). Histochemical and biochemical analyses of the stigmatic exudate show that it is heterogeneous and composed of lipids, polysaccharides, and proteins. Cresti et al. (1982) evaluated the stigma of Citrus limon and using SEM evaluations of fresh tissues
Hazel Y. Wetzstein and S. Edward Law
Ao Liu, Jibiao Fan, Margaret Mukami Gitau, Liang Chen, and Jinmin Fu
according to Duncan’s multiple range tests. Membrane injury and lipid peroxidation. MDA and EL can be used as efficient indicators of lipid peroxidation, which further reflects the extent of damage of cell membrane ( Södergren et al., 2001 ; Whitlow et al
Ningguang Dong, Jianxun Qi, Yuanfa Li, Yonghao Chen, and Yanbin Hao
and lipid peroxidation and significantly prevented the decreased F v / F m and survival induced by chilling stress ( Fig. 5A–D ). These observations were consistent with those of other studies in Trigonobalanus doichangensis ( Zheng et al., 2015
Stephen B. Ryu and Jiwan P. Palta
Lipids have been thought to be important largely in membrane structure and energy reserve. It is now evident that lipids and lipid-derived metabolites play a role in many critical cellular processes. Recent studies have shown that membrane lipid-based signaling mediated by phospholipases such as phospholipase A2 (PLA2), phospholipase C (PLC), and phospholipase D (PLD) constitutes a crucial step in plant responses to abiotic and biotic stresses. Phospholipases and their products also play a role during plant growth and development. For example, PLA2-derived lysophospholipids acted as growth regulators that retard senescence of plant tissues. Interestingly, the PLA2 products inhibited the activity of PLD, which has been suggested to be a key enzyme responsible for membrane lipid breakdown leading to plant senescence. Endogenous levels of lysophospholipids, such as lysophosphatidylethanolamine (LPE), could be increased in castor bean leaf discs by the treatment of auxin (50 μM), which is known to be a activator of PLA2. Pretreatment of leaf discs with a PLA2 inhibitor before auxin treatment nullified the auxin effect and rather resulted in accelerated senescence even compared to the nontreated control. Our recent results suggest a potential role of PLA2 products as biologically active molecules mediating hormonal regulation of growth and senescence. One such product LPE is being commercially exploited for retarding senescence and improving shelf life of fruits, vegetables, and cut flowers.
June Liu, Zhimin Yang, Weiling Li, Jingjin Yu, and Bingru Huang
nm, which was used to calculate chlorophyll content according to Arnon (1949) . Lipid peroxidation was measured based on malondialdehyde (MDA) content of leaves according to Dhindsa and Matowe (1981) with modifications. Fresh leaves (0.40 g fresh
Zhou Li, Yan Peng, and Bingru Huang
H 2 O 2 can cause lipid peroxidation, proteins degradation, accelerated senescence, and even programmed cell death, whereas the lower level and rapidly alteration of H 2 O 2 acts as critical regulatory roles in intermediate signaling transduction
Jen A. McComb, Chris Newell, and George Lullfitz
A naturally occurring mutant of Chamelaucium uncinatum Schauer (Geraldton wax) is described. It has double flowers with the staminodes transformed into petals. Pollen is exuded from the anthers but is not deposited on the pollen presenter in a lipid droplet, which is normal for the species. An anomalous secondary flower with petals, stamens, and gynoecium is present in the ovary.
Shiow Y. Wang, Miklos Faust, and Michael J. Line
The effect of IAA on apical dominance in apple buds was examined in relation to changes in proton density (free water) and membrane lipid composition in lateral buds. Decapitation induced budbreak and enhanced lateral bud growth. IAA replaced apical control of lateral buds and maintained paradormancy. Maximal inhibition was obtained when IAA was applied immediately after the apical bud was removed; delaying application reduced the effect of IAA. An increase in proton density in lateral buds was observed 2 days after decapitation, whereas the change in membrane lipid composition occurred 4 days later. Removing the terminal bud increased membrane galacto- and phospholipids and the ratio of unsaturated to corresponding saturated fatty acids. Decapitation also decreased the ratio of free sterols to phospholipids in lateral buds. Applying thidiazuron to lateral buds of decapitated shoots enhanced these effects, whereas applying IAA to the terminal end of decapitated shoots inhibited the increase of proton density and prevented changes in membrane lipid composition in lateral buds. These results suggest that change in water movement alters membrane lipid composition and then induces lateral bud growth. IAA, presumably produced by the terminal bud, restricts the movement of water to lateral buds and inhibits their growth in apple.
Chen Chen, Meng-Ke Zhang, Kang-Di Hu, Ke-Ke Sun, Yan-Hong Li, Lan-Ying Hu, Xiao-Yan Chen, Ying Yang, Feng Yang, Jun Tang, He-Ping Liu, and Hua Zhang
comparison with wild type cells ( Fig. 5B ). MDA, which is an index of lipid peroxidation, was determined in menadione-treated cell. As shown in Fig. 5C , the content of MDA in wild type increased slightly along with treatment time; however, MDA accumulated
Kristina F. Connor, Sharon Sowa, and Robert D. Borchert
A pollen grain undergoes a series of biochemical changes during germination. The technique of cylindrical internal reflectance FTIR was used to examine spectral frequencies associated with respiration, lipid and protein structure, polysaccharide content, and phosphate-containing metabolizes in pollen from pecan, blue spruce, cattail, and pine. Samples of both pollen and germination medium were analyzed at timed intervals. A microscopic evaluation of percent germination was also made at each sampling time. Preliminary analyses indicate that changes in respiration occur as evidenced by the presence of gaseous CO2, and that quantitative changes in lipid and protein occur. FTIR spectroscopy provides a noninvasive method to directly and quantitatively measure metabolic changes associated with pollen germination.