Response and resistance of cereal crops to pathogens

The special topic of the two papers is the systemic acquired resistance （SAR） and pathogenesis-related protein genes （PR）. SAR is an enhanced resistance against further potential parasite beyond the initial infection site, which can be induced by either pathogen infection or exogenous inducer, including synthetic chemicals and natural prod- ucts. As a ＂whole-plant＂ resistance defense, SAR confers broad-spectrum immunity to widely diverse pathogenic microorganisms, such as viruses, bacteria and fungi for a relatively long lasting period. Convincingly, it is a promising way to prevent crop diseases by activating the plants＇ own natural defenses via application of chemical inducers or creating resistant wheat cultivars.

The Resistance of Crops in Plant Protection

World crop production requires highly-productive varieties of agricultural crops,which are resistant to pest organisms.Such varieties are also of great importance for the Uzbekistan.Their

Hatching and development of maize cyst nematode Heterodera zeae infecting different plant hosts

The occurrence, distribution, and rapid molecular detection technology of Heterodera zeae Koshy et al. 1971, have been reported in China. We explored the biological characteristics of H. zeae sampled in Henan Province, China to understand its interaction with plants. Cysts and second-stage juveniles(J2s) were identified under an optical and scanning electron microscope, internal transcribed spacer(ITS) phylogenetic tree, and sequence characterized amplified region(SCAR)-PCR analyses. The optimum hatching temperatures of H. zeae were 30°C and 28°C, with cumulative hatching rates of 16.5 and 16.1%, respectively, at 30 days post-hatching(dph). The hatching rate of H. zeae eggs was improved by 20-and 50-time maize soil leachate and root juice, and 10-time root exudates. The hatching rate in 10-time root exudates was the highest(25.9%). The 10-time root exudates of maize and millet produced the highest hatching rate at 30 dph(25.9 and 22.9%, respectively), followed by wheat(19.9%), barley(18.3%), and rice(17.6%). Heterodera zeae developed faster in maize than in other crops. Fourth-stage juveniles(J4s) were detected in maize roots 8 days post-inoculation(dpi) at 28°C but not in other crops. Combined with hatching tests, the Huang–Huai–Hai summer maize region and the south and central-southwest mountainous maize areas are highly suitable for H. zeae in China. This is the first systematically study of the hatching and infection characteristics on different plant hosts of corn cyst nematode H. zeae in temperate regions. This study laid a theoretical foundation for the rapid spread and high environmental adaptability of corn cyst nematode.

Leaf Expansion and Transpiration Responses of Millet Species to Soil Water Deficit

Plant processes, such as leaf expansion, stomatal conductance and transpiration, are affected by soil water, particularly in waterstressed environments. Quantifying the effects of soil water on plant processes, especially leaf expansion and transpiration, could be useful for crop modeling. In order to quantify the leaf expansion and transpiration in response to soil water deficit in three millet species, common(Panicum miliaceum L.), pearl(Pennisetum glaucum L.) and foxtail(Setaria italica L.) millets, a pot experiment was performed at the Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. The soil water status was characterized by the fraction of transpirable soil water(FTSW). Leaf area and transpiration were measured daily. Relative leaf area expansion(RL) and relative transpiration(RT) data were plotted against FTSW. Finally the FTSW thresholds for RL and RT were calculated using linear-plateau and logistic models. The results showed that the thresholds for RL and RT were 0.68 and 0.62,respectively, based on all measured data of the three millet species using the linear-plateau model, indicating that RL and RT were constant when FTSW decreased from 1 to the threshold point. Thereafter, until FTSW = 0, RL and RT declined linearly with a slope of 1.48 and 1.43, respectively. Although millet is cultivated as a resistant crop in arid, semiarid and marginal lands, it showed an early response to soil water deficit at high FTSW thresholds. As leaf expansion and transpiration can be considered morphological and physiological variables, respectively, the results in this study indicate that millet has strong morphological flexibility when faced with soil water deficit.