Transcriptome data for Hevea brasiliensis associated with powdery Mildew infection

The Hevea brasiliensis or rubber tree belongs to the Euphorbiaceae family and is the only economically viable natural rubber source worldwide. The development of enhanced rubber tree clones with agronomically important traits is critical due to the growing demand for natural rubber around the world. Throughout the years, numerous disease-causing pathogens of H. brasiliensis have been identified and studied. One of the more prominent diseases affecting H. brasiliensis is powdery mildew caused by Oidium heveae. Oidium heveae primarily infects the newly formed leaves and buds of H. brasiliensis. Severe Oidium heveae infections cause extensive defoliation and yield loss. We performed RNA sequencing (RNA-Seq) for healthy and O. heveae-infected leaf tissues from RRIM 2025 and RRIM 929 rubber tree clones using the Illumina HiSeq 2000 platform. RNA-Seq generated 92007684 (12.9 GB) and 96070286 (13.5 GB) paired raw reads for healthy H. brasiliensis clones RRIM 2025 and RRIM 929 respectively. Similarly, RNA-Seq generated 93747858 (13.2 GB) and 93324564 (13.1 GB) paired raw reads for disease-infected H. brasiliensis clones RRIM 2025 and RRIM 929 respectively. The raw data were deposited in the NCBI under bio-project accession number PRJNA723431. The raw reads were quality trimmed and the reference-based transcriptome assembly was generated using the H. brasiliensis genome (ASM165405v1). The data were used to identify between the significantly differentially expressed genes of the healthy and diseased samples.


a b s t r a c t
The Hevea brasiliensis or rubber tree belongs to the Euphorbiaceae family and is the only economically viable natural rubber source worldwide. The development of enhanced rubber tree clones with agronomically important traits is critical due to the growing demand for natural rubber around the world. Throughout the years, numerous disease-causing pathogens of H. brasiliensis have been identified and studied. One of the more prominent diseases affecting H. brasiliensis is powdery mildew caused by Oidium heveae. Oidium heveae primarily infects the newly formed leaves and buds of H. brasiliensis . Severe Oidium heveae infections cause extensive defoliation and yield loss. We performed RNA sequencing (RNA-Seq) for healthy and O. heveae -infected leaf tissues from RRIM 2025 and RRIM 929 rubber tree clones using the Illumina HiSeq 20 0 0 platform. RNA-Seq generated 92007684 (12.9 GB) and 96070286 (13.5 GB) paired raw reads for healthy H. brasiliensis clones RRIM 2025 and RRIM 929 respectively. Similarly, RNA-Seq generated 93747858 (13.2 GB) and 93324564 (13.1 GB) paired raw reads for diseaseinfected H. brasiliensis clones RRIM 2025 and RRIM 929 respectively. The raw data were deposited in the NCBI under bio-project accession number PRJNA723431. The raw reads were quality trimmed and the reference-based transcriptome assembly was generated using the H. brasiliensis genome (ASM165405v1). The data were used to identify between the significantly differentially expressed genes of the healthy and diseased samples.

Value of the Data
• Transcriptome data generated from the leaves of plants infected with powdery mildew could provide information on the molecular mechanism related to disease tolerance • The differential expression analysis of controlled and diseased H. brasiliensis plants could compare the expression variability of the genes and subsequently help identify the pathogen response genes expressed specifically during pathogen invasion • The information obtained from these data will provide a baseline understanding of the genes of practical importance in a resistance breeding programme.

Data Description
The dataset contains raw sequencing data obtained through the transcriptome sequencing of leaf samples of the rubber tree ( Hevea brasiliensis ). The data files were deposited at the NCBI SRA database under project accession no. PRJNA723431. Table 1 describes the raw reads-generated assembly and annotation information for H. brasiliensis healthy and Oidium heveae -infected transcriptomes. Table 2 provides the information on transcriptome mapping statistics for healthy and Oidium heveae -infected examples of two H. brasiliensis clones. Fig. 1 shows the differentially expressed genes (DEG) in three gene ontology (GO) categories, viz., biological process, cellular component and molecular function, in the H. brasiliensis RRIM 929 clone. Fig. 2

Hevea brasiliensis and Oidium heveae
Hevea brasiliensis clones RRIM 2025 and RRIM 929 were obtained from the Liman Plantation, Kedah. A spore suspension of Oidium heveae with 1.8 × 10 5 spores per millilitre was prepared in 0.05% Tween 20 solution. The spore suspension was brushed onto the young leaves of test clones, which were kept at optimum infection conditions with high relative humidity above 85%, at a temperature range of 22-28 °C, for a 16h light/8h dark photoperiod [1][2][3]. The leaves with the visible fungal growth of infected trees as well as those from healthy trees were harvested for RNA extraction.

Total RNA isolation and sequencing
Total RNA for RNA sequencing was isolated from one plant per treatment for each rubber tree clone. For the infected tree, RNA was isolated 21 days after infection. The RNA from the leaf samples was extracted using Plant RNA Reagent (Invitrogen, USA) according to the manufacturer's protocol after the tissue was homogenized using liquid nitrogen. Agarose gel electrophoresis was used to check for sharp 16S and 23S RNA bands to verify the integrity of the RNA samples. The Nanophotometer® spectrophotometer was used to verify RNA purity (IMPLEN, USA). The Qubit® RNA Assay Kit in the Qubit® 2.0 Fluorometer was used to measure the RNA concentration (Life Technologies, CA, USA). The Bioanalyzer 2100 system's RNA Nano 6000 Assay Kit was used to determine the integrity of the RNA (Agilent Technologies, CA, USA). The cDNA library preparation was generated using the NEBNext® Ultra TM RNA Library Prep Kit for Illu-

RNA-Seq mapping
The Illumina sequencing generated 125 bp/150 bp paired-end reads in FASTQ format from two RRIM 2025 (healthy and infected) plants and two RRIM 929 (healthy and infected). The He- vea brasiliensis reference genome ASM165405v1 was used for the mapping-based transcriptome assembly of the RRIM 2025 and RRIM 929 data. The read quality assessment was performed using FastQC [4] to improve mapping accuracy. The Q30 score was above 91% for all samples. Tophat (v2.0.12) [5] successfully mapped the sequenced reads to the reference genome with 81% success. The transcript abundance was estimated using HTSeq (v0.6.1) software [6] . The expression normalization and differential expression was performed using DESeq2 (v1.12.0) [7] .
The transcriptome data from healthy and Oidium heveae-infected rubber trees should provide information on the disease resistance potential of rubber clone RRIM 2025 and the disease susceptibility of rubber clone RRIM 925 as well as genes associated with disease resistance.

Accession code
The raw read data was submitted to Sequence Read Archive database (SRA) and can be accessed using the Data identification number PRJNA578136.

Supplementary materials
Supplementary materials have been deposited to Mendeley Data and can be accessed through DOI:10.17632/2mcfj7hw2y

Ethics Statement
This article does not contain any studies with human participants or animals performed by any of the authors.

Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships which have, or could be perceived to have, influenced the work reported in this article.