Growth and Vegetative Development
Su, Hsing-Min , Leu, Wei-Ming .
Molecular characterization and genetic analysis reveal SA0420 as an early senescing rice mutant with pleotropic phenotypes.
SA0420 is a stable rice (Oryza sativa L.) mutant exhibiting multiple traits different from those of the local cultivar TNG67. Those traits include leaf-tip yellowing (YLT), taro fragrance (or aroma, A), and reduction in panicle number (PN), spikelet number (SN), plant height (PH), days to heading (DH), filled grain weight (FGW), and fertility rate (FR). Correlation analysis on F2 progenies of SA0420 and TNG67 revealed that, except for aroma which is inheritated independently, phenotypes including YLT, PN, SN, PH, and FGW are tightly associated with one another, indicating a simultaneous control by pleotropic genes. Among those phenotypes, YLT appears the earliest at vegetative stage. Therefore, it may act as a predisposing factor that give rise to other phenotypes. Genetic analysis suggested that YLT is controlled by a single recessive gene. By analyzing the recombinant inbreed lines (RILs) that produce YLT and normal green (G) progenies in a 1:3 ratio, the phenotypes associated with YLT were further confirmed. To investigate the molecular events of leaf-tip yellowing, microarray analyses were performed to compare the gene expression profiles between YLT and G plants of RILs. Clustering of genes according to their involved metabolic pathways revealed that various photosynthesis and carbon fixation gene expressions were lower (~55~75%) in YLT than in G plants, consistent with the observation that photosynthesis rate of SA0420 was only 60% to that of TNG67. Moreover, higher expressions of oxidative phosphorylation-related genes indicated that not only the reduced synthesis rate but also the elevated energy consumptions may synergistically decrease the growth vigor of SA0420. Dissection of the mature leaf revealed that chlorophyll is drastically reduced in the leaf-tip of SA0420 while carotenoids remain stable. This explains the appearance of leaf-tip yellowing and is reminiscent of early senescence. Several senescence-associated genes (SAG) examined subsequently by RT-PCR further support such a notion.
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1 - The College of Agriculture And Natural Resources, Graduate Institute of Biotechnology, National Chung Hsing University 250, Kuo Kuang Rd., Taichung, 402, Taiwan, R.O.C.
2 - The College of Agriculture And Natural Resources, Graduate Institute of Biotechnology
leaf senescence .
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM