Zinc finger-homeodomain transcriptional factors (ZF-HDs), a kind of plant-specific transcription factor, play important roles in plant growth, development and various stress responses. In this study, the genome-wide analysis of the ZF-HD gene family was performed in wheat. A total of 37 TaZF-HD genes were identified in T. aestivum and classified into six groups. The results of a synteny analysis showed that gene replication events contributed to the expansion of the TaZF-HD gene family. The TaZF-HD paralogous gene pairs with similar chromosomal locations in different subgenomes had similar expression patterns. TaZF-HDs were highly induced under PEG (polyethylene glycol), NaCl and cold stress but not induced under heat stress. Gene ontology (GO) annotation and protein-protein interactions suggested that TaZF-HD proteins may participate in various biological processes of plants. These results increase our understanding of ZF-HD genes and provide robust candidate genes for future functional investigations aimed at crop improvement.

Late embryogenesis abundant (LEA) proteins play important roles in plant defense response to drought stress. However, genome-wide identification of the LEA gene family was not revealed in Salvia miltiorrhiza. In this study, 61 SmLEA genes were identified from S. miltiorrhiza and divided into 7 subfamilies according to their conserved domains and phylogenetic relationships. SmLEA genes contained the LEA conserved motifs and few introns. SmLEA genes of the same subfamilies had similar gene structures and predicted subcellular locations. Our results indicated that the promoters of SmLEA genes contained various cis-acting elements associated with abiotic stress response. In addition, RNA-seq and real-time PCR results suggested that SmLEA genes are specifically expressed in different tissue, and most SmLEA genes can be induced by drought stress. These results provide a valuable foundation for future functional investigations of SmLEA genes and drought stress-resistant breeding of S. miltiorrhiza.

The distribution and content of auxin within plant tissues affect a variety of important growth and developmental processes. Polar auxin transport (PAT), mainly mediated by auxin influx and efflux transporters, plays a vital role in determining auxin maxima and gradients in plants. The auxin efflux carrier PIN-FORMED (PIN) family is one of the major protein families involved in PAT. Rice (Oryza sativa L.) genome possesses 12 OsPIN genes. However, the detailed functions of OsPIN genes involved in regulating the rice architecture and gravity response are less well understood. In the present study, OsPIN1b was disrupted by CRISPR/Cas9 technology, and its roles in modulating rice architecture and root gravitropism were investigated. Tissue-specific analysis showed that OsPIN1b was mainly expressed in roots, stems and sheaths at the seedling stage, and the transcript abundance was progressively decreased during the seedling stages. Expression of OsPIN1b could be quickly and greatly induced by NAA, indicating that OsPIN1b played a vital role in PAT. IAA homeostasis was disturbed in ospin1b mutants, as evidenced by the changed sensitivity of shoot and root to NAA and NPA treatment, respectively. Mutation of OsPIN1b resulted in pleiotropic phenotypes, including decreased growth of shoots and primary roots, reduced adventitious root number in rice seedlings, as well as shorter and narrower leaves, increased leaf angle, more tiller number and decreased plant height and panicle length at the late developmental stage. Moreover, ospin1b mutants displayed a curly root phenotype cultured with tap water regardless of lighting conditions, while nutrient solution culture could partially rescue the curly root phenotype in light and almost completely abolish this phenotype in darkness, indicating the involvement of the integration of light and nutrient signals in root gravitropism regulation. Additionally, amyloplast sedimentation was impaired in the peripheral tiers of the ospin1b root cap columella cell, while it was not the main contributor to the abnormal root gravitropism. These data suggest that OsPIN1b not only plays a vital role in regulating rice architecture but also functions in regulating root gravitropism by the integration of light and nutrient signals.

As functional proteins dehydrins are found in many maturing seeds and vegetable tissue under adverse environmental conditions. However, the regulation of dehydrin expression remains unclear. To explore regulatory mechanisms of wheat dehydrin WZY2 expression under abiotic stresses, we constructed a cDNA library from PEG- and cold-treated wheat seedlings and performed yeast one-hybrid assay and yeast two-hybrid assay to identify the upstream transcription factors and protein interacting with dehydrin WZY2 gene. Yeast one-hybrid assay illustrated that bHLH49-like (GenBank NO. XM_020296294), zinc finger A20 and AN1 domain-containing stress-associated protein 6-like (GenBank NO. XM_020341647), and bHLH47-like (GenBank NO. XM_020313116) proteins can bind and interact with the promoter of the WZY2, these sequences are Aegilops tauschii transcription factors, the diploid progenitor of the D genome of hexaploid wheat (Triticum aestivum, genomes AABBDD). Real-time PCR analyzes unraveled the stress responsive expression of XM_020296294, XM_020341647, and XM_020313116 in wheat. XM_020296294 and XM_020341647 showed a similar expression patterns with WZY2. Yeast two-hybrid assay indicated that PP2C (GenBank NO. XM_020293398) protein can interact with WZY2. These results provided evidences that WZY2 could be positively regulated by XM_020296294 and XM_020341647 transcription factors, and WZY2 may also play an important role in the ABA signaling pathway through interaction with PP2C to regulate stress-responsive genes expression in wheat. The obtained results contribute for provide a better understanding of the regulatory mechanism of dehydrin expression under abiotic stresses in wheat.

The auxin efflux transporter PIN-FORMED (PIN) family is one of the major protein families that facilitates polar auxin transport in plants. Here, we report that overexpression of OsPIN9 leads to altered plant architecture and chilling tolerance in rice. The expression profile analysis indicated that OsPIN9 was gradually suppressed by chilling stress. The shoot height and adventitious root number of OsPIN9-overexpressing (OE) plants were significantly reduced at the seedling stage. The roots of OE plants were more tolerant to N-1-naphthylphthalamic acid (NPA) treatment than WT plants, indicating the disturbance of auxin homeostasis in OE lines. The chilling tolerance assay showed that the survival rate of OE plants was markedly lower than that of wild-type (WT) plants. Consistently, more dead cells, increased electrolyte leakage, and increased malondialdehyde (MDA) content were observed in OE plants compared to those in WT plants under chilling conditions. Notably, OE plants accumulated more hydrogen peroxide (H₂O₂) and less superoxide anion radicals (${\mathrm{O}}_2^{-}$) than WT plants under chilling conditions. In contrast, catalase (CAT) and superoxide dismutase (SOD) activities in OE lines decreased significantly compared to those in WT plants at the early chilling stage, implying that the impaired chilling tolerance of transgenic plants is probably attributed to the sharp induction of H₂O₂ and the delayed induction of antioxidant enzyme activities at this stage. In addition, several OsRboh genes, which play a crucial role in ROS production under abiotic stress, showed an obvious increase after chilling stress in OE plants compared to that in WT plants, which probably at least in part contributes to the production of ROS under chilling stress in OE plants. Together, our results reveal that OsPIN9 plays a vital role in regulating plant architecture and, more importantly, is involved in regulating rice chilling tolerance by influencing auxin and ROS homeostasis.