| Rice, as a semi-aquatic crop, need a lot of water during its life. But there are certain limits. Submergence is a big problem in particular. Rice is the main food crop. The reduction of output or total crop failure caused by flooding is a main reason of hungry for a long time. Flood and drought occur frequently this year as global climate change and uneven rainfall. In our country, the planting season of Yangtze River and southern rice areas is the period of hign floods, with the feature of sudden and short-term. But we lack of submergence-tolerent rice varieties and favorable genetic resources. Therefore, the introduction of favorable submergence- tolerant, screening them, and breed for submergence-tolerant rice varieties for our country is significant. This study focuses on IR64-Sub1, which having a specific ability of submergence-tolerant imported from Philippines, and compare the phisiological indicators adapt to submergence with its parent IR64 and domestic conventional indica rice 9311, TXZ. we attempt to understand the main characters of "submergence-tolerant gene" Sub1 and then provide some reference to the value in use in our country. The main results are as follows:(1) We observed the behavior of IR64-Sub1 in different submergent situation and found main charactors as follows:IR64-Sub1 inhibit leaf elongation and reduce nutrient consumption, so the growth slowed or stopped in case of submergence. Therefore, the leaves of plant will stay green and resumption quickly when water receded. This kind of submergence-tolerant is opposite with the deep water rice avoiding submergence.(2) The submergence-tolerant confered by IR64-Sub1 closely relate to growing season and environment of submergence. Submergence-tolerant capability of IR64-Sub1 is very differnt at different growing season. Reproductive stage is the most sensitive time. Vegetative stage is a better period of tolerant submergence. IR64-Sub1 even stand up to 20 days of submergence with suitable water temperature, clear water in the tillering stage.(3) We compared the physiological indicators and related gene exprssion between IR64-Sub1 and IR64 under the stress of submergence. We found that the contain of catalase in root have little change befor and after submergence in IR64-Sub1, while the IR64 increase uncommonly after submergence in physiological detection. Then we detected the gene expression by real-time quantitative PCR of enzymes connected with active oxygen scavenging system in leaves between of two cultivars in different time of submergence. These enzymes include Cu/Zn-SOD (superoxide dismutase), APX (ascorbate peroxidase), GO (glycolate oxidase) and CAT (catalase). The resut indicate that IR64-Sub1 have a higher level expression of Cu/Zn-SOD and CAT compare with IR64 and the level of Cu/Zn-SOD have a more significant difference. The expression of APX and GO is down-regulated. And there is not much difference between two cultivars. IR64-Sub1 have a more active enzymes related to oxygen scavenging system, which plays an important role of removal of harmful substances generated within cells produced in flooded conditions.These results show that IR64-Sub1 has s strong capacity of submergence-tolerent and can be used for breeding submergence-tolerant varieties in our country. The related results of physiological and gene expression can be screened for proper physiological indictors or molecular markers to detect the capability of submergence-tolerant rapidly, which will improve efficiency of breeding. |
PDF Full Text Request