Executive Summary of Minor Research Project

EXECUTIVE SUMMARY OF THE MINOR RESEARCH PROJECT ON

 

“PHYLLOPLANE MICROBES IN FAMILY ANACARDIACEAE” - A STUDY.

‘Phyllosphere’ in a more general sense refers to the habitat adjacent to the plant and the habitat directly on the surface of plant is called as the phylloplane. All plants provide a home space to a variety of microorganism communities like bacteria, fungi, and yeasts, of these some microbes benefit the plant, while others damage or kill the host plant.

 

The number of microbes on leaf surfaces depends on the season and age of the leaf and bark. The density of their population in the adjacent air also determines the number of microbial cells on the leaf surface. The analysis of the phyllosphere diversity is used as an indirect estimate of the diversity of microbes in air.

 

Several methods are employed to study phylloplane microflora – direct (Direct observation, impression films, clearing, scanning microscopy and infra-red microscopy) and cultural (spore fall, plating, damp chamber, surface sterilization, leaf washing, leaf maceration, leaf impression) methods. Of this serial dilution plate method and leaf impression method are the most commonly employed techniques.

 

Keeping these aspects under focus this piece of work aimed at the identification of phyllosphere flora with special reference to fungi colonizing selected members of the family Anacardiaceae viz. Anacardium occidentale, Mangifera indica and Spondias pinnata available at different locations in Dakshina Kannada was carried out. 

 

1.      Study of the phylloplane fungal diversity on Anacardium occidentale, Mangifera indica and Spondias pinnata using Potato Dextrose Agar [PDA] and Czapek media.

 

2.      Study of the phylloplane fungal diversity as seasonal variations on Anacardium occidentale, Mangifera indica and Spondias pinnata during three seasons of the year viz. Monsoon [July – September], Post Monsoon [December – February] and Summer [March – May].

 

3.      Study of the phylloplane fungal diversity on Anacardium occidentale, Mangifera indica and Spondias pinnata using three locations in Dakshina Kannada viz. Mangalore, Bantwal & Haleyangadi.

4.      Comparison of data obtained for each genus under PDA and Czapek media to see dominance of a particular fungal genus. 

 

5.      Identification of the genera using Tsuneo Watanabe., 1937. Pictorial Atlas of Soil and seed Fungi. Morphologies of cultured fungi and Key to Species. Lewis Publishers

 

6.      To obtain pure cultures of as many isolates as possible.

 

The study was restricted to the commonly available genera of family Anacardiaceae viz. Anacardium occidentale, Mangifera indica and Spondias pinnata. These were collected on a monthly basis depicting monsoon [July – September], post monsoon [December – February] and summer [March – May] seasons of the year. 

The Leaf washing method was adopted to obtain the aliquot for inoculation. The washed aliquots of 1 ml per petriplate were pipetted and plated onto Potato Dextrose Agar (PDA) and Czapek media with mixtures of streptomycin.The plates were incubated at room temperature of 28⁰C for further observations. 

 

The petriplates were examined at weekly intervals until no new fungal colonies appeared. The data was tabulated to obtain a record of the time of emergence of colonies right up to the fruiting stage. Some colonies could be easily identified by their characteristic colours, while confirmation was done after sporulation.  Sterile mycelia were observed to see whether fruiting occurred. Fungi were identified using taxonomic keys when fruiting occurred, and the number of species recorded.

 

1.      Of the two fungal media employed different plant materials showed preference to different media based on the fungal diversity obtained.

 

2.      The leaf washing method provides a quantitative description of the species richness.

 

3.      Phylloplane communities show similarities in plants growing in different habitats like mangroves and terrestrial plants. Of the various species identified in the members of family Anacardiaceae Aspergillus, Trichoderma, Pestalotia and Yeast seem to be the most common species obtained. 

 

4.      The patterns of seasonal variations have been studied with a view to compare the results seen in the media used. Under PDA medium Mangifera indica indicated a peak in mid-monsoon; followed by another peak at the end of post monsoon and beginning of summer. Under Czapek medium Mangifera indica indicated a peak in late monsoon; again in late post monsoon and during the mid summer seasons.

 

5.      Seasonal variations are mainly due to the external environmental factors which play a major role in their colonization. It is extremely difficult to ascertain whether the isolates are purely of the phyllosphere or consist of some genera belonging to the endophytes.