The homologous HD‐Zip I transcription factors HaHB1 and AtHB13 confer cold tolerance via the induction of pathogenesis‐related and glucanase proteins

Abstract

SUMMARYPlants deal with cold temperatures via different signal transduction pathways. The HD-Zip I homologous transcription factors HaHB1 from sunflower and AtHB13 from Arabidopsis were identified as playing a key role in such cold response. The expression patterns of both genes were analyzed indicating an up-regulation by low temperatures. When these genes were constitutively expressed in Arabidopsis, the transgenic plants showed similar phenotypes including cell membrane stabilization under freezing treatments and cold tolerance. An exploratory transcriptomic analysis of HaHB1 transgenic plants indicated that several transcripts encoding glucanases and chitinases were induced. Moreover, under freezing conditions some proteins accumulated in HaHB1 plants apoplasts and these extracts exerted antifreeze activity in vitro. Three genes encoding two glucanases and a chitinase were overexpressed in Arabidopsis and these plants were able to tolerate freezing temperatures. All the obtained transgenic plants exhibited cell membrane stabilization after a short freezing treatment. Finally, HaHB1 and AtHB13 were used to transiently transform sunflower and soybean leading to the up-regulation of HaHB1/AtHB13-target homologues thus indicating the conservation of cold response pathways. We propose that HaHB1 and AtHB13 are involved in plant cold tolerance via the induction of proteins able to stabilize cell membranes and inhibit ice growth.

A Predictive Coexpression Network Identifies Novel Genes Controlling the Seed-to-Seedling Phase Transition in Arabidopsis thaliana

“…These TFs are paralogs and have similarities and differences in their response. AtHB13 is involved in cold tolerance (Cabello et al, 2012), whereas AtHB20 has been assigned roles in ABA, salt, and cold responses (Henriksson et al, 2005) as well as seed dormancy (Barrero et al, 2010). AtHB23 and AtHB20 play roles in light signaling (Barrero et al, 2010;Choi et al, 2014), but none of these have been related previously to the seed-to-seedling phase transition.…”

“…Mutant plants from genotypes athb13-1, athb13-2, and athb13-1 + 35S::AtHB13 (lines 1 and 2) were described previously (Cabello et al, 2012;Ribone et al, 2015). Seeds of these mutants were sown on 5-3 5-cm Rockwool blocks in a climate cell (20°C day and 18°C night) with a photoperiod of 16 h of light and 8 h of dark.…”

Coping with Drought and Salinity Stresses: Role of Transcription Factors in Crop Improvement

“…The observed improved yield could be associated with higher chlorophyll content in the transgenic plants leaves. Several pathogenesis-related proteins were induced in transgenic lines under stress treatments, which could be associated with a cell membrane stabilization mechanism of stress tolerance, similar to the previously reported mechanism for the tolerance of freezing temperatures [177]. There is an patent application as a result of this research [220].…”

“…Another relevant sunflower HD-ZIP I gene involved in the response to abiotic stress is HaHB1 and its Arabidopsis ortholog AtHB13. HaHB1 expression under the 35S promoter enhances tolerance to freezing, high salinity, and drought through a mechanism that involves cell membrane stabilization [56,177]. The NaHD20 HD-ZIP I transcription factor from Nicotiana attenuata induces the accumulation of ABA under water stress, and coordinates the responses to dehydration and its integration with changes in flower transitions [178].…”

RNAi-mediated silencing of the HD-Zip gene HD20 in Nicotiana attenuata affects benzyl acetone emission from corollas via ABA levels and the expression of metabolic genes

“…Casein kinases (CKs) are ubiquitous Ser/Thr kinases that play critical roles in all higher organisms including plants. For example, the Arabidopsis CK2 plays important roles in light signaling, circadian rhythms, hormone responses, cell cycle control and flowering time [6,38,39]. The strong down-regulation of casein kinase suggests that this protein kinase may be important in regulating directly or indirectly BA emissions by HD20-dependent mechanisms.…”