Higher accumulation of proteinase inhibitors in flowers than leaves and fruits as a possible basis for differential feeding preference of Helicoverpa armigera on tomato ( Lycopersicon esculentum Mill, Cv. Dhanashree)

• Published in: Phytochemistry (Oxford) 2005-11, Vol.66 (22), p.2659-2667
• Main Authors: Damle, Mrunal S., Giri, Ashok P., Sainani, Mohini N., Gupta, Vidya S.
• Format: Article
• Language: English
• Subjects: Accumulation of PI; Animals; bioaccumulation; Biological and medical sciences; Cattle; Chemical constitution; Chymotrypsin - antagonists & inhibitors; Chymotrypsin - metabolism; developmental stages; enzyme inhibition; feeding preferences; flowers; Flowers - chemistry; Flowers - metabolism; Food Preferences; Fruit - chemistry; Fruit - metabolism; Fundamental and applied biological sciences. Psychology; Helicoverpa armigera; insect behavior; insect pests; larvae; leaves; Lycopersicon esculentum; Lycopersicon esculentum - anatomy & histology; Lycopersicon esculentum - drug effects; Lycopersicon esculentum - metabolism; Lycopersicon esculentum - parasitology; Midgut proteinases; Moths - growth & development; Moths - physiology; Phytopathology. Animal pests. Plant and forest protection; plant biochemistry; Plant defense; Plant Leaves - chemistry; Plant Leaves - metabolism; plant pests; Plant physiology and development; Protease Inhibitors - chemistry; Protease Inhibitors - metabolism; Protease Inhibitors - pharmacology; Proteinase inhibitors; Protozoa. Invertebrates; Records, symptoms, damages, economic importance, population surveys; Solanum lycopersicum var. lycopersicum; tissue distribution; trypsin; Trypsin - metabolism; trypsin inhibitors; Trypsin Inhibitors - chemistry; Trypsin Inhibitors - metabolism; Trypsin Inhibitors - pharmacology
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2005.09.006

Tomato ( Lycopersicon esculentum, Mill; cultivar- Dhanashree) proteinase inhibitors (PIs) were tested for the potential inhibitory activity against Helicoverpa armigera gut proteases (HGP) by in vitro and in vivo studies. Analysis of TI and HGPI distribution among various plant parts of tomato showed that flowers accumulated about 300 and 1000 times higher TI while 700 and 400 times higher HGPI levels of inhibitors as compared to those in leaves and fruits, respectively. This can be attributed to the differential feeding preference of H. armigera on tomato. Tomato PIs inhibited about 50–80% HGP activity of H. armigera larvae feeding on various host plants including tomato, of larvae exposed to non-host plant PIs and of various larval instars. In addition, they were found to be highly stable to insect proteinases and exhibited similar isoform pattern against bovine trypsin, bovine chymotrypsin and HGP, when visualized by X-ray film contact print technique after native PAGE. Tomato ( Lycopersicon esculentum, Mill; cultivar- Dhanashree) proteinase inhibitors (PIs) were tested for their trypsin inhibitory (TI) and Helicoverpa armigera gut proteinases inhibitory (HGPI) activity in different organs of the tomato plants. Analysis of TI and HGPI distribution in various parts of the plant showed that flowers accumulated about 300 and 1000 times higher levels of TI while 700 and 400 times higher levels of HGPI as compared to those in leaves and fruits, respectively. Field observation that H. armigera larvae infest leaves and fruits but not the flowers could be at least partially attributed to the protective role-played by the higher levels of PIs in the flower tissue. Tomato PIs inhibited about 50–80% HGP activity of H. armigera larvae feeding on various host plants including tomato, of larvae exposed to non-host plant PIs and of various larval instars. Tomato PIs were found to be highly stable to insect proteinases wherein incubation of inhibitor with HGP even for 3 h at optimum conditions did not affect inhibitory activity. Bioassay using H. armigera larvae fed on artificial diet containing tomato PIs revealed adverse effect on larval growth, pupae development, adult formation and fecundity.