Plant Sciences Division, Research School of Biology, College of Medicine, Biology, and Environment, The Australian National University, Linneaus Bldg #134, Linneaus Way, Canberra, ACT 0200, Australia.
Planta. 2013 Jul;238(1):171-89. doi: 10.1007/s00425-013-1883-3. Epub 2013 Apr 27.
Flavonoids have broad cross-kingdom biological activity. In Arabidopsis, flavonoid accumulation in specific tissues, notably the root elongation zone and root/shoot junction modulate auxin transport, affect root gravitropism, and influence overall plant architecture. The relative contribution made by aglycones and their glycosides remains undetermined, and the longer-term phenotypic effects of altered flavonoid accumulation are not fully assessed. We tested Arabidopsis thaliana mutants that accumulate different flavonoids to determine which flavonoids were causing these affects. Tandem mass spectrometry and in situ fluorescence localisation were used to determine the in vivo levels of aglycones in specific tissues of 11 transparent testa mutants. We measured rootward and shootward auxin transport, gravitropic responses, and identified the long-term changes to root and shoot architecture. Unexpected aglycone species accumulated in vivo in several flavonoid-pathway mutants, and lower aglycone levels occurred in transcription factor mutants. Mutants accumulating more quercetin and quercetin-glycosides changed the greatest in auxin transport, gravitropism, and aerial tissue growth. Early flavonoid-pathway mutants showed aberrant lateral root initiation patterns including clustered lateral root initiations at a single site. Transcription factor mutants had multiple phenotypes including shallow root systems. These results confirm that aglycones are present at very low levels, show that lateral root initiation is perturbed in early flavonoid-pathway mutants, and indicate that altered flavonoid accumulation affects multiple aspects of plant architecture.
类黄酮具有广泛的跨物种生物学活性。在拟南芥中，类黄酮在特定组织（特别是根伸长区和根/茎交界处）的积累会调节生长素的运输，影响根的向重力性，并影响整体植物结构。糖苷配基及其糖苷的相对贡献仍未确定，而且改变类黄酮积累的长期表型效应尚未得到充分评估。我们测试了积累不同类黄酮的拟南芥突变体，以确定是哪种类黄酮引起了这些影响。串联质谱和原位荧光定位用于确定 11 个透明种皮突变体特定组织中糖苷配基的体内水平。我们测量了向根和向芽的生长素运输、向重力性反应，并确定了根和芽结构的长期变化。在几种类黄酮途径突变体中，体内意外地积累了非糖苷配基物质，而转录因子突变体中的非糖苷配基水平较低。积累更多槲皮素和槲皮苷的突变体在生长素运输、向重力性和地上组织生长方面变化最大。早期类黄酮途径突变体表现出异常的侧根起始模式，包括在单个位点簇状的侧根起始。转录因子突变体具有多种表型，包括根系较浅。这些结果证实了非糖苷配基的存在水平非常低，表明侧根起始在早期类黄酮途径突变体中受到干扰，并表明改变类黄酮积累会影响植物结构的多个方面。
