Browsing by Author "Krishnendu, M R"

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    Locating donors for genes for biotic stress resistance in tomato through molecular marker assisted selection
    (Department of Plant Biotechnology, College of Agriculture, Vellayani, 2022-01-17) Krishnendu, M R; Jayalekshmy, V G
    The study entitled “Locating donors for genes for biotic stress resistance in tomato through molecular marker assisted selection” was conducted at the Department of Seed Science and Technology, College of Agriculture, Vellayani, Thiruvananthapuram during 2020-2021. The primary objective of the study was to identify donors for genes for resistance to different biotic stresses viz., Tomato Yellow Leaf Curl Virus (TYLCV), verticillium wilt, fusarium wilt, late blight and root knot nematodes from tomato varieties and elite wild species through marker assisted selection using gene specific markers. The study was conducted in 30 tomato genotypes, collected from inside and outside of Kerala which included wild species as well cultivated varieties. The genotypes were screened for the presence of genes for resistance to various biotic stress inducing diseases like Tomato Yellow Leaf Curl Virus (TYLCV), verticillium wilt, fusarium wilt, late blight and root knot using tightly linked gene specific SCAR and CAPS markers. The genotypes resistant to Tomato Yellow Leaf Curl Virus (TYLCV) were screened for the presence of gene Ty2 located on chromosome 11 using the SCAR marker TG0302/TY2R1 which amplified a band of size 600 bp for genotypes with Ty2/Ty2 alleles and 450 bp for susceptible genotypes. None of the 30 genotypes screened for Ty2 gene were identified to consist the Ty2/Ty2 alleles. Another gene for resistance to TYLCV, ie, Ty3 located on chromosome 6, was screened using the SCAR marker FLUW25, which amplified the genotypes carrying Ty3/Ty3 alleles with a band of size 640 bp and 480 bp for genotypes corresponding to ty3/ty3 alleles. Presence of Ty3 gene was not found in any of the genotypes screened in the study. Verticillium wilt resistance in genotypes was screened for the presence of two closely linked genes, Ve1 and Ve2 of Ve locus. Ve1 specific CAPS marker Ve1 XbaI, distinguished the genotypes of Ve1/Ve1 alleles with restriction digested fragments of size 410bp and 332bp from the susceptible genotypes of restriction digested fragments 410bp, 310bp and 22bp. Ve2 specific CAPS marker V2LeO3F/V2LeO3R generated restriction digested products, 601 bp and 428 bp for Ve2/Ve2 alleles and undigested product of 1029bp for ve2/ve2 alleles. Among the 30 genotypes screened in the study, IIHR 2374 and Kashi Vishesh were identified for the presence of Ve1 and Ve2 genes and PNR 7 for Ve2 gene alone. The genotypes resistant to Fusarium wilt were screened for the presence of the genes I3 located on chromosome 7 and I7 located on chromosome 8. The gene I3 specific SCAR marker P743DF1/R1 amplified a band of size 1270bp for genotypes with I3/I3 alleles and 1060 bp for genotypes with i3/i3 alleles. None of the genotypes screened in the study were identified for the presence of I3 gene. The CAPS marker CAPS7774 specific to I7 gene generated restriction digested fragments of size 612bp and 196bp for genotypes of I7/I7 alleles and undigested fragment of 808 bp for susceptible genotypes. The genotypes IIHR 2205, IIHR 2374 and Vellayani Vijai were identified for the presence of I7/I7 alleles from the study. The genotypes resistant to Late blight were screened for the presence of the genes Ph3 located on chromosome 9 and Ph2 located on chromosome 10. The SCAR marker Ph3-SCAR amplified the genotypes of Ph3/Ph3 alleles with a band of size 176bp and 154 bp for the genotypes of ph3/ph3 alleles. Presence of the gene Ph3 was identified in the genotypes Pusa Ruby, CA 22053, Hisar Lalit, PKM-1 and Arka Vikas from the study. The CAPS marker dtG63 differentiated the genotypes of Ph2/Ph2 alleles with a restriction digested fragment of band size 245 bp from 221 bp of susceptible genotypes. In the study, the genotypes Shakthi, Pusa Ruby, Nenmara local, CA 22053, Manulakshmi, IIHR 2204, PNR 7 and Solanum torvum were identified for the presence of Ph2/Ph2 alleles. Resistance to Root knot in genotypes were screened for the presence of gene Mi1.2 using the SCAR marker Mi23, which amplified a band of size 380 bp for Mi/Mi alleles and 430 bp for mi/mi alleles. From the study it was confirmed that, none of the genotypes screened for the presence of Mi 1.2 gene were resistant to root knot. In accordance with the findings from the study, phenotypic analysis of the genotypes identified as donors for genes for resistan ce can be carried out, in order to ensure the disease resistance in field conditions as well as the credibility of the molecular markers used in the study. The genes for resistance to the diseases studied, located in the 30 genotypes, screened from the study could indicate the donors for tomato resistance breeding programs.