badagas tribal community of Yellanahalli hills is rich in ethnobiological knowledge and this knowledge is being transmitted from one generation to another generation. These traditional medicines are the primary health care resources for the Badagas tribes to protect their health.
Our present study findings that AM fungal colonization, the highest percent root colonization 81% was observed in the root samples from the plant species Solanum nigrum. A least number of 23% AM fungal infection was observed in Verbaseum thapsus. The maximum spore population was noted in Justicia procumbens (380/100 g of soil) belongs to the family Acanthaceae and minimum spore population was recorded in Crotalarieae juncea (102/100 g of soil) belongs to Fabaceae ( Fig. 5 and 6).      (Table. 3, Fig. 8, 9). Santhoshkumar and Nagarajan (15) reported that arbucular mycorrhizal fungal association in the rhizosphere soil and root colonization of some medicinal plant Species in Sirumalai Hills Eastern Ghats of Dindugul District, Tamilnadu and they were reported totally 39 AM fungal species belonging to six genera were isolated and identified. The genus Glomus were found dominate followed by Acaulospora, Sclerocystis, Entrophospora and Gigaspora. Priyadarshini et al. (16) also reported that occurrence of VAM fungi in Kalasalingam University campus.
They were isolated totally 26 species of vesicular arbuscular mycorrhizal fungal spores from the rhizosphere soil samples of the plant species belonging to 14 families was reported.

CONCLUSION
Based on this result, concluded that arbuscular mycorrhizal fungal root colonization and spore population were observed in the plant species of Yellanahalli hills. The symbiotic association of these arbuscular mycorrhizal fungal species Glomus was more abundant in all rhizosphere soil of the plant species. Further studies need for the tissue culture technique using mycorrhizal inoculation for ensuring enhanced the plant growth especially in agricultural crops..