Differential histolocalisation of certain phenolics and related enzymes in cashew (Anacardium occidentale L.) var. BPP-6
2002
Madhulety, T.Y. | Rao, I.V.S. | Neeraja, P.V. | Sukumaran, M.K. (College of Agriculture, Hyderabad (India). Dept. of Plant Physiology))
Intact sub-apical meristem (SAM) which contained lowest phenols and highest tannins was found associated with high in vivo activities of phenyl alanine ammonia-lyase (PAL), tyrosine ammonialayase (TAL) and nitrate reductase (NR) but with lowest activity of polyphenol oxidase. Phenols accumulated densely in endodermis and arch-shaped fibre cells (AFC) of SAM but found absent in resin canals and xylem cells. Densely stained AFC of shoot bud (SB) and SAM indicate high deposition of phenols, tannin-s, proteins and intense activities of polyphenol oxidase (PPO) and peroxidase (POD) in SAM (except AFC) and SB tissues respectively. Contrarily the SB, which had highest phenols, OD-phenols and moderately high tannins, was found associated with moderately high P AL, T AL, NRA and PPO activities. The SB, further, exhibited intensive localization of phenols in AFC, tannins in epidermis, cortex and AFC and high POD activity in AFC as well as epidermis. Young leaf(YL) showed highest PAL and TAL activities besides moderate NRA and undetectable PPO activity. But the nodal shoot exhibited lowest PAL, TAL but highest PPO and NRA. Pith tissues showed bighest PPO activity of all other tissues while TAL and NRA were moderately high, P AL being the minimum. Phenolics could not be detected in pith cells of SAM. The POD activity was confined to a few pith cells of SB. Xylem and resin canals of both SAM and SB did not stain for phenolics, enzymes, proteins and reducing sugars as well. Cambium cells of SB were stained for phenols, tannins and PPO activity but not for POD activity. Cambium of SAM stained for PPO activity only.
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