The Transcription Factor HcERF4 Confers Salt and Drought Tolerance in Kenaf (Hibiscus Cannabinus L.)

Ethylene response factors (ERF) are members of the APETALA2/ERF transcription factor family, and they play an important role in plant growth, development, and response to various environmental stresses. In the present study, an ERF transcription factor HcERF4 was isolated and characterized from kenaf. The protein encoded by the HcERF4 has 233 amino acid residues with a theoretical isoelectric point of 8.89 and a predicted molecular weight of 25.53 kDa. HcERF4 had an over than 86.97% identity to HsERF4(XP_039019980.1), and shared a closest phylogenetic relationship with Hibiscus syriacus. Subcellular localization analysis shows that HcERF4 is located in the nucleus. Transactivation assays in yeast demonstrated that HcERF4 functions as a transcriptional activator. The expression of HcERF4 was enriched in leaf and root, and can be induced by salt or drought treatments in kenaf. The VIGS-silenced HcERF4 plant showed significantly reduced plant height, stem diameter, fresh weight, and relative water content (RWC) compared with wild type plants under salt or drought stress condition; In addition, the contents of MDA, O2−, H2O2, and free proline is significantly increased, and the activities of SOD and CAT are significantly reduced. The DAB/NBT staining results showed that the H2O2 and O2− contents in HcERF4-silenced plants were consistent with the determination. Based on these results, it is proposed that HcERF4 plays an important role in regulating salt and drought stress in kenaf.

The growth and leaf chlorophyll in black rice (Oryza sativa L. Indica) plants induced by gamma rays as responses to the drought stress condition

The aims of this study to determine the growth and leaf chlorophyll content in black rice (Oryza sativa L. Indica) which were induced by gamma rays as responses to the drought stress conditions. This study was carried out on July–November 2020, at the experimental field (screenhouse), Medicinae Street, UNS Perum, Jati Village, Jaten District, Karanganyar Regency. Meanwhile, the chlorophyll content test was carried out at Plant Tissue Culture and Biotechnology Laboratory, Faculty of Agriculture, Universitas Sebelas Maret. The study was a field trial research design without replication. The research treatments were 24 genotypes as follows: 10 genotypes of 100 gray gamma-ray irradiation with 2 control genotypes; and 10 genotypes of 200 gray gamma-irradiation with 2 control genotypes. The results showed that the plant height was lower in plants with irradiation compared to the Control-01 plant. The crown-root ratio showed irradiated plants had higher average results than control plants. The leaf chlorophyll of 100 gray irradiated plants showed higher results than control; while 200 gray irradiated plants showed similar results.

Gene action of achene yield traits in sunflower under drought stress condition

Drought is one of the most damaging environmental stresses, which decreases the achene yield of sunflower (Helianthus annuus L.). The objectives of our experimentations were to determine the type of gene action in sunflower under drought stress, for the identification of the lines with higher achene yield for purpose of developing hybrid with higher achene yield. Thirty-two single cross hybrids from 12 inbred lines were developed through line × tester mating design through crossing 8 drought tolerant inbred lines with 4 drought susceptible lines. The evaluation experiment was performed under an alpha (0,1) lattice incomplete block design with three replications. The achene yield related traits like DF, DM, PH, NL/P, HD, SG, AY/P and TAW were evaluated under normal irrigation and drought stress conditions. Values of degree of dominance greater than one indicating that traits were under the control of dominant genetic effect. Based on GCA effects, L1 proved good combiner for early flowering, maturity and short stature; while L6 was a good combiner for NL/P, HD and AY/P while L8 for HD, SG, AY/P and TAW under drought stress condition. Based on SCA effects, Hybrid 20 was found a good SCA combiner for early flowering, early maturity, short stature, higher HD, AY/P and TAW under normal as well as drought stress conditions. It was suggested form our study that the lines L1, L6 and L8 can be further used to develop drought tolerant hybrids for higher yield and L5 × L12 (Hy 20) was proposed for general cultivation in irrigated as well as rainfed areas of Pakistan.

Natural variations in the non-coding region of ZmNAC080308 contributes maintaining grain yield under drought stress in maize

Background Natural variations derived from both evolutionary selection and genetic recombination, presume to have important functions to respond to various abiotic stresses, which could be used to improve drought tolerance via genomic selection. Results In the present study, the NAC-encoding gene of ZmNAC080308 was cloned and sequenced in 199 inbred lines in maize. Phylogenetic analysis showed that ZmNAC080308 is closely clusteredinto the same group with other well-known NAC genes responding to improve drought tolerance. In total, 86 SNPs and 47 InDels were identified in the generic region of ZmNAC080308, 19 of these variations were associated with GY (grain yield) in different environments. Nine variations in the 5’-UTR region of ZmNAC080308 are closely linked, they might regulate the gene expression and respond to improve GY under drought condition via Sp1-mediated transactivation. Two haplotypes (Hap1 and Hap2) identified in the, 5’-UTR region using the nine variations, and Hap2 containing insertion variants, exhibited 15.47 % higher GY under drought stress condition. Further, a functional marker was developed to predict the drought stress tolerance in a US maize inbred line panel. Lines carrying Hap2 exhibited > 10 % higher GY than those carrying Hap1 under drought stress condition. In Arabidopsis, overexpression ZmNAC080308 enhanced drought tolerance. Conclusions ZmNAC080308 is an important gene responding to drought tolerance, a functional marker is developed for improving maize drought tolerance by selecting this gene.

