Species Composition of the Harmful Entomocomplex of Sorghum (Sorghum bicolor (L.) Moench) in the Polissia Region of Ukraine

Rhizobacteria-induced systemic resilience in Sorghum bicolor (L.) moench against Fusarium pseudograminearum crown rot under drought stress conditions

Do cytokinins, volatile isoprenoids and carotenoids synergically delay leaf senescence?

Drought stress reduces soybean yield. Exploring the mechanism of improving drought tolerance and reducing yield loss is of great significance for soybean production. Melatonin application can alleviate the growth inhibition and oxidative damage of plants under drought stress. In this experiment, the effects of foliar application of melatonin on photosynthesis, stress resistance, carbon and nitrogen metabolism and yield of soybean during seed filling stage under drought stress were studied in 2017–2018. The application exogenous melatonin increased the antioxidant enzyme activity, inhibited the production of reactive oxygen species, decreased cell membrane damage under drought stress, alleviated the inhibition of photosynthetic capacity by drought stress, improved the carbon and nitrogen assimilation ability, and alleviated the yield loss caused by drought stress. Compared with drought stress, the treatment of melatonin increased the number of pods per plant, the grain number per plant and the hundred grain weight by 2.9%, 0.8%, and 17.2% on average of two years, respectively, and the yield (grain weight per plant) increased by 14.7%.

Genetic determinants of metabolites related to drought tolerance in maize. Water deficit or drought is one of the most serious abiotic stresses of plant development and greatly reduces crop production, and the plant's response to this deficit leads to many metabolic changes. To dissect the genetic basis of these metabolic traits in maize, we performed a genome-wide association analysis of drought-related traits using 156,599 SNPs in 318 maize inbred lines. In total, 123 significant SNP/trait associations (P≤6.39E-6) involving 63 loci were identified for related metabolic and physiological traits in multiple tissues and different environments under two irrigation conditions. Of the 63, 23 loci demonstrated a significant interaction effect between QTL and water status, indicating that these metabolite-associated loci were probably related to drought stress tolerance. To evaluate the potential utility of metabolite-associated loci appliedin hybrid maize breeding, we assembled two groups of hybrid entries with high or low drought tolerance and measured the metabolic and physiological traits. In the hybrid pools, a set of 10 metabolite-associated loci identified in leaf and ear were validated as responsive to drought stress. The favorable alleles of these ten loci were significantly enriched in hybrids with high drought tolerance, which jointly explained almost 18.4% of the variation in drought tolerance using a multivariate logistic regression model. These results provide clues to understanding the genetic basis of metabolic and physiological changes related to drought tolerance, potentially facilitating the genetic improvement of varieties with high drought tolerance in maize breeding programs.

Plant responses and adaptations to a changing climate.

تأثیر تنش رطوبتی بر صفات زراعی و مورفولوژیک لاینهای اینبرد نوترکیب گندم

Background: Drought stress affects crop wheat productivity by inducing biochemical changes in different tissues. Antioxidant enzymes, phenolic compounds and sugars are crucial in the plant’s defense against stress. Studying these responses in tolerant and susceptible genotypes can help improve our knowledge about drought tolerance.Objectives: This study aimed to evaluate tissue-specific (leaf, stem, spike and root) activities of antioxidant enzymes, phenolic content, soluble sugar accumulation, under moderate drought stress.Additionally, the expression of the PAL gene was analyzed in different tissues of drought-tolerant and susceptible wheat genotypes.Materials and Methods: Three wheat genotypes-susceptible (Marvdasht) and tolerants (82, 118)-were grown under drought stress and control conditions.Antioxidant enzyme activities, phenolic compounds, and sugar contents were measured in leaf, stem, and spike tissues. Quantitative Real-time PCR was used to assess PAL gene expression in leaf, stem, spike, and root tissues. Thousand-kernel weight (TKW) was measured as an indicator of performance.Results: Drought stress led to increased POD, CAT, PPO activities, and phenolic content in all tissues of the susceptible genotype (Marvdasht). However, SOD activity decreased in this genotype but increased in tolerant genotypes. Phenolic content and soluble sugar accumulation increased in all genotypes under drought, except for genotype 82, where soluble sugar decreased in the leaf tissue. PAL gene expression was down-regulated in the susceptible genotype’s stem, root, and spike, while up-regulated in the tolerant genotype’s stem. As a result of these adaptive responses, yield reduction, measured as TKW, was less severe in the tolerant genotypes compared to the susceptible genotype. Principal component analysis highlighted that drought-tolerant genotypes exhibited the highest levels of antioxidant enzyme activity and soluble sugars under stress.Conclusions: Enhanced antioxidant activity, phenolic accumulation and tissue-specific activation of the PAL gene are key factors contributing to drought tolerance in wheat.The PAL gene’s differential expression suggests distinct responses to drought stress, with the tolerant genotype exhibiting tissue-specific activation. These mechanisms moderate stress-induced damage and reduce yield loss. The study gives emphasis to the importance of integrating biochemical and molecular insights to develop drought-resistance cultivars, offering valuable implications for improving crop production under abiotic stress.

