Zhu-Salzman Keyan, Salzman Ron A, Ahn Ji-Eun, Koiwa Hisashi
Department of Entomology, Texas A&M University, College Station, Texas 77843, USA.
Plant Physiol. 2004 Jan;134(1):420-31. doi: 10.1104/pp.103.028324. Epub 2003 Dec 30.
When attacked by a phloem-feeding greenbug aphid (Schizaphis graminum), sorghum (Sorghum bicolor) activates jasmonic acid (JA)- and salicylic acid (SA)-regulated genes, as well as genes outside known wounding and SA signaling pathways. A collection of 672 cDNAs was obtained by differential subtraction with cDNAs prepared from sorghum seedlings infested by greenbug aphids and those from uninfested seedlings. Subsequent expression profiling using DNA microarray and northern-blot analyses identified 82 transcript types from this collection responsive to greenbug feeding, methyl jasmonate (MeJA), or SA application. DNA sequencing analyses indicated that these encoded proteins functioning in direct defense, defense signaling, oxidative burst, secondary metabolism, abiotic stress, cell maintenance, and photosynthesis, as well as proteins of unknown function. In response to insect feeding, sorghum increased transcript abundance of numerous defense genes, with some SA-dependent pathogenesis-related genes responding to greenbug more strongly than to SA. In contrast, only weak induction of MeJA-regulated defense genes was observed after greenbug treatment. However, infestation tests confirmed that JA-regulated pathways were effective in plant defense against greenbugs. Activation of certain transcripts exclusively by greenbug infestation was observed, and may represent unique signal transduction events independent of JA- and SA-regulated pathways. Results indicate that plants coordinately regulate defense gene expression when attacked by phloem-feeding aphids, but also suggest that aphids are able to avoid triggering activation of some otherwise potentially effective plant defensive machinery, possibly through their particular mode of feeding.
当受到吸食韧皮部的麦二叉蚜（Schizaphis graminum）攻击时，高粱（Sorghum bicolor）会激活茉莉酸（JA）和水杨酸（SA）调控的基因，以及已知的创伤和SA信号通路之外的基因。通过对受麦二叉蚜侵害的高粱幼苗和未受侵害的幼苗制备的cDNA进行差异消减，获得了672个cDNA的集合。随后使用DNA微阵列和Northern印迹分析进行表达谱分析，从该集合中鉴定出82种转录本类型对麦二叉蚜取食、茉莉酸甲酯（MeJA）或SA处理有反应。DNA测序分析表明，这些编码的蛋白质在直接防御、防御信号传导、氧化爆发、次生代谢、非生物胁迫、细胞维持和光合作用中发挥作用，以及功能未知的蛋白质。响应昆虫取食，高粱增加了许多防御基因的转录丰度，一些SA依赖的病程相关基因对麦二叉蚜的反应比对SA的反应更强。相比之下，在麦二叉蚜处理后，仅观察到MeJA调控的防御基因有微弱的诱导。然而，侵染试验证实JA调控的途径在植物对麦二叉蚜的防御中是有效的。观察到某些转录本仅由麦二叉蚜侵染激活，可能代表独立于JA和SA调控途径的独特信号转导事件。结果表明，植物在受到吸食韧皮部的蚜虫攻击时会协调调节防御基因的表达，但也表明蚜虫可能通过其特殊的取食方式避免触发一些原本可能有效的植物防御机制的激活。
