Changes of Photochemistry Activity during Senescence of Leaves in Stay Green and Quick-Leaf-Senescence Inbred Lines of Maize

Abstract

In order to explore the changes of photochemistry activity and the contribution of photochemistry activity to the maintenance of photosynthetic capacity in maize leaves during senescence, the chlorophyll content, photosynthetic rate, PSI and PSII activities during senescence of leaves in the stay green maize (Zea mays L.) inbred line Qi 319 and the quick-leaf-senescence maize inbred line Huangzaosi were investigated by analyzing chlorophyll a fluorescence transient and 820 nm transmission. This study showed that both the chlorophyll content and the photosynthetic capacity in leaves decreased later and slower in Qi 319 than in Huangzaosi, indicating that Qi 319 is a functional stay-green inbred line. The L, K, J, and I steps of chlorophyll a fluorescence transient (OJIP transient) increased during senescence, which accompanied by a decrease in the amplitude of 820 nm transmission. Compared with Qi 319, the changes of OJIP transient and 820 nm transmission were more prominent in Huangzaosi. The results indicated that the quicker decrease in PSI and PSII photochemistry activities and severer deterioration of electron transfer activity are two of the most important reasons to cause earlier senescence in quick-leaf-senescence maize inbred line Huangzaosi; and the synthetic capacity of photosynthesis related protein, especially the fast turn-over protein in leaves may be one of the factors in maintenance of the photosynthetic capacity.