Arbuscular mycorrhizal (AM) fungal diversity of arid lands : from AM fungal species to AM fungal communities

Principal component analysis was used to search for relationships among communities of predators (Coccinellidae, Syrphidae, and Chrysopidae), aphids, and environmental conditions in crops of sorghum (Sorghum bicolor (L.) Moench) in 2016, 2017, and 2018. The aphid species collected were Schizaphis graminum (Rondani), Rhopalosiphum maidis (Fitch), and Melanaphis sacchari (Zehntner). M. sacchari was most abundant, with abrupt decrease in abundance over the years. Twelve species of Coccinellidae predators, two Chrysopidae, and 13 of Syrphidae were identified. Principal component analysis revealed a stronger relationship between M. sacchari and predators than weather. The relationship among Hippodamia convergens Guérin-Méneville, Scymnus (Pullus) dozieri Gordon, and M. sacchari was excellent.

Abiotic stress such as cold, drought, salt, and heavy metals largely influences plant development and crop productivity. Abiotic stress has been becoming a major threat to food security due to the constant changes of climate and deterioration of environment caused by human activity. To cope with abiotic stress, plants can initiate a number of molecular, cellular, and physiological changes to respond and adapt to such stresses. Better understanding of the plant responsiveness to abiotic stress will aid in both traditional and modern breeding applications towards improving stress tolerance. Studies on some special wild plant species with high stress tolerance also greatly contribute to our understanding of stress tolerance. With the development of modern molecular biology, genomics approaches have been applied in crop breeding while not popularly in practice. In this special issue, B. A. Akpinar et al. present a compressive review on genomic approaches, including structure genomics, comparative genomics, and functional genomics, for crop improvement against abiotic stress. Some traditional and modern genomics approaches of crop improvement, such as expressed sequence tag (EST) profiling, microarray, Targeting Induced Local Lesions IN Genomes (TILLING), and next generation sequencing (NGS), are summarized in this review. In the other review paper, H. Budak et al. focused on the studies of drought tolerance in modern and wild wheat. They reviewed recent advances on drought related gene/QTL identification, studies on drought related molecular pathways, and current efforts on the improvement of wheat cultivars for drought tolerance. The exploitation and utilization of crop germplasm resources are the basis of crop breeding. However, with continuous collection of germplasm resources, the size of populations has been becoming bigger, which hinders the evaluation and utilization of the germplasm resources. Constructing core collection is an efficient way to solve the problem. A core collection is a representative sample of the whole collection which has minimum repetitiveness and maximum genetic diversity of a plant species. J. Wang et al. suggest a strategy to construct a core collection based on drought resistant germplasm resources in wheat. The results showed that the strategy was effective and was valuable in another crop's core collection construction. The wild plant species with high tolerance to abiotic stress have attracted more and more attentions of plant biologists, especially when the studies within a crop species on improving the stress tolerance show the limitation. Understanding the mechanisms for stress tolerance achieved by these wild species will help in crop improvement; even some relatives can be directly or indirectly applied in crop breeding by cytological ways. H. Budak et al. introduce the research advances on wild emmer wheat which is important for its high drought tolerance. W. Liu et al. present cold induced physiological responses of naked oats (Avena nuda L.), a cold-tolerant plant species, and show that the cold tolerance involves the increase of antioxidant activities of several reactive oxygen species (ROS) savaging enzymes. The heavy metal contamination is an environmental problem in the margin sea. H.-p. Jiang et al. studied the responses of green algae species Ulva prolifera and Ulva linza to Cd2+ and concluded the major physiological parameters involved in the Cd2+ adaptation. It is necessary to further clarify the mechanisms underlying plant stress responses through modern biological technologies, especially to understand stress responses of some wild plant species with extremely high stress tolerance, which will be eventually applied in developing crops with high stress tolerance. Ji Huang Alexander Levine Zhoufei Wang

