Induced mutagenesis for improvement of bean ( Phaseolus vulgaris L.) production in Bulgaria.

Abstract

Although historically a surplus food producer, Bulgarian agriculture has faced a downturn in recent decades. Local legume cultivars have lost favour with farmers and the canning industry, due to their low productivity in comparison with imported ones. Diseases and abiotic stresses are the most important factors limiting the production of edible legumes, costing farmers hundreds of euros in lost revenue each year. The overall objective of our ongoing bean mutation breeding programme was to enrich the gene pool of Phaseolus vulgaris L. and to develop genotypes resistant to Xanthomonas axonopodis pv. phaseoli (Smith) (Xap) and Pseudomonas savastanoi pv. phaseolicola (Burkh.) (Psp) using EMS. An elite line and common cultivar (an heirloom and a snap bean type) in Bulgaria, were selected as parents and the chemical mutagen EMS was used for generating mutations. In total, 1000 seeds were treated and the two generated M1 populations were grown in the field. All M2 mutant plants (1650 from initial line IP564 and 2420 from initial cultivar 'Mastilen 11b') were grown in field conditions and a number of phenotypic changes were observed on these mutated plants. They were also screened for Xap disease resistance via leaf artificial inoculation under greenhouse conditions. Individual plant selection was performed for the putatively resistant M2 plants. In the M3 generation these lines were screened using artificial inoculation with Xap and Psp pathogens (leaves and pods) under field conditions. Selected M3-M4 lines with confirmed disease resistance were tested for fresh pod quality. Yield tests were started in M4 and M5 generations and, according to their productivity performance, mutants were advanced to the M6/M7 generation for validation. The expression patterns of genes putatively involved in the resistance reactions towards two races of Psp were determined using qRT-PCR for the specific and reference genes. In conclusion, 50 plants with visible morphological changes and/or increased tolerance to the two targeted bacterial diseases were selected. A total of 20 advanced mutant bean lines are currently being evaluated for their competitiveness in multiple sites.

Phaseolus vulgaris mutants reveal variation in the nuclear genome

“…The experiments were carried out with the following Bulgarian Phaseolus vulgaris L. genotypes: two local accessions, BM2 and 2 BM4, Evros cultivar, that is initial line for five mutants marked as M4, M8, M11, M19 and M26. The mutant lines in M 7 generation were obtained from Evros cultivar by treatment with 6.2 mM ethyl methanesulfonate (EMS) (year 2009)( Sofkova-Bobcheva et al., 2021 ). 1650 plants were grown in M 2 generation in a field conditions and observed for phenological differences and resistance to Xap and Psp pathogens ( Sofkova-Bobcheva et al., 2021 ).…”

“…The mutant lines in M 7 generation were obtained from Evros cultivar by treatment with 6.2 mM ethyl methanesulfonate (EMS) (year 2009)( Sofkova-Bobcheva et al., 2021 ). 1650 plants were grown in M 2 generation in a field conditions and observed for phenological differences and resistance to Xap and Psp pathogens ( Sofkova-Bobcheva et al., 2021 ). The selected breeding lines in M 3 -M 4 generations were tested for productivity, and 30 plants are distinguished by this feature ( Sofkova-Bobcheva et al., 2021 ).…”

“…1650 plants were grown in M 2 generation in a field conditions and observed for phenological differences and resistance to Xap and Psp pathogens ( Sofkova-Bobcheva et al., 2021 ). The selected breeding lines in M 3 -M 4 generations were tested for productivity, and 30 plants are distinguished by this feature ( Sofkova-Bobcheva et al., 2021 ). Among them 20 mutant breeding lines were chosen which are still being examined ( Sofkova-Bobcheva et al., 2021 ).…”

“…The successful development of new bean varieties was accompanied by techniques based on molecular markers that show the genetic variation of diversity ( Rossi et al., 2009 ; Mavromatis et al., 2010 ; Shi et al., 2011 ; Lioi and Piergiovanni, 2013 ; Castro-Guerrero et al., 2016 ; Campa et al., 2018 ; Ozturk et al., 2020 ; Sofkova-Bobcheva et al., 2021 ). Among them, the molecular markers based on the variable genome regions, such as transposable elements, restriction sites, and microsatellites, are the most often used to assess genetic diversity among mutant lines of bean.…”

Evaluation of Polyphenols Synthesized in Mature Seeds of Common Bean (Phaseolus vulgaris L.) Advanced Mutant Lines

“…Later the same generation was used for screening for drought tolerance [36,37]. The selected breeding lines in M3-M4 generations were evaluated for increased productivity, as total 30 plants were distinguished by these traits [5]. As promising in terms of productivity 5 mutant lines were selected as the best (M 564-110 [36].…”