Effects of auxin and cytokinin on the regeneration and growth of shoot tomato ( Solanum lycopersicum L.) in drought stress

Tomato is one of the most popular foods in the world. However, drought stress has strongly decreased the growth and yield of tomatoes. Therefore, the study on drought-tolerant tomatoes is essential. In this paper, tomato cultivar TN704, which is popularly grown in Vietnam's Southeast and Vietnam's Mekong Delta was selected. The combination of auxin (IAA, indoleacetic acid) and cytokinin (zeatin) at different concentrations was investigated to determine the effective regeneration media. Then, the drought pretreatment was applied to obtain drought-tolerant shoots. The drought tolerance of regenerated shoots was checked by culture in the drought stress condition after two generations (F1 and F2). The physiological and biochemical changes of regenerated shoots in the drought stress condition were analyzed. The MS 1 2 medium supplemented with 0.2 mg/L IAA and 0.5 mg/L zeatin was the effective medium for in vitro shoot regeneration from tomato leaves. The drought pretreatment (MS 1 2 with 20 g/L mannitol) increased the number of regenerated shoots which can develop in the drought stress condition. The regenerated shoots in the F1 and F2 generations grew strongly under drought conditions. The content of chlorophyll, carotenoid and proline, the intensity of respiration and photosynthesis, and the activity of auxin and cytokinin in leaves of F1 and F2 plant were higher than the control.

Effect of drought stress on crop physiology: A mini-review

Global climate change, in the form of increasing temperature and fluctuating soil moisture conditions including drought stress, is projected to decrease the crop physiology of food crops over the next 50 years. Drought stress is an effect of considered as the lowering in the rate of respiration or decrease in the level of photosynthesis. This mini-review tells us the latest information about the drought stress and its effect on the growth of the plant with relation to photosynthesis and water and the mechanism of adaptation. There are numerous ways of the mechanism of adaptation that allows the plant to tolerate the drought stress condition. This mini-review we can prove the statement of different authors on the tolerance of drought stress and the slight changes in the environmental conditions may lead to the fast flexibility of the cell metabolism is the first and main step in the avoidance of drought stress.

Effects of drought stress on shoot development of tomato (Solanum lycopersicum L.)

In recent years, drought stress was strongly affected on the development and yield of tomatoes. There are increasing interests in the study of physiological transformations in adaption to stress in plants In this study, effects of drought stress (mannitol at different concentration) on the development of tomato shoot were studied. Morphological and physiological changes during the development of shoot under drought stress conditions were analyzed. Based on the analysis results, the combination of cytokinin and gibberellin was treated to increase the drought stress tolerance of plants. Results showed that mannitol at 20 g/L induced tomato drought stress. Shoot height, number of leaves, leaf area, and the number of roots significantly decreased in the drought stress condition compared to the control. The formation superoxide (O2-) and hydrogen peroxide (H2O2) occurred in the meristem, elongation region and cap of the roots in the drought stress condition instead of only cap root in the control. In the drought stress condition, there was an increase in respiration intensity, proline and carotenoid content, and abscisic acid activity. In contrast, the content of chlorophyll, photosynthesis intensity, cytokinin and gibberellin activity decreased in comparison with the control. The combination treatment of zeatin 0.5 mg/L and GA3 0.5 mg/L improved the drought stress tolerance of plants. The shoot height, number of leaves, leaf area and number of roots of the treated plants were higher than those of the control plants.

Identification of Local Rice Genotypes from Deli Serdang, North Sumatera, Indonesia to Drought Stress Condition

Regency of Deli Serdang in the Province of Sumatera Utara has high diversity of landrace rice that has adapted to various climatic and edaphic condition including drought. Studies on various local rice genotypes tolerant to drought is of important to be carried out. This will help plant breeders with germplasms for future breeding program. Polyethylene glycol (PEG) is a water-soluble compound with high osmotic pressure and unlikely to have specific interaction with biological chemicals. With these properties, PEG is often be used in studies of plant response to drought stress. The experiment reported here was aimed at determining rice genotypes, local to Regency of Deli Serdang, tolerant to drought. The experiment was carried out at Laboratory of Physiology and Glass House of Faculty of Agriculture, Universitas Islam Sumatera Utara, Medan from February to April 2020. A two-way factorial experiment was assigned in a completely randomized design (CRD) with 3 replicates. The first factor was 23 local rice genotypes plus 4 genotypes tolerant to drought and the second factor was the concentration of PEG 6000 i. e 0 and 20% (w/v). Observations included percent of germination, plant height, length and number of roots protruding from paraffin-wax layer, leaf chlorophyll content, seedling fresh and dry weight, index of tolerance, probability of resistance, and proline content. Data were analyzed with analysis of variance and mean separation of DNMRT at 5%. Results demonstrated that 6 local rice genotypes, Gemuruh, Ramos Merah, Arias, Sialus, Silayur, and Sirabut were resistant to drought stress under the experimental condition.