TITLE:
Molecular Marker-Assisted Backcrossing of Anthracnose Resistance Genes into Common Beans (Phaseolus vulgaris L.) Varieties
AUTHORS:
Annuarite Uwera, John Nzungize Rusagara, Susan Nchimbi Msolla, Augustine Musoni, Teshale Assefa
KEYWORDS:
Anthracnose, Common Bean, Resistance Genes, Pythium Root Rot
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.12 No.5,
May
26,
2021
ABSTRACT: Anthracnose,
caused by Colletotrichum lindemuthianum, is a major disease of common
bean and results in high yield loss. Due to the high degree of pathogenic
variability of the fungus and the continual emergence of new races, genetic
resistance in the host is not durable. Gene pyramiding using Marker Assisted
Selection (MAS) is proposed as a viable approach to improve the durability of
major genes conditioning resistance to anthracnose. In this study a common bean
line Urugezi x AND 1062 susceptible to anthracnose but already improved for Pythium root rot resistance was improved for anthracnose resistance through a
backcross breeding program. Genotypic selection was done in Rubilizi laboratory
in Kigali, Rwanada whereas phenotypic selection was conducted in an anthracnose
hotspot at Rwerere, a research Centre of the Rwanda Agricultural and Animal
Resources Development Board (RAB). Analysis of variance for effect of bean varieties and anthracnose isolates on
disease expression showed significant differences (p 2F1 plants were 41% of them resistant and 59%
susceptible to anthracnose. However,
the observed proportion of 26 resistants and 37 susceptible in BC2F1 plants didn’t fit the goodness of fit of the expected proportion of 75
resistants to 25 susceptible. Only 41% of BC2F1 plants
inherited the resistance genes and were phenotypically resistant. Presence of
SCAR-markers, SAB3 and SBB14, in the developed resistant lines h suggested successful resistance transfer of anthracnose resistance
genes.