The pollen-specific DEFH125 promoter from Antirrhinum is bound in vivo by the MADS-box proteins DEFICIENS and GLOBOSA

Abstract

The Antirrhinum DEFH125 MADS-box protein is expressed in maturing pollen and thus likely participates in the regulation of pollen development. Here, we describe the characterization of a 2.5 kbp promoter fragment conferring pollen-specific GUS expression in Antirrhinum, as well as in the distantly related species Arabidopsis. Taking advantage of the higher sensitivity of the diphtheria toxin A-chain (DTA) reporter gene assay, onset of DEFH125 promoter activity could be defined to start at the late unicellular microspore stage. Stamen development in Antirrhinum is governed by the class B MADS-box genes DEFICIENS (DEF) and GLOBOSA (GLO). The respective proteins form a heterodimer and are expressed throughout stamens, except for microspores. Complementary expression patterns of DEFH125 and DEF/GLO during later stamen development tempted us to investigate whether the DEF/GLO heterodimer might bind the DEFH125 promoter and could thus be involved in repressing the DEFH125 expression. The ChIP technique was applied to investigate protein/DNA interactions occurring in vivo. We report the identification of a 200 bp DEFH125 promoter fragment that is in vivo bound by DEF and GLO proteins. This fragment contains a CArG-box motif, known to mediate DNA binding of MADS-box proteins. Implications for a likely function of DEF and GLO in the transcriptional control of DEFH125 are discussed.

Promoters for Transgenic Horticultural Plants

“…AmDEFH125 promoter drives GUS expression in pollen and pollen tubes in Antirrhinum (Lauri et al 2006 ). A lilium ( Lilium longifl orum ) generative cellspecifi c gene promoter ( LGC1 ) is suffi cient to regulate reporter gene expression in the mature pollen of L. longifl orum (Singh et al 2003 ).…”

Do Transcription Factors Play Special Roles in Adaptive Variation?

“…In addition, empirical evidence shows that TFs that operate early in a regulatory hierarchy often continue to work controlling processes later in differentiation as well (Stern, 2000;Wray et al, 2003). This can be seen in the operation of some MADS domain proteins in plants, including AP1 that plays a role in determining the induction of the transition to the floral meristem and also in determining floral organ identity (Becker and Theissen, 2003), and the B-function proteins Deficiens and Globosa in Antirrhinum (equivalent to AP1 and PI, respectively, in Arabidopsis) that control later stages of petal and stamen differentiation as well as determining organ identity (Schwarz Sommer et al, 1992;Zachgo et al, 1995;Bey et al, 2004;Lauri et al, 2006). This feature of higher-order TFs adds to their potential for causing pleiotropic effects when misexpressed, but also complicates the possible outcomes of variation in their expression on phenotype.…”

Pollen-Specific Expression of Oryza sativa Indica Pollen Allergen Gene (OSIPA) Promoter in Rice and Arabidopsis Transgenic Systems

“…In diverse plants, various promoters such as the flowerspecific promoter (chi-A) of petunia [15], fruit-specific promoter (2A11) of tomato [16], root-specific promoter (TobRB7) of tobacco [17], and phloem-specific promoter (TGG1) of Arabidopsis [18], have been cloned and characterized. Similarly, pollen-specific promoters have been isolated and analyzed from various plant species [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. Transgenic rice has been exploited to analyze the functional aspects of various regulatory elements of different promoters exhibiting tissue-specific and inducible expression [39].…”