Novel Zinc Finger-Homeodomain Gene from Barley (HvZFHD1) is Differentially Regulated During Spike Development and under Hormonal Treatments and Abiotic Stresses

Plant zinc finger-homeodomains (ZFHDs) are transcriptional factors that play an important role in regulating plant growth and development. Several ZFHD genes were cloned and characterized in many plant species. In the present study, a full-length cDNA sequence of ZFHD gene was cloned from barley (termed as HvZFHD1) using reverse transcription polymerase chain reaction (RT-PCR). The sequence analysis showed that the HvZFHD1 was 1477 bp in length, and contained a complete open reading frame (ORF) of 1161 bp. The deduced protein is composed of 386 amino acids, with a predicted molecular weight of 40.46 kDa and a theoretical isoelectric point of 8.5. Multiple sequence alignment indicated that HvZFHD1 protein shared high identity with ZFHD proteins from wheat, maize, and rice. The predicted HvZFHD1 protein contained the characteristic putative zinc finger domain in the N-terminus and a DNA binding homeodomain in the C-terminus. The expression level of HvZFHD1 was investigated using qRT-PCR during spike development and in response to exogenous phytohormones and abiotic stresses. The results showed that the expression level of HvZFHD1 was fluctuated during spike development with higher expression during anthesis, medium milk, late milk, and early dough stages. The expression of barley ZFHD1 was strongly responsive to abscisic acid treatment and was up-regulated in seedlings treated with methyl jasmonate, salicylic acid, and ethephone. In addition, the expression levels of HvZFHD1 were increased by dehydration, salinity, and heat stress, but not affected by cold stress. The expression patterns of HvZFHD1 suggest that it might play a role in flowering and flower development and is involved in plant responses to abiotic stresses

A putative pectin acetylesterase gene family in Arabidopsis thaliana

Pectin is a class of acidic plant cell wall polysaccharides that comprises a major fraction of the Type I primary cell wall, typical of dicotyledonous species. Galacturonic acid residues of pectin can be acetylated at the O-2 and O-3 positions. The enzyme pectin acetylesterase (PAE) can hydrolyze acetyl esters in homogalacturonan regions of pectin. Decreasing the degree of acetylation of pectin gels in vitro alters their physical properties. In vivo acetylesterase activity in Arabidopsis root cell walls was detected with an apparent optimum pH of 6.5. The degree of acetylation of two-week-old Arabidopsis shoot and root cell walls were 10% and 6% respectively. Eleven putative genes have been identified in the Arabidopsis genome with sequence similarity to known PAE encoding genes. Atpae3 × Atpae6 double mutant line had 70% and 83% of wild type root tissue of fresh weight and dry weight respectively. This significant difference could be the result of structural changes of cell wall of the double mutant line, since no difference was observed of root length or number of lateral roots between the wild type and Atpae3 x Atpae6 double mutant line. FTIR analysis on PGA with two different degrees of acetylation showed a wave number peak of 1747 cm-1