1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Etiology and management of mosaic disease in ginger (Zingiber officinale Roscoe)(Department of Plant Pathology, College of Agriculture, Vellayani, 2018) Ananthu, N; Umamaheswaran, KItem Identification of graft transmissible resistant factors and development of si RNA mediated resistance in cassava against cassava mosaic geminivirus(Department of Plant Pathology, College of Agriculture, Vellayani, 2017) Asha B Nair; Umamaheswaran, KItem Optimisation of process parameters for preparation of flavoured instant green tea(Department of Food and Agricultural Process Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur, 2017) Sankalpa, K B; Santhi Mary, MathewItem Elucidating the biochemical basis of interaction between tea mosquito bug, helopeltis antonii signoret (hemiptera:miridae) and cashew (anacardium occidentale)(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2018) Nimisha, T; Deepthy, K BCashew is one of the important foreign exchange earning crops of India with an export value of Rs. 5,077 crores during 2016-17.Cashew production is not in tune with increase in area under its cultivation. Low productivity in cashew is mainly due to the incidence of pests and diseases. Among the insect pests, tea mosquito bug (TMB), Helopeltis antonii Signoret (Hemiptera: Miridae) is the most important. It causes 30-50 per cent yield loss and during outbreak situations even up to 100 per cent loss has been reported. Cashew varieties exhibit wide variation in response to TMB infestation. Hardly any variety has ever been recorded as resistant to TMB till date. However, a few accessions are reported to be capable of withstanding TMB infestation and hence have been grouped as less susceptible category. Understanding the basis of interaction between the bug and the cashew is a prerequisite in developing varieties resistant to TMB. The present study entitled “Elucidating the biochemical basis of interaction between tea mosquito bug, Helopeltis antonii Signoret (Hemiptera: Miridae) and cashew (Anacardium occidentale)” was undertaken at the Department of Agricultural Entomology, College of Horticulture, Vellanikkara during September 2017 to July 2018. The objective of the study was to understand the variation in secondary metabolites and defense enzymes in selected cashew varieties induced by tea mosquito bug infestation and to elucidate the secondary metabolite detoxification mechanisms in the pest. Three months old grafts of four cashew varieties viz., two from the highly susceptible category (Anagha, Madakkathara-1) and two from less susceptible category (Damodar, Raghav) were used to conduct the experiment. Female adult bug (0-24 h old) was allowed to feed on each variety for different time intervals of 6, 24, 48 and 72 h. The biochemical parameters such as protein, phenol, tannin and defense enzymes viz., polyphenol oxidase (PPO) and phenyl alanine ammonia lyase (PAL) in leaves of TMB infested and non infested cashew grafts were analysed before release (0 h) as well as at different intervals of release. Biochemical analysis of the released TMB (crude homogenate of whole insect) viz., variation in total protein, SDS PAGE profiling of TMB crude protein, detoxifying enzymes viz., carboxyl esterase, cytochrome P450, and glutathione-s-transferases (GST) were carried out before releasing on the plant and at different intervals after release. The total leaf protein was found to be highest in the less susceptible variety Damodar (0.9925 mg g-1) and the lowest in the highly susceptible Madakkathara-1 (0.6729 mg g-1). Total phenol content was highest in the less susceptible Damodar (69.834 mg g-1) and Raghav (67.207 mg g-1) and the lowest was recorded in Anagha (29.625 mg g-1). Regardless of the varieties, highest phenol content was recorded in samples taken after 72 h of TMB infestation. Tannin content was also high in the less susceptible varieties Raghav (4.420 mg g-1) and Damodar (4.276 mg g-1) while highly susceptible varieties Anagha and Madakkathara-1 recorded lower values. Irrespective of the varieties, the highest tannin content was recorded in samples before the release of TMB (6.662 mg g-1). Results of the present study revealed that, detoxifying enzyme specific activity of PPO was highest in Damodar (0.003158 EU g-1min-1) and observed lowest value in Anagha (0.001406 EU g-1min-1). Irrespective of the varieties, enzyme activity reached highest at 48 h of release (0.00367 EU g1min-1). PAL specific activity was highest in Madakkathara-1 (0.575 μg g-1 min-1) and lowest in Anagha and was on par with Raghav and Damodar. In SDS PAGE, the whole body homogenate of adult female TMB revealed presence of bands in the range of ̴ 63 kDa and 35-48 kDa in the early stage of infestation. However, as the exposure time increased, protein bands ranging from 17-75 kDa appeared. Defensive enzymes viz., carboxyl esterase and GST expressed elevated activity in TMB that fed on less susceptible Raghav (258.117 μmol min-1mg-1 protein, and 365.262 μmol min-1mg-1 protein respectively) and Damodar (208.916 μmol min-1mg-1protein, and 501.879 μmol min-1mg-1protein respectively) when compared to the highly susceptible varieties. Cytochrome P450 showed highest activity in TMB fed on Damodar (0.372 nmol min-1mg-1 protein) and it was having lowest activity in insect fed on other three varieties. The study revealed that, the secondary metabolites viz., phenol, tannin and PPO have a definite role in imparting resistance in cashew to TMB attack. These metabolites have potential use in early detection of resistance in cashew against TMB. The enhanced levels of detoxification enzymes in TMB indicate plasticity of the pest against host plant defense and chance of resistance development against synthetic insecticides.Item Nutrio-physiological and molecular analyses and carbon dioxide enrichment studies of coconut palms (Cocos nucifera L.) with foliar yellowing(Department of Plant Physiology, College of Agriculture, Vellayani, 2017) Deepa, S; Manju, R VItem Screening and biochemical characterization of tomato genotypes for resistance to bacterial wilt(Department Of Olericulture, College Of Horticulture, Vellanikkara, 1999) Subash Chandra Bose, S; Rajan, SInvestigation on 'Screening and biochemical characterization of tomato genotypes for resistance to bacterial' wilt' was carried out in the Department of Olericulture, and Biochemistry Laboratory, College of Horticulture, Vellanikkara 1 during 1997-99. The objectives of this study were to identify tomato genotypes resistant to bacterial wilt and to find the possibility for biochemical cataloguing of bacterial wilt resistant tomato genotypes. Evaluation for bacterial wilt resistance revealed that Sakthi, Mukthi and LE-474 were consistently resistant to bacterial wilt. Four additional sources of bacterial wilt resistance were identified, viz. LE-214, LE-415, LE-470 and LE-421. Based on the percentage wilting the twenty four genotypes included in this study were classified into four groups, viz. Resistant, Moderately Resistant, Susceptible and Highly susceptible. -.: All the bacterial wilt resistant and moderately resistant genotypes had a higher content of total phenols in roots and leaves at 45th and 60th day of plant growth; O.D. phenol content in roots of resistant varieties were higher than susceptible varieties. In leaf, the O.D. phenol content was high in moderately resistant genotypes at 45th and 60th day. All the genotypes were studied for isozyme variation with respect to two enzymes, viz. polyphenol oxidase and peroxidase. 10 general the roots had more number of bands compared to leaves at both the stages. '.. The root samples at 45th day showed two polyphenol oxidase bands, viz. PPO-I (~=0.074) and PPO-12 (Rm=0,414) which were specific to resistant varieties alone. This combination along with high total phenols may be considered as a biochemical marker for resistance to bacterial wilt in tomato. In 60 days old roots of resistant and moderately re istant genotypes the protein band PPO-9 (Rm=0.851) was predominantly present Regarding peroxidase, 45 . days old leaf samples had a combination of protein bands, viz. PRX-7 (Rm=0.361) and PRX-8 (Rm=O.382) in resistant and moderately resistant varieties. But at 60 days the roots and leaves did not show any specific band for resistance. In general at 45 days both leaf and root samples had more number of bands for polyphenol oxidase and peroxidase in resistant varieties compared to susceptible varieties. The study revealed that it was possible to arrive at a combination of specific isozyme bands at a particular growth stage, which can be used as a marker for bacterial wilt resistant tomato genotypes.