Nutrio-physiological and molecular analyses and carbon dioxide enrichment studies of coconut palms (Cocos nucifera L.) with foliar yellowing (Record no. 157925)
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| 000 -LEADER | |
|---|---|
| fixed length control field | 06107nam a22001697a 4500 |
| 082 ## - DEWEY DECIMAL CLASSIFICATION NUMBER | |
| Classification number | 571.2 |
| Item number | DEE/NU |
| 100 ## - MAIN ENTRY--PERSONAL NAME | |
| Personal name | Deepa S |
| 245 ## - TITLE STATEMENT | |
| Title | Nutrio-physiological and molecular analyses and carbon dioxide enrichment studies of coconut palms (Cocos nucifera L.) with foliar yellowing |
| 260 ## - PUBLICATION, DISTRIBUTION, ETC. (IMPRINT) | |
| Place of publication, distribution, etc | Vellayani |
| Name of publisher, distributor, etc | Department of Plant Physiology, College of Agriculture |
| Date of publication, distribution, etc | 2017 |
| 300 ## - PHYSICAL DESCRIPTION | |
| Extent | 142p |
| 502 ## - DISSERTATION NOTE | |
| Dissertation note | PhD |
| 520 3# - SUMMARY, ETC. | |
| Abstract | A study entitled “Nutrio-physiological and molecular analyses and carbon dioxide enrichment studies of coconut palms (Cocos nucifera L.) with foliar yellowing” was carried out with the objective to analyze the nutrio - physiological changes occurring in the palms affected with foliar yellowing and to assess the impact of enhanced carbon dioxide on phytoplasmal response. In this study, palms showing mid whorl yellowing (MWY), root (wilt) affected palms (RW) and healthy palms were selected from two different locations viz the Instructional Farm, College of Agriculture, Vellayani (location 1) and Venganoor region (location 2) in the Thiruvananthapuram district. Coconut seedlings showing yellowing were selected from the Instructional Farm, College of Agriculture, Vellayani to study the effect of enhanced carbon dioxide on phytoplasmal response. Catharanthus and brinjal plants with ‘little leaf symptom’ maintained at the Department of Plant Pathology were utilised for grafting into healthy catharanthus and brinjal plants and these were also taken for studying the phytoplasmal response under elevated carbon dioxide condition. Physiological and biochemical analyses revealed significant variations in all the parameters studied. Palms with mid whorl yellowing (MWY) showed a significant reduction in the chlorophyll a, b and total chlorophyll contents, relative water content, membrane integrity and phenol content compared to the healthy palms. An increase in the protein (88%), carbohydrate (25.14%), reducing sugar (28%) and starch content (28.33%) was noted in palms with MWY. In the case of antioxidant enzymes there was build up of polyphenol oxidase (145.38%) and peroxidase activities in palms with MWY compared to the healthy palms. A similar trend was observed in almost all cases of RW affected palms. Nutrient analyses revealed significant alterations in the nutrient content of the selected palms. Significant reduction in the nitrogen (47.74%), magnesium (22.72%) and zinc content (24.19%) was observed in palms with yellowing compared to the healthy palms. Accumulation of elements like potassium (37.96%) calcium (40.79%), iron (54%) and copper (35.75%) was observed in palms with mid whorl yellowing compared to the healthy palms. These variations in the nutrient levels can have an influence on symptom development in coconut palms. The results on the soil nutrient analyses did not show any particular role in development of yellowing symptoms. Phytoplasma cells were detected in the phloem tissues of both mid whorl yellowing and root wilt affected palms under Scanning Electron Microscopy (SEM) study. Morphological and anatomical analyses of fresh roots indicated browning and necrosis of roots and vascular disintegration in MWY and RW affected palms. The presence of phytoplasma in the selected samples were checked by nested PCR analysis using phytoplasma specific universal primers-P1/P7- R16F2n/ R16R2, Phytoplasma 16S rDNA specific semi nested primers 1F7/7R3 - 1F7/7R2 and by real time PCR technique using real time primers QPF2/R2. Semi- nested PCR yielded an amplicon of 493 bp in all the MWY and RW palms in both the locations. Real time PCR yielded an amplicon of 140 bp in the RW palms, 3 MWY palms in location 1. Nested PCR with phytoplasma specific universal primer pairs P1/P7-R16F2n/ R16R2 yielded an amplicon of 1.2 kb in MWY palm and RW palm. Sequence analysis of the mid whorl yellowing phytoplasma revealed 89% similarity to the root wilt phytoplasma. In experiment II, nested PCR with universal primer pairs showed no amplification in the coconut seedlings and hence only catharanthus and brinjal grafts with phytoplasmal infection were kept in Open Top Chamber (OTC) with 500 ppm Carbon dioxide concentration for a period of one month. After the exposure period, the plants kept in OTC showed an increased rate of growth and development with phytoplasmal symptoms. Physiological and biochemical analyses showed a significant increase in the reducing sugar content (63%), protein content (147%) and PAL activity (32%) and significant reduction in the phenol content (37%), and polyphenol oxidase activity (62%) in the infected plants kept in OTC compared to the infected plants kept in open condition. Molecular analyses of the infected samples using real time PCR kept in OTC and open condition with the DNA samples isolated at the 15th and 30th day of exposure was done. No significant variation was observed in the phytoplasmal load after elevated carbon dioxide exposure. The role of phytoplasma in causing MWY was established by molecular and anatomical studies. Sequencing of the PCR product revealed that MWY phytoplasma can be a variant of root (wilt) phytoplasma. The present study indicated that the overall health status of the palms with MWY was highly deteriorated. Significant variation in the nutrient profile was noted which emphasise the need for proper nutrient management. Semi- nested PCR was found to be more accurate and specific in phytoplasmal detection which can be utilised for phytoplasmal indexing and mother palm and disease free seedling selection. Elevated carbon dioxide showed an improved growth and development and activated defense response to phytoplasma in the infected plants but the CO2 induced modifications in phytoplasmal load was not detected. The results indicated a better tolerance strategy to environmental conditions. phytoplasma under changing |
| 650 ## - SUBJECT ADDED ENTRY--TOPICAL TERM | |
| Topical term or geographic name as entry element | Plant Physiology |
| 700 ## - ADDED ENTRY--PERSONAL NAME | |
| Personal name | Manju, R V (Guide) |
| 856 ## - ELECTRONIC LOCATION AND ACCESS | |
| Uniform Resource Identifier | http://krishikosh.egranth.ac.in/handle/1/5810141463 |
| 942 ## - ADDED ENTRY ELEMENTS (KOHA) | |
| Source of classification or shelving scheme | |
| Item type | Theses |
| Not for loan | Collection code | Permanent location | Current location | Shelving location | Date acquired | Full call number | Barcode | Date last seen | Koha item type |
|---|---|---|---|---|---|---|---|---|---|
| Not For Loan | Reference Book | KAU Central Library, Thrissur | KAU Central Library, Thrissur | Theses | 2017-12-26 | 571.2 DEE/NU | 174056 | 2017-12-26 | Theses |