West Bengal Biodiversity Board Department of Environment, Government of West Bengal
পশ্চিমবঙ্গ জীবববশ্চিত্র্য পর্ষদ Vol. 5, No. 2
From the desk of the Chairman
an earlier editorial column I wrote that the Biodiversity Management Committee (BMS) through community participation is acting as a vital instrument in the preparation of People’s Biodiversity Register (PBR). Now I am happy to inform all that the West Bengal Biodiversity Board has achieved exceptionally good results in constituting BMCs and in preparing PBRs during the last six months. This momentum in the process of successful implementation of BD Act in the State was gained mainly due to the spontaneous participation of the communities of rural Bengal. The present issue includes an article on Guttation – a unique physiological process in plants. It is a means of production of recombinant proteins that are used as pharmaceuticals, industrial enzymes, etc. We are thankful to the authors for the valuable article. The Board appreciates the views and suggestions received from the readers/user groups about the newsletter. I personally thank Sri Pallab Bhattacharjee and all other colleagues in the Board for their sincere efforts in preparation and publication of this issue.
Special Article in this issue Guttat ion—A Natural Phenomenon : Useful medium for production of Recombinant Proteins -- Dr. A.K . Mondal & Prof. S. P. Mondal
Biodiversity Management Committee (BMC) : The Manager of Biodiversity
People’s Biodiversity Register (PBR): The Mirror of Biodiversity
UNEP—GEF—MoEF ABS Project (Progress made so far)
International Day for Biological Diversity
Publications of the Board
Guttation—A Natural Phenomenon : Useful medium for production of Recombinant Proteins Dr. A.K. Mondal & Prof. S.P. Mondal
Biodiversity Management Committee (BMC): The Manager of Biodiversity The local level Biodiversity Management Committees (BMCs) are the custodian, within their jurisdiction, for managing biodiversity sustainably. For that the Committees are to prepare People‟s Biodiversity Registers (PBRs) within their area to get an overall idea of biodiversity and associated Traditional Knowledge (TK) and practices prevailing there. The Board has the responsibility to facilitate this process in making people aware of it.
During the period under report, 20 BMCs have been constituted in the following places: 1. Binpur I Panchayat Samiti, Paschim Medinipur district 2. Basanti Panchayat Samiti, South 24 Pargana district 3. Chandipur Panchayat Samiti, Purba Medinipur district 4. Contai III Panchayat Samiti, Purba Medinipur district 5. Coochbehar I Panchayat Samiti, Coochbehar district 6. Gaighata Panchayat Samiti, Paschim Medinipur district 7. Keshpur Panchayat Samiti, Paschim Medinipur district 8. Narayangarh Panchayat Samiti,Paschim Medinipur district 9. Raina II Panchayat Samiti, Paschim Medinipur district 10. Ranaghat Municipality, Nadia district 11. Tamluk Panchayat Samiti, Purba Medinipur district
12. Kalimpong I Block, Darjeeling district 13. Sankrail Panchayat Samiti, Paschim Medinipur district 14.Medinipur Sadar Panchayat Samiti, Paschim Medinipur district 15.Nanoor Panchyat Samiti, Birbhum district 16.Raipur Panchayat Samiti, Bankura district 17.Gopiballavpur I Panchayat Samiti, Paschim Medinipur district 18.Gopiballavpur II Panchyat Samiti, Paschim Medinipur district 19.Kalchini Panchyat Samiti, Jalpaiguri district 20.Shalboni Panchayat Samity, Paschim Medinipur district
Till June, 2014 a total of 105 BMCs have been constituted in West Begal.
Board officials attended at a meeting with BMC members of Dantan II BMC on 16th April, 2014
Board officials visited Gonpur and Md.Bazar Block Development Office on 10th June, 2014 and had meeting with the Block Development Officer and Sabhapati, Md.Bazar Panchayat Samity for reconstitution of BMC.
Board officials visited Domjur Block Office, Howrah on 19th June, 2014 and had discussion/ meeting with Block Development Officer and Savapati, Domjur Panchayat Samiti for reconstitution of Biodiversty Management Committee.
Board officials visited Uluberia-I Block Office, Howrah on 23rd June, 2014 and had discussion/ meeting with Block Development Officer and Sabhapati, Panchayat Samiti for reconstitution of Biodiversity Management Committee.
