Wide-scale screening of T-DNA lines for transcription factor genes affecting male gametophyte development in Arabidopsis

Abstract

Male gametophyte development leading to the formation of a mature pollen grain is precisely controlled at various levels, including transcriptional, post-transcriptional and post-translational, during its whole progression. Transcriptomic studies exploiting genome-wide microarray technologies revealed the uniqueness of pollen transcriptome and the dynamics of early and late successive global gene expression programs. However, the knowledge of transcription regulation is still very limited. In this study, we focused on the identification of pollen-expressed transcription factor (TF) genes involved in the regulation of male gametophyte development. To achieve this, the reverse genetic approach was used. Seventy-four T-DNA insertion lines were screened, representing 49 genes of 21 TF families active in either early or late pollen development. In the screen, ten phenotype categories were distinguished, affecting various structural or functional aspects, including pollen abortion, presence of inclusions, variable pollen grain size, disrupted cell wall structure, cell cycle defects, and male germ unit organization. Thirteen lines were not confirmed to contain the T-DNA insertion. Among 61 confirmed lines, about half (29 lines) showed strong phenotypic changes (i.e., ≥ 25% aberrant pollen) including four lines that produced a remarkably high proportion (70-100%) of disturbed pollen. However, the remaining 32 lines exhibited mild defects or resembled wild-type appearance. There was no significant bias toward any phenotype category among early and late TF genes, nor, interestingly, within individual TF families. Presented results have a potential to serve as a basal information resource for future research on the importance of respective TFs in male gametophyte development.

Suppression of ASKβ (AtSK32), a Clade III Arabidopsis GSK3, Leads to the Pollen Defect during Late Pollen Development

“…6). Consistent with the current results, the expression of DAF1 , PCR11 , TIP5;1 , ATTLP6 , and ACA9 is more pronounced after the tetrad stage when ASKβ expression is strong, and altering the expression of these genes also causes abnormal microgametogenesis (Borg et al, 2011; Reňák et al, 2012; Schiott et al, 2004; Soto et al, 2010). ASK β may activate regulatory protein(s) that transcriptionally induce the expression of these genes.…”

“…Six ASKβ co-expressed and TDF1 -regulated genes can be categorized by their putative functions or expression characteristic, as summarized in Table 1. Knock-out of BCP1 and ATTLP6 mutations leads to cytoplasmic degradation and defects in late pollen development, respectively (Reňák et al, 2012; Xu et al, 1995). While DAF1 , PCR11 , and TIP5;1 are involved in sperm cell formation (Borg et al, 2011), ACC9 is important for fertility and mutation in ACC9 results in more than 80% reduction of seed set (Schiott et al, 2004).…”

“…Numerous ASKβ co-expressed genes are involved in sperm cell differentiation (genes and their references are found in Table 1). Among these, mutants of AGD13 , ATTLP7 , ATTLP6 , and MYB101 exhibit two-celled pollen grains or misarranged male sperm units (Reňák et al, 2012), while mutants of PDD6 have no sperm cells in their mature pollen grains and exhibit cytoplasmic degradation (Boavida et al, 2009). Recently, DAF1 , PCR11 , and TIP5;1 were reported to be target genes of the male germline-specific transcription factor DUO POLLEN 1 , which is also required for germline nucleus development (Borg et al, 2014).…”

Identification of genes specifically or preferentially expressed in maize silk reveals similarity and diversity in transcript abundance of different dry stigmas

“…Most (58.6%) belonged to six families: MYB, WRKY, NAC, C2C2-CO-like, bHLH, and AP2-EREBP (Figure 5A, Additional file 8A). Expression and genetic analyses have substantiated the involvement of all six TF families in flower development and reproduction [21-24]. It is unclear, however, whether these TFs are directly involved in pollen-stigma interaction.…”

Characterization of a novel male sterile mutant of Tagetes patula induced by heat shock

“…These components are vital for the normal development of anthers, microspore/pollen formation, and pollen wall formation (Li et al 2006Parish and Li 2010;Shi et al 2011;Clements et al 2012). Reňák et al (2012) have reported that mutations of two tapetum-expressed genes, TAZ1 and MEZ1, can cause aberrant meiosis and pollen abortion, and can trigger the process of programmed cell death in Petunia hybrida. In the fertile wild type plants of T. patula, the binucleate microspore progressed to become a trinucle at pollen grain surrounded by the periplasmodial tapetum.…”