Jia Qiaojun, Li Chengdao, Shang Yi, Zhu Jinghuan, Hua Wei, Wang Junmei, Yang Jianming, Zhang Guoping
Institute of Crop Science, Zhejiang University, Hangzhou, 310058, China.
Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, China.
BMC Genomics. 2015 Nov 14;16:927. doi: 10.1186/s12864-015-2116-x.
sdw1/denso is one of the most important and useful semi-dwarf genes in barley breeding. At least four sdw1/denso alleles have been reported and HvGA20ox 2 is considered as the candidate gene. Up to date, results of studies have not univocally proven the genetic relationship between sdw1/denso and HvGA20ox 2 .
In the present study, a complete deletion of Morex_contig_40861 including both HvGA20ox 2 and Mloc_56463 genes was identified at the sdw1 locus from a semi-dwarf mutant Riso no. 9265. Expression of the genes encoding gibberellin biosynthesis (HvGA20ox 1 and HvGA3ox 2 ) were increased in the mutant compared to the wild type Bomi, while the expression of GA catabolic gene HvGA2ox 3 was decreased. Over-expression of HvGA20ox 2 could rescue the semi-dwarf phenotype and increase GAs concentration.
We confirmed that a GA biosynthetic enzyme HvGA20ox2, acted as GA 20-oxidase, is the functional gene for the sdw1/denso semi-dwarfism. Lose of HvGA20ox 2 is partially compensated by HvGA20ox 1 and further feedback is regulated by gibberellin. We also deduced that the sdw1/denso allele itself affects later heading owing to its reduced endogenous GAs concentration.
sdw1/denso是大麦育种中最重要且最有用的半矮秆基因之一。已报道至少有四个sdw1/denso等位基因，HvGA20ox 2被认为是候选基因。迄今为止，研究结果尚未明确证实sdw1/denso与HvGA20ox 2之间的遗传关系。
在本研究中，从半矮秆突变体Riso no. 9265的sdw1位点鉴定出包含HvGA20ox 2和Mloc_56463基因的Morex_contig_40861的完全缺失。与野生型Bomi相比，突变体中赤霉素生物合成相关基因（HvGA20ox 1和HvGA3ox 2）的表达增加，而GA分解代谢基因HvGA2ox 3的表达降低。HvGA20ox 2的过表达可挽救半矮秆表型并增加赤霉素浓度。
我们证实GA生物合成酶HvGA20ox2作为GA 20-氧化酶，是sdw1/denso半矮化的功能基因。HvGA20ox 2的缺失部分由HvGA20ox 1补偿，并且赤霉素进一步反馈调节。我们还推断sdw1/denso等位基因本身由于其内源赤霉素浓度降低而影响抽穗期延迟。
