Microbial Biotechnology and Biofertilizer Laboratory, Department of Botany, J.N.V. University, Jodhpur (Rajasthan) India – 342 003

Corresponding author email: mamtasharma019@gmail.com

Article Publishing History

INTRODUCTION

Mycorrhizae has  a well-established mutual relationship between plant root and fungi found in association with roots of land plants. Mycorrhizae  are naturally occurring soil borne fungi which can potentially increase nutrient availability, biomass and make plant stress resistant (Sun et al., 2018).Besides growth promotion the major role of Arbuscular Mycorrhizal (AM) fungi is provide protection against various pathogen (Jung et al., 2012). AM fungi are obligate symbiont that means they required host root for their growth and complete  their lifecycle. Once they get successful association, the mycorrhizal fungi starts to form arbuscules, vesicles hyphae and spores. Among all spores and hyphae also found in rhizosphere soil. Arbuscules are   branching pattern which provide the place to facilitate the   nutrient exchange and also accumulate reserve nutrient. Vesicles are bulbous structure which contains reserve food as glycogen and fat granules. Mycorrhizal hyphae extends deeply   in soil in search of water hence it maintain the water level of plant, (Symanchik 2018 Wipf et al., 2019 Montero et al 2019).

Many research have been done to explore the contribution of AM fungi in plant growth and development, plant safety, soil health. In this continuation this research study has been done to evaluate the significant changes in Sorghum when inoculated with AM species. Sorghum is scientifically known as Sorghum bicolor L. Moench,.It  is also known as sweet sorghum which belongs to family Poaceae.  Sorghum is cultivated all over the world for food, feed, forage, fuel,  and ranks fifth among the major cereal crops in terms of production (FAOSTAT, 2015).Sorghum belongs to  C4 grass family which has well adaption to grow in arid or semi-arid region and also has a fibrous root system  thus it easily interact with AM fungi. Root associations with arbuscular mycorrhizal fungi enhance plant growth by increasing P uptake, N uptake (Gerdemann, 1964; Janos, 1987; Stribely, 1987,Montero et al 2019).

According to Cavagnaro et al. (2015) the nutrient loss from soil can be reduced by potential use of AM fungi due to increasing the absorption zone. It was analysed that Sorghum absorbed more P from soils when colonized with AMF than non mycorrhizal   plants (Krishna and Bagyaraj, 1981). For preparing pot culture, sorghum plant treated with AM inoculums which were obtained from trap culture. These AM inoculums belong to genus Glomus Acaulospora Scutellospora Gigaspora. In the meanwhile studied the growth stages of development of mycorrhizal fungi such as infection, apprisoria formation, hyphae development, arbuscule, vesicles and spore formation. From the pot culture study also it has been compared and analysed the effects of AM fungal spore on the plant growth and physiological changes. Besides physiological changes this interaction also enhances root growth, leaf surface area.  Besides these AM fungi plays a important role to maintain soil texture, improve  quality of soil, nutrient cycling, hence it contribute to balance our ecosystem.AM inoculated Sorghum shows significant increase in all parameter as compare to control. Increased in photosynthetic rate, protein and sugar content, uptake of N P promote overall growth and yield of plant, (Montero et al 2019, Wipf et al  2019).

According to Amiri et al., (2017), increased  concentration of N P Fe  was found in Pelargonium graveolens. The present research describes  the beneficial effect of AM fungi that can improve nutrient status by changing the  host plants physiology and  improving  the biomass.

MATERIAL AND METHODS

A field survey conducted at six sites near Jodhpur area. Rhizosphere soil along with root sample collected in three replicate. As rhizosphere soil considered to be a source of AM spores that’s why AM spores were collected from rhizosphere soil. For the extraction of AM spore   wet sieving and decanting technique has been carried out from soil sample. (Gerdemann and Nicolson1963).   The isolated AM fungi were identified by key of Trappe and   manual of identification of AM fungi of Trappe (1962) Schenck and  Perez. (1987).  In the present work root samples were collected from the field  and were cleared and stained using trypan blue in lactophenol (Phillips and Hayman, (1970).) AM spore percentage  and  root colonization were evaluated by  the gridline intersect method (Giovannetti  and Mosse, (1980).).After identification AM spores Glomus fasciculatum, Glomus mossae.  Sclerocystis rubiformis, Acaulospora morrowae and Acaulospora leavis, Scutellospora calospora, Gigaspora margarita,   were seen mostly. These AM spores were transferred to  various pot cultures with host plant  Cenchrus ciliaris or Sorghum bicolor for mass multiplication .After one month when AM spores were germinate then infected root segments of host plant with  hyphae, vesicles and spore used as inoculum for experimental plant i.e. Sorghum. These pot were kept in isolated condition. The pot which had no AM inoculum served as control. Plants root and rhizospheric soil were collected after 15days, 30 days, 45days, 60days,90 days for biochemical estimation.

