Effects of water stress on light-harvesting complex II (LHCII) and expression of a gene encoding LHCII in Zea mays

Summary Ten-day-old Zea mays L. Xinyu No. 4 seedlings were naturally stressed by stopping irrigation. Water content and water potential in attached leaves were reduced after treatments of 48 and 72 h, which represent moderate and severe water stress, respectively. At moderate water stress, the apoproteins of light-harvesting complex II (LHCII) decreased more rapidly than the content of chlorophyll. However, the contents of both chlorophyll and apoproteins decreased markedly in severe water-stressed maize leaves. Northern blotting showed that the loss of apoproteins of LHCII in water-stressed maize leaves is partially due to the decline of the steady state level of mRNA for LHCII, which indicated that the expression of LHCII under water stress is regulated at the transcript level. Circular dichroism measurements of LHCII in thylakoids isolated from water-stressed maize leaves revealed that the LHCII was dissociated and the conformation of LHCII in thylakoids was also altered by water stress.