Department of Chemistry, Chonbuk National University, Jeonju 561-756, Korea.
BMC Plant Biol. 2013 Jul 13;13:101. doi: 10.1186/1471-2229-13-101.
Floral nectar (FN) contains not only energy-rich compounds to attract pollinators, but also defense chemicals and several proteins. However, proteomic analysis of FN has been hampered by the lack of publically available sequence information from nectar-producing plants. Here we used next-generation sequencing and advanced proteomics to profile FN proteins in the opportunistic outcrossing wild tobacco, Nicotiana attenuata.
We constructed a transcriptome database of N. attenuata and characterized its nectar proteome using LC-MS/MS. The FN proteins of N. attenuata included nectarins, sugar-cleaving enzymes (glucosidase, galactosidase, and xylosidase), RNases, pathogen-related proteins, and lipid transfer proteins. Natural variation in FN proteins of eleven N. attenuata accessions revealed a negative relationship between the accumulation of two abundant proteins, nectarin1b and nectarin5. In addition, microarray analysis of nectary tissues revealed that protein accumulation in FN is not simply correlated with the accumulation of transcripts encoding FN proteins and identified a group of genes that were specifically expressed in the nectary.
Natural variation of identified FN proteins in the ecological model plant N. attenuata suggests that nectar chemistry may have a complex function in plant-pollinator-microbe interactions.
花卉花蜜（FN）不仅含有吸引传粉者的富含能量的化合物，还含有防御化学物质和几种蛋白质。然而，由于缺乏来自产蜜植物的公共可用序列信息，FN 的蛋白质组学分析受到了阻碍。在这里，我们使用下一代测序和先进的蛋白质组学技术对机会性异交野生烟草 Nicotiana attenuata 的 FN 蛋白进行了分析。
我们构建了 N. attenuata 的转录组数据库，并使用 LC-MS/MS 对其花蜜蛋白质组进行了表征。N. attenuata 的 FN 蛋白包括花蜜素、糖裂解酶（葡萄糖苷酶、半乳糖苷酶和木糖苷酶）、RNases、与病原体相关的蛋白和脂质转移蛋白。11 个 N. attenuata 品系的 FN 蛋白的自然变异表明，两种丰富蛋白（nectarin1b 和 nectarin5）的积累呈负相关。此外，对蜜腺组织的微阵列分析表明，FN 中蛋白质的积累与编码 FN 蛋白的转录本的积累并不完全相关，并鉴定了一组在蜜腺中特异性表达的基因。
生态模式植物 N. attenuata 中鉴定出的 FN 蛋白的自然变异表明，花蜜化学物质在植物-传粉者-微生物相互作用中可能具有复杂的功能。