BIOCHEMICAL DETERMINATION: The parameters studied include chlorophyll and carotenoid, proteins, total sugar, total phenol, peroxidase, polyphenol oxidase.Chlorophyll and carotenoid content in leaves was estimated using Arnons method (1949). The protein content in leaves   of mycorrhizal inoculated and non-mycorrhizal Sorghum plant was estimated using Bradford(1976)  method. The total sugar content was estimated in leaves of AM inoculated plant and controlplant using the method Mc. Cready et al,.(1950).The total amount of peroxidase enzyme was estimated from AM inoculated and control plants using modification method proposed by Putter (1974) and Malik and Singh (1980).  The total amount of polyphenol oxidase enzyme in root was calculated from mycorrhiza inoculated   and control plant using the method proposed by Esterbaner et al(1977) modified by Fujita et al. (1995). Total phenol content  was estimated by   Mahadevan’s method (1975).

RESULTS AND DISCUSSION

AM fungi association found to be most common relationship in nature which affect cultivated plants as well as  the plants growing in natural ecosystems, thus it is most important finding in agriculture research field (Brundrest 2018).   AM fungal association with Sorghum plant affects plant growth, nutrient content, and enzymatic activity. In present study result was based on comparison of mycorrhiza treated plant with control plant. Amount measured of chlorophyll and carotenoid   from AM inoculated leaf significantly higher as compare to uninoculated control plant.. The highest concentration of chlorophyll were seen in Acaulospora laevis (121 mg/gm fresh wt.) and Acaulospora morrowae (119 mg/gm fresh wt.) while least were observed in Gigaspora margarita that is (108 mg/gm fresh wt.) inoculated Sorghum plant. Carotenoid content were observed higher in (41.7 mg/gm fresh wt.).The increased concentrations of  these  pigments directly affected the rate of photosynthesis and metabolism in host plants. By the experimental result of (Bhosale and Shinde 2011) the rate of photosynthesis  was found to be higher in mycorrhizal treated   plants compared to non- mycorrhizal control plants.

Chlorophyll and carotenoids are important plant pigment which plays significant role to accelerate the process of photosynthesis and biomass production. AMF can modified the nutritional value of grains in many   agricultural crops and improve the production of carotenoids and certain volatile compounds Bona et al. (2017). When   total sugar content of AM treated Sorghum plant compared to control plant then   increase concentration   in total sugar content was observed in Acaulospora laevis (2.79 mg/gm fresh wt.) inoculated plant followed by Acaulospora morrowae (2.61mg/gm fresh wt.) treated plant.

Baslam et al (2011) used   Mycorrhiza as a bioinoculant to test whether  the plant shows enhanced accumulation in terms of chlorophyll, carotenoids, total soluble phenol, tocopherols, and various essential nutrients or not. Inoculated plants get better accumulation in contrast to control. Peroxidase activity was analysed for both control and AM inoculated plant which resulted that peroxidase activity is higher in fresh root weight of Glomus fasciculatum inoculated plants. Increasing amount of both enzymes that is Peroxidise and polyphenoloxidase positively correlated with increase in phosphorus concentration because in previous research resulted that  AM fungi increases phosphate uptake which ultimately increase peroxidase and polyphenoloxidase activity of host plant. Peroxidase activity observed higher in Glomus fasciculatum that is 21.33 / mg fresh wt and polyphenoloxidase activity also in Glomus fasciculatum that is 23.1 / mg fresh wt. As a result of metabolic activity (ROS) species were formed as a by product thus it is necessary to  detoxify reactive oxygen species (ROS)  by the enzymes such as superoxide dismutase, catalase, peroxidase, and enzymatic level enhance significantly after mycorrhizal treatment, (Ahanger and Agarwal, 2017 Montero et al., (2019).

