The biosynthesis and accumulation of resveratrol in grape may be regulated by genetic and environmental factors [i.e., ultraviolet-C (UV-C) irradiation]. However, there is a lack of research on the biosynthesis and accumulation of resveratrol in grape leaves responding to UV-C irradiation at sequential developmental stages. In this study, leaf resveratrol concentration during different developmental stages of three grape cultivars, Jingxiu, Beifeng, and MRH3, under natural conditions, and of ‘Beifeng’ leaves exposed to UV-C irradiation was investigated. Results showed that resveratrol synthesis was related to the developmental stages under natural conditions. In young leaves, resveratrol concentration was low, but it increased continuously during leaf development, mainly as piceid forms. UV-C irradiation greatly stimulated resveratrol synthesis in ‘Beifeng’ leaves, and young leaves at 20 days were most sensitive to the irradiation. The total resveratrol in the skin of UV-C irradiated berries is about 19 times higher than that of the control, mainly in the forms of trans-resveratrol (trans-res)/cis-resveratrol (cis-res). These results provide a basis for increasing resveratrol concentration by artificial means.
Junfang Wang, Yuxia Sun, Hengzhen Wang, Xueqiang Guan and Lijun Wang
B. Shaun Bushman, Lijun Wang, Xin Dai, Alpana Joshi, Joseph G. Robins and Paul G. Johnson
Much of semiarid western North America is salt affected, and using turfgrasses in salty areas can be challenging. Kentucky bluegrass (Poa pratensis L.) is relatively susceptible to salt stress, showing reduced growth, osmotic and ionic stress, and eventual death at moderate or high salt concentrations. Considerable variation exists for salt tolerance among kentucky bluegrass germplasm, but gaining consistency among studies and entries has been a challenge. In this study, two novel kentucky bluegrass accessions recently reported as salt tolerant (PI 371768 and PI 440603) and two cultivars commonly used as references (Baron and Midnight) were compared for their turf quality (TQ), stomatal conductance (g S), leaf water potential (ψLEAF), electrolyte leakage (EL), and accumulation of inorganic ions under salt stress. TQ, ψLEAF, and EL were highly correlated with each other while only moderately correlated with g S. The tolerant accessions showed higher ψLEAF and lower EL than the cultivars Midnight and Baron at increasing salt concentrations and over 28 days of treatment. The accumulation of sodium (Na) and calcium (Ca) in the leaves was highly correlated and did not vary significantly among the four entries. Genes involved in ion transport across membranes, and in antioxidant activities, were significantly induced on salt stress in the tolerant accessions relative to the susceptible. These data indicate the ability of tolerant accessions to ameliorate oxidative stress and prevent EL, and confirmed the tolerance of germplasm previously reported on while indicating mechanisms by which they tolerate the salt stress.