Tropical plants are sensitive to chilling temperatures above zero but it is still unclear whether photosystem I (PSI) or photosystem II (PSII) of tropical plants is mainly affected by chilling temperatures.
The chilling temperature above zero is the major limitation to the distribution of tropical plants to higherl atitudes and altitudes. Tropical plants are especially sensitive to chilling temperatures above zero because of the photoinhibition induced by the chilling-and-light stress.
Prof. Cao Kunfang and his research team of XTBG investigated the effect of chilling (4℃)associated with various ambient light intensities on PSI and PSII and subsequent recovery in seedlings of four tropical hardwood timber species in an open field, Khaya ivorensis, Pometia tomentosa, Dalbergia odorifera, and Erythrophleum guineense, in a marginal tropical area, of which three species are introduced from low tropics and one species is native.
The results of this study indicated that in the four tropical tree species, PSII was more sensitive to chilling temperature under moderate light than PSI. The photoinhibition of PSII and closure of PSII reaction centers under chilling stress serve to protect PSI in tropical trees from chilling-and-light stress.
The anonymous referees said that the research results have important implications for the understanding of the chilling sensitivity of chilling-sensitive species under natural conditions.
Entitled “The different effects of chilling stress under moderate light intensity on photosystem II compared with photosystem I and subsequent recovery in tropical tree species”, the research details have been published in Photosynthesis Research (2010) 103: 175-182. DOI: 10.1007/s11120-010-9539-7