Transcriptome of ZmPMP3g overexpressing maize inbred line Ye478, and wild type Ye478 under control, moderate drought, exogenous abscisic acid, or treatment combinations

This study is to identify the role of maize ZmPMP3g (GenBank accession no. EC869579.1), a proteolipid membrane potential modulator 3 (PMP3) domain gene, in drought tolerance of maize, and the genes and signaling pathways under over-expression of ZmPMP3g The tillage soil from the experimental field of Guangxi University was collected, sun-dried, sieved, and then fully mixed with the local commercial organic fertilizer (8:2/w:w) as pot mix. The pot mix was loaded in pots (31 cm in diameter and 21 cm in height), 5 kg per pot. The pot mix of each pot was saturated with tap water and then monitored for moisture by using a Dong mei DT001 soil tester (Shanghai, China) equipped with a thin and long detector. When the moisture of the pot mix reached about 70%, pot experiment started. The maize ZmPMP3g (GenBank accession no. EC869579.1) ranging from start codon to stop codon was cloned into NcoI and BamHI restriction sites downstream of the 3×CaMV35S (3×200) promoter of plasmid pGSA1252 of Basta resistance gene, generating an expression construct, pGSA1252::ZmPMP3g. The construct was introduced into mature embryos of Chinese maize inbred line Ye478 by Agrobacterium tumefaciens strain LBA4404 mediated infection. The LBA4404-infected maize embryos were transferred onto Murashige and Skoog medium plates containing 0.1 mg/L IAA, 250 mg/L cefotaxime, 20 ppm herbicide Basta and 30 g/L sucrose, and then allowed to grow for 7 d at 28 °C under a cycle of light/16 h and dark/8 h. The regenerated Basta-resistant maize plantlets were transplanted into sandy soil in trays and then grew for 10 d at room temperature followed by foliar-spraying 40 ppm Basta once. The maize seedlings that survived 7 d after spraying Basta were transferred into pot mix and allowed to grow in the glass greenhouse at 20-25 °C and with 50%-60% air humidity under a cycle of light/16 h and dark/8 h. The transformed plants were subjected to identification by PCR, Southern blotting, and real-time quantitative PCR. Drought treatment started at 5-leaf stage of maize through natural mix drought without watering until to moderate drought (50% moisture for pot mix). The pot mix moisture in the parallel control was controlled at 70% by watering. When the pot mix was in moderate drought and severe drought respectively, sampling started and exogenous ABA was applied. The exogenous ABA application was conducted by spraying 15 mg/L ABA (Sigma, USA) on whole plants once while the leaves in control treatment were sprayed with an equal volume of tap water. The transcriptome sequencing was conducted on the second fully-expanded leaves down from the top of T4 transgenic line plants 9 d after spraying ABA on whole plants and parallel control plants, which were sampled at 10:00 a.m.