4.1. Plant Materials and Stress Treatment

In this study, L. hybrid seedlings were generated from callus-based somatic embryogenesis of L. hybrid. The L. hybrid seedlings were planted in pots with soil in a greenhouse at 22 °C under16 h light/8 h dark and 75% relative humidity for four weeks, then irrigated with 15% PEG6000 to simulate drought stress for three days. For temperature stress treatment, the prepared plants were moved into a chamber at 4 °C or 37 °C for three days. In order to study the response of LcPYL genes to ABA, the L. hybrid plants in a cold environment were sprayed with 50 mg/L ABA. The plants cultured under the normal condition were set as the control group. During the stress treatment, the L. hybrid plants were harvested at 1 h, 3 h and 3 d using liquid nitrogen and stored at −80 °C for RNA extraction. To check the transcription of LcPYLs in response to biotic stress, the first and second L. hybrid leaves infected by female whitefly and scale insect were harvested for qPCR testing. The plants grown under normal conditions were taken as the control. The samples were frozen in liquid nitrogen and stored at −80 °C for RNA extraction. Three biological replicates were conducted for each treatment.