Taxonomic significance of megaspores in some species of Selaginella from Arunachal Pradesh in India.

The present study was carried out to record the color, size, and ornamentation of megaspores in 18 species of the family Selaginellaceae from Arunachal Pradesh using scanning electron microscope (SEM) and light microscope (LM). Electron microscopic study of the spore features revealed the type of ornamentation and microsculptural detail. SEM study on megaspore of Selaginella pentagona (S. pentagona), Selaginella tenuifolia, Selaginella semicordata, and Selaginella chrysorrhizos is presented for the first time. Variation in the megaspore ornamentation is noted at the interspecific level and intraspecific level in some cases. Examination of the megaspores under study found all the megaspores as trilete, with a size ranging from 116 to 560 µm in diameter. Taxonomic key is prepared to differentiate the species. Short descriptions of megaspores are provided and supported by photo plates. New features are recorded for seven species. The study contributes to the separation of species within the genus Selaginella based on the spore feature and brings forward the use of spore as a diagnostic tool in the taxonomy of the genus. These works contribute to the systematic of the family Selaginellaceae and provide useful information in the field of palynology. RESEARCH HIGHLIGHTS: Study on megaspore features of Selaginella species collected from Arunachal Pradesh, using SEM and LM. Taxonomic key is provided for each species based on megaspores features. New megaspore features are recorded for the seven species. The study brings forward the use of spore as a diagnostic tool in the taxonomy of the genus. These works provide useful information in the field of systematic and palynology.

Phyto-microbiome to mitigate abiotic stress in crop plants.

Plant-associated microbes include taxonomically diverse communities of bacteria, archaebacteria, fungi, and viruses, which establish integral ecological relationships with the host plant and constitute the phyto-microbiome. The phyto-microbiome not only contributes in normal growth and development of plants but also plays a vital role in the maintenance of plant homeostasis during abiotic stress conditions. Owing to its immense metabolic potential, the phyto-microbiome provides the host plant with the capability to mitigate the abiotic stress through various mechanisms like production of antioxidants, plant growth hormones, bioactive compounds, detoxification of harmful chemicals and toxins, sequestration of reactive oxygen species and other free radicals. A deeper understanding of the structure and functions of the phyto-microbiome and the complex mechanisms of phyto-microbiome mediated abiotic stress mitigation would enable its utilization for abiotic stress alleviation of crop plants and development of stress-resistant crops. This review aims at exploring the potential of phyto-microbiome to alleviate drought, heat, salinity and heavy metal stress in crop plants and finding sustainable solutions to enhance the agricultural productivity. The mechanistic insights into the role of phytomicrobiome in imparting abiotic stress tolerance to plants have been summarized, that would be helpful in the development of novel bioinoculants. The high-throughput modern approaches involving candidate gene identification and target gene modification such as genomics, metagenomics, transcriptomics, metabolomics, and phyto-microbiome based genetic engineering have been discussed in wake of the ever-increasing demand of climate resilient crop plants.

Resveratrol- and melatonin-abated ovariectomy and fructose diet-induced obesity and metabolic alterations in female rats.

OBJECTIVE: This study was designed to investigate the effects of bilateral ovariectomy and fructose diet on obesity-related metabolic parameters in female rats. The potential of resveratrol, alone and in combination with melatonin, to counter ensuing obesity and precipitated metabolic disturbances was explored. METHODS: Eight-week-old female Sprague-Dawley rats were subjected to bilateral ovariectomy (OVX) or sham operation and randomly assigned to standard diet (SD) or fructose diet (FD) groups (n = 6 rats per group) as follows: Sham; OVX + FD; OVX + SD; OVX + FD + resveratrol 50 mg/kg/day PO (RESV); OVX + SD + RESV; OVX + FD + melatonin 3 mg/kg/day PO in drinking water (M); OVX + SD + M; OVX + FD + RESV + M; OVX + SD + RESV + M. All treatments were given for 7 weeks. Biochemical, dietary, and anthropometrical parameters were estimated, and abdominal fat pads and the liver were examined for histopathological alterations. RESULTS: Ovariectomy caused an increase in body weight, body mass index, feed efficiency, serum glucose, cholesterol, triglycerides, and free fatty acids, which was further exacerbated by fructose diet. These parameters were significantly decreased by resveratrol, alone and in combination with melatonin. Histopathological examination revealed reduced hypertrophy of adipocytes in adipose tissue and reduced macrophage infiltration in the liver. CONCLUSIONS: Resveratrol/melatonin combination effectively normalizes anthropometrical, biochemical, and histopathological parameters in ovariectomized rats with fructose diet-induced obesity and associated metabolic alterations. The combination should be explored for potential benefits in postmenopausal women.

Resveratrol attenuated smokeless tobacco-induced vascular and metabolic complications in ovariectomized rats.

OBJECTIVE: The aim of this study was to evaluate the effect of smokeless tobacco extract on ovariectomized female rats and to investigate the role of resveratrol in alleviating associated vascular and diabetic complications. METHODS: Thirty-six female Wistar rats (8 wk old) were subjected to bilateral ovariectomy (OVX) or sham operation and randomly assigned to six groups: sham operation; OVX; OVX + aqueous extract of smokeless tobacco (AEST); OVX + AEST + 17ß-estradiol; OVX + AEST + resveratrol 25 mg/kg/day PO; and OVX + AEST + resveratrol 50 mg/kg/day PO. All treatments were given for 60 days. Various vascular and metabolic markers (such as serum glucose, triglycerides, cholesterol, insulin, estradiol, glycosylated hemoglobin, glucose tolerance), ex vivo vascular reactivity of aortic ring, and aortic collagen levels were estimated after the treatments. RESULTS: Oral exposure to smokeless tobacco extract in ovariectomized female rats triggered a significant increase in metabolic markers (viz, serum triglycerides, cholesterol, glucose, insulin, glycosylated hemoglobin), and aortic collagen levels. It also led to decreased serum nitrate-nitrite levels and vascular reactivity. Resveratrol 50 mg/kg/day PO attenuated detrimental changes in aortic reactivity and aortic collagen levels, improved glucose tolerance, and reversed the deleterious effects on other serum parameters comparable to 17ß-estradiol. CONCLUSIONS: Resveratrol treatment for 60 days abrogates the deleterious effects of smokeless tobacco on ovariectomized female rats. Resveratrol in adequate doses can be effectively used as an alternative to estrogen therapy for smokeless tobacco-induced vascular and diabetic complications.