Producing chickpea resistance line to Fusarium Wilt (Fusarium oxysporum ) using Marker-Assisted Backcrossing

Fusarium wilt (FW) caused by F. oxysporum f. sp. ciceris causes extensive damage to chickpea in many parts of the Iran. The technique of Marker-assisted backcrossing (MABC) is one of the effective and accurate methods in transferring specific genes such as disease resistance genes in a short time in self-pollination plants. Hashem is one of Iranian chickpea cultivars with high yield, plant height and tall stems which its cultivation is limited due to susceptibility to the fusarium wilt. Therefore, Purpose of this study was to introgression resistance to fusarium wilt from Ana cultivar, as a donor, to Hashem as a recurrent and susceptible cultivar using molecular marker-assisted backcrossing.

This research was conducted during five cropping seasons (2018-2023). Crossing was done between the selected parents of chickpea cultivar Ana (as a donor parent) and Hashem (as a recurrent parent) and the F1 progeny was backcrossed with Hashem to produce the BC1F1 generation. By using three backcrosses and one rounds of selfing, BC3F2 progeny was obtained. Foreground selection (FGS) was conducted with four markers (TA59, TA96, TR19, and CaM1402) linked to FW resistance genes. Background selection (BGS) was employed with evenly distributed 16 (Ana × Hashem) SSR markers in the chickpea genome to select plant(s) with higher recurrent parent genome (RPG) recovery. Finally, the selected lines of BC3F2 generation were phenotypically evaluated in terms of Fusarium disease resistance.

In first year, from the crossing of two parents, 20 real F1 plants were obtained and backcrossed with Hashem to produce BC1F1 plants. Based on results of foreground selection (FGS), was undertaken using four markers (TA59, TA96, TR19, and CaM1402) linked to resistance genes, 6 BC1F1 plants contained 4 resistant alleles and participated in the second backcrossing to produce BC2F1 plants. In the following, from a total of 52 BC2F1 plants 12 BC2F1 plants contained 4 resistant alleles, for background selection (BGS) to observe the recovery of recurrent parent genome using 16 SSRs, At this stage based on the BGS results 5 plant, with the highest background recovery, selected and backcrossed with recurrent parent to produce BC3F1 plants. Followed by cycles of, 6 plants in BC3F1 containing resistant genes and most similar to the recurrent parent were selected. The identified plants were selfed to obtain 6 BC3F2 lines which were screened phenotypically for resistance to fusarium wilt. Finally, 12 BC3F2 lines were obtained which led to identification of 3 highly resistant lines of Hashem with FWR gene introgressed in them. Also, in this study using Meta-QTL analysis region associated with genetic resistance to different race of fusarium wilt were identified on chromosomes 2, 4, 5 and 6.