Mapping of fruit length related QTLs in interspecific cross (Capsicum annuum L. × Capsicum galapagoense Hunz.) of chilli

Abstract

Fruit length in chilli is quantitatively inherited trait and selection based on phenotypic performance is tedious and time consuming. To detect QTLs determining fruit length in Capsicum spp., an interspecific F₂ mapping population was developed from the cross of C. annuum L. cv. 'FL 201' with C. galapagoense Hunz. accession 'TC 07245'. Fruit length in this cross showed a quantitative inheritance with the population depicting a symmetric distribution in histogram. To map quantitative trait loci (QTLs) for fruit length 400 SSR markers were surveyed on the parental genotypes but only 28 markers were observed to be polymorphic indicating less genetic diversity between the two Capsicum species. Polymorphic markers were then analyzed in F₂ population consisting of 210 plants and 24 of these markers were mapped on to three linkage groups (LGs): LG 1, LG 2 and LG 3. Two fruit length determining QTLs designated as paufl2.1 and paufl2.2 were identified and both the QTLs were mapped on to LG 2. The two QTLs together explained 21.78 per cent of the phenotypic variation. Apart from the two QTLs, positive alleles were detected in the small fruited parent 'TC 07245' which might be of potential use in chilli breeding programs.

Keywords: QTL mapping; chilli pepper; fruit length; molecular markers; paufl2.1; paufl2.2.

Fig. 1

Phenotypic variability for fruit length between parental lines ‘FL 201’ and ‘TC 07245’.

Fig. 2

Phenotypic variation for fruit length in F₂ population derived from the cross C. annuum ‘FL 201’ × C. galapagoense ‘TC 07245’ chilli.

Fig. 3

Frequency distribution for fruit length in 210 F₂ population derived from the cross C. annuum. ‘FL 201’ × C. galapagoense ‘TC 07245’.

Fig. 4

(a) Segregation pattern of SSR marker GPMS100 on 4% agarose gel in F₂ mapping population derived from the cross C. annuum ‘FL 201’ × C. galapagoense ‘TC 07245’. (b) Segregation pattern of AVRDC*MD782 marker on 6% PAGE in F₂ mapping population derived from the cross C. annuum. ‘FL 201’ × C. galapagoense ‘TC 07245’.

Fig. 5

Genetic linkage map derived from the cross C. annuum. ‘FL 201’ × C. galapagoense ‘TC 07245’ using Kosambi mapping function. Marker names and the map distances (cM) are indicated on the right and left of linkage groups, respectively. Red colored regions in the linkage map denotes the two fruit length related QTLs designated as paufl2.1 and paufl2.2.

Fig. 6

QTL likelihood plots of LG-2 showing LOD peaks for fruit length in F₂ population. Two peaks depict two fruit length related QTLs designated as paufl2.1 and paufl2.2 with LOD peak value of 5.53 and 5.26, respectively. The two QTLs together explained 21.8% of the phenotypic variation.