Inheritance of herbicide resistance in two germplasm lines of Clearfield* rice (Oryza sativa L.)

Abstract

Wenefrida, I., Utomo, H. S., Meche, M. M. and Nash, J. L. 2007. Inheritance of herbicide resistance in two germplasm lines of Clearfield* rice (Oryza sativa L.). Can. J. Plant Sci. 87: 659-669. Inheritance of imidazolinone resistance in two germplasms of Clearfield rice lines, 93AS3510 and PWC-16, was studied using parents, F 1 hybrids, F 2 populations, and F 2:3 families. Germination tests were conducted in Petri dishes under controlled environments to reveal any discrete phenotypic responses to herbicide treatments. PWC-16 has a herbicide resistance level 4.9 times higher than that of 93AS3510. A concentration of 1 mg L -1 a.i. (active ingredient) of imazethapyr herbicide produced three distinctive response types in 93AS3510 crosses, while a concentration of 10 mg L -1 was required to differentiate the three response types in PWC-16 crosses. The segregation of the herbicide-resistant gene from both Clearfield rice lines fit into the Mendelian 1:2:1 (susceptible:intermediate:resistant) ratio. There was no maternal effect associated with the inheritance of the trait. The imidazolinone resistance, therefore, is governed by a single incomplete dominant nuclear gene. The F 1 hybrid from a cross between resistant and non-resistant lines will produce resistant plants. Clearfield rice provides an effective use of imidazolinone herbicides to control red rice, the most troublesome weed of rice, along with other rice weeds. Preventing transfer of the herbicide-resistant gene into red rice is crucial to maintain its effectiveness.

Maximum Outcrossing Rate and Genetic Compatibility between Red Rice (Oryza sativa) Biotypes and Clearfield™ Rice

“…All the plants that survived imazethapyr applications were confirmed as outcrosses by genetic analysis (Figure 2). The imazethapyr-resistant gene in CL161 rice is governed by a single incompletely dominant nuclear gene (Shivrain et al 2006;Wenefrida et al 2007). For CL161 rice the allele size was 130 and 135 base pairs (bp) with primers RM253 and RM234, respectively.…”

Susceptibility to imazamox in Italian weedy rice populations and Clearfield® rice varieties

“…Tolerance to imazamox, in terms of resistance index, among these varieties, varied between 1.2 and 4.2 (Table ). A study conducted on the germplasm of two IMI‐tolerant rice lines in the USA has established that the PWC‐16 line (derived from mutagenesis with EMS of USA rice variety Cypress) is 4.9‐fold more tolerant than the 93AS3510 line (Wenefrida et al ., ). A change to the size of the amino acid side‐chain may be the cause of insufficient herbicide binding, which may affect resistance level (Lee et al ., ).…”

“…It has been suggested that this differential susceptibility results from a combination of the parent lines used to develop the new variety and the type of amino acid substitution. For example, serine‐asparagine substitution in the AHAS gene in rice line PWC‐16 has determined more herbicide‐tolerant rice than has glycine for glutamic acid substitution in this same gene in rice line 93AS3510 (Wenefrida et al ., ). In fact, this line was the progenitor of the first IMI‐tolerant rice variety in Brazil, and the glycine for glutamic acid substitution in the line was also found in weedy rice populations that escaped herbicide control with imazethapyr + imazapic in Brazilian rice fields (Roso et al ., ).…”

Ser-653-Asn substitution in the acetohydroxyacid synthase gene confers resistance in weedy rice to imidazolinone herbicides in Malaysia

“…Petri dish seed bioassay provides a reliable and simple method to evaluate IMI resistance in weed populations [ 35 ]. Results from the seed bioassay in the present study indicated that continuous exposure of pre-germinated seeds to IMI herbicides can significantly affect seed growth.…”