Functional characterization of a novel Brassica LEAFY homolog from Indian mustard: Expression pattern and gain-of-function studies.
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 (T1) 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.
Department of Biotechnology, TERI University, 10 Institutional Area, Vasant Kunj, Delhi 110070, India.
Priyanka
P
Dhakate
Department of Biotechnology, TERI University, 10 Institutional Area, Vasant Kunj, Delhi 110070, India.
Shikha
S
Tyagi
Department of Biotechnology, TERI University, 10 Institutional Area, Vasant Kunj, Delhi 110070, India.
Anupama
A
Singh
Department of Biotechnology, TERI University, 10 Institutional Area, Vasant Kunj, Delhi 110070, India. Electronic address: asingh@teri.res.in.
Anandita
A
Singh
D001937:Brassica / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D000066630:Ectopic Gene Expression; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics* / Q000502:physiology; D017343:Genes, Plant / Q000235:genetics* / Q000502:physiology; D018519:Meristem / Q000235:genetics / Q000378:metabolism; D009149:Mustard Plant / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D010802:Phylogeny; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism / Q000502:physiology
Brassica transformation; Evolution; Fatty-acids; Flowering time; Neo-functionalization; Polyploidy