Characterization of defense-related genes in the ‘Qinguan’ apple in response to Marssonina coronaria

Marssonina coronaria is a serious fungal disease causing heavy loss of apple production in East Asia including China and Japan. Suppression subtractive hybridization (SSH) was used to identify differentially expressed genes in the ‘Qinguan’ apple (Malus × domestica) in response to challenge with M. coronaria. The samples were collected at 3, 6, 12, 24, 48, 72, and 96 hours post-inoculate (hpi). A forward subtractive cDNA library was constructed and 2349 cDNA fragments were screened and sequenced. 175 unique cDNA sequences were obtained from the library. The sizes of the sequenced fragments ranged from ~ 200 to ~ 1000 bp. Based on BLAST analysis, functions of these ESTs were classified into ten categories, among which the largest three groups were defense/stress, protein metabolism, and photosynthesis. These ESTs were successfully deposited in GenBank, and their accession numbers (JK263619, JK263620, JK263621, JK263622, JK263623, JK263624, JK263625, JK263626, JK263627, JK263628, JK263629, JK263630, JK263631, JK263632, JK263633, JK263634, JK263635, JK263636, JK263637, JK263638, JK263639, JK263640, JK263641, JK263642, JK263643, JK263644, JK263645, JK263646, JK263647, JK263648, JK263649, JK263650, JK263651, JK263652, JK263653, JK263654, JK263655, JK263656, JK263657, JK263658, JK263659, JK263660, JK263661, JK263662, JK263663, JK263664, JK263665, JK263666, JK263667, JK263668, JK263669, JK263670, JK263671, JK263672, JK263673, JK263674, JK263675, JK263676, JK263677, JK263678, JK263679, JK263680, JK263681, JK263682, JK263683, JK263684, JK263685, JK263686, JK263687, JK263688, JK263689, JK263690, JK263691, JK263692, JK263693, JK263694, JK263695, JK263696, JK263697, JK263698, JK263699, JK263700, JK263701, JK263702, JK263703, JK263704, JK263705, JK263706, JK263707, JK263708, JK263709, JK263710, JK263711, JK263712, JK263713, JK263714, JK263715, JK263716, JK263717, JK263718, JK263719, JK263720, JK263721, JK263722, JK263723, JK263724, JK263725, JK263726, JK263727, JK263728, JK263729, JK263730, JK263731, JK263732, JK263733, JK263734, JK263735, JK263736, JK263737, JK263738, JK263739, JK263740, JK263741, JK263742, JK263743, JK263744, JK263745, JK263746, JK263747, JK263748, JK263749, JK263750, JK263751, JK263752, JK263753, JK263754, JK263755, JK263756, JK263757, JK263758, JK263759, JK263760, JK263761, JK263762, JK263763, JK263764, JK263765, JK263766, JK263767, JK263768, JK263769, JK263770, JK263771, JK263772, JK263773, JK263774, JK263775, JK263776, JK263777, JK263778, JK263779, JK263780, JK263781, JK263782, JK263783, JK263784, JK263785, JK263786, JK263787, JK263788, JK263789, JK263790, JK263791, JK263792 and JK263793) have been released. Quantitative Real Time-PCR (qRT-PCR) was used to characterize the relative expression of catalase (CAT), hypersensitive-induced response protein (HIR), calmodulin (CaM) and distinctive expression patterns of three genes were found in ‘Qinguan’ and ‘Fuji’ hit by spores of M. coronaria. In conclusion, responses to M. coronaria were complex in apples, nevertheless, certain common genes were found in apples regarding reactions to fungal infection such as Venturia inaequalis.

► 175 ESTs from ‘Qinguan’ suffering from M. coronaria were obtained using a SSH method.
► EST functions were classified into 10 categories and a few were deeply discussed.
► Expression patterns of 3 genes, CAT, HIR and CaM were characterized using RT-PCR.
► Responses to M. coronaria were complex in apples.
► A few common genes were found between interactions to M. coronaria and V. inaequalis.