03814naa a2200253 a 450000100080000000500110000800800410001910000160006024501160007626000090019252029900020165300220319165300270321365300150324065300230325565300230327870000210330170000160332270000160333870000230335470000190337770000180339677301460341411295282020-04-01       2020    bl uuuu     u00u1 u    #d1 aANDRADE, A.  aInduced mutation technique to the development of cultivars with tolerance to herbicides.h[electronic resource]  c2020  aThe Epagri?s rice breeding program has been working since 1985 in collaboration with the Center of Nuclear Energy in Agriculture (CENA/USP) for the development of new cultivars through mutation with gamma rays. The partnership allowed the development of two mutant rice cultivars SCS114 Andosan (2006) and SCS118 Marques (2014). These mutant cultivars showed good resistance to lodging, high yield potential and long grains with good quality. Weeds are considered the major constraints to obtain high yield in paddy rice productions systems. Weed control has become a difficult task in commercial rice fields in Southern Brazil, mainly due to the increasing occurrence of herbicide-resistant (HR) species. One of the main limiting factors in irrigated rice fields is weedy rice (O. sativa L.) infestation, also known as red rice, which can severely infest rice fields due to its close genetic relationship to commercial rice. The use of herbicide resistant rice cultivars may improve weed control, reducing costs and labour. The HR Clearfield rice technology using imidazolinone herbicides has proved to be an effective method for the selective control of weedy rice infestations in rice crop. The continuous use of the Clearfield technology has selected resistant weedy rice populations. The development of HR rice cultivars with different mechanism of action is an alternative strategy for managing weedy rice-resistant populations in rice fields. The herbicides inhibiting acetyl-coenzyme A carboxylase (ACCase) are very effective to control grass weeds including weedy-rice in paddy rice production systems. ACCase inhibitors affect the enzyme by blocking fatty acid biosynthesis resulting in plant death. Through induced mutation of rice seeds with gamma rays, rice lines resistant to APPs were developed. Plant dose-response assays confirmed the resistance to the APPS herbicides quizalofop-p-ethyl and haloxyfop-p-methyl. The carboxyl-transferase (CT) domain fragments of ACCase from the resistant line and the susceptible control were sequenced and compared. Results indicated that herbicide resistance in rice is conferred by a single point mutation resulting in an amino acid substitution of the carboxyl transferase domain of ACCase. A point mutation was detected in the amino acid position 2027. This substitution confers resistance more than 70 times to APPs herbicide in Epagri?s rice lines. APPs resistant rice provides an option to improve the efficiency of weed management in the rice crop. The practical development of the trait for weed control in rice based on the application of FOP?s type herbicides is now possible. Previously, this herbicide had no application in rice because they would injury rice plants. Any of the rice lines described is suitable to be developed into a rice cultivar or hybrid and used in commercial rice production as a weed control method. The resistant trait was demonstrated to be fully heritable allowing for breeding and development.  aACCase inhibitors  aAcetyl-CoA carboxylase  aGamma rays  aHaloxyfop-p-methyl  aQuizalofop-p-ethyl1 aTULMANN NETO, A.1 aPEREIRA, A.1 aWICKERT, E.1 aSCHEUERMANN, K. K.1 aMARSCHALEK, R.1 aNOLDIN, J. A.  tIn: SIMP??SIO LATINO AMERICANO DE APLICA????ES NUCLEARES NA AGRICULTURA , 2., 2020, Quito, Equador. Resumos... Quito: USFQ PRESS, 2020. p. 20