Using Simple Sequence Repeats in 9 Brassica Complex Species to Assess Hypertrophic Curd Induction

Abstract

Five Simple Sequence Repeats (SSRs) were used to assess the relationship between inflorescence characteristics and their allelic variation in 53 Brassica oleracea and Brassica wild relatives (n = 9). Curd morphometric traits, such as weight (CW), height (CH), diameter (CD1), shape (CS) inflorescence curvature angle (CA), and its curd stem diameter (CD2), were measured. The aim of the work was to analyze the relationships among the allelic patterns of the SSRs primers utilized, and their status of homo or heterozygosity registered at each locus, as well as the inflorescence morphometric traits in order to individuate genomic regions stimulating the hypertrophy of this reproductive organ. The relationships found explain the diversity among B. oleracea complex species (n = 9) for the inflorescence size and structure, allowing important time reduction during the breeding process by crossing wild species, transferring useful resistance, and organoleptic and nutraceutical traits. The five SSRs loci were BoABI1, BoAP1, BoPLD1, BoTHL1, and PBCGSSRBo39. According to the allelic variation ascertained, we evaluated the heterozygosity index (H) for each SSR above cited. The results showed a significant interaction between the H index of the BoPLD1 gene and the inflorescence characteristics, summarized by the First Principal Component (PC1) (p-value = 0.0244); we ascertained a negative correlation between the H index and inflorescence characteristics, namely CW, CH, CD1, CD2, CA. The homozygosity BoPLD1 alelles, indicated by the H index, affect the inflorescence characteristics and broccoli and cauliflower yields.

Molecular Markers for Detecting Inflorescence Size of Brassica oleracea L. Crops and B. oleracea Complex Species (n = 9) Useful for Breeding of Broccoli (B. oleracea var. italica) and Cauliflower (B. oleracea var. botrytis)

“…In our work, the main inflorescence morphometric traits (IW, IH, ID1, ID2, IS and IA) allow us to distinguish among the B . oleracea inflorescence morphotypes, in accordance with Branca et al [ 32 ] and Treccarichi et al [ 20 ]. The plant materials were selected from the B .…”

“…In our previous work, we already detected for each SSR locus different numbers of alleles among the accessions and the inflorescence morphotypes studied; BoAP1 (P1) showed 12 alleles, BoTHL1 (P2) 8 alleles, BoABI1 (P3) 9 alleles, BoPLD1 (P4) 6 alleles, and PBCGSSRBo39 (SP5) 39 11 alleles, in accordance with Branca et al [ 32 ] and Treccarichi et al [ 20 ]. Several of the following alleles, were unconsciously selected and maintained by the growers selected for the size of the hypertrophic inflorescence and probably they were also introgressed by the genetic flux among the B. oleracea wild relatives (n = 9) and the first domesticated kales and sprouting broccoli landraces [ 13 ].…”

“…The correlation among the allelic variants and the inflorescence bio-morphometric traits showed that they increase in terms of value when BoPLD1 (P4) locus tends to heterozygosity. In reality we have observed the P4_288 allele which is homozygous or heterozygous for broccoli and cauliflower whereas for all the B. oleracea complex species (n = 9), except for one of the two B. incana studied (BY2), it is absent ( Figure 1 ) [ 20 ].…”

“…Molecular markers have proven to be important tools for assessing genetic variation and relationships in plant species above all for organic breeding and for establishing the organic heterogenic materials as described by the EU Directive 848/2018 [ 20 ]. Some molecular markers are represented by simple sequence repeats (SSRs), alternately known as microsatellite markers, which have been successfully used for evaluating the genetic variability and for distinguishing among them the nearly related Brassica genotypes [ 21 , 22 , 23 ], because of their codominance and ability to reveal a high number of alleles for locus, resulting in a high degree of reproducibility and variability [ 24 ].…”

“…Sheng et al [ 33 ] characterized and mapped 91 MADS-box transcription factors able to discern from type I (Mα, Mβ, Mγ) and type II (MIKCC, MIKC*) genetic groups as a consequence of phylogenetic and gene structure analysis: 59 genes were randomly distributed on 9 chromosomes, and 23 were located in 19 scaffolds, while 9 of them were not located due to the lack of information on the NCBI database (Sheng et al, 2019). Treccarichi et al [ 20 ] used the set of markers used by Branca et al [ 34 ] to calculate the genetic diversity among nine accessions of B. oleracea crops and B . oleracea complex species (n = 9) and to evaluate the hypertrophic induction of the curd.…”