Enhancing rainfed safflower yield, oil content, and fatty acid composition through intercropping with chickpea and stress-modifier biostimulants

This study investigated the impact of stress modifiers in intercropping systems on seed yield and yield components, physiological traits, and antioxidant activity of safflower (Carthamus tinctorius L.) and chickpea (Cicer arietinum L.) under rainfed (water deficit) conditions. The experimental design included three stress modulator levels [control, 1 mM salicylic acid (SA), and 10 mM selenium (Se)] and five planting patterns [intercropping one row of safflower and two rows of chickpeas (1S:2C), two rows of safflower and four rows of chickpeas (2S:4C), and three rows of safflower and five rows of chickpeas (3S:5C), and sole cropping of safflower (Ss) and chickpea (Cs)]. The results revealed that Ss treated with Se produced the highest safflower biological yield (4,905.50 kg ha−1) and seed yield (1,259.50 kg ha−1), while Cs produced the highest chickpea biological yield (2,799.67 kg ha−1) and seed yield (852.44 kg ha−1), followed by Cs treated with SA (2,419.25 kg ha−1 and 764.83 kg ha−1, respectively). Conversely, the 3S:5C intercropping ratio (IR) with Se application recorded the highest safflower oil content (32.08%), while Ss treated with Se produced the highest oil yield (358.62 kg ha−1). The 2S:4C configuration with Se application produced the highest unsaturated fatty acid (oleic and linoleic acids) concentrations in safflower, while 2S:4C and 3S:5C treated with Se produced the highest chlorophyll a and chlorophyll b contents in safflower and chickpea. Furthermore, 1S:2C and 2S:4C treated with SA or Se produced the highest proline and total soluble sugars in safflower and chickpea. The SA and Se treatments in the intercropping systems increased catalase, ascorbate peroxidase, and superoxide dismutase activities compared to the respective control plants (sole cropping) and enhanced oil contents, fatty acid composition, physiological traits, and antioxidant properties. These results underscore the potential of intercropping systems coupled with stress modulator treatments as a sustainable approach for safflower and chickpea cultivation under rainfed conditions

Plant–Microbe Interaction

Plant–microbe interaction is a complex, dynamic and continuous process that is as old as plant colonization on Earth [...

Impact of Exogenous Ascorbic Acid on Antioxidant Activity and Some Physiological Traits of Common Bean Subjected to Salinity Stress

The role of ascorbic acid as a key molecule antioxidant involves in biotic and abiotic stress has already been well described. Recent study indicates that it also participates in the detoxification of generated reactive oxygen species due to abiotic stresses. Thus, In order to study effects of salt stress and ascorbic acid on antioxidant enzyme activity, chlorophyll content, lipid peroxidation and abscisic acid accumulation of bean an experiment was conducted. The exogenous application of ascorbic acid in nutrition solution of bean plants indicated that later is involve in reduction of antioxidant enzyme activity and increase of resistance to salt stress. We observed that antioxidant enzyme activity increased due to salt stress and ascorbic acid via eliminating of reactive oxygen species decreased activities. Moreover, abscisic acid and lipid peroxidation were affected of salt stress. Increase of ascorbic acid concentration at 100 mM NaCl treatment prevented of lipid peroxidation and decreased generation of malondialdehyde as final product of peroxidation of membrane lipids. However, at high level of salinity, ascorbic acid did not significant effect on reduction of lipid peroxidation. Whereas, chlorophyll content decreased by reactive oxygen species. Ascorbic acid increased chlorophyll content at all of stressed and non-stressed treatments. Abscisic acid assay showed that, accumulation of this hormone increased under salt stress treatments and raise of ascorbic acid concentration in nutrition solution of stressed plants prevented of abscisic acid accumulation. Our data provide strong support to the hypothesis that exogenous of ascorbic acid reduces the harmful effects of salinity and increases resistance to salinity in bean plant

Genomic Variations and Mutational Events Associated with Plant–Pathogen Interactions

Phytopathologists are actively researching the molecular basis of plant–pathogen interactions. The mechanisms of responses to pathogens have been studied extensively in model crop plant species and natural populations. Today, with the rapid expansion of genomic technologies such as DNA sequencing, transcriptomics, proteomics, and metabolomics, as well as the development of new methods and protocols, data analysis, and bioinformatics, it is now possible to assess the role of genetic variation in plant–microbe interactions and to understand the underlying molecular mechanisms of plant defense and microbe pathogenicity with ever-greater resolution and accuracy. Genetic variation is an important force in evolution that enables organisms to survive in stressful environments. Moreover, understanding the role of genetic variation and mutational events is essential for crop breeders to produce improved cultivars. This review focuses on genetic variations and mutational events associated with plant–pathogen interactions and discusses how these genome compartments enhance plants’ and pathogens’ evolutionary processes

