Overexpression of a Potato Sucrose Synthase Gene in Cotton Accelerates Leaf Expansion, Reduces Seed Abortion, and Enhances Fiber Production

作     者：Shou-Min Xu Elizabeth Brill Danny J. Llewellyn Robert T. Furbank Yong-Ling Ruan 

作者机构：CSIRO Plant Industry GPO Box 1600 Canberra ACT 2601 Australia School of Environmental and Life Sciences University of Newcastle Newcastle NSW 2308 Australia 

出 版 物：《Molecular Plant》 (分子植物（英文版）)

年 卷 期：2012年第5卷第2期

页      面：430-441页

核心收录：

学科分类：09[农学] 0901[农学-作物学] 0902[农学-园艺学] 090201[农学-果树学] 

基　　金：BayerCropScienceandUniversityofNewcastle 

主　　题：cotton fiber invertase leaf expansion seed abortion seed development sucrose synthase sugar signaling. 

摘      要：Sucrose synthase （Sus） is a key enzyme in the breakdown of sucrose and is considered a biochemical marker for sink strength, especially in crop species, based on mutational and gene suppression studies. It remains elusive, however, whether, or to what extent, increase in Sus activity may enhance sink development. We aimed to address this question by expressing a potato Sus gene in cotton where Sus expression has been previously shown to be critical for normal seed and fiber development. Segregation analyses at T1 generation followed by studies in homozygous progeny lines revealed that increased Sus activity in cotton （1） enhanced leaf expansion with the effect evident from young leaves emerging from shoot apex; （2） improved early seed development, which reduced seed abortion, hence enhanced seed set, and （3） promoted fiber elongation. In young leaves of Sus overexpressing lines, fructose concentrations were significantly increased whereas, in elongating fibers, both fructose and glucose levels were increased. Since hexoses contribute little to osmolality in leaves, in contrast to developing fibers, it is concluded that high Sus activity promotes leaf development independently of osmotic regulation, probably through sugar signaling. The analyses also showed that doubling the Sus activity in 0-d cotton seeds increased their fresh weight by about 30%. However, further increase in Sus activity did not lead to any further increase in seed weight, indicating an upper limit for the Sus overexpression effect. Finally, based on the observed additive effect on fiber yield from increased fiber length and seed number, a new strategy is proposed to increase cotton fiber yield by improving seed development as a whole, rather than solely focusing on manipulating fiber growth.