فصلنامه ژنتیک نوین
سال نوزدهم شماره 2 (پیاپی 77، تابستان 1403)

The Snakin/GASA family consists of small, cysteine-rich peptides that are widely distributed across plant genomes, playing crucial roles in plant growth, development, and responses to biotic and abiotic stresses. In this study, the presence of the GASA gene family across various organisms was examined, and structural and expression variations of these genes were compared in different plant species. Additionally, post-translational modifications and the antimicrobial properties of GASA proteins were predicted to provide further insight into their regulatory mechanisms. Key characteristics observed for all GASA genes included the presence of the GASA domain, signal peptides, extracellular accumulation, six disulfide bridges, post-translational phosphorylation, and antimicrobial activity. Differential expression patterns were noted in various tissues (logFPKM = 0-2.5), with induction under biotic, abiotic, and hormonal stresses (logFold Change ranging from -10 to +5, particularly under drought and heat conditions). Furthermore, key cis-regulatory elements were identified in the promoter regions of these genes, highlighting the diverse roles and functions of the Snakin/GASA gene family. Physicochemical analysis revealed that most of the studied GASA proteins were unstable and hydrophobic. A strong interaction was also predicted between the GASA gene family and transcription factors from the Dof, ERF, and MYB families in both Arabidopsis and rice. Overall, these findings provide valuable insights into the functional diversity of GASA genes and offer a foundation for future research.

Nitrogen (N) is an essential macronutrient for plant growth and development, and its uptake by plants is significantly influenced by environmental stresses. Enhancing nitrogen use efficiency (NUE) is therefore crucial for minimizing nitrogen fertilizer consumption, mitigating environmental pollution, promoting plant growth, and optimizing agricultural management systems, especially in response to changing environmental stresses. Plants possess the ability to withstand potentially lethal high temperatures through thermopriming and the establishment of heat stress memory. However, the relationship between nitrogen uptake and the acquisition of thermal tolerance remains unclear. In this study, the hub proteins involved in nitrogen uptake in canola plants were first identified as having the most interactions among all nodes in the protein network, using four computational algorithms available in the CytoHubba software. Considering the negative impact of heat stress on nitrogen uptake by plants, the relationship between heat stress memory and the expression of key genes involved in nitrogen uptake was evaluated using the qRT-PCR technique. It was observed that heat stress and heat stress memory affected the expression levels of BnNRT1 (low-affinity nitrate transporter) and BnNRT2 (high-affinity nitrate transporter). The expression levels of these transporters increased after exposure to high temperatures following thermopriming, compared to non-primed plants. Therefore, it appears that the effects of heat stress memory on the expression of nitrogen transporter genes can be used as an efficient strategy for reducing the sensitivity threshold of rapeseed plants to recurrent high-temperature stresses by maintaining nitrogen uptake under heat stress.

There has been extensive ongoing research on honey bees over the last 100 years, mainly due to their vital role in society, particularly in agriculture, economics, food security, medicine, and even computing technologies. Our knowledge is growing faster than our ability to absorb it. The most common and prominent honey bee species in Iran is the western honey bee, Apis mellifera, which includes the Iranian honey bee, Carniolan, and Iranian × Carniolan hybrids. The objective of this study was to identify the effects of crossbreeding on population dynamics, egg-laying rate, propolis production, honey yields, pollen collection, and defensive behavior in Iranian (Apis mellifera meda) bees. In early March 2021 (the end of the colonies' wintering season), eight colonies of each of the three bee breeds were randomly selected and standardized based on honey and pollen storage, the number of brood frames, initial population, and hive type (Langstroth hives). The tested colonies did not receive any chemical treatments during the experiment. Data collection and recording of egg-laying rates and brood rearing were conducted weekly during spring 2021 at the Honey Bee Research Centre, University of Kurdistan, Sanandaj, Iran (35.27788; 46.99562). Data quality control and analysis were performed using the SAS program. The results showed that Iranian × Carniolan hybrids were more efficient than the parental stocks in terms of population dynamics and pollen collection (p<0.05), indicating positive heterosis and complementarity between the breeds. Carniolan (Apis mellifera carnica) bees demonstrated significantly favorable performance for honey yields (p<0.05). Iranian (Apis mellifera meda) bees were superior in propolis production and exhibited higher levels of aggressiveness, significantly (p<0.05). Heterosis was estimated based on the superiority of observed phenotypes in the hybrids relative to their inbred parents. The estimated heterosis values were -3.8% for honey yields, 32.6% for pollen collection, 10.0% for egg-laying rate, 24.5% for population growth rate, -2.1% for propolis production, and -16.3% for aggressiveness. The highest level of phenotypic diversity was observed in the Iranian honey bee, suggesting the potential benefits of this breed for selection programs. Additionally, the findings revealed that the controlled use of higher-performance lines, either in pure or hybrid forms, will improve the efficiency of honey bee colonies and is recommended.

