Abstract
Paraquat (1,1’-dimethyl-4,4’-bipyridinium) tolerance is an important trait in the weed control during crop production. The paraquat tolerant (Pq72) and susceptible (Pq1192) mutants are pure lines derived from the mutation pool of rice cultivar TNG67. Two reciprocal crosses, Pq72/Pq1192 and Pq1192/Pq72, were conducted between Pq72 and Pq1192 mutant lines for studying the genetic of paraquat tolerance by investigations of physiological characteristics related to paraquat tolerance including leaf injury index, leaf chlorophyll fluorescence (Fv/Fm) and electrolyte leakage in the F2 populations of two reciprocal crosses after paraquat treatment. The results suggested that a maternal inheritance of paraquat tolerance is existed in these mutants. Further analysis found that the F2 population of Pq72/Pq1192 segregated 3:1 (tolerant to susceptible) in both Fv/Fm and electrolyte leakage, respectively. This result implies that the paraquat tolerance of the Pq72 mutant is controlled by a single dominant gene.
Highlights
Weed control has become a problem for farmers in most rice production areas
The results suggested that a maternal inheritance of paraquat tolerance is existed in these mutants
Some significant water soaking injured spots were observed on the leaves of TNG67 after treatment. These results indicate that Pq72 has a better paraquat tolerance than the other two lines
Summary
Weed control has become a problem for farmers in most rice production areas. Paraquat (PQ, 1,1’-dimethyl-4,4’-bipyridinium; methyl viologen) is a rapid acting and non-selective herbicide for controlling weeds in cultivated as well as non-cultivated land throughout Taiwan [1]. Fuerst and Vaughn [14] proposed mechanisms of paraquat resistance as follows: reducing quantities of paraquat absorbed by leaf surface; reducing the efficiency of electron acceptation of paraquat, i.e. modification of photosystem I; increasing paraquat metabolic rate; increasing the enzymatic activities for free radical scavenging; and sequestration of paraquat. The first three mechanisms still need to be defined experimentally, the increase of enzymatic activities for free radical scavenging and sequestration of paraquat have been considered as the critical mechanisms for paraquat resistance [15]. The induction of enzymatic activities for free radical scavenging played a critical role in paraquat tolerance [15]. The inheritance of paraquat tolerance in rice mutant was studied based on the tolerance expression in F2 populations from the reciprocal crosses of Pq72 (T) and Pq1192 (S) pure lines
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