Pollen used to track structural and functional evolution in plants as well as to investigate the problems relative to plant classification. Pollen characters including ornamentation, shape, apertural pattern, pollen symmetry, colpus length, width, and margins used to detect the similarities and dissimilarities between genera and also species of the same genus. In this study pollen features of 20 monocot species belonging to 15 genera of the Amaryllidaceae, Asparagaceae, Iridaceae, Ixioliriaceae, Liliaceae, and Xanthorrhoeaceae were studied using scanning electron microscopy (SEM) and light microscopy (LM). In this study two species that is Zephyranthes citrina and Tulbaghia violacea were reported for the first time from Pakistan. Pollen grains were visualized with LM. Non-acetolyzed and acetolyzed pollen were examined using SEM. A taxonomic key was developed to highlight the variation in pollen features in order to make their systematic application for correct species identification.

Brassinosteroids (BRs) play pivotal roles in modulating plant growth, development, and stress responses. In this study, a Medicago truncatula plant pretreated with brassinolide (BL, the most active BR), enhanced cold stress tolerance by regulating the expression of several cold-related genes and antioxidant enzymes activities. Previous studies reported that hydrogen peroxide (H2O2) and nitric oxide (NO) are involved during environmental stress conditions. However, how these two signaling molecules interact with each other in BRs-induced abiotic stress tolerance remain largely unclear. BL-pretreatment induced, while brassinazole (BRZ, a specific inhibitor of BRs biosynthesis) reduced H2O2 and NO production. Further, application of dimethylthiourea (DMTU, a H2O2 and OH− scavenger) blocked BRs-induced NO production, but BRs-induced H2O2 generation was not sensitive to 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO, a scavenger of NO). Moreover, pretreatment with DMTU and PTIO decreased BL-induced mitochondrial alternative oxidase (AOX) and the photosystem capacity. However, pretreatment with PTIO was found to be more effective than DMTU in reducing BRs-induced increases in Valt, Vt, and MtAOX1 gene expression. Similarly, BRs-induced photosystem II efficiency was found in NO dependent manner than H2O2. Finally, we conclude that H2O2 was involved in NO generation, whereas NO was found to be crucial in BRs-induced AOX capacity, which further contributed to the protection of the photosystem under cold stress conditions in Medicago truncatula.

Brassinosteroids (BRs) are growth-promoting plant hormones that play a crucial role in biotic stress responses. Here, we found that BR treatment increased nitric oxide (NO) accumulation, and a significant reduction of virus accumulation in Arabidopsis thaliana. However, the plants pre-treated with NO scavenger [2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-1-oxyl-3-oxide (PTIO)] or nitrate reductase (NR) inhibitor (tungstate) hardly had any NO generation and appeared to have the highest viral replication and suffer more damages. Furthermore, the antioxidant system and photosystem parameters were up-regulated in brassinolide (BL)-treated plants but down regulated in PTIO- or tungstate-treated plants, suggesting NO may be involved in BRs-induced virus resistance in Arabidopsis. Further evidence showed that NIA1 pathway was responsible for BR-induced NO accumulation in Arabidopsis. These results indicated that NO participated in the BRs-induced systemic resistance in Arabidopsis. As BL treatment could not increase NO levels in nia1 plants in comparison to nia2 plants. And nia1 mutant exhibited decreased virus resistance relative to Col-0 or nia2 plants after BL treatment. Taken together, our study addressed that NIA1-mediated NO biosynthesis is involved in BRs-mediated virus resistance in A. thaliana.

Statistics around the world show an increased risk of high allergies associated with plants. The role of allergenic pollen is now well known. The most serious allergenic diseases are asthma and rhinitis, which affect 5–30% of the population of industrialized countries. This work focuses on the exploration of allergenic grass species of Islamabad, Pakistan and use microscopic techniques to correctly identify them. This study contains 11 species of grasses which showed variations in pollen morphological features. The dominant pollen shape was prolate, prolate‐spheroidal and sub oblate. The largest polar diameter was calculated for Echinochloa crus‐galli (56.00 μm) while the largest equatorial diameter was found in Cenchrus ciliaris (45.00 μm). Exine ornamentation varied from Gemmate–verrucate, Scabrate–reugulate, Verrucate–reticulate, Gemmate–Scabrate, Fine–Gemmate, Gemmate–rugulate, Gemmate–reticulate, Gemmate–scabrate, Scabrate–verrucate, and Scabrate. Maximum exine thickness was found in Eleusine indica (4.90 μm) while in C. ciliaris (1.50 μm) the minimum thickness of exine was measured. In E. crus‐galli (1.54 μm), the largest P to E value was measured and the smallest value was noticed in Setaria verticillata (0.86 μm). The study was performed with an aim to identify the allergenic plant species in Islamabad‐Pakistan using pollen morphological studies. This study provides significant information, to arrange the pollen types within their defined classes and to discuss various pollen features for developing an allergenic pollen atlas.