The New Zealand Institute for Plant & Food Research Limited, 120 Mt. Albert Road, Auckland 1142, New Zealand.
BMC Genomics. 2013 Jan 16;14:28. doi: 10.1186/1471-2164-14-28.
Red colour in kiwifruit results from the presence of anthocyanin pigments. Their expression, however, is complex, and varies among genotypes, species, tissues and environments. An understanding of the biosynthesis, physiology and genetics of the anthocyanins involved, and the control of their expression in different tissues, is required. A complex, the MBW complex, consisting of R2R3-MYB and bHLH transcription factors together with a WD-repeat protein, activates anthocyanin 3-O-galactosyltransferase (F3GT1) to produce anthocyanins. We examined the expression and genetic control of anthocyanins in flowers of Actinidia hybrid families segregating for red and white petal colour.
Four inter-related backcross families between Actinidia chinensis Planch. var. chinensis and Actinidia eriantha Benth. were identified that segregated 1:1 for red or white petal colour. Flower pigments consisted of five known anthocyanins (two delphinidin-based and three cyanidin-based) and three unknowns. Intensity and hue differed in red petals from pale pink to deep magenta, and while intensity of colour increased with total concentration of anthocyanin, no association was found between any particular anthocyanin data and hue. Real time qPCR demonstrated that an R2R3 MYB, MYB110a, was expressed at significant levels in red-petalled progeny, but not in individuals with white petals.A microsatellite marker was developed that identified alleles that segregated with red petal colour, but not with ovary, stamen filament, or fruit flesh colour in these families. The marker mapped to chromosome 10 in Actinidia.The white petal phenotype was complemented by syringing Agrobacterium tumefaciens carrying Actinidia 35S::MYB110a into the petal tissue. Red pigments developed in white petals both with, and without, co-transformation with Actinidia bHLH partners. MYB110a was shown to directly activate Actinidia F3GT1 in transient assays.
The transcription factor, MYB110a, regulates anthocyanin production in petals in this hybrid population, but not in other flower tissues or mature fruit. The identification of delphinidin-based anthocyanins in these flowers provides candidates for colour enhancement in novel fruits.
猕猴桃的红色来自于花青素色素的存在。然而，它们的表达非常复杂，并且因基因型、物种、组织和环境而异。需要了解参与的花青素的生物合成、生理学和遗传学，以及它们在不同组织中的表达调控。一个由 R2R3-MYB 和 bHLH 转录因子与 WD-重复蛋白组成的复杂的 MBW 复合物，激活花青素 3-O-半乳糖基转移酶（F3GT1）来产生花青素。我们研究了在表现为红色和白色花瓣颜色的猕猴桃杂种家族的花朵中花青素的表达和遗传控制。
鉴定出四个与中华猕猴桃（Actinidia chinensis Planch. var. chinensis）和美味猕猴桃（Actinidia eriantha Benth.）杂交的回交家族，它们在红色或白色花瓣颜色上分离为 1:1。花朵色素由五种已知的花青素（两种飞燕草素为基础，三种矢车菊素为基础）和三种未知的组成。红色花瓣的强度和色调从淡粉色到深洋红色不等，尽管颜色强度随着花青素总浓度的增加而增加，但没有发现任何特定的花青素数据与色调之间存在关联。实时 qPCR 表明，一个 R2R3-MYB，MYB110a，在红色花瓣的后代中表达水平显著，但在白色花瓣的个体中不表达。开发了一个微卫星标记，该标记可识别与红色花瓣颜色分离的等位基因，但与这些家族中的子房、雄蕊花丝或果实果肉颜色无关。该标记在猕猴桃的 10 号染色体上定位。白色花瓣表型通过向花瓣组织中注射携带猕猴桃 35S::MYB110a 的农杆菌来互补。红色色素在白色花瓣中发展，无论是与猕猴桃 bHLH 伴侣共转化，还是没有共转化。在瞬时测定中，MYB110a 被证明可以直接激活猕猴桃 F3GT1。
在这个杂种群体中，转录因子 MYB110a 调节花瓣中的花青素合成，但在其他花组织或成熟果实中不调节。在这些花朵中鉴定出的飞燕草素为基础的花青素为新型果实的颜色增强提供了候选物。
