创新背景

茎锈病的一种新菌株——1999年在乌干达发现后被称为Ug99——正在整个地区传播。全世界种植的大约90%的小麦品种对Ug99敏感。

创新过程

小麦和秆锈病在进化上的军备竞赛已经持续了一万多年。在20世纪50年代，一场主要的瘟疫在北美蔓延，摧毁了高达40%的小麦作物，小麦是世界上仅次于大米的第二大谷物。

从那时起，科学家们开发出了抗锈病品种，以提高小麦对茎锈病的免疫力。但病原体正在卷土重来。茎锈病的一种新菌株——1999年在乌干达发现后被称为Ug99——正在整个地区传播。全世界种植的大约90%的小麦品种对Ug99敏感。

加州大学戴维斯分校植物科学系教授、霍华德·休斯医学研究所研究员杜布科夫斯基发现，Ug99已经扩展到非洲大部分小麦种植区，并穿过红海到达也门和伊朗。Ug99已经进入了旁遮普地区——亚洲的面包篮子——识别和部署有效的抗性基因对于减轻这一威胁至关重要。

杜布科夫斯基和他的团队发现了Sr13的三种不同的抗性形式，一种来自面食小麦的基因对Ug99有效，还有另一组来自也门和埃塞俄比亚的强毒茎锈病菌株。2013年，杜布科夫斯基和其他研究人员发现了另一种名为Sr35的基因，它也对Ug99具有耐药性。研究小组即将确定第三种基因，这种基因可以保护人们免受这种毒株的侵袭。

为了培育出更好的品种，育种者将具有所需性状的植物杂交，并在多个世代中选择最佳的后代。一旦茎秆锈病抗性基因被鉴定出来，育种者就可以利用分子标记(DNA的特定区域)来选择种子或幼苗阶段的基因。这加快了作物改良的进程。

这些分子标记使育种者能够在同一株植物中金字塔形排列多个抗茎锈基因，以延长抗性的持久性。

创新价值

研究人员的这项发现将帮助育种者更快地培育出能够抵御致命病原体并阻止全球小麦流行的品种。

创新关键点

为了培育出更好的品种，育种者将具有所需性状的植物杂交，并在多个世代中选择最佳的后代。一旦茎秆锈病抗性基因被鉴定出来，育种者就可以利用分子标记(DNA的特定区域)来选择种子或幼苗阶段的基因。这加快了作物改良的进程。

Using a gene to protect against a devastating stem rust strain

Wheat and stem rust have been in an evolutionary arms race for more than 10,000 years. In the 1950s, a major plague spread across North America, destroying up to 40 percent of the wheat crop, the world's second-largest grain after rice.
Since then, scientists have developed rust-resistant varieties to boost wheat's immunity to stem rust. But the pathogen is making a comeback. A new strain of stem rust -- known as Ug99 after it was discovered in Uganda in 1999 -- is spreading across the region. About 90 percent of wheat varieties grown worldwide are susceptible to Ug99.
Dubkowsky, a professor in the Department of Plant Sciences at the University of California, Davis, and a Howard Hughes Medical Institute investigator, found that Ug99 has spread across much of Africa's wheat-growing region and across the Red Sea to Yemen and Iran. Ug99 has made its way into Punjab - the bread basket of Asia - and identifying and deploying effective resistance genes is crucial to mitigate this threat.
Dubkowsky and his team found three different forms of resistance to Sr13, a gene from pasta wheat that is effective against Ug99, and another set of virulent stem rust strains from Yemen and Ethiopia. In 2013, Dubkowsky and other researchers discovered another gene, called Sr35, that was also resistant to Ug99. The team is close to identifying a third gene that could protect people from the strain.
To create better varieties, breeders cross plants with desired traits and select the best offspring over multiple generations. Once stem rust resistance genes have been identified, breeders can use molecular markers (specific regions of DNA) to select genes at the seed or seedling stage. This accelerated the process of crop improvement.
These molecular markers allow breeders to pyramid multiple stem rust resistance genes in the same plant to prolong resistance persistence.