Weighted Gene Co-Expression Analysis Network-Based Analysis on the Candidate Pathways and Hub Genes in Eggplant Bacterial Wilt-Resistance: A Plant Research Study

Solanum melongena L. (eggplant) bacterial wilt is a severe soil borne disease. Here, this study aimed to explore the regulation mechanism of eggplant bacterial wilt-resistance by transcriptomics with weighted gene co-expression analysis network (WGCNA). The different expression genes (DEGs) of roots and stems were divided into 21 modules. The module of interest (root: indianred4, stem: coral3) with the highest correlation with the target traits was selected to elucidate resistance genes and pathways. The selected module of roots and stems co-enriched the pathways of MAPK signalling pathway, plant pathogen interaction, and glutathione metabolism. Each top 30 hub genes of the roots and stems co-enriched a large number of receptor kinase genes. A total of 14 interesting resistance-related genes were selected and verified with quantitative polymerase chain reaction (qPCR). The qPCR results were consistent with those of WGCNA. The hub gene of EGP00814 (namely SmRPP13L4) was further functionally verified; SmRPP13L4 positively regulated the resistance of eggplant to bacterial wilt by qPCR and virus-induced gene silencing (VIGS). Our study provides a reference for the interaction between eggplants and bacterial wilt and the breeding of broad-spectrum and specific eggplant varieties that are bacterial wilt-resistant.

Screening and Validation of Drought Tolerance and Fusarium Wilt Resistance in Advance Breeding Lines of Chickpea (Cicer arietinum L.)

Background: Approximately 90% of the world’s chickpea is grown under rainfed conditions where terminal drought is one of the major constraints limiting productivity. The need of short-duration, Fusarium wilt tolerant cultivars/elite lines and able to escape drought due to early maturity were required. Methods: The present investigation was carried out using 54 genotypes, generated from six diverse crosses, along with ten checks (resistant/tolerance, susceptible) were screened against drought and Fusarium wilt at Zonal Agricultural Research Station, Kalaburagi, Karnataka (Latitude: 17.36 and Longitude: 76.82) during crop season 2018-19. Result: The results revealed that higher PCV, GCV, heritability, percent genetic advance were exhibited by number of pods per plant and seed yield per plot, whereas lower PCV, GCV recorded for days to 50% flowering and days to maturity in both normal and late sown conditions. The advanced breeding lines viz., KCD-8, KCD-24, KCD-28, KCD-32, KCD-37 and KCD-53 were identified as drought tolerant lines based on drought tolerant indices (viz., MP, YSI, DTE and DSI). The lines KCD-48 and KCD-32 were identified as Fusarium wilt resistance with lowest PDI of 1.47 and 2.46 respectively, as they were screened in wilt sick plot and further these were validated and confirmed the resistant alleles using two unpublished SNP markers (FW2_30366110 and FW2_30365816). The advanced breeding lines KCD-32 and KCD-37 were identified as drought tolerant and Fusarium wilt resistant.

Genomic regions associated with resistance to Fusarium wilt in castor identified through linkage and association mapping approaches

Fusarium wilt caused by <i>Fusarium oxysporum</i> f. sp <i>ricini</i> is the most destructive disease in castor. Host plant resistance is the best strategy for management of wilt problem. Identification of molecular markers linked to wilt resistance will enhance the efficiency and effectiveness of breeding for wilt resistance. In the present study, mapping of genomic regions linked to wilt resistance was attempted using a bi-parental population of 185 F₆- RILs and a genetically diverse panel of 300 germplasm accessions. Quantitative trait loci (QTL) analysis performed using a linkage map consisting of 1,090 SNP markers identified a major QTL on chromosome-7 with LOD score of 18.7, which explained 44 per cent of phenotypic variance. The association mapping performed using genotypic data from 3,465 SNP loci revealed 69 significant associations (p <1×10-4) for wilt resistance. The phenotypic variance explained by the individual SNPs ranged from 0.063 to 0.210. The QTL detected in the bi-parental mapping population was not identified in the association analysis. Thus, the results of this study indicate the possibility of vast gene diversity for Fusarium wilt resistance in castor.

Molecular Mapping of a Gene Conferring Fusarium Wilt Resistance in Lentil (Lens culinaris Medikus subsp. culinaris) using Bulked-segregant Analysis

Background: Vascular wilt caused by Fusarium oxysporum f.sp. lentis Vasu. and Srini. is a serious disease of lentil (Lens culinaris Medikus), causes severe yield losses worldwide. For effective disease resistance breeding the inheritance and mapping of wilt resistance gene (s) is necessary. Therefore, the present investigation was focused on study the mode of inheritance and tag/map gene (s) for fusarium wilt resistance in lentil. Methods: Bulked segregant analysis (BSA) approach was used to identify markers that were tightly linked to Fusarium wilt resistance gene. The inheritance and mapping of wilt-resistance gene (s) in lentil was investigated in F2 and F2:3 populations derived from L9-12×ILL10965 cross, whereas L9-12 and ILL10965 were susceptible and resistant parents, respectively. Result: More than two hundreds SSRs markers were surveyed for the parental polymorphism, of which twenty nine were found polymorphic. These polymorphic SSRs were used for the bulked-segregant analysis (BSA) using both parents and its respective resistant and susceptible bulks, and three SSRs viz. PBALC233, PBALC1409 and PBALC203 could distinguish the respective bulks. Linkage analysis showed two SSR markers, PBALC203 and PBALC1409 flanking the wilt resistance gene at 8.2 cM and 9.4 cM distance, respectively. Further, PBLAC233 was also found present on the same linkage group at a distance of 10.2 cM from PBLAC1409.