P. rufescens (Franch.) Burtt is native to south of China and north of Thailand. It is a resurrection plant. It is a light-demanding herbaceous species and grows on the top of limestone in marginal tropical areas (21°54′N, 101°46′E). It shows very strong drought-resistance
It is well known that resurrection plants could survive extreme drought stress. However, the underlying mechanisms for protecting their photosynthetic apparatus against drought stress are unclear. Choosing Paraboea rufescens as their material, Dr. HUANG Wei and his supervisor Prof. CAO Kunfang of Xishuangbanna Tropical Botanical Garden (XTBG) conducted a project to study how the resurrection plant survives drought stress.
Since drought stress could induce up-regulation of components involved in ferredoxin-dependent cyclic electron flow (CEF) that is an important mechanism for protecting photosystem I (PSI) and photosystem II (PSII), the researchers hypothesized that resurrection plants would show strong cyclic electron flow activity because they often undergo drought stress in life. In their study, the researchers determined the effect of mild drought stress on light energy distribution and P700 redox state in the resurrection plant P. rufescens to examine the response of cyclic electron flow (CEF) to drought stress in resurrection plants.
They found that cyclic electron flow (CEF) was very responsive to mild drought stress in the resurrection plant P. rufescens. The mild drought stress caused large decrease in the ability of the leaves to utilize the products of linear electron flow. Meanwhile, the resurrection plant P. rufescens showed high CEF and non-photochemical quenching (NPQ) to protect PSII from photo-inhibition. The over-reduction of PSI under mild drought stress was alleviated by the strong stimulation of CEF. Therefore, the researchers concluded that CEF plays an important role in photoprotection for resurrection plants under drought stress.
The study entitled “Cyclic electron flow plays an important role in photoprotection for the resurrection plant Paraboea rufescens under drought stress” has been published online in Planta, DOI:10.1007/s00425-011-1544-3