Silicon enhances photochemical efficiency and adjusts mineral nutrient absorption in Magnaporthe oryzae infected rice plants

Abstract

Silicon (Si) has been verified to play an important role in enhancing plant resistance against pathogens, but the exact mechanisms remain unclear. Two near-isogenic lines of rice (Oryza sativa L.), CO39 (blast susceptible), and C101LAC (Pi-1) (blast resistant), were hydroponically grown to study the effects of exogenous silicon application on the changes of disease incidence, mineral nutrient concentrations, chlorophyll content, and photochemical efficiency in Magnaporthe oryzae infected rice plants. Si amendment in nutrient solution at a concentration of 2.0 mM significantly reduced the disease index of rice plants of CO39 and C101LAC (Pi-1). Silicon application alone had no effects on mineral nutrient contents, chlorophyll content, maximum/potential quantum efficiency (F v /F m ), and the maximum primary yield (F v /F 0 ) of photochemistry of PS II in healthy rice leaves. M. oryzae inoculation significantly increased the content of K, Na, Ca, Mg, Fe, and reduced the value of F v /F 0 and F v /F m in rice leaves. However, Si treatment suppressed M. oryzae induced increase of mineral nutrient contents, and significantly increased F v /F 0 and F v /F m value compared with Sideficient infected plants. These results suggest that siliconenhanced resistance to rice blast is associated with an enhancement of photochemical efficiency and adjustment of mineral nutrient absorption in M. oryzae-infected rice plants.

Effect of deficit irrigation and growing seasons on plant water status, fruit yield and water use efficiency of squash under saline soil

“…High numbers for LAI appear to produce the best yields, and early signs of good leaf growth can predict yield. These results are in agreement with those of Amer (2010) working on corn and Amer (2011) on squash, also this finding was noted earlier in some crop plants (Degu et al, 2008;Gao et al, 2011;Habibi, 2012). HI recorded under FS (0.54) was higher than under SS (0.42) by 28.6% (Table 8) the same trend was obtained by Amer (2011) on squash and Wajid (1990) on corn.…”

Changes in leaf gas exchange and chlorophyll a fluorescence on soybean plants supplied with silicon and infected by Cercospora sojina

“…However, in sharp contrast with the results of the present study, Gao et al. () reported a positive effect of Si on the photochemical efficiency (evidenced by a lower decrease in the F v / F m values and high concentration of photosynthetic pigments) for rice plants infected by P. oryzae . Similarly, the infection of rice and sorghum plants by B. oryzae and C. sublineolum , respectively, impaired photosynthesis, but for a lesser extent on plants supplied with Si (Dallagnol et al., ; Resende et al., ).…”

“…() demonstrated that A values were less compromised due to an increase in foliar Si concentration (FSC) of rice plants infected by Bipolaris oryzae . Additionally, on rice plants supplied with Si and infected by Pyricularia oryzae , the values of the maximum photochemical efficiency of the photosystem II (PSII) ( F v / F m ) were similar to the ones obtained from noninfected plants nonsupplied with Si (Gao et al., ).…”

“…Notably, changes in the photosynthetic apparatus of plants infected by pathogens can be detected via alterations in the chlorophyll (Chl) a fluorescence emission kinetics (Alves, Guimarães, Chaves, DaMatta, & Alfenas, 2011;Berger, Sinha, & Roitsch, 2007;Gao et al, 2011;Rahoutei, García-Luque, & Barón, 2000). Reduction in photosynthesis may decrease the availability of carbon skeletons for carbohydrates metabolism and also for the production of defencerelated compounds that help the plants to counteract the infection by pathogens (Bispo, Araujo, Ávila, DaMatta, & Rodrigues, 2016).…”

“…Resende et al (2012) reported that sorghum plants inoculated with Colletotrichum sublineolum and supplied with Si showed lower decreases in the values of net carbon assimilation rate (A), stomatal conductance to water vapour (g s ) and transpiration rate (E) in contrast to noninfected and non-Sisupplied plants. Dallagnol et al (2013) (Gao et al, 2011).…”