Department of Agricultural and Environmental Sciences (DISAA), University of Milan, 20133, Milan, Italy.
DAFNE Department - University of Tuscia, 01100, Viterbo, Italy.
BMC Plant Biol. 2022 Jul 4;22(1):318. doi: 10.1186/s12870-022-03691-w.
With the domestication of ornamental plants, artificial selective pressure favored the propagation of mutations affecting flower shape, and double-flower varieties are now readily available for many species. In peach two distinct loci control the double-flower phenotype: the dominant Di2 locus, regulated by the deletion of the binding site for miR172 in the euAP2 PETALOSA gene Prupe.6G242400, and the recessive di locus, of which the underlying factor is still unknown.
Based on its genomic location a candidate gene approach was used to identify genetic variants in a diverse panel of ornamental peach accessions and uncovered three independent mutations in Prupe.2G237700, the gene encoding the transcript for microRNA miR172d: a ~5.0 Kb LTR transposable element and a ~1.2 Kb insertion both positioned upstream of the sequence encoding the pre-miR172d within the transcribed region of Prupe.2G237700, and a ~9.5 Kb deletion encompassing the whole gene sequence. qRT-PCR analysis confirmed that expression of pre-miR172d was abolished in di/di genotypes homozygous for the three variants.
Collectively, PETALOSA and the mutations in micro-RNA miR172d identified in this work provide a comprehensive collection of the genetic determinants at the base of the double-flower trait in the peach germplasms.
随着观赏植物的驯化，人工选择压力有利于影响花形的突变的传播，现在许多物种都有双瓣品种。在桃中，有两个不同的基因座控制双瓣表型：显性 Di2 基因座，由 euAP2 PETALOSA 基因 Prupe.6G242400 中 miR172 结合位点缺失调控；隐性 di 基因座，其潜在因子尚不清楚。
基于其基因组位置，采用候选基因方法鉴定了不同观赏桃品种中的遗传变异，在编码 microRNA miR172d 转录物的 Prupe.2G237700 基因中发现了三个独立的突变：一个约 5.0 Kb 的 LTR 转座元件和一个约 1.2 Kb 的插入，均位于 Prupe.2G237700 转录区中 pre-miR172d 编码序列的上游，以及一个约 9.5 Kb 的缺失，包含整个基因序列。qRT-PCR 分析证实，三个变异的 di/di 基因型中 pre-miR172d 的表达被完全抑制。
综上所述，PETALOSA 和本工作中鉴定的 micro-RNA miR172d 突变提供了桃种质中双瓣性状遗传决定因素的综合集合。
