Graduate School of Agricultural Science, Kobe University, Nada-ku, Kobe 657-8501, Japan.
BMC Plant Biol. 2011 Jan 4;11:2. doi: 10.1186/1471-2229-11-2.
Alloplasmic wheat lines with Aegilops crassa cytoplasm often show homeotic conversion of stamens into pistils under long-day conditions. In the pistillody-exhibiting florets, an ectopic ovule is formed within the transformed stamens, and female sterility is also observed because of abnormal integument development.
In this study, four wheat Bell1-like homeobox (BLH) genes were isolated and named WBLH1 to WBLH4. WBLH1/WBLH3/WBLH4 expression was observed in the basal boundary region of the ovary in both normal pistils and transformed stamens. WBLH2 was also strongly expressed in integuments not only of normal ovules in pistils but also of the ectopic ovules in transformed stamens, and the WBLH2 expression pattern in the sterile pistils seemed to be identical to that in normal ovules of fertile pistils. In addition, WBLH1 and WBLH3 showed interactions with the three wheat KNOX proteins through the BEL domain. WBLH2, however, formed a complex with wheat KNOTTED1 and ROUGH SHEATH1 orthologs through SKY and BEL domains, but not with a wheat LIGULELESS4 ortholog.
Expression of the four WBLH genes is evident in reproductive organs including pistils and transformed stamens and is independent from female sterility in alloplasmic wheat lines with Ae. crassa cytoplasm. KNOX-BLH interaction was conserved among various plant species, indicating the significance of KNOX-BLH complex formation in wheat developmental processes. The functional features of WBLH2 are likely to be distinct from other BLH gene functions in wheat development.
含有 Aegilops crassa 细胞质的异质小麦系在长日照条件下常表现出雄蕊的同花异位转化。在表现出雌蕊化的小花中，在转化的雄蕊内形成异位胚珠，并且由于外果皮发育异常，还观察到雌性不育。
在这项研究中，分离并命名了四个小麦 Bell1 类同源盒（BLH）基因，分别命名为 WBLH1 到 WBLH4。在正常雌蕊和转化雄蕊的子房基部边界区域观察到 WBLH1/WBLH3/WBLH4 的表达。WBLH2 在正常雌蕊的胚珠以及转化雄蕊的异位胚珠的外果皮中也强烈表达，并且不育雌蕊中的 WBLH2 表达模式似乎与可育雌蕊的正常胚珠相同。此外，WBLH1 和 WBLH3 通过 BEL 结构域与三个小麦 KNOX 蛋白相互作用。然而，WBLH2 通过 SKY 和 BEL 结构域与小麦 KNOTTED1 和 ROUGH SHEATH1 同源物形成复合物，但不与小麦 LIGULELESS4 同源物形成复合物。
四个 WBLH 基因在包括雌蕊和转化雄蕊在内的生殖器官中的表达是明显的，并且与含有 Ae. crassa 细胞质的异质小麦系的雌性不育无关。KNOX-BLH 相互作用在各种植物物种中保守，表明 KNOX-BLH 复合物形成在小麦发育过程中的重要性。WBLH2 的功能特征可能与小麦发育中其他 BLH 基因的功能不同。
