TY - JOUR
T1 - Allelic interactions defining Raphanus raphanistrum AHAS resistance level
T2 - strong vs weak target-site AHAS resistance alleles
AU - Gil, Mercedes
AU - Garcia, Federico
AU - Breccia, Gabriela
AU - Ochogavía, Ana C.
AU - Nestares, Graciela
AU - Gundel, Pedro E.
AU - Han, Heping
AU - Yu, Qin
AU - Powles, Stephen B.
AU - Vila-Aiub, Martin
N1 - Publisher Copyright:
© 2024 Society of Chemical Industry.
PY - 2024/10/16
Y1 - 2024/10/16
N2 - BACKGROUND: Chlorsulfuron resistance and genetic dominance was evaluated in Raphanus raphanistrum genotypes homozygous (122-RR, 376-RR), heterozygous (122-RS, 376-RS) and compound heterozygous (122-R/376-R) for the target-site resistance mutations Ala-122-Tyr and Asp-376-Glu in the AHAS (acetohydroxyacid synthase) gene. RESULTS: At the AHAS level, 122-RR and 122-RS plants exhibited significantly higher I50 values than 376-RR and 376-RS plants, respectively. However, plants of the compound heterozygous genotype (122-R/376-R), showed no difference in AHAS activity compared to the 122-RS genotype but lower activity than the 122-RR genotype, and showed a nearly 400-fold greater I50 value than both genotypes (376-RR and 376-RS) carrying the 376-Glu allele. At the whole-plant level, 100% survival was observed for 122-RR plants at the highest chlorsulfuron dose of 640 g ha−1, yet 376-RR plants showed no survival at 380 g ha−1. Thus, this survival difference resulted in different median lethal dose (LD50) estimates [>640 (122-RR) versus 330 g ha−1(376-RR)]. The effect of chlorsulfuron in reducing aboveground growth of surviving plants also was markedly lower for the homozygous 122-RR (GR50 = 566 g ha−1) than for 376-RR plants (GR50 = 66). Heterozygous plants carrying the 122-Tyr allele (122-RS) exhibited two- and five-fold higher LD50 values than both homozygous and heterozygous plants carrying the 376-Glu allele (376-RR, 376-RS), respectively. Along the difference in plant survival, 122-RS plants also showed four-fold higher GR50 than both 376-RR and 376-RS plants. Survival of plants with the compound heterozygous genotype (122-R/376-R) under increasing chlorsulfuron doses was similar to 122-RR or 122-RS genotypes. However, this compound heterozygous genotype showed two- and six-fold higher LD50 values than 376-RR or 376-RS genotypes, respectively. However, both resistance 122-Tyr and 376-Glu alleles were dominant or nearly dominant over the wild-type susceptible alleles (ALA-122 and ASP-376), and the resistance 122-Tyr allele was dominant over the 376-Glu allele. CONCLUSIONS: These results broaden our understanding of AHAS target-site resistance in R. raphanistrum and strengthens the hypothesis that the AHAS 122-Tyr allele corresponds to a stronger target-site resistance allele than the 376-Glu allele.
AB - BACKGROUND: Chlorsulfuron resistance and genetic dominance was evaluated in Raphanus raphanistrum genotypes homozygous (122-RR, 376-RR), heterozygous (122-RS, 376-RS) and compound heterozygous (122-R/376-R) for the target-site resistance mutations Ala-122-Tyr and Asp-376-Glu in the AHAS (acetohydroxyacid synthase) gene. RESULTS: At the AHAS level, 122-RR and 122-RS plants exhibited significantly higher I50 values than 376-RR and 376-RS plants, respectively. However, plants of the compound heterozygous genotype (122-R/376-R), showed no difference in AHAS activity compared to the 122-RS genotype but lower activity than the 122-RR genotype, and showed a nearly 400-fold greater I50 value than both genotypes (376-RR and 376-RS) carrying the 376-Glu allele. At the whole-plant level, 100% survival was observed for 122-RR plants at the highest chlorsulfuron dose of 640 g ha−1, yet 376-RR plants showed no survival at 380 g ha−1. Thus, this survival difference resulted in different median lethal dose (LD50) estimates [>640 (122-RR) versus 330 g ha−1(376-RR)]. The effect of chlorsulfuron in reducing aboveground growth of surviving plants also was markedly lower for the homozygous 122-RR (GR50 = 566 g ha−1) than for 376-RR plants (GR50 = 66). Heterozygous plants carrying the 122-Tyr allele (122-RS) exhibited two- and five-fold higher LD50 values than both homozygous and heterozygous plants carrying the 376-Glu allele (376-RR, 376-RS), respectively. Along the difference in plant survival, 122-RS plants also showed four-fold higher GR50 than both 376-RR and 376-RS plants. Survival of plants with the compound heterozygous genotype (122-R/376-R) under increasing chlorsulfuron doses was similar to 122-RR or 122-RS genotypes. However, this compound heterozygous genotype showed two- and six-fold higher LD50 values than 376-RR or 376-RS genotypes, respectively. However, both resistance 122-Tyr and 376-Glu alleles were dominant or nearly dominant over the wild-type susceptible alleles (ALA-122 and ASP-376), and the resistance 122-Tyr allele was dominant over the 376-Glu allele. CONCLUSIONS: These results broaden our understanding of AHAS target-site resistance in R. raphanistrum and strengthens the hypothesis that the AHAS 122-Tyr allele corresponds to a stronger target-site resistance allele than the 376-Glu allele.
KW - AHAS activity
KW - AHAS mutations
KW - dominance relationships
KW - herbicide resistance
KW - plant survival and growth
KW - wild radish
UR - http://www.scopus.com/inward/record.url?scp=85206639673&partnerID=8YFLogxK
U2 - 10.1002/ps.8471
DO - 10.1002/ps.8471
M3 - Article
C2 - 39412163
AN - SCOPUS:85206639673
SN - 1526-498X
JO - Pest Management Science
JF - Pest Management Science
ER -