People’s Biodiversity Register (PBR): The Mirror of Biodiversity
PBR Workshop of Satyapur Gram Panchayat, Paschim Medini pur (organized by Debra Panchayat Samiti BMC) on 6th June, 2014
PBR Workshop of Madarihat Gram Panchayat, Jalpaiguri (organized by Birpara-Madarihat Panchayat Samiti BMC) on 16th & 17th June, 2014
PBR Workshop of Baneswar Gram Panchayat, Coochbehar (organized by Coochbehar II Panchayat Samiti BMC) on 18th June, 2014
PBR Monitoring of Alikosha GP, Dantan I BMC, P a s c h i m Medinipur on 12th April, 2014
PBR Monitoring at Haldia Municipality BMC, Purba Medinipur on 22nd April, 2014
Board Officials visited Naipur G.P. Ffor monitoring the ongoing PBR process and had discussion with the members of Pataspur-I Panchayat Samity Biodiversity Management Commit tee on 2nd June, 2014
PBRs formally released during this period of report:
Darjeeling Municipality (32 Wards) prepared by Darjeeling Municipality BMC in association with Darjeeling Govt. College.
Soureni GP of Mirik Block, prepared by Mirik Block BMC.
Hazipur GP, Kamarpukur GP and Shyambazar GP of Goghat II Panchayat Samiti, prepared by Goghat II Panchyat Samiti BMC.
Lahiripur GP of Gosaba Panchayat Samiti prepared by Gosaba Panchayat Samiti BMC.
Bidhannagar Municipality (23 wards); 10 Wards prepared by Bidhannager C o l l e g e and 13 Wards prepared by Academy of B i o dive r si t y Conservation (ABC).
Madhyamgram Municipality (25 wards) Prepared by Madhyamgram Municipality BMC.
At present, PBR activities are going on at 30 Gram Panchayats/ Municipalities in different areas of the state.
Till June, 2014 a total of 73 PBRs have been completed in West Begal.
IPR consent forwarded by NBA – No pending application NOC issued for access to bio-resources for commercial utilization – 3
Research Project approved: Project Reports submitted:
Board officials participated in a Radio Awareness programme “Panchayat- O- Gramonnayan-er Asor” and discussed on “Biodiversity, its Conservation and Sustainable use” on 17th May,014.
Chairman, Member Secretary and other Board officials participated in Inaugural programme of National Green Tribunal (NGT) and attended a seminar there after in Kolkata on 24th May, 2014.
Board officials participated in students‟ awareness programme “ICHHEDANA” which was on air by FM Rainbow Radio Station on 24th May, 2014.
Moments of different PBR workshop programmes
Board official attended a programme in observation of International Day for Biological Diversity Celebration at Serampore College, on 29th May, 2014.
Chairman, WBBB delivered lecture on „Biodiversity Conservation- Opportunities and Challenges‟ at IBRAD, Kolkata on 7th May, 2014.
Chairman, WBBB attended special meeting of Biodiversity Boards held at Delhi on 13th May, 2014.
Board Official delivered one lecture on „Local Biodiversity Conservation issues‟ at Dantan High School, Paschim Medinipur on the celebration of „International Day for Biological Diversity‟ organized by Dantan-I Panchayat Samity Biodiversity Management Committee on 30th May, 2014
Board Official delivered a talk on „Local Biodiversity and Conservation Issues‟ at Egra College, East Midnapur on the celebration of „ International Day for Biological Diversity‟ organized by Pataspur-I Panchayat Samity Biodiversity Management Committee on 1st June, 2014
Chairman and other Board Officials have been participated as Resource Person in the training programmes namely “Poribesh O Jibbaichitro Rakshay Panchayat - er Bhumika” to build capacity of „Karmadhakshya of Janasasthya - Paribesh Sthayee Samiti‟ in State Institute of Panchayat and Rural Development, Kalyani on every Wednesday since 4th June, 2014.
Chairman, WBBB attended observe „World Environment
all the State
different functions organized to Day‟ and delivered lecture on
„Biodiversity ---- Island Biodiversity‟ at Kolkata on 5th June, 2014.
