Characterization of ALBA Family Expression and Localization in Arabidopsis thaliana Generative Organs

Abstract

ALBA DNA/RNA-binding proteins form an ancient family, which in eukaryotes diversified into two Rpp25-like and Rpp20-like subfamilies. In most studied model organisms, their function remains unclear, but they are usually associated with RNA metabolism, mRNA translatability and stress response. In plants, the enriched number of ALBA family members remains poorly understood. Here, we studied ALBA dynamics during reproductive development in Arabidopsis at the levels of gene expression and protein localization, both under standard conditions and following heat stress. In generative tissues, ALBA proteins showed the strongest signal in mature pollen where they localized predominantly in cytoplasmic foci, particularly in regions surrounding the vegetative nucleus and sperm cells. Finally, we demonstrated the involvement of two Rpp25-like subfamily members ALBA4 and ALBA6 in RNA metabolism in mature pollen supported by their co-localization with poly(A)-binding protein 3 (PABP3). Collectively, we demonstrated the engagement of ALBA proteins in male reproductive development and the heat stress response, highlighting the involvement of ALBA4 and ALBA6 in RNA metabolism, storage and/or translational control in pollen upon heat stress. Such dynamic re-localization of ALBA proteins in a controlled, developmentally and environmentally regulated manner, likely reflects not only their redundancy but also their possible functional diversification in plants.

Genome-wide identification and expression profiling of Alba gene family members in response to abiotic stress in tomato (Solanum lycopersicum L.)

“…In agreement with the previous reports (Goyal et al, 2016;Náprstková et al, 2021), in-depth analysis of the phylogenetic relationships among Alba proteins revealed two types. Some of the proteins are relatively large, with an RGG/RG repeat motif or other domain in addition to the generic single Alba domain; most of these proteins belong to the RPP25-like family.…”

“…Alba proteins are associated with stress tolerance due to their involvement in genome packaging and organization, transcriptional and translational regulation, post-translational regulation, and RNA metabolism, in addition to responses to different environmental stresses (Goyal et al, 2012(Goyal et al, , 2016Verma et al, 2018). The possible roles of Alba family genes in plant stress responses were supported by previous studies reporting the stress-induced expression of Alba genes in several plant species, such as cotton, Arabidopsis, and rice (Magwanga et al, 2019;Náprstková et al, 2021;Verma et al, 2018). The role of OsAlba1 as a DNA binding protein involved in oxidative stress tolerance was revealed by complementation analysis in yeast.…”

“…Stress-induced differential expression has also been observed for Alba genes from rice treated with different abiotic stresses and phytohormones (Verma et al, 2018). Mild heat stress (37 •C) altered the expression of most Arabidopsis Alba genes in in orescences (Náprstková et al, 2021). In cotton (Gossypium hirsutum), GhALBA4 and GhALBA5 were signi cantly induced by water de cit and salinity treatment, and plants in which the expression of these genes was repressed by virus-induced gene silencing (VIGS) were highly sensitive to dehydration as well as salt stress, pointing to their putative roles in abiotic stress tolerance (Magwanga et al, 2019).…”

“…Alba proteins exist in two forms: relatively small proteins with a single generic Alba domain; and larger proteins with an Alba domain plus RGG/RG repeat motifs or additional domain/s (Goyal et al, 2016;Náprstková et al, 2021). All archaeal Alba homologs, which belong to the Archaea Alba protein family, are relatively small proteins with only a single Alba domain.…”

“…Alba genes encoding proteins with RGG/RG repeat motifs have been identi ed in many species (Dupé et al, 2014;Gissot et al, 2013;Náprstková et al, 2021). Various types of domains with diverse biological functions have also been identi ed in combination with the Alba domain in numerous Alba family proteins in many domains of life, such as the F-box domain in the fungus Taphrina; the CLIP1 zinc nger domain in the nematode Pristionchus; the ATP synthase subunit H domain in the protozoan parasite Theileria; the sugar transporter domain in the Florida lancelet; the DEAD/DEAH box helicase domain in plants; and so forth (Goyal et al, 2016).…”