Proteomic Analysis Of Maize Under Drought Stress At Meiotic Stage And Genetic Diversity Of170Maize Landraces From Southwest China

Maize (Zea mays L.) is a very important feed, grain and industrial crop, which plays an important role in the development of national economy. Drought stress is one of the major environmental stresses that greatly affect plant growth and maize production. The period from meiosis to tetrad break-up in anthers is one of the most sensitive stages; crop yield will be caused serious reduction when the maize encounters drought stress at this stage. Meanwhile, the maize genetic background in China was narrow. However, maize landraces have strong compatibility in local environment, rich genetic background and a lot of useful characters. In order to find drought tolerance genes, widen maize hereditary basis and conserve germplasms, the physiological and proteomic analysis of maize inbred lines with different tolerance at meiotic stage and the genetic diversity of170landraces from southwest China were analyzed. The main results are as follows:(1) As the drought stress intensified, the Fv/Fm and chlorophyll content of Han21and Ji81162were significantly decreased.(2) As for the ear under control and drought stress, the activity of APX in both two inbred lines was decreased first and then increased. The activity of GR was significantly increased with the stress time prolonged. The GR activities of Han21were higher than Ji81162. The activity of CAT was first increased and then decreased with prolonged drought stress time. The SOD and DHAR activities of Han21were slightly decreased, while they were markedly declined. These results suggested that APX, GR and CAT were the key active oxygen scavenging enzymes in ears.(2) As for the leaves under control and drought stress, the SOD and APX activities were higher than control, and the active of Han21were increased fasterly than Ji81162. The DHAR activities had no change between control and drought. The activity of GR was significantly decreased. The activity of CAT was decreased first and then increased for two inbred lines. These results indicated that SOD, APX and CAT were the key enzymes in leaves under drought stress.(4) After proteomic analysis by two-dimensional gel electrophoresis and peptide mass fingerprinting,114and100proteins were found in Han21and Ji81162, respectively.13and9proteins, respectively, which were responed to drought stress, were identidied. APX and actin were found in two inbred lines. Pectinesterase inhibitor domain containing protein, legumin-like protein, profiling, triosephosphate isomerase, NAD dependent epimerase/dehydratase, GTP-binding protein,14-3-3-like protein and eukaryotic translation initiation factor5A (eIF-5A) were only found in Han21. While ferredoxin, eIF-4A, hypothetical protein, actin-depolymerizing factor (ADF) and ADF-3were only expressed in Ji81162.(5) The genetic diversity of landraces from southwest China were rich; the gene flow among provinces was strong enough to prevent differentiation through drift among provinces. The genetic distance-based and the model-based clustering both grouped170landraces into3groups:group â…  contained landraces mainly from Guizhou and Guangxi provinces; group â…¡ was the mixed group; group â…¢ consisted of landraces mainly from Yunnan and Guangxi provinces.