Chairman, WBBB delivered lecture on „Biodiversity‟ in a programme organized by WWF- India to observe „World Environment Day‟ at Kolkata on 12th June, 2014.
Chairman, WBBB delivered lecture on „Excitement in Taxonomy and Ethno Botany‟ in a programme organized by Botanical Survey of India at Kolkata on 19th June, 2014.
Chairman, WBBB delivered lecture on „Biodiversity‟ in a programme organized by Madhyamgram Green Manch at Madhyamgram on 21st June, 2014. Later on visited Bat Restoration site at Bandurtala, Badu of North 24 PGS district.
Moments of „Observation of World Environment Day‟ at Kolkata
UNEP-GEF-MoEF ABS Project (progress made-so-far):
A visit was made to Egra II Block BMC, East Midnapur district to monitor the ongoing process of PBR preparation at Manjusree Gram Panchayat on 2nd & 3rd May, 2014. Also visited Noyapara, Madhavpur, and Khejurda Village which led to identification of Flora and Fauna.
The Board selected one Organization under the project for “The study on Tradable Bioresources in West Bengal”. Dr. A K Ghosh, President, ENDEV has been engaged as consultant for the said study.
A Meeting Was organized between Member Secretary and Other Officials of WBBB and representatives of the Confederation of Indian Industries (CII) on ABS Provisions at Conference Hall, Deptt of Environment, Govt. Of West Bengal on 27th June, 2014
Project Management Unit (PMU), NBA, Chennai and WBBB UNEP-GEF- MoEF- ABS Project team conducted a comprehensive field visit at Kalimpong area ( Darjeeling District) and Digha area (East Midnapur District) to study the value chain of selected Bio-resources and Meeting with Traditional Knowledge Holders in West Bengal from 24th may to 31st may, 2014. During the vist the team members had meeting with BMC members, local Medical practitioners, businessmen, and Traditional Knowledge holders to identify commonly used Bio-resource from those localities. Respective Technical Support Group (TSG) Personnel Dr. Somnath Hazra (CTRAN Consulting Ltd.) and Mr. Priti Ranjan Maity accompanied the team in their respective areas. Depending on the available data a list of 64 Bio-resources were prepared, of which 20 components may have potentiality for ABS agreements.
Moments of „Field visit at Kalimpong area (Darjeeling District) and Digha area (East Midnapur District)‟
International Day for Biological Diversity 22 May 2014 Theme: Island Biodiversity The West Bengal Biodiversity Board celebrated the International Day for Biological Diversity on 22nd May, 2014 at Asutosh Birth Centenary Hall, Kolkata amidst a huge enthusiasm and fanfare. The function was witnessed by nearly 200 participants from different sectors of the society among which there were members of t h e B o a r d / E x p e r t s c o m m i t t e e s , representatives of BMCs/ Research Institutes/ Govt. Organizations/ NGOs, students / Teachers of Schools, Colleges, and Universities etc. The programme started with the inauguration of Tableau by the Hon‟ble Minister-in-Charge, Department of Environment, GoWB. The Tableau was made depicting the theme of climate change, pollution and loss of habitat due to rise of water level underlining the threat to Island diversity. The programme was arranged in two consecutive sessions. The first session was the Inaugural Session which started with a Vedic hymn and watering of plant. Welcoming all, Dr. A. K. Sanyal, Chairman of the Board pointed out the theme of this year‟s programme- „Island Biodiversity‟ and highlighted the activities & achievements of the Board of the last year. The inaugural speech was delivered by the Chief Guest, Dr. Sudarsan Ghosh Dastidar, Hon‟ble Minister-in-charge, Department of Environment, Govt.
