AtZAT4, a C2H2-Type Zinc Finger Transcription Factor from Arabidopsis thaliana, Is Involved in Pollen and Seed Development

Genome-wide identification of the Q-type C2H2 zinc finger protein gene family and expression analysis under abiotic stress in lotus (Nelumbo nucifera G.)

BACKGROUND

Lotus (Nelumbo nucifera G.) is an important aquatic plant with high ornamental, economic, cultural and ecological values, but abiotic stresses seriously affect its growth and distribution. Q-type C2H2 zinc finger proteins (ZFPs) play an important role in plant growth development and environmental stress responses. Although the Q-type C2H2 gene family has been identified in some plants, limited reports has been carried out it in lotus.

RESULTS

In this study, we identified 45 Q-type NnZFP members in lotus. Based on the phylogenetic tree, these Q-type NnZFP gene family members were divided into 4 groups, including C1-1i, C1-2i, C1-3i and C1-4i. Promoter cis-acting elements analysis indicated that most Q-type NnZFP gene family members in lotus were associated with response to abiotic stresses. Through collinearity analyses, no tandem duplication gene pairs and 14 segmental duplication gene pairs were identified, which showed that duplication events might play a key role in the expansion of the Q-type NnZFP gene family. The synteny results suggested that 54 and 28 Q-type NnZFP genes were orthologous to Arabidopsis and rice, respectively. The expression patterns of these Q-type NnZFP genes revealed that 30 Q-type NnZFP genes were expressed in at least one lotus tissue. Nn5g30550 showed relatively higher expression levels in all tested tissues. 12 genes were randomly selected with at least one gene from each phylogenetic clade, and the expression of these selected genes were confirmed by qRT-PCR (quantitative real-time polymerase chain reaction). The results indicated that Q-type NnZFP genes were extensively involved in cadmium, drought, salt and cold stresses responses. Among them, 11 genes responded to at least three different stress treatments, especially Nn2g12894, which induced by all four treatments.

CONCLUSIONS

These results could increase our understanding of the characterization of the Q-type NnZFP gene family and provide relevant information for further functional analysis of Q-type NnZFP genes in plant development, and abiotic stress tolerance in lotus.

Plant reproduction research in Latin America: Toward sustainable agriculture in a changing environment

Food production and food security depend on the ability of crops to cope with anthropogenic climate change and successfully produce seed. To guarantee food production well into the future, contemporary plant scientists in Latin America must carry out research on how plants respond to environmental stressors such as temperature, drought, and salinity. This review shows the opportunities to apply these results locally and abroad and points to the gaps that still exist in terms of reproductive processes with the purpose to better link research with translational work in plant breeding and biotechnology. Suggestions are put forth to address these gaps creatively in the face of chronic low investment in science with a focus on applicability.

Transcription Factors and Their Regulatory Roles in the Male Gametophyte Development of Flowering Plants

Male gametophyte development in plants relies on the functions of numerous genes, whose expression is regulated by transcription factors (TFs), non-coding RNAs, hormones, and diverse environmental stresses. Several excellent reviews are available that address the genes and enzymes associated with male gametophyte development, especially pollen wall formation. Growing evidence from genetic studies, transcriptome analysis, and gene-by-gene studies suggests that TFs coordinate with epigenetic machinery to regulate the expression of these genes and enzymes for the sequential male gametophyte development. However, very little summarization has been performed to comprehensively review their intricate regulatory roles and discuss their downstream targets and upstream regulators in this unique process. In the present review, we highlight the research progress on the regulatory roles of TF families in the male gametophyte development of flowering plants. The transcriptional regulation, epigenetic control, and other regulators of TFs involved in male gametophyte development are also addressed.

Self S-RNase reduces the expression of two pollen-specific COBRA genes to inhibit pollen tube growth in pear

Due to self-incompatibility (SI) prevents self-fertilization, natural or artificial cross-pollination has been conducted in many orchards to stabilize fruit yield. However, it is still puzzled which routes of self S-RNase arresting pollen tube growth. Herein, 17 COBRA genes were isolated from pear genome. Of these genes, the pollen-specifically expressed PbCOB.A.1 and PbCOB.A.2 positively mediates pollen tube growth. The promoters of PbCOB.A.1 and/or PbCOB.A.2 were bound and activated by PbABF.E.2 (an ABRE-binding factor) and PbC2H2.K16.2 (a C2H2-type zinc finger protein). Notably, the expressions of PbCOB.A.1, PbCOB.A.2, and PbC2H2.K16.2 were repressed by self S-RNase, suggesting that self S-RNase reduces the expression of PbCOB.A.1 and PbCOB.A.2 by decreasing the expression of their upstream factors, such as PbC2H2.K16.2, to arrest pollen tube growth. PbCOB.A.1 or PbCOB.A.2 accelerates the growth of pollen tubes treated by self S-RNase, but can hardly affect level of reactive oxygen species and deploymerization of actin cytoskeleton in pollen tubes and cannot physically interact with any reported proteins involved in SI. These results indicate that PbCOB.A.1 and PbCOB.A.2 may not relieve S-RNase toxicity in incompatible pollen tube. The information provides a new route to elucidate the arresting pollen tube growth during SI reaction.

Genome-wide identification of the C2H2-Zinc finger gene family and functional validation of CsZFP7 in citrus nucellar embryogenesis

KEY MESSAGE

Genome-wide identification of C2H2-ZF gene family in the poly- and mono-embryonic citrus species and validation of the positive role of CsZFP7 in sporophytic apomixis. The C2H2 zinc finger (C2H2-ZF) gene family is involved in plant vegetative and reproductive development. Although a large number of C2H2 zinc-finger proteins (C2H2-ZFPs) have been well characterized in some horticultural plants, little is known about the C2H2-ZFPs and their function in citrus. In this work, we performed a genome-wide sequence analysis and identified 97 and 101 putative C2H2-ZF gene family members in the genomes of sweet orange (C. sinensis, poly-embryonic) and pummelo (C. grandis, mono-embryonic), respectively. Phylogenetic analysis categorized citrus C2H2-ZF gene family into four clades, and their possible functions were inferred. According to the numerous regulatory elements on promoter, citrus C2H2-ZFPs can be divided into five different regulatory function types that indicate functional differentiation. RNA-seq data revealed 20 differentially expressed C2H2-ZF genes between poly-embryonic and mono-embryonic ovules at two stages of citrus nucellar embryogenesis, among them CsZFP52 specifically expressed in mono-embryonic pummelo ovules, while CsZFP7, 37, 44, 45, 67 and 68 specifically expressed in poly-embryonic sweet orange ovules. RT-qPCR further validated that CsZFP7 specifically expressed at higher levels in poly-embryonic ovules, and down-regulation of CsZFP7 in the poly-embryonic mini citrus (Fortunella hindsii) increased rate of mono-embryonic seeds compared with the wild type, indicating the regulatory potential of CsZFP7 in nucellar embryogenesis of citrus. This work provided a comprehensive analysis of C2H2-ZF gene family in citrus, including genome organization and gene structure, phylogenetic relationships, gene duplications, possible cis-elements on promoter regions and expression profiles, especially in the poly- and mono-embryogenic ovules, and suggested that CsZFP7 is involved in nucellar embryogenesis.