Response of stigma receptivity in CMS and male fertile line of Indian mustard (B. juncea) under variable thermal conditions.

Field experiments were conducted for 2 years to examine the response of stigma in two different pollination systems, viz., CMS line (MJA5) and open-pollinated variety (Pusa Bold) of Indian mustard (Brassica juncea), to varying weather conditions created by different sowing dates. The CMS line MJA5 (female) with its male line in 8:2 (A:R) row ratio, and Pusa Bold in an isolated field were sown on 21st of October, 30th of October, and 18th of November in 2 consecutive years in North Indian condition. Temporal differences in sowing provided differed weather conditions during flowering, which resulted in variations in the duration to attain the peak flowering stage. Stigma was receptive for longer duration (8 days from the day of anthesis) in CMS line which needs an external pollen source for fertilization to happen, whereas it was only 4 days in open-pollinated variety, assessed in terms of siliqua set and number of seeds/siliqua. Substantial effect of sowing date on stigma receptivity was observed; it was longer in plants sown during October in comparison to those of November in both years. The energy requirement parameters, viz., growing degree days and photo-thermal unit, confirmed that plants sown later failed to accumulate sufficient energy for satisfactory phenological growth and for good seed development.

Coenzyme Q10 production in plants: current status and future prospects.

Coenzyme Q10 (CoQ10) or Ubiquinone10 (UQ10), an isoprenylated benzoquinone, is well-known for its role as an electron carrier in aerobic respiration. It is a sole representative of lipid soluble antioxidant that is synthesized in our body. In recent years, it has been found to be associated with a range of patho-physiological conditions and its oral administration has also reported to be of therapeutic value in a wide spectrum of chronic diseases. Additionally, as an antioxidant, it has been widely used as an ingredient in dietary supplements, neutraceuticals, and functional foods as well as in anti-aging creams. Since its limited dietary uptake and decrease in its endogenous synthesis in the body with age and under various diseases states warrants its adequate supply from an external source. To meet its growing demand for pharmaceutical, cosmetic and food industries, there is a great interest in the commercial production of CoQ10. Various synthetic and fermentation of microbial natural producers and their mutated strains have been developed for its commercial production. Although, microbial production is the major industrial source of CoQ10 but due to low yield and high production cost, other cost-effective and alternative sources need to be explored. Plants, being photosynthetic, producing high biomass and the engineering of pathways for producing CoQ10 directly in food crops will eliminate the additional step for purification and thus could be used as an ideal and cost-effective alternative to chemical synthesis and microbial production of CoQ10. A better understanding of CoQ10 biosynthetic enzymes and their regulation in model systems like E. coli and yeast has led to the use of metabolic engineering to enhance CoQ10 production not only in microbes but also in plants. The plant-based CoQ10 production has emerged as a cost-effective and environment-friendly approach capable of supplying CoQ10 in ample amounts. The current strategies, progress and constraints of CoQ10 production in plants are discussed in this review.

Plant regeneration from mature embryo of commercial Indian bread wheat (Triticum aestivum L.) cultivars.

A simple, efficient, reproducible and comparatively genotype-independent in vitro plant regeneration protocol was developed for ten commercial Indian bread wheat cultivars using mature embryos as the explants. Three different auxins and five different combinations of growth regulators in a modified Murashige and Skoog's basal medium were assessed for their effect on callus induction and plant regeneration, respectively, in a high yielding and widely grown cultivar, PBW-343. The optimized conditions were further evaluated with nine other commercial cultivars. A simple novel approach of physical isolation of regenerable calli from non regenerable structures during the early callus phase was used to improve plant regeneration. Callus induced on 2.0 mg(-1) 2,4-dichlorophenoxyacetic acid (2,4-D) showed a regeneration frequency of 86 % with 7.5 shoots per explants on hormone-free medium. A considerable improvement in the regeneration frequency (up to 97 %) and the average of shoots (19 shoots per explants) was obtained with a combination of thidiazuron (TDZ) and 2,4-D.