Does breeding system affect pollen morphology? A case study in Zygophylloideae (Zygophyllaceae).

KEY MESSAGE: We found a correlation between large pollens and selfing and between psilate pollen walls and cleistogamy. Flowering plants display extraordinary diversity in pollen morphology, yet the functional significance of this variation is not well understood. Zygophylloideae is a lineage characterized by high diversity of breeding systems, ranging from obligate selfing to facultative selfing and further to facultative outcrossing. This group is particularly suitable for testing hypotheses about the influence of breeding system on pollen morphology. We studied pollen morphology in 20 species of Zygophylloideae and one species of Tribuloideae as an outgroup. A phylogeny of Zygophylloideae was created based on available DNA sequences and used to trace the evolution of pollen characters. We performed a phylogenetic analysis of correlated evolution between breeding system and several pollen characters. Three types of pollen morphology were found in the studied species. Tricolporate pollen with a small apocolpium, microreticulate ornamentation and medium size was determined as the ancestral state in Zygophylloideae. The correlation analysis indicated an association between large pollens and selfing and between psilate pollen wall and cleistogamy. We hypothesize that large size of pollen in selfing species is mainly associated with the low number of produced pollen indicating a trade-off between pollen size and number. The independence from pollen vector in cleistogamous flowers accounts for the evolution of smooth pollen walls in these species.

Synergistic effects of melatonin and distinct spectral lights for enhanced production of anti-cancerous compounds in callus cultures of Fagonia indica.

Fagonia indica is one of the commercially vital medicinal plant species. It is well-known for biosynthesis of anticancer phenolics and flavonoids metabolites. The plant has been exploited for in vitro studies and production of vital phytochemicals, however, the synergistic effects of melatonin and lights remains to be investigated. In current study, we have evaluated the synergistic effects of melatonin and different light emitting diodes (LEDs) in callus cultures of F. indica. Both, light and melatonin play vital role in physiological and biochemical processes of plant cell. The highest Fresh weight (FW: 320 g/L) and Dry weight (DW: 20 g/L) was recorded in cultures under white LEDs. Optimum total phenolics content (11.3 µg GAE/mg), total flavonoids content (4.02 µg QAE/mg) and Free radical scavenging activity (97%) was found in cultures grown under white LED and melatonin. Furthermore, cultures maintained under white light were also found with highest levels of phenolic and flavonoids production (total phenolic production; 226.9 µg GAE/mg, Total flavonoid production; 81 µg QAE/mg) than other LED-grown cultures. However, the antioxidant enzymes; Superoxide dismutase (SOD: 0.53 nM/min/mg FW) and Peroxidase (POD:1.18 nM/min/mg FW) were found optimum in cultures grown under blue LED. The HPLC data showed that enhanced total production of metabolites was recorded in cultures under white LED (6.765 µg/mg DW) than other lights and control. The findings of this study comprehend the role of melatonin and influence of light quality on biomass accumulation and production of phytochemicals in callus cultures of F. indica.

Differential Effects of Thidiazuron on Production of Anticancer Phenolic Compounds in Callus Cultures of Fagonia indica.

Fagonia indica, a very important anticancer plant, has been less explored for its in vitro potential. This is the first report on thidiazuron (TDZ)-mediated callogenesis and elicitation of commercially important phenolic compounds. Among the five different plant growth regulators tested, TDZ induced comparatively higher fresh biomass, 51.0 g/100 mL and 40.50 g/100 mL for stem and leaf explants, respectively, after 6 weeks of culture time. Maximum total phenolic content (202.8 µg gallic acid equivalent [GAE]/mL for stem-derived callus and 161.3 µg GAE/mL for leaf-derived callus) and total flavonoid content (191.03 µg quercetin equivalent [QE]/mL for stem-derived callus and 164.83 µg QE/mL for leaf-derived callus) were observed in the optimized callus cultures. The high-performance liquid chromatography (HPLC) data indicated higher amounts of commercially important anticancer secondary metabolites such as gallic acid (125.10 ± 5.01 µg/mL), myricetin (32.5 ± 2.05 µg/mL), caffeic acid (12.5 ± 0.52 µg/mL), catechin (9.4 ± 1.2 µg/mL), and apigenin (3.8 ± 0.45 µg/mL). Owing to the greater phenolic content, a better 2-2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity (69.45 % for stem explant and 63.68 % for leaf explant) was observed in optimized calluses. The unusually higher biomass and the enhanced amount of phenolic compounds as a result of lower amounts of TDZ highlight the importance of this multipotent hormone as elicitor in callus cultures of F. indica.