Abstract

Banded leaf and sheath blight (BLSB) caused by Rhizoctonia solani Kühn is an emerging problem in maize worldwide. To study gene expression in maize plants infected by R. solani Kühn, we constructed two suppression subtractive hybridization (SSH) library using complementary DNA (cDNA) from uninoculated plants as a driver and those from inoculated plants as a tester. After two cycles of hybridization, 84 cDNA clones from the forward and reverse SSH library were obtained and sequenced. Gene analysis indicated that these clones represented 51 single genes, and the functions of 35 genes could be assigned using existing databases. Thirty-five expression sequences tags (ESTs) were classified in fuctional categories, such as: transcription, regulation, protein processing, metabolism, defense, disease response and other functions. The expression of 15 genes was analyzed by semi-quantitative reverse-transcription-polymerase chain reaction (RT-PCR) and found to be up-regulated or down-regulated in response to R. solani Kühn re-infection. In conclusion, this study provides a basis for a molecular understanding of host reaction in response to pathogen.

Key words: Banded leaf and sheath blight, expressed sequence tag, gene expression, maize, suppression subtractive hybridization.

Abbreviation

Abbreviations: ABA, Abscisic acid; AG1-IA, anastomosis group IA; BLSB, banded leaf and sheath blight; bZIP, basic zipper; CAT, catalase; cDNAs, complementary DNA; DIG, digoxigenin; EST, expressed sequence tag; Fd, ferredoxin; Ft, ferritin;GCA, general combining ability; GR, glutathione reductase; GST, glutathione-S-transferase; IPTG, isopropyl-b-D-thiogalactopyranoside; ivr2, vacuolar invertase 2;LB, Luria–Bertani; MA, malic acid; MDH, malate dehydrogenase; PCD, programmed cell death; PCR, polymerase chain reaction; PDA, potato dextrose agar; PEP, phosphoenolpyruvate; PPDK, pyruvate phosphate-dikinase; QTL, quantitative trait loci; ROS, reactive oxygen species; PR, pathogenesis-related; RT-PCR, reverse transcription polymerase chain reaction; SA, salicylic acid; SDS, sodium dodecyl sulfate; SNF1, sucrose non-fermenting-1-related protein; Snrk1, sucrose non-fermenting-1-related protein kinase 1; Trx, thioredoxin; X-gal, 5-bromo-4-chloro-3-indolyl-b-D-galactopyranoside; SSH, suppression subtractive hybridization.