ABSTRACT: Cotton seeds (Gossypium hirsutum cv. CCRI12) were grown in a growth chamber under 29/25°C temperature and a 16:8 h light:dark cycle, and water was added every two days. All plants were used in experiments at the 6-7 fully expanded true leaf stage, which occurred 5-6 weeks after sowing. Cotton bollworm (CBW; Helicoverpa armigera) larvae were reared on an artificial diet and maintained at 27 ± 2°C, 75 ± 10% relative humidity, and 14:10 h light:dark in the laboratory. For insect treatment, seven H. armigera larvae (third instars) were placed on a group of three plants, which were kept within plastic bags (30 Ã? 40 cm), until time of harvest, with samples for each time point maintained separately. Undamaged plants maintained under the same conditions were used as controls. Cotton leaves from control plants and plants exposed to H. armigera were harvested at 6 h, 12 h, 24 h, and 48 h after onset of herbivory. For each treatment group and time point, cotton leaves were harvested from the three plants per treatment group and flash frozen in liquid nitrogen. For each time point, three replicate treatments and controls were performed. For insect treatment, seven H. armigera larvae (third instars) were placed on a group of three plants, which were kept within plastic bags (30 Ã? 40 cm), until time of harvest, with samples for each time point maintained separately. Undamaged plants maintained under the same conditions were used as controls. Cotton leaves from control plants and plants exposed to H. armigera were harvested at 6 h, 12 h, 24 h, and 48 h after onset of herbivory. For each treatment group and time point, cotton leaves were harvested from the three plants per treatment group and flash frozen in liquid nitrogen. For each time point, three replicate treatments and controls were performed. In this study we present dynamic transcriptome analysis and volatile profiling of cotton plants fed upon by larvae of a leaf-chewing herbivore CBW. Plant transcriptomic changes induced by CBW were analyzed using Affymetrixâ??s Cotton GeneChips. Samples from a time course of six hour to 48 hours following onset of CBW feeding were analyzed to identify target genes and key pathways involved in the activation of herbivory-induced indirect defense and to explore genetic basis of such defense. In addition, we monitored the accumulation of VOCs, which represent changes in cotton plant phenotype, following CBW infestation.
