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Author: Amandeep Kaur × End date: 2023 × Start date: 2020 ×
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    Mapping of Phytophthora resistance in intergeneric rootstock population of citrus
    (Punjab Agricultural University, 2023) Amandeep Kaur; Sidhu, Gurupkar Singh
    The investigations entitled “Mapping of Phytophthora resistance in intergeneric rootstock population of citrus” were carried out in 2020-22. In the present study, screening of Phytophthora related traits of 88 F1 hybrids population (pseudo-testcross) of Rough lemon × Swingle citrumelo was done by spore suspension and filter method. Data were recorded after 90 days of inoculation for different symptoms and growth attributes related to Phytophthora. Phenotypic characterization for qualitative and quantitative characters of F1 hybrids were done based on IPGRI descriptor. Hybrids were showed great variation in percentage of unifoliate, bifoliate and trifoliate leaves, spine length, habitus, branch size, shoot tip colour, young leaf colour, adaxial colour, abaxial colour, leaf lamina shape, leaf apex, leaf margin and petiole colour. Based on the studied 14 attributes, 88 F1 rootstock hybrids revealed different degree of response to Phytophthora. Out of 14 traits, feeder root rot rating, chlorotic leaves and gummosis rating scale (0 to 4), 23 plants were highly susceptible, 19 plants susceptible, 6 plants moderately resistant, 12 plant resistant and 28 plants in highly resistant. In vitro filter method, lesion size was used to find the degree of resistance and observed that 20 were highly susceptible, 19 susceptible, 12 moderately resistant, 13 resistant and 24 in highly resistant. For genotyping, 165 SSR markers were used for parental polymorphism. Further, a genetic linkage map of citrus F1 hybrids has been constructed by using 116 polymorphic SSR markers comprising of 9 linkage groups, spanning a distance of 1476.19 cM. From the identified, twenty six major Quantitative trait loci (QTL), two QTLs for feeder root rot rating observed on chromosome 2 at 32.54 cM and 14.26 cM having Left flanking marker HvSSRCM-241. A total of 2 QTLs (qGR.RL.pau-5 and qGR.RL.pau-8) for gummosis rating were detected on LG5 & LG8. The proportion of the total variation (R2) ranged from 10.98 to 14.52%, respectively. Third experiment was conducted for mass multiplication and conservation of potential hybrids through cutting. Different types of cutting viz., soft, medium and hard wood cuttings from unifoliate and multifoliate hybrids in rainy and spring season were treated with 500, 1000, 1500, 2000 ppm IBA along with control. Among the cutting taken, medium wood cutting during rainy season and spring season in unifoliate performed better in all the parameters whereas during spring season hardwood cutting of multifoliate hybrids performed better. IBA concentration @ 1000 ppm followed by 500 ppm was the best concentration for all the parameters. Overall, the unifoliate hybrids RL×SW-19 & RL×SW-29 and multifoliate hybrids RL×SW-6 & RL×SW-7 were performed better for all the parameters. The phenotypic linkage so constructed will pave the path for high resolution mapping of Phytophthora resistance traits with high throughput marker segregation techniques like genotyping by sequencing on citrus genetic map. Cutting propagation will provide new insights for future mass multiplication from the limited material.
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    ThesisItemOpen Access
    Biochemical evaluation of immature pods and mature seeds of wild abelmoschus genotypes
    (Punjab Agricultural University, Ludhiana, 2021) Amandeep Kaur; Sangha, Manjeet Kaur
    In the present study the immature pods and seeds of wild Abelmoschus species were biochemically characterised. Total carbohydrates in pods varied from 22.34- 93.10% DW. Total soluble sugars (TSS), reducing sugars and non-reducing sugars exhibited range of 13.74- 84.36%, 0.17- 19.41% and 31.25- 64.95% DW respectively. Mucilage, dry matter, ash, crude protein and total soluble protein depicted range of 6.64- 19.64% DW, 11.18- 27.59%, 1.10- 6.94%, 2.13- 6.32% and 0.93- 3.56% FW respectively. Free amino acids range was 0.16- 0.27% (FW). Carotenoids, phenolics, O-dihydroxyphenols and flavonols varied from 4.48- 13.25 mg/100 g FW, 122.95- 412.01 mg/100 g DW, 4.30- 17.99 mg/100g and 63.63- 274.49 mg/100g DW respectively. Vitamin E and C varied from 15.14- 51.24 mg/100 g DW and 41.26- 120.10 mg/100 g FW respectively. DPPH and FRAP activity ranged from 39.74- 62.90% and 4.54- 11.22 mg AAE/g DW respectively. Phytate, oxalate, saponin and tannins depicted variation of 0.65- 2.08% DW, 0.23- 0.63% DW, 0.19- 1.04% DW, and 1.26- 3.30% DW respectively. Seed oil ranged from 10.68-27.61% DW. A. manihot and A. tetraphyllus pods were high in antioxidants, mucilage and low in tannins and saponins. A. moschatus was rich in nutrients in pods and Vit. E, oleic, linoleic acid and minerals in seeds, while A. tetraphyllus possessed high antioxidants and was low in phytate and oxalate and A. mizonagenesis exhibited high seed oil content. These genotypes can be used for improvement of cultivated okra for end product diversification.