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as they were screened in wilt sick plot and further these were validated and confirmed the resistant alleles using two unpublished SNP markers (FW2_30366110 and FW2_30365816).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.

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.

Characterization of Elite Genotypes for Fusarium Wilt Resistance in Pigeonpea [Cajanus cajan (L.) Millspaugh]

Background: The development of Fusarium wilt resistant varieties is a major challenge in pigeonpea breeding and need to be addressed on priority basis. In this study, efforts had been made to characterize the elite pigeonpea genotypes for Fusarium wilt resistance at morphological and molecular level. Methods: The present study was undertaken during kharif season of year 2018-19 at NEB, Crop Research Centre, G.B.P.U.A and T, Pantnagar. The experimental materials for present study consisted of 15 elite pigeonpea genotypes and three commercially grown popular varieties as checks. The molecular analysis was conducted during year 2019-20 and a susceptible variety BAHAR was used as check. The nine yield based indices were used for morphological analysis. The molecular analysis was carried out by using five already reported Fusarium wilt linked SSR markers. Result: The results revealed that the marker ASSR 363, ASSR 366, ASSR 1, ASSR 23 and ASSR 148 were highly effective in differentiating the resistant and susceptible genotypes of pigeonpea for wilt disease. On the basis of morphological and molecular studies, it was concluded that the genotype PA 626 was the most superior genotype as it not only yielded higher than all the three checks but also shown resistance against wilt at both phenotypic and genotypic level.

Transcriptome Analysis of Resistance to Fusarium Wilt in Mung Bean (Vigna radiata L.)

Fusarium wilt is a destructive soil-borne disease that threatens the production of mung bean. Mung bean lines Zheng8-4 and Zheng8-20 show high resistance and high susceptibility to Fusarium wilt, respectively. Transcriptome analysis was carried out to identify candidate genes involved in Fusarium wilt resistance using Zheng8-4 and Zheng8-20 at 0, 0.5, 1, 2, and 4 days post inoculation (dpi). Differential expression analysis showed that 3,254 genes responded to pathogen infection and were differentially expressed in the resistant and susceptible lines. Weighted gene co-expression network analysis (WGCNA) was also performed to identify five modules highly correlated with Fusarium wilt resistance, in which 453 differentially expressed genes (DEGs) were considered likely to be involved in Fusarium wilt resistance. Among these DEGs, we found 24 genes encoding resistance (R) proteins, 22 encoding protein kinases, 20 belonging to transcription factor families, 34 encoding proteins with oxidoreductase activity, 17 involved in stimulation/stress responses, and 54 annotated to pathogen resistance-related pathways. Finally, 27 annotated genes were further selected as candidate genes of Fusarium wilt resistance in mung bean. This study identifies novel potential resistance-related genes against Fusarium wilt and provides a theoretical basis for further investigation of Fusarium wilt resistance in mung bean breeding.