The phosphorus availability with in the soil is taken up with phosphate transporter located in the extra-radical hyphae of this fungus (Harrison and Buuren 1995). Glomus fasciculatom (2.2 mg/gm fresh wt.) and Glomus mossae (2.1 mg/gm fresh wt.) came out to be most active in enhancing phenolic accumulation. Total increase in phenol content may be due to an increased   phosphorus level and PPO activity. Accumulation of phenol in AM plants which has been reported by   (Covacevich and Berbara (2011).As concentration of PRO and PPO enzymes increase they oxidised phenol compound into Quinone or increase in phenyl propane i.e. lignin precursor which are well known for antimicrobial property. It is toxic for attacking pathogen so it is important content of plant defence mechanism.

The findings of Nisha and Kumar (2010) also support these results that higher levels of polyphenoloxidase and peroxidise  are observed   in mycorrhizal plants. They used seven different types of AM species, inoculated with Wedilla plant and observed increase concentration in enzyme as compare to non inoculated. Protein content in all AM inoculated plant resulted almost similar still  The maximum protein content found in Glomus fasciculatum (2.31mg/gm fresh wt. ) and Glomus mossae ( 2.25 mg/gm fresh wt. ) inoculated plant.  Hence this AM endophyte can improve the nutritive value as well as enzymatic value of  host plant.  Through the mycorrhizal symbiosis an increase in protein content in grains of chickpea has also been reported by Pellegrino and Bedini (2014).

The present investigation demonstrate  that inoculation with  Acaulospora laevis, Acaulospora morrowae  and Glomus fasciculatom can enhance the enzymatic activity of Sorghum plant that is good for plant defence system.AM inoculated plant also enhance the accumulation of sugar, chlorophyll, protein which collectively enhance biomass and more highly proteinaceous grain. Occurrence of AM fungi have been reported almost all soil type ( Bernaola,  et al.,2018). Any of soil condition semi-arid, arid, humid it can perform vigorously and make a plant nutrient stable for biomass, defence stable for pathogenic attack. The obligatory relationship of plant and fungi are bidirectional because mycorrhizae  provides nutritional benefits to the plant in exchange fungus receives carbon compound to complete its life cycle, (Wipf et al 2019).  It is very helpful for soil health as well as plant development.

Table 1. Effect of different Arbuscular mycorrhizal fungi on biochemical changes in Sorghum plant after one month

Treatment	Total protein mg/gm fresh wt.	Total phenol mg/gm fresh wt.	Total sugar mg/gm fresh wt.	Total chlorophyll mg/gm fresh wt.	Total carotenoid mg/gm fresh wt.
Control	2.2	1.10	1.27	99	31
Glomus fasciculatum	2.31	2.2	2.19	116	39
Glomus mossae	2.25	2.1	1.99	112	37.1
Acaulospora leavis	2.1	1.91	2.79	121	41.7
Acaulospora morrowae	2.1	1.86	2.61	119	40.1
Sclerocystis rubiformis	2.09	1.78	1.91	114	37.6
Scutellospora calospora	2.11	1.87	1.68	110	39.1
Gigaspora margarita	2.15	1.89	1.71	108	39.8

Table 2. Effect of different AM fungi on enzymatic changes in Sorghum plant After one month

Treatment	PRO activity (Units mg-1 protein)	PPO activity (DA420/100 mg fw)
Control	16	17.1
Glomus fasciculatum	21.33	23.1
Glomus mossae	20.91	22.4
Acaulospora leavis	18.6	20.1
Acaulospora morrowae	19.1	21.5
Sclerocystis rubiformis	18.2	20.2
Scutellospora calospora	19.5	20.11
Gigaspora margarita	19.7	22

ACKNOWLEDGEMENTS

The authors are thankful to Head of Department of Botany  Prof. P.K. Kasera for providing  support. Department of Botany JNV University and Microbial Biotechnology and Biofertilizer Lab  Jodhpur (Rajasthan) for providing instrumentation facility.

Conflict Of Intrests:There is no conflict of interest.

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