Effects of ozone on cell organelles of alfalfa (Medicago sativa L.) seedlings.

Seedlings of alfalfa (Medicago sativa L.) were exposed to different concentrations of atmospheric ozone (20-30 (control), 40-60, 65-80, and 85-120 ppb) in four distinct areas in the Riyadh region, so as to decide how ozone affected some of the seedling cellular organelles. Results acquired utilizing transmission electron microscopy demonstrated certifiable impacts to exist on the cell organelles in the tissues of both the leaf mesophyll and stem cortex; contrasted with control plants, the chloroplasts seemed enlarged, irregular, different sizes, decomposed, and possibly dissolved, while the plastoglobules seemed deformed, more widely spaced, and enlarged, also the vacuoles contained no clear non-living components. Moreover, some parts of the cytoplasmic membranes were ruptured, with only a few vesicles created at all concentrations, particularly in plants exposed to concentrations of 65-80 and 85-120 ppb, while no effects were noted in these organelles in control plants or plants exposed to 40-60 ppb. High concentrations (85-120 ppb) led to enlarged, irregularly shaped nuclei and chromatin intensification; however, no clear effects of ozone were noted on the shapes of chloroplast starch grains or the mitochondria in leaf mesophyll and cortex cells in the stem. The high ozone concentrations can cause negative effects on the growth of alfalfa seedlings, leading to imbalances in their vital functions and acceleration of aging, thus potentially decreasing the total plant yield. The discoveries hence propose that alfalfa plants should not be planted near polluted areas, and that they can be utilized as bioindicators of air pollution by ozone.

First report of detection of the putative receptor of Bacillus thuringiensis toxin Vip3Aa from black cutworm (Agrotis ipsilon).

Black cutworm (BCW) Agrotis ipsilon, an economically important lepidopteran insect, has attracted a great attention. Bacillus thuringiensis (Bt) is spore forming soil bacteria and is an excellent environment-friendly approach for the control of phytophagous and disease-transmitting insects. In fact, bio-pesticide formulations and insect resistant transgenic plants based on the bacterium Bt delta-endotoxin have attracted worldwide attention as a safer alternative to harmful chemical pesticides. The major objective of the current study was to understand the mechanism of interaction of Bt toxin with its receptor molecule(s). The investigation involved the isolation, identification, and characterization of a putative receptor - vip3Aa. In addition, the kinetics of vip toxin binding to its receptor molecule was also studied. The present data suggest that Vip3Aa toxin bound specifically with high affinity to a 48-kDa protein present at the brush border membrane vesicles (BBMV) prepared from the midgut epithelial cells of BCW larvae.