Study of the physiological mechanism of delaying cucumber senescence by wheat intercropping pattern.

This paper investigates the physiological mechanism of the effect of delaying cucumber senescence on protein levels under the experimental model of monoculture and wheat intercropping. We analyzed cucumber roots for differential protein expression, and protein types were identified by core technology of proteomics. 45 differential proteins were identified as being differentially expressed between monoculture and intercropping of wheat, which were involved in carbohydrate metabolism, antioxidant and stress response, growth and development regulation, biological information transfer, and nucleic acid biosynthesis. The results showed the rate of photosynthesis of cucumber was increased under wheat intercropping pattern due to three enzymes being up-regulated. The respiration of cucumber was reduced when five enzymes were down-regulated. The antioxidant and resistant capacity of cucumber was enhanced significantly under wheat intercropping pattern because two enzymes were down-regulated while the activity of four other antioxidant enzymes was up-regulated. Intercropping wheat could delay the senescence of cucumber leaves by increasing the expression of IPT gene, reducing the expression of PAO and ETR2 gene, and inhibiting the expression of Cu/Zn-SOD and GS1 gene in later stages. Two proteins related to growth and development in cucumber were up-regulated, and one was down-regulated, while two proteins related to nucleic acid biosynthesis and chaperonin showed obvious down-regulation under wheat intercropping. Therefore, the growth and development was improved and senescence of cucumber could be delayed. Under intercropping pattern, the fresh weight, chlorophyll content, photosynthetic rate, and peroxidase activity of cucumber plants were higher than those of cucumber monoculture groups. Thus, the senescence of cucumber could be delayed under wheat intercropping by regulating its physiological mechanisms, such as by improving photosynthesis, reducing respiratory consumption, slowing the cell apoptosis rate, and enhancing the antioxidant and resistant capacity significantly, etc.