Eggplant berries are rich in anthocyanins like delphinidin-3-rutinoside (D3R) and nasunin (NAS), which are accumulated at high amounts in the peel. NAS is derived by D3R through acylation and glycosylation steps. The presence of D3R or NAS is usually associated with black-purple or lilac fruit coloration of the most cultivated varieties, respectively. Building on QTL mapping position, a candidate gene approach was used to investigate the involvement of a BAHD anthocyanin acyltransferase (SmelAAT) in determining anthocyanin type. The cDNA sequence comparison revealed the presence of a single-base deletion in D3R-type line ‘305E40’ (305E40_aat) with respect to the NAS-type reference line ‘67/3’. This is predicted to cause a frame shift mutation, leading to a loss of SmelAAT function and, thus, D3R retention. RT-qPCR analyses confirmed SmelAAT and 305E40_aat expression during berry maturation. In D3R-type lines, ‘305E40’ and ‘DR2’ overexpressing the functional SmelAAT allele from ‘67/3’, the transcript levels of the transgene, correlated with the accumulation of NAS in fruit peel. Furthermore, it was also found a higher expression of the transcript for glucosyltransferase Smel5GT1, putatively involved with SmelAAT in the last steps of anthocyanin decoration. Finally, an indel marker matching with anthocyanin type in the ‘305E40’ × ’67/3’ segregating population was developed and validated in a wide number of accessions, proving its usefulness for breeding purposes.
Background 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. Results 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. Conclusions 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.
IntroductionAppropriate postharvest treatment, as well as adequate conditions of storage, can be adopted to elongate the lifespan of cut flowers. Thidiazuron (TDZ), a substituted phenylurea, and 1-methylcycloproene (1-MCP), a non-toxic inhibitor of ethylene perception, are nowadays substances commonly used to prevent early damage caused by senescence and to delay chlorophyll degradation. Ranunculus asiaticus L. is cultivated for cut flower production and is highly sensitive to ethylene and leaf yellowing. In this study, the effect of different pulse-tratment in prolonging cut ranunculus vase life was analyzed.MethodsTDZ 10 µM, 1-MCP 500 ppb, and a combination of both were applied for 24 hours after harvest. The effect of the treatments was evaluated by performing non-destructive (% loss of fresh weight, chlorophyll a fluorescence, in vivo chlorophyll content, and Nitrogen Flavonol Index – NFI) and destructive (chlorophyll, carotenoids, anthocyanins concentration, and phenolic index) analyses at 0, 1, 12, and 14 days from treatments. Results and DiscussionFlower wilting was delayed by 4 days in 1-MCP + TDZ 10 µM treatments, which also reduced weight loss and chlorophyll degradation compared to controls. The effectiveness of these compounds in preventing senescence has been confirmed by the decreased biosynthesis of phenolic compounds.
Eggplant (Solanum melongena L.), similar to many other crops, suffers from soil-borne diseases, including Fusarium oxysporum f. sp. melongenae (Fom), causing wilting and heavy yield loss. To date, the genetic factors underlying plant responses to Fom are not well known. We previously developed a Recombinant Inbred Lines (RILs) population using as a female parent the fully resistant line ‘305E40’ and as a male parent the partially resistant line ‘67/3’. The fully resistant trait to Fom was introgressed from the allied species S. aethiopicum. In this work, the RIL population was assessed for the responses to Fom and by using a genomic mapping approach, two major QTLs on chromosomes CH02 and CH11 were identified, associated with the full and partial resistance trait to Fom, respectively. A targeted BSAseq procedure in which Illumina reads bulks of RILs grouped according to their resistance score was aligned to the appropriate reference genomes highlighted differentially enriched regions between resistant/susceptible progeny in the genomic regions underlying both QTLs. The characterization of such regions allowed us to identify the most reliable candidate genes for the two resistance traits. With the aim of revealing exclusive species-specific contigs and scaffolds inherited from the allied species and thus associated with the full resistance trait, a draft de-novo assembly of available Illumina sequences of the ‘305E40′ parent was developed to better resolve the non-recombining genomic region on its CH02 carrying the introgressed Fom resistance locus from S. aethiopicum.
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