Cold stress is one of the major factors limiting rice (Oryza sativa L.) productivity and yield. Two rice cultivars were chosen for this study: a japonica rice, ‘Gerde’, and an indica rice, ‘Shiroodi’, representing tolerant and sensitive cultivars, respectively. In this work, the early physiological and molecular responses of these two cultivars to 4°C cold stress were investigated. We found that cold stress caused a significant decrease in the content of chlorophyll a, chlorophyll b, and carotenoids in both rice cultivars. However, the photosynthetic pigment content in the Shiroodi cultivar decreased to a greater extent, indicating its limited genetic capacity to protect its photosynthetic machinery. During cold stress, the amounts of hydrogen peroxide and malondialdehyde produced by the Shiroodi cultivar were significantly higher than those in Gerde, suggesting a lower capacity of Shiroodi to scavenge reactive oxygen species. The higher level of beta-glucosidase gene expression in the final hours of cold treatment in the Gerde cultivar indicates the involvement of this enzyme in elevating cellular levels of active abscisic acid. Moreover, the significant increase observed in the transcript level of phenylalanine-ammonia-lyase in Gerde indicates the induction of defense responses related to the phenylpropanoid pathway. Altogether, one can conclude that the higher cold tolerance of the Gerde cultivar is multifaceted, involving various factors such as its ability to protect its photosynthetic machinery, its greater capacity for cell protection against oxidative stress, and the expression modulation of genes involved in abscisic acid metabolism and secondary metabolism.

Queen breeding has always been one of the main pillars of beekeeping, requiring experience and the use of modern, scientific techniques. The use of advanced tools in queen bee rearing, including breeding cells, significantly impacts various aspects related to the quality, as well as the physiological and morphological parameters of the queen. Additionally, it is widely accepted that queen quality is directly related to their weight and size at birth. Therefore, the purpose of this study was to compare queen rearing in three different sizes (small, medium, and large) and examine the effect of temperature stresses on the expression of heat shock protein genes. To achieve this goal, 36 queens were used in a factorial 3×2 experiment, with three queen sizes (large, medium, and small) and two levels of stress (temperatures below 4°C and above 40°C). The experiment followed a completely randomized design with 6 treatments and 6 repetitions. RNA was extracted from frozen samples of the combined thoracic region of 3 queens to assess its quality. The quality and quantity of the extracted RNA were analyzed using agarose gel and nanodrop, respectively. Subsequently, cDNA was synthesized, and the relative gene expression was analyzed using Real-Time PCR. The results showed that larger queens exhibited greater resistance to heat stress (P=0.01). Under cold stress conditions, no significant difference was observed in terms of queen size. In summary, the size of the queen rearing cells affected tolerance to heat stress but had no effect on cold stress.

Ashwagandha, or Indian ginseng (Withania somnifera), is of considerable importance in the Solanaceae family due to the presence of a group of steroid lactones called withanolides. Given the limited production of these metabolites in the roots and leaves of the plant under natural conditions and the high demand from the pharmaceutical industry, it is crucial to use the hairy root method to increase metabolite production. To induce bacteria under laboratory conditions, tissue culture and its various steps are typically required. However, nowadays, an alternative and simpler transgenic method is used that does not rely on tissue culture and can produce transgenic plants with an increased yield of secondary metabolites. In this experiment, Agrobacterium rhizogenes strain A4 was injected into the plant at the wound site located at the first node of the seedling. Fifteen days later, hairy roots appeared, and after the growth of the transgenic plants in the greenhouse, growth characteristics (such as root volume and root area) were measured, and phytochemical analyses were performed on both transgenic and control plants. The experiment followed a completely randomized design with 3 replications. The transgenic plants outperformed the controls in terms of agronomic traits: root length (1.12 times longer), root volume (2 times greater), and root area (1.49 times larger). As a result of this study, catalase enzyme activity and flavonoid levels were found to be lower in transgenic plants than in control plants. Correlation results showed that catalase enzyme activity and flavonoid content had positive and significant correlations with root length, volume, and area. Based on the findings of this research, the transgenic method, without the need for tissue culture, can be introduced as a useful approach in this plant to increase root hair production without increasing antioxidant enzyme activity.