RESUMEN
Hybrids of cauliflower are in high demand world over due to their high yield potential, earliness, better quality, better resistance to biotic and abiotic stresses. Conventionally, hybrids are developed from the intercrossing of two diverse inbred parental lines which are developed through continuous inbreeding for 8-10 generations and still don't attain complete homozygosity. Doubled haploid technology on the other hand generate completely homozygous inbred lines in a single step. Therefore, a study was undertaken at Punjab Agricultural University, Ludhiana, to develop a protocol for the development of doubled haploid lines in cauliflower. The anthers were excised from the flower buds of different genotypes viz. Jyoti, Pusa Sharad, Kartiki, CAUMH-2, CAUMH-10, LS-2, LS-3, and LS-5 followed by their culture on five different callus induction media compositions. Genotypes differed significantly in the ability to induce callus which was maximum in Jyoti followed by LS-2. Different media compositions also varied significantly in callus induction efficiency which was maximum on MS media+1.5 mg/L 2,4-D +1.0 mg/L NAA. Maximum shoot regeneration was recorded in genotype Kartiki followed by LS-2 when cultured on MS media+3.0 mg/L BAP+2.0 mg/L Kin. The regenerated shoots thus obtained were rooted on ½ MS media +1.0 mg/L IBA. Ploidy analysis of root tips revealed that 22.2% of the regenerated plantlets were haploids, 27.8% were spontaneous doubled haploids, 16.7% were tetraploids and remaining 33.3% were mixoploids.
RESUMEN
Bitter gourd (Momordica charantia L.) is an important vegetable crop having numerous medicinal properties. Earliness and yield related traits are main aims of bitter gourd breeding program. High resolution quantitative trait loci (QTLs) mapping can help in understanding the molecular basis of phenotypic variation of these traits and thus facilitate marker-assisted breeding. The aim of present study was to identify genetic loci controlling earliness, fruit, and seed related traits. To achieve this, genotyping-by-sequencing (GBS) approach was used to genotype 101 individuals of F4 population derived from a cross between an elite cultivar Punjab-14 and PAUBG-6. This population was phenotyped under net-house conditions for three years 2018, 2019, and 2021. The linkage map consisting of 15 linkage groups comprising 3,144 single nucleotide polymorphism (SNP) markers was used to detect the QTLs for nine traits. A total of 50 QTLs for these traits were detected which were distributed on 11 chromosomes. The QTLs explained 5.09-29.82% of the phenotypic variance. The highest logarithm of the odds (LOD) score for a single QTL was 8.68 and the lowest was 2.50. For the earliness related traits, a total of 22 QTLs were detected. For the fruit related traits, a total of 16 QTLs and for seed related traits, a total of 12 QTLs were detected. Out of 50 QTLs, 20 QTLs were considered as frequent QTLs (FQ-QTLs). The information generated in this study is very useful in the future for fine-mapping and marker-assisted selection for these traits in bitter gourd improvement program.