of West Bengal. He stressed on generating awareness, particularly among school students. He also suggested to find out possibilities to interlink livelihood generation with biodiversity conservation. The speech was followed by a folk song related to biodiversity conservation. The Guests of Honour Mr. N. C. Bahuguna, IFS, Principal Chief Conservator of Forests & HoFF, Govt. of West Bengal and Prof. Binay K. Dutta, Chairman, West Bengal Pollution Control Board delivered their brief speech on the importance of biodiversity conservation and induct school children, as many as possible, in this process. Next was the release of publications a booklet “Jib Boichitra” by the Hon‟ble MIC Dr. Sudarsan Ghosh Dastidar. The booklet – published by the Board was mainly for awareness generation and comprising of basics of biodiversity in a very lucid manner in Bengali. A total of 8 (eight) People‟s Biodiversity Registers (among those 3 G.Ps–Kamarpukur, Shyambazar and Hajipur–from Goghat II PanchayatSamity, Hooghly district; Sourini G. P. of Mirik block and Darjeeling Municipality, Darjeeling district; Madhyamgram Municipality, North 24 Pargana district; Bidhannagar Municipality, Kolkata; Lahiripur G. P. of Gosaba P.S., South 24 Pargana district) were formally handed over to the Board by the members of the respective BMCs. This year also the West Bengal Biodiversity Board conferred the Biodiversity Award for notable contribution towards biodiversity conservation. Sri Pritiranjan Maiti of Ramnagar- I P.S., Paschim Medinipur was felicitated by this award for his contribution towards local biodiversity conservation through implementation of BD Act & Rules in the area. Sri Dinanbandhu Biswas from Birbhum district was felicitated for his contribution towards generation of awareness on biodiversity and its conservation and rescue of distressed wild animals of biodiversity. Another recipient of the Biodiversity Award was Joygopalpur Gram Vikas Kendra, an NGO of South 24 Parganas for their contribution in awareness generation, documentation and conservation activities related to biodiversity of the area. A special Award was conferred upon Dr. A. K. Ghosh, President, ENDEV for his outstanding pioneering contributions towards biodiversity conservation and sustainable
development. This session was concluded with the remarks and pledge of Member Secretary of the Board and also by thanks giving by him. After a short break, the technical session-I began with the deliberation of Dr. Rajkumar Rajan, Scientist, Zoological Survey of India, Chennai. In his presentation on “Island Biodiversity – Significance and Challenges” he focused on the theme of the programme i.e., Island biodiversity, its importance, common challenges of island biodiversity and its significance, with special reference to islands of India. The Technical Session-II started with a panel discussion on “Biodiversity and Livelihood Development” with dignitaries including Prof. Sarmila Banerjee, Department of Economics, University of Calcutta; Shri Dilip Ghosh, IAS, Member, 4th State Finance Commission and Senior Fellow, Pratichi Trust; Prof. S. B. Roy, Chairman, Indian Institute of Bio-Social Research & Development (IBRAD) and Dr. M. Padmavati, Associate Professor, Rajiv Gandhi School of IP Law, IIT, Kharagpur; whereas Dr. J. R. B. Alfred, Former Director, Zoological Survey of India, acted as a moderator. It was followed by an open discussion with the audience. The discussion was focused on the need to document biodiversity and associated traditional knowledge and practice involving local people as far as possible and to identify potential bioresources of respective areas for livelihood generation. The programme ended with conveying thanks to the all concerned by the Sr. Research Officer of the Board. Beside this programme, there were fifteen other programmes organised by various BMCs, schools and colleges in different parts of the state on the occasion of observation of International Day for Biological Diversity-2014 which were supported by the State Board. The programmes included rally, quiz com- petition, essay writing, seminar etc. involving the local people, particularly the students.
Moments from Celebration on „International Day for Biological Diversity 2014‟ at Kolkata
Publications of the board Atlas of Insects and Spider of Buxa Tiger Reserve This document, a startlingly beautiful field guide, accommodates 830species of insects and spiders found in the wild environs of Buxa Tiger Reserve and its surroundings tea estates.
Wetland Faunal Diversity of West Bengal This book is the first comprehensive account of wetland faunal resources of West Bengal occurring in fresh water, blackish water and costal ecosystems.
Kemon Kore Korbo Janjibbaichitro Nathi (PBR) This manual on preparation of Peoples Biodiversity Register explains in detail the method of preparing PBR, the mandatory activity of the local level Biodiversity Management Committee.
