Luzhen Chen, Li Huang, Xiaofei Li, Siyang You, Shengchang Yang

,Yihui Zhang Wenqing Wang.Functional Plant Biology, 2013, 40:

475–483.

Xylem-tapping mistletoes are

known to have generally higher transpiration rate (Tr), lower CO2 assimilation rate

(A) and therefore lower water-use efficiency (WUE) than their hosts. There are

long-standing contradictions in water relations and nitrogen use in

photosynthesis. Gas exchange, chlorophyll fluorescence and nutrition components

were investigated in a special mistletoe–host pair, Viscum

ovalifolium–Sonneratia caseolar is, as the host was a mangrove growing in a

saline environment. Our results show that both plants had high foliar N

content, therefore it was consistent with the Nparasitism hypothesis, although

the mistletoe had a lower Tr than its mangrove host. It was suggested that the

mistletoe reduces its Tr under salt stress with N sufficient conditions. The

mistletoe had a fundamental limitation of photosynthesis, and was

photoinhibited with regard to high salinity, but it developed more

photoprotection to thermal radiation. Additionally, both stomatal conductance

(gs) and mesophyll conductance (gm) limitations on photosynthesis dominated in

the mistletoe under salt stress even though it had a high foliar N content

similar to the host.

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