Histochemical evaluation of catechins in PEG stressed transgenic tea plants using catechin-specific-diazotized sulfanilamide reagent

Abstract

We investigated the applicability of catechin-specific-reagent (CSR) for histochemical evaluation of catechins. The diazotized arylamine moiety in CSR reacts specifically with the A-ring of catechins to yield a golden yellow complex. This makes it highly specific for spectrophotometric quantification of catechins. Therefore, microtome cut sections of untransformed and osmotin-expressing transgenic leaves and stem of tea were stained with CSR. We found catechins in the form of golden yellow globules. The catechin globules increased in the structurally intact and highly turgid cells of osmotin expressing transgenic tea plants after stress treatment with 20% PEG; by contrast, the cells in non-transgenic plants accumulated fewer catechin globules. Spectrophotometric quantification of catechins also confirmed higher levels in transgenics compared to untransformed plants. We found elevated accumulation of catechins in stress tolerant cells of tea leaves.

Key words::

• Camellia sinensis
• catechins
• sulfanilamide
• tea
• transgenic

Acknowledgments

We thank Mr. Ajay Rana for his valuable input in the discussion of the reaction of catechins with procyanidins, Dr. Avnesh Kumari, Senior Technical Officer, for her assistance with scanning electron microscopy and Dr. Kiran Devi and Miss Pooja Thapa for statistical analysis. The financial assistance from the Council of Scientific and Industrial Research, New Delhi, India is gratefully acknowledged.

Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and writing of this paper.