More than half of the maize crops in the Russian Federation are located in areas with insufficient and unstable moisture. With this in mind, Z. mays breeding for drought tolerance is extremely important. The purpose of the current study is: investigate the drought tolerance of self-pollinated maize lines by various methods, identify the best samples for further breeding, establish indirect criteria for estimating drought tolerance. The study was conducted at the Agricultural Research Center “Donskoy” located in the southern part of the Rostov region, which is characterized by unstable moisture. The years of the study turned out to be dry (Selyaninov Hydrothermal Coefficient (HTC) = 0.32–0.89). The new self-pollinated lines of maize were used as initial material and studied for resistance to water stress (41 pcs. in 2011–2013, 39 pcs. in 2015–2017, 25 pcs. in 2018–2020). According to the guidelines for maize breeding, the following indicators of productivity were taken into account: number of ears per plant, weight of one ear, 1000-grain weight, number of grains per ear, etc. In 2011–2013, based on the comprehensive estimation, new middle-early drought-tolerant self-pollinated lines of maize ‘DK47111’, ‘SP203’, ‘KS211’, ‘S204’ and ‘S238’ were identified. They were characterized by the low values of residual water deficit both in the flowering (6.9 – 12.8%) and milk-wax (9.0 – 13.4%) stage, high drought tolerance index (68.6 – 85.6%), deep root system (force of uprooting the plants from the ground was 54.0–67.7 kgf), minimum gap in the flowering of male and female inflorescences (1–2 days). In 2015–2017, according to the method of residual water deficit (RWD), the following lines were identified ‘KV334’, ‘RD6’, ‘DS498/217-4’, ‘DS257/85-3’, ‘DS257/85-1’, ‘DS257/85-6’, ‘DS257/85-4’. In 2018–2020, the new self-pollinated lines of maize ‘KS317A’, ‘KV240’, ‘LSh16’, ‘S86’, ‘LSh17’ and ‘LSh2’ showed high resistance to water stress. We recommend the following selection criteria when creating new lines: absence of infertility and kernel percentage of the ears.

BackgroundAbiotic stresses due to environmental factors could adversely affect the growth and development of crops. Among the abiotic stresses, drought and heat stress are two critical threats to crop growth and sustainable agriculture worldwide. Considering global climate change, incidence of combined drought and heat stress is likely to increase. The aim of this study was to shed light on plant growth performance and leaf physiology of three tomatoes cultivars (‘Arvento’, ‘LA1994’ and ‘LA2093’) under control, drought, heat and combined stress.ResultsShoot fresh and dry weight, leaf area and relative water content of all cultivars significantly decreased under drought and combined stress as compared to control. The net photosynthesis and starch content were significantly lower under drought and combined stress than control in the three cultivars. Stomata and pore length of the three cultivars significantly decreased under drought and combined stress as compared to control. The tomato ‘Arvento’ was more affected by heat stress than ‘LA1994’ and ‘LA2093’ due to significant decreases in shoot dry weight, chlorophyll a and carotenoid content, starch content and NPQ (non-photochemical quenching) only in ‘Arvento’ under heat treatment. By comparison, the two heat-tolerant tomatoes were more affected by drought stress compared to ‘Arvento’ as shown by small stomatal and pore area, decreased sucrose content, ΦPSII (quantum yield of photosystem II), ETR (electron transport rate) and qL (fraction of open PSII centers) in ‘LA1994’ and ‘LA2093’. The three cultivars showed similar response when subjected to the combination of drought and heat stress as shown by most physiological parameters, even though only ‘LA1994’ and ‘LA2093’ showed decreased Fv/Fm (maximum potential quantum efficiency of photosystem II), ΦPSII, ETR and qL under combined stress.ConclusionsThe cultivars differing in heat sensitivity did not show difference in the combined stress sensitivity, indicating that selection for tomatoes with combined stress tolerance might not be correlated with the single stress tolerance. In this study, drought stress had a predominant effect on tomato over heat stress, which explained why simultaneous application of heat and drought revealed similar physiological responses to the drought stress. These results will uncover the difference and linkage between the physiological response of tomatoes to drought, heat and combined stress and be important for the selection and breeding of tolerant tomato cultivars under single and combine stress.

Synergistic regulatory networks mediated by microRNAs and transcription factors under drought, heat and salt stresses in Oryza Sativa spp.

Drought and heat tolerance tests that were developed for sorghum (Sorghum bicolor L. Moench) were adapted to and evaluated in field grown wheat (Triticum aestivum L. and T. durum Desf.) during 1977/1978 and 1978/1979.The drought tolerance test is based on the measurement of the electroconductivity of aqueous media containing leaf discs that were previously water stressed in vitro by exposure to a solution of polyethylene glycol‐6,000 (PEG). The heat tolerance test is similarly based on exposure of leaf discs to heating, in vitro, to 44 C.Drought tolerance of wheat leaves decreased with plant age. For a given plant growth stage, some variation was revealed in drought tolerance, according to leaf position. Maximal separation of wheat cultivars in drought tolerance was obtained with 40% (w/v) solution of PEG, when plants were grown under conditions of favorable moisture regime and sampled during the late jointing growth stage.Wheat was more drought tolerant than maize, sorghum or millet, based on published data.When plants were sampled during a period of water stress, they were more drought tolerant than well‐watered plants, indicating adjustment of cell membrane stability to drought stress. Wheat cultivars varied in their ability to adjust, in this respect.Unlike in sorghum, drought and heat tolerance were not correlated in wheat.The inclusion of a limited number of barley (Hordeum vulgare) and triticale (X Triticosecale Wittmark) genotypes in this study indicated that the methods discussed work equally well with these crop plants.

Genome-wide in silico analysis of dehydrins in Sorghum bicolor, Setaria italica and Zea mays and quantitative analysis of dehydrin gene expressions under abiotic stresses in Sorghum bicolor