Guttation-A Natural Phenomenon: Useful medium for production of Recombinant Proteins Dr. Amal Kumar Mondal1 & Prof. Sanjukta Parui Mondal2 1 FLS, FIAAT, Professor of Botany and Deputy Coordinator of UGC-DRS-SAP, PI-UGCMRP, Department of Botany and Forestry, Plant Taxonomy, Biosystematics and Molecular Taxonomy Laboratory, VIDYASAGAR UNIVERSITY, Midnapore- 721 102, West Bengal, India. Email: [email protected]
; [email protected]
; [email protected]
2 Associate Professor and HOD, PI-UGC- MRP,Department of Zoology, Lady Brabourne College, Kolkata – 700 017, West Bengal, India. Email: [email protected]
Guttation is the natural phenomena in all groups of plants (except in algae) which is not just restricted to leaf margins and tips but to entire leaf surface. This natural fluid can now serve as a medium for production of recombinant proteins.
are very familiar with the dew drops
found on the grasses and the leaves of other plants, in the early morning hours, giving the plants the fresh young look, soothing our eyes during our morning walks. But these drops of water are not always dewdrops, but are instead, water exuded by the leaves of the plants - a process called guttation. It is the secretion of water on to the leaf surface, particularly along the leaf margin, through specialized pores called hydathodes. This process occurs most frequently during conditions of high humidity, when the rate of transpiration is low. It has been observed during warm humid nights. However it occurs maximum during day and minimum during nights. The term “guttation” was proposed by Burgerstien for the exudation of water from plants in the form of liquid. The leaf blade (lamina) as we know consists of an upper and lower epidermis, which is a thin, usually transparent, colourless layer of cells, and is generally referred to as the skin of the leaf blade. Sandwiched in between these two layers of epidermis is the spongy layer of tissue, called the mesophyll, in which runs a branching system of veins. The epidermis is most often covered by a layer of cutin
called cuticle, which is a waxy substance secreted by the epidermal cells. The epidermis together with the cuticle prevents excessive loss of water from the leaves and also protects the leaves from injury. The plant generally transpires through pores called stomata, which are scattered throughout the epidermis. However, the numbers of stomata are more on the under surface of the leaf, than on the upper surface, which prevents excessive loss of water from evaporating from the upper surface of the leaf, which is exposed to the sun. The stomata however does not always remain open and the opening and closing of each stomata is regulated by a pair of bean-shaped cells called guard cells, in response to heat and light. The stomata usually close at night, which further helps in water conservation. Guttation on the other hand occurs through other pores called hydathodes, and not through stomata. The amount of water lost through guttation is negligible when compared to that lost by transpiration. The hydathodes are large specialized water pores found in the epidermis, which unlike the stomata remains open all the time. The pore of each hydathode in the epidermis is followed by loosely arranged parenchyma with large intercellular spaces called the epithem, followed by blindly ending xylem elements. The tracheids of the xylem terminate below the air chamber. The hydathodes are thus supplied by a vascular bundle that ends either directly within it or just at its border. Often the epithem is separated from the rest of leaf cells by compact boundary layer called the sheath. The epithem cells absorb mineral nutrients out of the xylem sap and transfer them to the leaf tissues. The excess water accumulates in the intercellular spaces due to which pressure builds within the aerenchymatous epithem. This pressure forces water out of the water pore (hydathode). Hydathodes in plants are of two types – Epithem hydathodes and Active hydathodes. In case of Epithem hydathode, water is forced out by the root pressure whereas in case of Active hydathode, water is secreted by the force developed within the cells themselves. However root pressure is generally the main cause of guttation and the guttation rate is reduced by
conditions reducing root pressure such as cold and dry aerated soil and also mineral deficiency. The force that drives the water through the root is based on differences in the water potential of the soil i.e. the root‟s surrounding and the xylem sap of the root. The ions that pass through the endodermis of the root along with the water is trapped and cannot leave the stele any more. Due to osmosis, a pressure called endosmotic root pressure develops in the xylem that presses or forces the water along with the dissolved ions upwards. This root pressure acts most efficiently at night, but its efficiency decreases during the day when it‟s rate becomes much smaller than the rate of transpiration. The guttated water contains various kinds of sugars, amino acids, enzymes, organic acids, vitamins, other organic compounds and minerals such as calcium. This leaves a white crust on the leaf surface when the guttated water dries. A typical example is the lime secretion of Saxifraga sp. and the salt glands of halophytes. Guttation has however not been observed universally. This process has been reported to occur in 333 genera belonging to 115 families. It is restricted to certain genera of mostly herbaceous plants. Heavy guttation has been observed in Colocasia antiquorum, in which the amount of guttated water ranges from a few drops to 100 ml or even more per day. Other common guttating plants include the grasses, Ambrosia trifida, Brassica oleracea, Cleome viscosa, Commelina benghalensis, Hordeum vulgare (barley), Hydrocotyle, Lactuca, Lycopersicon esculentum (tomata), Physocarpus, Pilea pumila, Potentilla palustris, Spilanthes, Trifolium, Tropoelum sp., Urtica dioica, Vitex trifolia, Equisitum (Pteridophyte), etc. Further, the hydathodes are restricted to the tips and margins of leaves, due to which the droplets are seen deposited on the margin and tips of leaves. However recently guttation has been observed in some unreported genera like Ficus hispida, Ficus cunea and Fleurya interupta. More interestingly, the guttated water has been observed on the entire leaf blade and not just restricted to leaf tips and margins. This study indicates that although hydathodes represent the main points of guttation fluid production, but guttation fluid can also be released through the cuticle or stomata, as has been reported earlier by Lausberg (1935) and Baid (1952) respectively.
