Thumbnail Image

Thesis

Browse

20221
Reset filters
Subject: Biochemistry × Author: Aggarwal, Jatin × Start date: 2021 × Type: Thesis ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemOpen Access
    Biochemical and molecular probing of resistant determinants in Brassica juncea derived lines following Lipaphis erysimi herbivory
    (Punjab Agricultural University, Ludhiana, 2022) Aggarwal, Jatin; Rimaljeet Kaur
    Lack of resistance to Lipaphis erysimi in cultivated Brassicas caused this pest highly devastating which resulted in significant limit to the productivity of rapeseed-mustard in India. B. fruticulosa, a wild crucifer is known as an excellent source of resistance to L. erysimi. Therefore, we planned to assess defense associated biochemical alterations and molecular components in B. juncea-B-fruticulosa ILs to mustard aphid. Phenotypic assessment of ILs on the basis of aphid population per plant categorized genotypes into resistant, moderately resistant and susceptible genotypes. The maximum increase in catalase (CAT) activity was determined in B. fruticulosa and resistant ILs after 48 hrs and one week of mustard aphid infestation. The strong induction of CAT2 transcripts (19.25 fold) and CAT activity (5.88 fold) along with low aphid count in resistant IL, Ad4-64 suggested the pivotal role of CAT in resistance to mustard aphid. Guaiacol peroxidase significantly decreased following pest infestation at both infestation stages. Significant increase in lipoxygenase (LOX) activity was determined in B. fruticulosa while decline in RLC-1 was determined at 48 hrs post aphid infestation. Moderately resistant IL, Ad4-144 showed highest increase in LOX activity (14.50 fold) after 48 hrs of infestation. The highest upregulation in LOX2 expression was also determined in Ad4-144 at 48 hrs (122.78 fold) and one week (47.94 fold) of aphid infestation. The ascorbate content was highest in moderately resistant genotype, Ad4-144 (5.69 fold) and resistant IL, ADV-6RD (2.14 fold) after 48 hrs and one week of aphid infestation, respectively. H2O2 content rapidly increased in B. juncea- B. fruticulosa derived lines after 48 hrs of aphid infestation. Negative and significant association between APP and CAT, glutathione, H2O2 at both infestation stages signified their role in deterring mustard aphid infestation. Greater induction of total sugars, reducing sugars and sucrose content following L. erysimi infestation indicated their role towards susceptibility to mustard aphid in Brassica. Positive and significant association between sugars and APP indicated that higher the sucrose content, higher will be mustard aphid infestation in B. juncea derived ILs. The information being generated and candidates being identified may help in effective deployment of B. fruticulosa resistance in mustard breeding.