Effect of Salinity on Growth, Xylem Structure and Anatomical Characteristics of Soybean

This research was conducted in order to evaluation the salinity stress effect on growth parameters and stem anatomical changes of soybean grown under controlled conditions. Soybean seeds were surface sterilized and then sown into plastic pots filled up with perlite and vermiculite. Seeds were irrigated with Broughton and Dilworth solution daily. At full folded cotyledons stage (5 day after sowing), salinity stress was induced by adding NaCl into nutrition solution with final concentration of 0, 25, 50 and 100 mM. Thirty days after sowing plants were harvested and growth parameters and anatomical changes were evaluated. The results showed that, salinity stress was significantly decreased shoot and root weight either fresh weight or dry weight, in addition, total plant weight, plant height and leaf number were decreased due to salinity stress. Interestingly, leaf area was not affected by salinity stress. Stem microscopic study demonstrated that, salinity stress significantly increased cutin mass and trichome density on epidermal cells. On the other hand, cortex thickness was decreased because of salinity stress while xylem thickness had upward increase when soybean plants were grown under salinity stress especially high level of salinity. Additionally, there were changed in xylem formation and arrangement in stressed plants

Impact of Inter-Row Spacing on Yield and Yield Components of several Annual Medics Species

A field study was conducted in Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran to evaluate the effects of three within-row spacing treatments (20, 30 and 40 cm) on forage and seed production of five species of annual medics (Medicago scutellata cv. �Sava�; M. littoralis cv. �Herald�; M. polymorpha cv. �Santiago�; M. minima cv. �Orion� and M. truncatula cv. �Mogul�). The experiment was carried out in Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran. The results of the experiment indicated that M. polymorpha had the highest forage yield out of the highest plant population. Latter with average 443.09 Kg ha-1 and M. scutellata with average 409.99 Kg ha-1 produced the highest seed yield. Also, the last species with 1306.78 Kg ha-1 had the highest pod yields. The highest seed yield and pod yield were produced at 20 cm within-row spacing because there were not adequate plants for maximum seed and pod yields in 30 and 40 cm within-row spacing. The tested plant densities did not affect on seeds number per pod, 1000 seeds weight and seeds to burr pod weight ratio. The M. truncatula and M. minima have the highest seeds number per pod. In addition, M. scutellata had the highest 1000 seeds weight with an average of 12.57 g. The highest seeds to burr pod ratio was observed in M. polymorpha. The most pod numbers were obtained in 20 and 30 cm within-row spacing and M. polymorpha while, the least pod numbers was observed in M. scutellata. Plant densities did not affect on pod numbers of the mentioned species. The highest dry forage yield was produced in 20 cm within-row spacing. Among the tested tested species, M. truncatula had the highest forage yield with average 870.07 Kg ha-1. This experiment indicated that there is possibility for seed and forage production of tested annual medics in the mentioned zone with the considering suitable plant densities

Copy number variation and disease resistance in plants

Plant genome diversity varies from single nucleotide polymorphisms to large-scale deletions, insertions, duplications, or re-arrangements. These re-arrangements of sequences resulting from duplication, gains or losses of DNA segments are termed copy number variations (CNVs). During the last decade, numerous studies have emphasized the importance of CNVs as a factor affecting human phenotype; in particular, CNVs have been associated with risks for several severe diseases. In plants, the exploration of the extent and role of CNVs in resistance against pathogens and pests is just beginning. Since CNVs are likely to be associated with disease resistance in plants, an understanding of the distribution of CNVs could assist in the identification of novel plant disease-resistance genes. In this paper, we review existing information about CNVs; their importance, role and function, as well as their association with disease resistance in plants

Effect of Ascorbic Acid Foliar Application on Yield, Yield Component and several Morphological Traits of Grain Corn under Water Deficit Stress Conditions

