Tagging blast and sheath blight resistance genes/quantitative trait loci in rice (Oryza sativa L.)

• Main Author: Le Cam Loan
• Format: Publication
• Language: English
• Published: College, Laguna (Philippines) 01.12.2002
• Subjects: BLIGHTS; CARTE GÉNÉTIQUE; CONTROL GENÉTICO; DISEASE RESISTANCE; GENES; GENETIC CONTROL; GENETIC MAPS; GÈNE; LUTTE GÉNÉTIQUE; MAPAS GENÉTICOS; ORYZA SATIVA; RESISTENCIA A LA ENFERMEDAD; RÉSISTANCE AUX MALADIES

Genetic control of resistance to rice blast and mapping of loci involved in high and partial resistance against ten single spore races from the Philippines and Vietnam (M36-1-3-10-1, M64-1-3-9-1, BN111, M39-1-2-21-2, V86010, 142A, 101A, 110A, RB and 138A) were studied in the F14 recombinant inbred population of the cross Lemont x Teqing. The three identified major resistance genes were each associated with hypersensitivity to race M64-1-3-9-1 and V86010. Fourteen main effect QTLs (M-QTLs) were detected, nine of which with the resistance allele coming from Teqing. The contribution of epistatic QTLs (E-QTLs) were higher (14.6-51.0%) than those of M-QTLs (3.5-16.1%). Most of the M-QTLs showed specificity against only one race. M-QTL bracketed by J01100-AJ13060 on chromosome 11 that was derived from Lemont was mapped to the same genomic region of previously identified qualitative resistance genes. Using 266 Near Isogenic Introgression Lines with randomly introgressed Lemont segment of a cross between Lemont x Teqing, the genetic control of resistance to sheath blight of rice was also studied. Based on disease evaluation and a genetic map with 148 molecular markers, 15 M-QTLs detected for lesion height (LH) and actual lesion length (ALL) over assessment times were mapped on seven chromosomes (1, 2, 3, 4, 5, 9, and 12), explaining 35.8%-93.8% of the phenotypic variation. The QTLs with high additive effects for most resistance traits were found at the markers RM341 (on chromosome 2), RM156 (on chromosome 3), and RM280 (on chromosome 4). All the QTLs had the positive alleles from parent Teqing, Lemont did not contribute any alleles associated with higher disease resistance. Despite different assessment methods for host plant resistance, most QTLs controlling lesion height and actual lesion length in each assessment time were approximately mapped at the same chromosomal regions. Additive effects appeared to be more important than digenic interactions. Rice sheath blight resistance was found influenced by some morphological characters such as heading date but had no correlation with plant height. However, it can be ascertained if the association between sheath blight resistance and morphological traits is due to pleiotrophic effect or to close linkage. Four QTLs, namely, QSbr1a, QSbr2, QSbr4c, and QSbr9c that were found not associated with plant morphology or heading date are potentially useful in breeding programs for sheath blight resistance