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The common wheat (Triticum aestivum L.) is a poly(hexa)ploid, derived from an amphi-diploidization process involving the donor species—Triticum urartu, Aegilops speltoides, Triticum turgidum, and Aegilops tauschii. The genetic diversity of the autogamous wheat is narrow, which is a major reason for lesser rate of yield gain in wheat, in contrast to rice and maize. It is desirable to encourage hybrid breeding, i.e., combining different lines into genetically divergent heterotic pools. Thus, hybrid plants are a unique combination of desired alleles produced by crossing between genetically different parental lines. Hybrid seed production in a crop requires male-sterile female parents along with a reliable outcrossing system. The male-sterile female parent prevents pollen shedding and self-fertilization, maintaining the purity of hybrid seeds. An outcrossing system enhances hybrid seed production. This article emphasizes the biological relevance of crossbreeding and self-pollination in wheat, and reviews different male sterility systems which could be utilized for the development of hybrid wheat. Several biotechnological approaches and their practical utility in generating crosscompatible male-sterile female parent lines have been discussed.
Cyanobacteria are known to biosynthesize mycosporine-like amino acids (MAAs) as photoprotective compounds against ultraviolet radiation. Anabaena sp., isolated from the hot springs of Rajgir, India, produces a single MAA shinorine (retention time = 2.2 min and absorption maximum at 334 nm) as purified by high-performance liquid chromatography. The MAA biosynthesis was under constitutive control in this cyanobacterium; however, PAR + UV-A + UV-B radiation was found to have highest impact on MAA synthesis. MAA biosynthesis is dependent on photosynthesis for the carbon source since the inhibitory effect of DCMU on MAA synthesis was overcome by externally added fructose. Our results suggest that there is no direct involvement of photosystem II dependent linear electron transport in MAA biosynthesis. However, utilization of energy derived from photosystem I dependent cyclic electron transport in MAA biosynthesis cannot be ruled out. This study also reveals that photoheterotrophic growth can support highest MAA biosynthesis under laboratory conditions in comparison with photoautotrophic and photomixotrophic growth. Thus, photoheterotrophic growth condition can be used for the large-scale production of pharmaceutically important MAAs from cyanobacteria for an industrial application.
A pot experiment was carried out under controlled conditions to evaluate the combined effect of chemical oxygen demand and heavy metals in synthetic irrigation water on the accumulation of heavy metals in perennial rye grass (Lolium perenne) grown during 30 days on two soils: an acidic sandy soil (pH = 4.0), and the same soil amended with 5% clay (pH = 6.7). The dry matter yield of rye grass decreased and heavy metal concentrations in plant tissue increased with heavy metal concentration in the irrigation water. A higher COD concentration in the irrigation water also resulted in an overall decrease of dry matter yield and higher metal contents. The addition of 5% clay to the acidic soil reduced these effects. However, the clay content of the soil was by far the most important factor in controlling plant growth and metal uptake.
This study reports a comparison of differential physiological and biochemical changes in two Indian Mustard (Brassica juncea L.) cultivars viz. CS-52 (salinity tolerant) and Ashirwad (salinity susceptible) after 15 days of gradual increase in NaCl concentration in the nutrient solution. The increase in the NaCl concentration in the nutrient solution was as follows: 25 mM for 2 days, 50 mM for 2 days, 75 mM for 2 days, 100 mM for 2 days, 125 mM for 2 days, and 150 mM for 5 days. After 15 days of salinity stress, we observed a sharp decline in dry matter content and leaf area in Ashirwad. These effects were, however, less pronounced in CS-52. Under high salinity conditions, CS-52 maintained a better physiological status as determined by higher relative water content, higher water use efficiency, and lower leaf temperature and electrolytic leakage ratio, compared to Ashirwad. CS-52 was also observed to be more efficient regarding gas-exchange parameters (stomatal conductance and transpiration) and photosynthetic capacity. Moreover, salt-induced changes in accumulation and distribution patterns, and the ratios of major macro- and microelements were recorded to be more favorable in CS-52 compared to Ashirwad. The study also revealed that salinity-induced relative changes in the concentrations and compositions of biomolecules such as lipids, proteins, and carbohydrates, and structural rearrangements in the side chains of proteins were less prominent in CS-52 indicating better preparedness and thus more adaptability of CS-52 towards salinity.
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