In order to study effect of ascorbic acid foliar application on morphological traits, yield and yield components of grain corn under conditions of water stress, an experiment was conducted in Tarbiat Modares University, Tehran, Iran in 2006 growing season. Experimental design was RCBD (Randomized Complete Block Design) and treatments were sat in split-split plot arrangement. Water deficit stress treatment with three levels (no stress, vegetative phase stress and reproductive phase stress) was allocated to main plots. Ascorbic acid was used at two time (vegetative phase and reproductive phase) and four concentration (0, 50, 100 and 150 mgl-1) as sub plots and sub-sub plots, respectively. The results demonstrated that water deficit stress and ascorbic acid foliar application had significant effect on upon traits. Water deficit stress significantly decreased dry or fresh weight of plants at two growing phases, but leaf area was just decreased due to water deficit stress at vegetative phase. Regarding yield and yield components, a significant decrease was observed when plants were water stressed. Its notable that final yield was more affected when plants were stressed at reproductive phase than those were stressed at vegetative phase. Ascorbic acid foliar application increased stem and leaf dry weight and leaf fresh weight. In addition, an increase was observed in grain weight when plants were treated by 150 mgl-1 ascorbic acid at two growing phases and no stress and vegetative stress. The highest infertile grains were observed in reproductive stress and without ascorbic acid plots while ascorbic acid foliar application led to increase of grain fertility. In general, these results suggests that ascorbic acid foliar application decreases adverse effects of water deficit stress and improves growth and production at normal and stressed conditions

Agrobacterium rhizogenes transformed soybean roots differ in their nodulation and nitrogen fixation response to genistein and salt stress

We evaluated response differences of normal and transformed (so-called 'hairy') roots of soybean (Glycine max L. (Merr.), cv L17) to the Nod-factor inducing isoflavone genistein and salinity by quantifying growth, nodulation, nitrogen fixation and biochemical changes. Composite soybean plants were generated using Agrobacterium rhizogenes-mediated transformation of non-nodulating mutant nod139 (GmNFR5α minus) with complementing A. rhizogenes K599 carrying the wild-type GmNFR5α gene under control of the constitutive CaMV 35S promoter. We used genetic complementation for nodulation ability as only nodulated roots were scored. After hairy root emergence, primary roots were removed and composite plants were inoculated with Bradyrhizobium japonicum (strain CB1809) pre-induced with 10 μM genistein and watered with NaCl (0, 25, 50 and 100 mM). There were significant differences between hairy roots and natural roots in their responses to salt stress and genistein application. In addition, there were noticeable nodulation and nitrogen fixation differences. Composite plants had better growth, more root volume and chlorophyll as well as more nodules and higher nitrogenase activity (acetylene reduction) compared with natural roots. Decreased lipid peroxidation, proline accumulation and catalase/peroxidase activities were found in 'hairy' roots under salinity stress. Genistein significantly increased nodulation and nitrogen fixation and improved roots and shoot growth. Although genistein alleviated lipid peroxidation under salinity stress, it had no significant effect on the activity of antioxidant enzymes. In general, composite plants were more competitive in growth, nodulation and nitrogen fixation than normal non-transgenic even under salinity stress conditions

Exogenous 5-Aminolevulenic Acid Promotes Antioxidative Defence System, Photosynthesis and Growth in Soybean against Cold Stress

In the present study, the possibility of enhancing cold stress tolerance of young soybean plants (Glycine max [L.] Merr) by exogenous application of 5-aminolevulinic acid (ALA) was investigated. ALA was applied at various concentrations (0, 0.3, 0.6 and 0.9 mM) by seed priming and foliar application method. After ALA treatment, the plants were subjected to cold stress at 10 ± 0.5 °C for 72 h. Cold stress significantly decreased plant growth, relative water content, chlorophyll, photosynthesis and stomatal conductivity, while it increased electrolyte leakage and proline accumulation. ALA at low concentrations (0.3 mM) protected plants against cold stress, enhancing plant height, shoot fresh and dry weight, chlorophyll content, photosynthesis, stomatal conductivity as well as relative water content. Increase of electrolyte leakage was also prevented by 0.6 mM ALA. ALA also enhanced superoxide dismutase and catalase activities at 0.6 mM concentration especially under cold stress conditions. Proline increased with increasing in ALA concentration under both temperature conditions. In most cases, application of ALA by spraying method was better than seed priming method. Results showed that ALA, which is considered as an endogenous plant growth regulator, can be used effectively to protect soybean plants from the damaging effects of cold stress, by enhancing the activity of antioxidative enzymes, protecting cell membrane against reactive oxygen species and finally by promoting chlorophyll synthesis, leading to more intense photosynthesis and more carbon fixation, without any adverse effect on the plant growth