Department of Biotechnology, TERI University, 10 Institutional Area, Vasant Kunj, Delhi 110070, India.
Department of Biotechnology, TERI University, 10 Institutional Area, Vasant Kunj, Delhi 110070, India.
Plant Sci. 2017 May;258:29-44. doi: 10.1016/j.plantsci.2017.02.003. Epub 2017 Feb 16.
LEAFY plays a central role in regulation of flowering time and floral meristem identity in plants. Unfortunately, LFY function remains uncharacterized in agronomicaly important Brassicas. Herein, we illustrate fine-mapping of expression domains of LFY in 15 cultivars of 6 Brassica species and describe gain-of-function phenotypes in Arabidopsis and Brassica. We depict early flowering and altered fatty-acid composition in transgenic seed. The cDNA encoding BjuLFY (417aa) shared only 85% identity with reported homolog of B.juncea implying distinctness. Quantitative RT-PCR based coarse expression mapping of BjuLFY in tissue samples representing 3 time points at specific days after sowing (DAS), pre-flowering (30 DAS), flowering (75 DAS) and post-flowering (110 DAS), depicted an intense pulse of BjuLFY expression restricted to primary floral buds (75 DAS) which subsided in secondary floral buds (110 DAS); expression in root samples was also recorded implying neo-functionalization. Fine-mapping of expression during flowering confirmed tightly regulated LFY expression during early stages of bud development in 15 cultivars of 6 Brassica species implying functional conservation. Ectopic expression of BjuLFY in A. thaliana and B. juncea caused floral meristem defects and precocious flowering. B. juncea transgenics (T) over-expressing BjuLFY flowered 20days earlier produced normal flowers. GC-MS analysis of mature seed from Brassica transgenics showed an altered fatty-acid profile suggestive of seed maturation occurring at lower temperatures vis-à-vis control. Our findings implicate BjuLFY as a regulator of flowering in B. juncea and suggest its application in developing climate resilient crops.
拟南芥 LEAFY 基因在植物开花时间和花分生组织身份的调控中起着核心作用。不幸的是，LFY 功能在农业上重要的芸薹属作物中仍然没有得到描述。本文阐述了 LEAFY 在 6 种芸薹属作物的 15 个品种中的表达域的精细定位，并描述了在拟南芥和芸薹属中的功能获得表型。我们描述了转基因种子的早期开花和脂肪酸组成的改变。编码 BjuLFY（417aa）的 cDNA 与报道的 B.juncea 同源物仅共享 85%的同一性，这表明它们是不同的。基于组织样本的定量 RT-PCR 粗表达图谱，代表播种后特定天数（DAS）、开花前（30 DAS）、开花（75 DAS）和开花后（110 DAS）的 3 个时间点，描绘了 BjuLFY 表达的强烈脉冲，仅限于初级花芽（75 DAS），然后在次级花芽（110 DAS）中减弱；在根样本中也记录到了表达，这暗示了新功能化。开花期间的精细表达图谱证实了在 6 种芸薹属作物的 15 个品种中，在芽发育的早期阶段对 LFY 表达进行了严格调控，这表明了功能的保守性。在拟南芥和 B. juncea 中异位表达 BjuLFY 导致花分生组织缺陷和早熟开花。过表达 BjuLFY 的 B. juncea 转基因（T）比对照提前 20 天开花，产生正常的花朵。对来自 Brassica 转基因的成熟种子的 GC-MS 分析显示，脂肪酸图谱发生了改变，这表明种子成熟是在较低温度下发生的，与对照相比。我们的发现表明 BjuLFY 是 B. juncea 开花的调节剂，并暗示其在培育抗气候作物中的应用。
