Functional and Transcriptome Analysis Reveals an Acclimatization Strategy for Abiotic Stress Tolerance Mediated by Arabidopsis NF-YA Family Members

Abstract

Nuclear Factor Y (NF-Y) is a heterotrimeric complex formed by NF-YA/NF-YB/NF-YC subunits that binds to the CCAAT-box in eukaryotic promoters. In contrast to other organisms, in which a single gene encodes each subunit, in plants gene families of over 10 members encode each of the subunits. Here we report that five members of the Arabidopsis thaliana NF-YA family are strongly induced by several stress conditions via transcriptional and miR169-related post-transcriptional mechanisms. Overexpression of NF-YA2, 7 and 10 resulted in dwarf late-senescent plants with enhanced tolerance to several types of abiotic stress. These phenotypes are related to alterations in sucrose/starch balance and cell elongation observed in NF-YA overexpressing plants. The use of transcriptomic analysis of transgenic plants that express miR169-resistant versions of NF-YA2, 3, 7, and 10 under an estradiol inducible system, as well as a dominant-repressor version of NF-YA2 revealed a set of genes, whose promoters are enriched in NF-Y binding sites (CCAAT-box) and that may be directly regulated by the NF-Y complex. This analysis also suggests that NF-YAs could participate in modulating gene regulation through positive and negative mechanisms. We propose a model in which the increase in NF-YA transcript levels in response to abiotic stress is part of an adaptive response to adverse environmental conditions in which a reduction in plant growth rate plays a key role.

Arabidopsis DPB3-1, a DREB2A Interactor, Specifically Enhances Heat Stress-Induced Gene Expression by Forming a Heat Stress-Specific Transcriptional Complex with NF-Y Subunits

“…However, this percentage was not different between all genes in Arabidopsis and the upregulated genes in the DPB3-1 (NF-YC10)-overexpressing plants under heat stress (Supplemental Data Set 2). No enrichment of the CCAAT motif was also observed in the promoters of differentially expressed genes in NF-YA2-overexpressing Arabidopsis in a previous study (Leyva-González et al, 2012).…”

Quantitative expression analysis of drought responsive genes in clones of Hevea with varying levels of drought tolerance

“…They bind DNA at CCAAT sites as heterotrimeric complexes composed of single subunits and are reported to be regulating drought responses in many plant species (Stephenson et al 2007;Hackenberg et al 2012). NFYA's expression is regulated at transcriptional and post transcriptional level by miR169 (Petroni et al 2012) and has positive and negative effects on gene expression (González et al 2012). Upregulation of NFYA in tolerant clones of Hevea in this study indicates its strong association with drought tolerance.…”

Arabidopsis AHP2, AHP3, and AHP5 histidine phosphotransfer proteins function as redundant negative regulators of drought stress response

“…In an attempt to explain this phenomenon at a molecular level, we performed a comparative microarray analysis of ahp2,3,5 and WT plants under both well-watered and drought stress conditions to identify the downstream genes of CK signaling that function in drought response. Many ABA-and/or stress-responsive genes, such as DREB1A, DREB1B, AtMYC2, and NF-YA10 (Dataset S2B), whose overexpression enhanced drought tolerance (24,25,30,31), were upregulated in either well-watered or drought-stressed ahp2,3,5 relative to WT. These data indicate that both ABA-dependent and ABA-independent pathways cross-talk with the CK pathway to regulate drought response.…”

“…In addition, genes encoding heat shock proteins were also found among up-regulated genes. Several key transcription factor encoding genes that were up-regulated, such as DREB1A/CBF3, DREB1B/CBF1, and NF-YA10/At5G06510, are worth mentioning because their overexpression is well known to significantly enhance drought tolerance in transgenic plants (24,25). Because we observed the up-regulation of several key salt stress-responsive genes in ahp2,3,5 during drought stress (compare M-D/W-D), such as HKT1, SOS3, and SOS4, we were interested to characterize the response of ahp2,3,5 to salt stress.…”