design: RNA was extracted from three plants roots pool. The tissues (100 mg) were powdered in liquid nitrogen. Total RNA was extracted and purified by using RNeasy Plant Mini Kit (Qiagen), following the manufacturer's protocol. RNA quantity and quality were determined with a Nanodrop 2000 spectrophotometer (Thermo Fisher Scientific Inc., Wilmington, Delaware, USA) and a Bioanalyzer 2100 (Agilent Technologies, Santa Clara, CA, USA). cDNA libraries  were prepared from 4 g total RNA using TruSeq RNA Sample Preparation Kit v2 (Illumina, Inc., San Diego, CA, USA) and validated according to the Illuminas low-throughput protocol. After normalization, cDNA libraries were pooled for multiplexing before loading onto a flow cell. The hybridization and cluster generation were performed on a cBot System using TruSeq SR Cluster Kit v3. Sequencing was performed on Illumina HiScanSQ, using TruSeq SBS kit v3 (Illumina, Inc.).