Gibberellin regulates post‐microsporogenesis processes in petunia anthers

Abstract

Previous studies have suggested that gibberellins (GAs) are produced in petunia anthers and transported to the corolla to induce growth and pigmentation. In this work, we studied the role of GA in the regulation of anther development. When petunia plants were treated with the GA-biosynthesis inhibitor paclobutrazol, anther development was arrested. Microscopic analysis of these anthers revealed that paclobutrazol inhibits post-meiotic developmental processes. The treated anthers contained pollen grains but the connective tissue and tapetum cells were degenerated. A similar phenotype was obtained when the Arabidopsis GA-signal repressor, SPY, was over-expressed in transgenic petunia plants, i.e. anther development was arrested following microsporogenesis. The expression of the GA-induced gene, GIP, can be used in petunia as a molecular marker to study GA responses. GA3 treatment of young anthers promoted, and paclobutrazol inhibited, GIP expression, suggesting that the hormone controls the natural activation of the gene in the anthers. Analyses of GIP expression during anther development revealed that the gene is induced only after microsporogenesis. This observation further suggests a role for GA in the regulation of post-meiotic processes during petunia anther development.

Reduction of Gibberellin by Low Temperature Disrupts Pollen Development in Rice

“…GA deficiency or insensitivity causes abnormal development of anthers and leads to male sterility in tomato, petunia, Arabidopsis, and rice (Nester and Zeevaart, 1988;Izhaki et al, 2002;Jacobsen and Olszewski, 1991;Cheng et al, 2004;Aya et al, 2009). All these studies suggest that GA is essential for normal development of tapetal cells and pollen.…”

SPL8, a local regulator in a subset of gibberellin-mediated developmental processes in Arabidopsis

“…SPL8 positively modulates GA signalling in the flower Sterility and reduced stamen filaments are characteristic features of most GA-deficient/insensitive mutants and depending on the plant species, GA-deficiency/ insensitivity affects different stages of anther development (Jacobsen and Olszewski 1991;Izhaki et al 2002;Huang et al 2003;Cheng et al 2004). Sterility has also been reported in case of a GA overdose (Colombo and Favret 1996) and due to a constitutive GA response caused either by removing the SLENDER RICE1 gene function in rice (Ikeda et al 2001), by removing the function of a negative GA signalling regulator SPY in Arabidopsis (Jacobsen and Olszewski 1993), by overexpressing a positive GA signalling regulator HvG-AMYB in barley (Murray et al 2003) or by overexpressing a soluble GA receptor GID1 in rice (Ueguchi-Tanaka et al 2005).…”

Gibberellic acid in plant

“…53 The tapetum, essential for pollen development providing nutrients, contains pollen coat and allowing dehiscence. 54,55 The tapetum seems to be a major site of GA biosynthesis in developing anthers in rice and Arabidopsis. 22,46,56 The expression of GA genes was reported in anthers only after meiosis 45 and it is interesting to speculate on the extent and distance GAs are exported from anthers.…”