蔗糖 synthase (怀疑) 是在蔗糖的故障的关键酶并且为水池力量被认为一个生物化学的标记特别在庄稼种类，基于 mutational 和基因，抑制学习。它留下逃犯，然而是否，或到什么程度，的增加怀疑活动可以提高水池开发。我们由表示一个土豆瞄准了这个问题到地址在怀疑表达式的棉花怀疑基因以前被显示了为正常批评种子和纤维开发。那增加了的在产生在揭示的同型结合的子孙线由研究跟随了的 T1 的分离分析在提高的棉花(1 ) 怀疑活动有从从射击顶出现的年轻叶子明显的效果的叶扩大；(2 ) 早改善了种子开发，减少了种子流产，因此提高了种子集合，并且(3 ) 支持的纤维延伸。在年轻叶子怀疑 overexpressing 线，果糖而，集中显著地被增加，在伸长纤维，果糖并且葡萄糖层次被增加。自从 hexoses，在叶子贡献很少到 osmolality，与开发纤维相对照，高怀疑活动，这被结束独立于渗透的规定支持叶开发，可能通过糖发信号。分析也证明在 0-d 棉花种子加倍 Sus 活动增加了他们的新鲜重量大约 30% 。然而，进一步增加在怀疑活动没更进一步在种子重量导致增加，为 Sus overexpression 效果显示上面的限制。最后，从增加的纤维长度和种子数字基于纤维上的观察添加剂效果让步，新策略被建议由总体上，而非完全改进种子开发增加棉花纤维产量集中于操作纤维生长。
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.
The work was supported by Bayer CropScience and University of Newcastle. ACKNOWLEDGMENTS We thank Pinghua He for assistance of cotton transformation, Richard James for measuring photosynthesis, and Tony Arioli and Bill Taylor for discussion. No conflict of interest declared.
To whom correspondence should be addressed. E-mail Yong-Ling.Ruan@newcastle.edu.au, tel. 061-02-62464909, fax 061-02-62464950.