Characterization Of Alternative Splicing In Response To Low-nitrogen In Maize Ears

Alternative splicing( AS) is one of significant modes in gene expression regulation at post-transcriptional level in higher plants. AS has been considered to play an important role in plant development, stress adaptability, etc. However, AS in response to low-nitrogen(LN) adaptability has not been characterized. In this study, ye478 and xu178, LN sensitive and res istant line, were subjected to nitrogen treatment before and after self-pollination. Ears of these lines were sampled and their RNA were extracted to conduct sequencing as well as both transcriptome and AS were analyzed. The following conclusions had been drawn.1. Intron retention(IR) was the main type of AS in these samples. IR events had the highest proportion in eight samples, about 50%-60%. Frequency of IR events was mostly one or two. Higher frequencies of IR events were rare.2. Under LN condition before pollination, 20.83% of LN responsive IR gene was found in xu178, while 26.66% of LN responsive IR gene was detected in ye478. Among GO biological process, 222 and 275 genes were related to nitrogen metabolism. 196 and 272 genes were involved in biosynthesis. 146 and 186 genes were stress responsive genes, respectively. In addition, protein modification, morphogenesis, process of reproductive development were also demonstrated, etc. Under LN condition at 10 DAP, 26.17% of LN responsive IR gene was identified in xu178, while 25.44% of LN responsive IR gene was probed in ye478. In terms of GO biological process, 255 and 240 genes were associated with nitrogen metabolism. 241 and 224 genes were discovered to be related to biosynthesis processes. 218 and 177 genes were associated with stress response. Besides, carbohydrate metabolism, protein modification, amino acid metabolism, esters metabolism, transport, catalytic processes, signal transduction, morphogenesis, embryonic development and reproduction were also illustrated. Moreover, LN responsive IR genes with differential expressed profiles did not affect the occurrence of IR events.3. Splicing-related IR genes under LN condition were retrieved. For instance, GRMZM2G060540 and GRMZM2G053196 were identified in xu178. GRMZM2G130207, GRMZM2G044306 and GRMZM2G320920 were found in ye478. Predicted motifs had high similar ity among four different materials. GC content of IR events was generally higher than that of total introns and constitutive introns in eight samples. Distribution of intron length was concentrated in a short region. IR in transcripts generated premature termination codon(PTC: premature termination codon) in eight samples, with approximate 92%.