Incorporation of resistance to angular leaf spot and bean common mosaic necrosis virus diseases into adapted common bean (Phaseolus vulgaris L.) genotype in Tanzania

Abstract

Angular leaf spot (ALS) caused by the fungus Pseudocercospora griseola and Bean common mosaic and necrosis virus (BCMV/BCMNV) are important diseases of common bean in Tanzania that can cause severe yield reduction when uncontrolled. This study was conducted to incorporate resistant genes for ALS and BCMV/BCMNV diseases into adapted, market class and farmers and consumers preferred bean genotype using marker assisted selection. The parents Mexico 54 and UBR(25)95 donor of Phg-2 and I/bc-3 genes for ALS and BCMV/BCMNV, respectively were used for the recipient being Kablanketi. In selection, SCAR markers SNO2, ROC11 and SW13 linked to Phg-2, bc-3 and I gene, respectively were used. A parallel backcrossing (modified double cross) procedure was used. The F 1 , F 2 and backcrosses from single crosses were characterized. The Chi square values for ALS were 0.081 (P<0.776) and 0.017 (P<0.896) and for BCMNV were 1.609 (P<0.205) and 1.2 (P<0.273) for molecular and phenotypic screening, respectively. The resistance to ALS and BCMNV was found to be monogenic and the genes involved are dominant and recessive, respectively. The heritability of ALS was found to be high (0.772) implying that selection for ALS can be done early in segregating populations. High correlation values, r = 0.741 and 0.624 for ALS and BCMNV, were obtained between phenotypic and molecular data, indicating high reliability for markers. In selection, it was possible to select lines with multiple disease resistances. This work signified the use of MAS for multiple gene screening.

A Review of Angular Leaf Spot Resistance in Common Bean

“…Resistance loci are stated with their new name accepted by the Bean Improvement Cooperative Genetics Committee and their originally published name. P. griseola, though this cultivar was resistant to only 5 of 19 Colombian races used in one study (CIAT, 2005;Chilagane et al, 2013;Ng'ayu-Wanjau, 2013;Ddamulira et al, 2015). The putative Phg-2 allele of G10474 confers broad resistance to most races of P. griseola, and it has been extensively used in breeding at CIAT.…”

“…Research on ALS in East Africa has focused on the identification and genetic characterization of new sources of resistance in local landraces and released varieties (Ng'ayu-Wanjau, 2013;Ddamulira et al, 2014a;Leitich, 2016;Kijana et al, 2017). In these studies, Mexico 54 was found to be resistant to most races of P. griseola, and this cultivar is the most common source of ALS resistance in breeding in Uganda and East Africa (Namayanja et al, 2006;Chilagane et al, 2013;Ng'ayu-Wanjau, 2013;Ddamulira et al, 2015;Miller et al, 2018).…”

Introduction of foliar disease resistance into bean bruchid resistant genotypes and heritability studies at F2:3

“…Biotic factors includes, insect pest such as bean weevils (Kusolwa, 2007;Kipato et al, 2015;Kusolwa et al, 2016), and major diseases constraints to common bean production in East and Central Africa include Common bacterial blight (CBB) caused by Xanthomonas axonopodis pv Phaseoli (Tryphone et al, 2012;Alladasi et al, 2018;Mondo et al, 2019), root rots caused by either Pythium spp, Fusarium spp., Sclerotium rolfsii, or Rhizoctonia solani (Nzungize et al, 2011a;Obala et al, 2012;Burachara et al, 2015;Mukankusi et al, 2018), Angular Leaf Spot (ALS) caused by Pseudocercospora griseola (Sacc.) (Chilagane et al, 2013: Leitich et al, 2016, Anthracnose caused by Colletotrichum lindemuthianum (Sacc. and Magn.)…”

“…and Magn.) (Kiryowa et al, 2016) and Bean common mosaic and bean common mosaic necrosis viruses (BCMV/BCMNV) caused by a group of Potyviruses (Chilagane et al, 2013;Mwaipopo et al, 2017). Wortmann et al (1998) estimated that in Eastern Africa the annual production losses caused by CBB to be 145 900 tons, BCMV 144 600 tons, root rot 179 800 tons, ALS 281 300 tons, and Anthracnose being 247 400 tons.…”

“…Reduction in yield have been attributed to the effects of insect and disease especially bean weevils (bruchids) CBB, ALS, BCMNV and BCMV (Mwaipopo et al, 2018). These constraints have been accelerated by the use of unimproved cultivars which are susceptible to abiotic and biotic factors (Tryphone et al, 2012;Chilagane et al, 2013). Using of improved cultivars with resistance to biotic factors will increase yield, reduce production costs, and stabilize food security and benefit both smallholder farmers and the environment (Wortmann et al, 1998;Mahuku et al, 2007) Either use of plant host resistance (PHR) or use of eco-friendly practices has been suggested to be the best option to control the diseases (Conner et al, 2020).…”