Screening of the Rice Viviparous Mutants Generated by Endogenous Retrotransposon Tos17 Insertion. Tagging of a Zeaxanthin Epoxidase Gene and a Novel OsTATCGene

Abstract

The rice (Oryza sativa) retrotransposon Tos17 is one of a few active retrotransposons in plants and its transposition is activated by tissue culture. Here, we present the characterization of viviparous mutants of rice induced by tissue culture to demonstrate the feasibility of the use of retrotransposon Tos17 as an endogenous insertional mutagen and cloning of the tagged gene for forward genetics in unraveling the gene function. Two mutants were shown to be caused by the insertion of Tos17. Osaba1, a strong viviparous mutant with wilty phenotype, displayed low abscisic acid level and almost no further increase in its levels upon drought. The mutant is shown to be impaired in the epoxidation of zeaxanthin. On the other hand, Ostatc, a mutant with weak phenotype, exhibited the pale green phenotype and slight increase in abscisic acid levels upon drought. Deduced amino acids of the causative genes of Osaba1 and Ostatc manifested a significantly high homology with zeaxanthin epoxidase isolated from other plant species and with bacterial Sec-independent translocase TATC protein, respectively. This is the first example of transposon tagging in rice.

Genetic Analysis of Water Use Efficiency in Rice (Oryza sativa L.) at the Leaf Level

“…However, although the range was small, there was some variation in leaf water status in experiment E4, as measured by relative water content, suggestive of genetic differences in baseline concentrations of ABA in minimally stressed plants or sensitivities to factors that regulate ABA homeostasis. In rice and numerous other species, evidence from mutants that are defective in ABA synthesis or components of ABA signaling indicates that ABA plays a role in stomatal regulation even in environments that are not stressful for wild types (Agrawal et al 2001;Taylor et al 2005). ABA levels were negatively correlated with stomatal conductance, C i /C a , and Δ 13 C in the overall RIL mapping population, consistent with the expected effect of ABA in closing stomata and a functional link between these traits.…”

Characterization and fine mapping of a new early leaf senescence mutant es3(t) in rice

“…Powdered specimens(100 mg fresh weight) were weighed, freezedried for 3 h, and extracted with MilliQ water at 4 °C in dark for 16 h. Quantitative analysis of ABA was performed using the Phytodetek ABA ELISA Kit (Agdia, Inc, Elkhart, IN) according to the manufacturer's instructions (Agrawal et al 2001).…”

Abscisic Acid Uridine Diphosphate Glucosyltransferases Play a Crucial Role in Abscisic Acid Homeostasis in Arabidopsis

“…All steps in the de novo ABA biosynthetic pathway occur in plastids, with the exception of the last two steps that occur in the cytosol (Marin et al, 1996;Tan et al, 1997;Seo and Koshiba, 2002). All reactions in the de novo biosynthetic pathway have been elucidated in detail in various plant species (Marin et al, 1996;Tan et al, 1997;Qin and Zeevaart, 1999;Iuchi et al, 2000;Agrawal et al, 2001). Many mutants in the biosynthetic pathway have been isolated and used to define the exact steps and reaction sequences (Cheng et al, 2002;Xiong et al, 2002).…”