Institute of Cytology and Genetics, SB RAS, Lavrenvieva ave. 10, Novosibirsk, 630090, Russia.
Novosibirsk State University, Pirogova, 2, Novosibirsk, 630090, Russia.
BMC Plant Biol. 2017 Dec 28;17(Suppl 2):252. doi: 10.1186/s12870-017-1191-3.
Inflorescences of wheat species, spikes, are characteristically unbranched and bear one sessile spikelet at a spike rachis node. Development of supernumerary spikelets (SSs) at rachis nodes or on the extended rachillas is abnormal. Various wheat morphotypes with altered spike morphology, associated with the development of SSs, present an important genetic resource for studies on genetic regulation of wheat inflorescence development.
Here we characterized diploid and tetraploid wheat lines of various non-standard spike morphotypes, which allowed for identification of a new mutant allele of the WHEAT FRIZZY PANICLE (WFZP) gene that determines spike branching in diploid wheat Ttiticum monococcum L. Moreover, we found that the development of SSs and spike branching in wheat T. durum Desf. was a result of a wfzp-A/TtBH-A1 mutation that originated from spontaneous hybridization with T. turgidum convar. сompositum (L.f.) Filat. Detailed characterization of the false-true ramification phenotype controlled by the recessive sham ramification 2 (shr2) gene in tetraploid wheat T. turgidum L. allowed us to suggest putative functions of the SHR2 gene that may be involved in the regulation of spikelet meristem fate and in specification of floret meristems. The results of a gene interaction test suggested that genes WFZP and SHR2 function independently in different processes during spikelet development, whereas another spike ramification gene(s) interact(s) with SHR2 and share(s) common functions.
SS mutants represent an important genetic tool for research on the development of the wheat spikelet and for identification of genes that control meristem activities. Further studies on different non-standard SS morphotypes and wheat lines with altered spike morphology will allow researchers to identify new genes that control meristem identity and determinacy, to elucidate the interaction between the genes, and to understand how these genes, acting in concert, regulate the development of the wheat spike.
小麦属植物的花序为穗状，特征为不分枝，在穗轴节上着生一个无柄小穗。穗轴节上或延伸的小穗轴上产生额外小穗（SS）是不正常的。各种穗形改变的小麦形态型，与 SS 的发育有关，为研究小麦花序发育的遗传调控提供了重要的遗传资源。
本研究对各种非标准穗形的二倍体和四倍体小麦品系进行了表征，鉴定出一个决定二倍体小麦 Triticum monococcum L. 穗分枝的 WHEAT FRIZZY PANICLE（WFZP）基因的新突变等位基因。此外，我们发现小麦 T. durum Desf. 的 SS 发育和穗分枝是由 wfzp-A/TtBH-A1 突变引起的，该突变源于与 T. turgidum convar. сompositum（L.f.）Filat 的自发杂交。对四倍体小麦 T. turgidum L. 中隐性假分枝 2（shr2）基因控制的假-真分枝表型的详细特征分析，使我们能够推测 SHR2 基因的可能功能，该基因可能参与小穗分生组织命运的调控和小花分生组织的特化。基因互作测试的结果表明，WFZP 和 SHR2 基因在小穗发育的不同过程中独立发挥作用，而另一个穗分枝基因与 SHR2 相互作用并具有共同的功能。
SS 突变体是研究小麦小穗发育和鉴定控制分生组织活性的基因的重要遗传工具。对不同的非标准 SS 形态型和穗形改变的小麦品系进行进一步研究，将有助于识别控制分生组织身份和确定性的新基因，阐明基因之间的相互作用，并了解这些基因如何协同作用，调节小麦穗的发育。