As mentioned earlier, some proteins are naturally secreted into the plant guttation fluid. Proteins like catalase and peroxidase enzyme have been reported in the guttation fluid of Zea mays (maize), Avena sativa (oat), several peroxidases in Fragaria ananassa (strawberry), Lycopersicon esculentum (tomato) and Cucumis sativus (cucumber) and reductase in Phleum pzatense (timothy). Very recently guttation has been successfully used as a vehicle for recombinant protein production in plants by a process termed “phyllosecretion” by a group of scientists of Biotech Center, Cook College, Rutgers University, New Jersey and Phytomedics, Dayton, New Jersey. They engineered the tobacco plant (Nicotiana tabacum L. cv Wisconsin) to secrete human placental secreted alkaline phosphatase (SEAP), green fluorescent protein (GFP) from jellyfish (Aequorea victoria) and xylanase from Clostridium thermocellum through the plant cell default secretion pathway. They found that recombinant proteins directed to the leaf intercellular space i.e. apoplast are effectively released into the plant guttation fluid, which can be collected continuously throughout the plant‟s lifetime. Plants serve as suitable bioreactors for the production of many valuable recombinant proteins used as pharmaceuticals, industrial enzymes, etc. Foreign genes are now being routinely expressed in many plant species to produce recombinant proteins because of their ability to carry out numerous post-translational protein modifications required for biological activity, and they can be easily cultivated. Till date numerous heterologous proteins have been expressed in different plant organs and plant cell compartments. However, the major obstacle for the large-scale protein production in plants is the high cost of protein extraction and purification from biochemically complex plant tissues. This obstacle has been partially overcome by aseptically cultivated cell cultures or plant organs that secrete recombinant proteins into the surrounding medium. These in vitro systems however can be expensive, slow growing, unstable, and relatively low yielding. In this respect the production of recombinant proteins in guttation fluid has several advantages and is comparatively a much easier process and cost effective. The advantage of using phyllosecretion is that, this method allows continuous and non-destructive recovery of recombinant proteins from a living plant, as guttation fluid can be collected throughout a plant's life. Guttation fluid also has the potential of increasing yield, abolishing the need
for tissue extraction, and simplifying its downstream processing i.e. simplifies complex protein purification procedures, thus increasing the efficiency of recombinant protein production technology. It is non-destructive. Also, recombinant biopharmaceutical proteins purified from leaf exudates are less likely to be contaminated with pathogenic viruses, which may be present in the milk or urine of transgenic animals. The plant protein phyllosecretion system is easy to scale up and is less sensitive to the cytotoxicity of the final products. The guttation fluid can be easily collected, by shaking them off the leaves into a collection vessel, or a method for large-scale collection of guttation fluid can be developed like removing them from the leaf surface with a vacuum or blotting. Another system called Rhizosecretion system for the production of recombinant proteins has been developed recently, which takes advantage of the ability of roots of hydroponically cultivated plants to secrete properly targeted recombinant proteins into the surrounding medium. Now what exactly is Phyllosecretion? Phyllosecretion is a method, which exploits leaf guttation as a medium to continuously “wash away” recombinant proteins from a living plant. Guttation fluid is transformed into a concentrated solution of recombinant proteins. Eukaryotic cells have a highly evolved process of secretion. Proteins of interest targetted for the outside are synthesized by ribosomes which are attached to the rough endoplasmic reticulum. As they are synthesized, these proteins are translocated into the lumen of the endoplasmic reticulum, where they are glycosylated and molecular chaperones aid the protein