Marigold (Tagetes erecta L.) is an important ornamental plant with a wide variety of flower colors. Despite its economic value, few biochemical and molecular studies have explored the generation of flower color in this species. To study the mechanism underlying marigold petal color, we performed a metabolite analysis and de novo cDNA sequencing on the inbred line ‘V-01’ and its petal color mutant ‘V-01M’ at four flower developmental stages. A total of 49,217 unigenes were identified from 24 cDNA libraries. Based on our metabolites and transcriptomic analyses, we present an overview of carotenoid biosynthesis, degradation, and accumulation in marigold flowers. The carotenoid content of the yellow mutant ‘V-01M’ was higher than that of the orange inbred line ‘V-01’, and the abundances of the yellow compounds lutein, neoxanthin, violaxanthin, zeaxanthin, and antheraxanthin were significantly higher in the mutant. During flower development, the carotenoid biosynthesis genes were upregulated in both ‘V-01’ and ‘V-01M’, with no significant differences between the two lines. By contrast, the carotenoid degradation genes were dramatically downregulated in the yellow mutant ‘V-01M’. We therefore speculate that the carotenoid degradation genes are the key factors regulating the carotenoid content of marigold flowers. Our research provides a large amount of transcriptomic data and insights into the marigold color metabolome.

Salvia splendens, scarlet or tropical sage, is a tender perennial herbaceous flowering plant popularly grown in public and private gardens all over the world. In this study, we developed a set of simple sequence repeats (SSRs) from genome-wide sequences to assess the genetic diversity and population structure among 112 cultivars. We obtained 364,379 SSRs by mining scarlet sage’s recently published whole genome sequence; 14,545 gene-associated SSR loci were identified in 2 kb gene flanking regions. Among the 768 gene-associated SSR primer sets we screened, 576 loci successfully amplified in DNA pools of 3–4 different cultivars, of which 271 remained polymorphic when tested across eight individual plants. We searched for the related gene functions attributable to these gene-associated SSRs using diverse databases, resulting in 259 Non-redundant matching sequences, 205 individual Gene Ontology (GO) terms, 236 assigned to eukaryotic orthologous groups, and 67 KEGG-annotated (Kyoto Encyclopedia of Genes and Genomes) sequences. We finally selected 41 polymorphic SSR loci to infer genetic diversity and population structure among 112 S. splendens accessions. Based on the developed gene-associated SSRs, clustering analyses consistently revealed two distinct genetic groups within the core collection of S. splendens cultivars. This work developed and characterized an exhaustive set of genome-wide gene-associated SSR markers for scarlet sage. These SSRs can provide species identification, genetic diversity and population structure information for S. splendens, and will therefore be important tools for the management and protection of S. splendens germplasm.

Seven interspecific crosses of Tagetes erecta × T. patula were conducted in this study. The cross compatibility index, seed setting rate, germination rate, phenotype, ploidy level, heterosis over male parent and field performance were tested. The results showed that different cross compatibility indices of Tagetes vary greatly, from 10.44~114.41, which is far less than that of the intraspecific hybridization S-121 × I-506 index. The seed setting rate of each cross ranged from 15.67% to 49.0%, and the cross S-121 × TP-512 scored the highest seed setting rate, which was higher than that of the intraspecific cross S-121 × I-506 (35.85%). Compared with the male parent, F1 has higher plant height, wider crown width, larger flower diameter and more ray florets and earlier bloom with two exceptions. The S-121 of T. erecta was diploid. All of the male parents of T. patula were tetraploids, and the combinations were triploids. The traits of plant height, plant width, flower size and number of ray florets showed positive heterosis over the male parents, and the days leading to flowering showed both positive and negative ones. Finally, S-121 × TP-379 and S-121 × TP-512 were selected as the two best combinations. This study confirmed that the two species of marigold could be crossed for better F1 varieties with improved performance. ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********