Arabidopsis lox3 lox4 double mutants are male sterile and defective in global proliferative arrest

Abstract

Fertility and flower development are both controlled in part by jasmonates, fatty acid-derived mediators produced via the activity of 13-lipoxygenases (13-LOXs). The Arabidopsis thaliana Columbia-0 reference genome is predicted to encode four of these enzymes and it is already known that one of these, LOX2, is dispensable for fertility. In this study, the roles of the other three 13-LOXs (LOX3, LOX4 and LOX6) were investigated in single and double mutants. Four independent lox3 lox4 double mutants assembled with different mutated lox3 and lox4 alleles had fully penetrant floral phenotypes, displaying abnormal anther maturation and defective dehiscence. The plants were no longer self-fertile and pollen was not viable. Fertility in the double mutant was restored genetically by complementation with either the LOX3 or the LOX4 cDNAs and biochemically with exogenous jasmonic acid. Furthermore, deficiency in LOX3 and LOX4 causes developmental dysfunctions, compared to wild type; lox3 lox4 double mutants are taller and develop more inflorescence shoots and flowers. Further analysis revealed that developmental arrest in the lox3 lox4 inflorescence occurs with the production of an abnormal carpelloid flower. This distinguishes lox3 lox4 mutants from the wild type where developmentally typical flower buds are the terminal inflorescence structures observed in both the laboratory and in nature. Our studies of lox3 lox4 as well as other jasmonic acid biosynthesis and perception mutants show that this plant hormone is not only required for male fertility but also involved in global proliferative arrest.

Transcriptional Mechanism of Jasmonate Receptor COI1-Mediated Delay of Flowering Time in Arabidopsis

“…Other examples in which different members of a gene family contribute to different aspects of the JA response come from the JA synthesis gene family 13-LIPOXYGENASE. Among the four LOX genes in the Arabidopsis genome (i.e., LOX2, LOX3, LOX4, and LOX6), it is already known that LOX2 is mainly involved in wound-induced JA biosynthesis but has a negligible effect on fertility (Glauser et al, 2009;Seltmann et al, 2010), whereas LOX3 and LOX4 act redundantly to regulate fertility (Caldelari et al, 2011). It is of great interest to identify the JA biosynthesis genes that are specifically involved in the control of flowering.…”

Arabidopsis Pollen Fertility Requires the Transcription Factors CITF1 and SPL7 That Regulate Copper Delivery to Anthers and Jasmonic Acid Synthesis

“…Therefore, we tested whether exogenous JA application could rescue the fertility defect of the citf1 spl7 double mutant as it does for some male infertile JA biosynthesis mutants. In addition to the citf1 spl7 plants, we used the male sterile lox3 lox4 double mutant lacking two lipoxygenases, LOX3 and LOX4, that are essential for JA synthesis (Supplemental Figure 6; Caldelari et al 2011) and the expression of their genes is regulated by CITF1 and SPL7 ( Figure 8A). Consistent with previous findings (Caldelari et al, 2011), the male sterility of this mutant was rescued by the exogenous application of JA to flower buds (Supplemental Figure 7B).…”

“…In addition to the citf1 spl7 plants, we used the male sterile lox3 lox4 double mutant lacking two lipoxygenases, LOX3 and LOX4, that are essential for JA synthesis (Supplemental Figure 6; Caldelari et al 2011) and the expression of their genes is regulated by CITF1 and SPL7 ( Figure 8A). Consistent with previous findings (Caldelari et al, 2011), the male sterility of this mutant was rescued by the exogenous application of JA to flower buds (Supplemental Figure 7B). By contrast, JA application did not rescue the fertility defect of the citf1 spl7 double mutant (Supplemental Figure 7B).…”

“…Seeds of the lox3 lox4 double mutant were a generous gift of Edward Farmer (University of Lausanne, Switzerland). These mutants were previously described (Caldelari et al, 2011;Yamasaki et al, 2009). Two CITF1 mutant alleles, SALK_073160 (alias citf1-1) and SAIL_711_B07 (alias citf1-2), were obtained from the ABRC (Alonso et al, 2003).…”

“…2010). Mutants with defects in JA biosynthesis and/or signaling are male sterile, and this defect can be corrected by exogenous JA application (Caldelari et al, 2011;Ishiguro et al, 2001;McConn and Browse, 1996;Staswick et al, 2002;Feys et al, 1994;Park et al, 2002;von Malek et al, 2002;Stintzi and Browse, 2000). JA-dependent fertility defects are manifested by the decreased viability of pollen grains, delayed anther dehiscence, and the reduced length of stamen filaments (Caldelari et al, 2011;Ishiguro et al, 2001;McConn and Browse, 1996;Staswick et al, 2002).…”