folding. The misfolded proteins are retrotranslocated to the cytosol where they are degraded by a proteasome by the endoplasmic reticulum associated degradation system. The vesicles containing the properly-folded proteins then enter the Golgi apparatus. In the Golgi apparatus, the glycosylation of the proteins is modified and further posttranslational modifications takes place, including cleavage and functionalization. The proteins are then moved into secretory vesicles which travel along the cytoskeleton to the edge of the cell where the vesicle fuses with the cell membrane in a process called exocytocis, releasing its contents out of the cell's environment. During this entire sequence, strict biochemical control is maintained by usage of a pH gradient. The pH of the cytosol is 7.4, the endoplasmic reticulum‟s pH is 7.0, and the
cis-golgi has a pH of 6.5. Secretory vesicles have pH ranging between 5.0 and 6.0. In the process of phyllosecretion, the proteins destined for export must first be labelled correctly so that the trans-Golgi network can dispatch the proteins to their correct destination. The labelling may be either in the form of a signal sequences at the end of the polypeptide chain or signal patches, which are dispersed throughout the polypeptide chain, but are brought together when in a 3D conformation. All cells must export proteins to the exterior of the plasma membrane, but specialized secretory cells must also control what domain of the plasma membrane the proteins are released on. Thus, all cells have the constitutive secretory pathway, or default pathway, but specialized secretory cells also have a regulated secretory pathway. In the secretory pathway, proteins are packaged into secretory vesicles, which then aggregate next to the plasma membrane where they await an extracellular signal to fuse with the plasma membrane and release their contents.
Thus by using endoplasmic reticulum signal peptides fused to the recombinant protein sequences, these scientists have generated transgenic tobacco (Nicotiana tabacum L. cv Wisconsin) plants that secrete three heterologous proteins of different genetic backgrounds (bacterial xylanase, green fluorescent protein of jellyfish [Aequorea victoria], and human placental alkaline phosphatase) through the leaf intercellular space into tobacco guttation fluid. Thus, guttation fluid can have numerous applications in future scientific investigations, apart from its role in helping plants to get rid of the excess water, which will no longer go as a waste. Another future prospect would be to assess the ability of the simultaneous use of both the phyllosecretion and rhizosecretion systems. If successful, the combination of both these techniques can significantly increase the total yield of heterologous proteins production by plants in the easily accessible form of a water solution.
Figure 1: The structure of a leaf showing the position of the hydathodes (A) Entire leaf (B) Anatomical structure of a leaf
Figure 2: Guttation along the leaf margin observed in the early morning hours in Vitex trifolia (Vitaceae)
Figure 3: Guttation along the leaf margin observed in the early morning hours in Hibiscus safdarifa (Malvaceae)
Figure 4: Guttation along the leaf margin observed in the early morning hours in Vitex pedata (Vitaceae)
Figure 5: Guttation along the leaf margin observed in the early morning hours in Mikenia scandens (Asteraceae)
Figure 6: Guttation along the leaf margin observed in the early morning hours in Globba bulbifera (Zingiberaceae)
Figure 7: Guttation in Typhenium trilobatum (Araceae) showing fewer numbers of hydathodes not on margins but on the leaf surface
Figure 8: Guttation is not just restricted to leaf margins but is also seen on the entire leaf surface, as seen in (A) Ficus hispida (Moraceae) and (B) Fleurya interupta (Urticaceae)
Figure 9: Guttation in a free-floating aquatic angiosperm [Pistia stratiotes (Araceae)] – a rare view.
West Bengal Biodiversity Board (Department of Environment, Government of West Bengal) Poura Bhawan (4th Floor) FD-415A, Sector-III, Salt Lake City, Kolkata - 700106 Telephone: (033) 2358-2743/2763; (033) 2335-2731 (Fax) E mail: [email protected]
Compiled by: Pallab Bhattacharjee
Edited by: The Chairman, WBBB