In Arabidopsis thaliana, the R2R3 MYB-like transcription factor MYB30 is a positive regulator of the pathogen-induced hypersensitive response and of brassinosteroid and abscisic acid signaling. Relatively little is known about the cross-talk and potential overlap between the gene networks regulating flowering time, pathogen defense and response to biotic stress. MYB30 is an interesting candidate, which has the potential to mediate cross-talk between the flowering and stress pathways.

Under joint guidance of Dr. Franziska Turck with Max Planck Institute of Plant Breeding Research and Prof. YU Diqiu of Xishuangbanna Tropical Botanical Garden (XTBG), Dr. LIU Liangyu conducted a study to show how MYB30 could integrate into the flowering time regulatory network.

The study found that strong expression of MYB 30 in phloem companion cells promoted flowering under long days and short days in Arabidopsis. Overexpression of MYB30 in the phloem increased FLOWERING LOCUS T (FT) and reduced TWIN SISTER OF FT (TSF) expression in absence and presence of CONSTANS (CO). MYB30 induced 1.0 kb FT promoter activity in transient bombardment assay of leaves. MYB30 promoted flowering independently of salicylic acid (SA) levels and FLOWERING LOCUS C (FLC).

The researchers thus concluded that increased expression of MYB30 in the phloem could modulate flowering by increasing the expression of FT through a pathway that acted either independent of or additively to CO. Increased FT expression by MYB30 was independent of FLC and did not require the presence of SA.

The study entitled “Elevated Levels of MYB30 in the Phloem Accelerate Flowering in Arabidopsisthrough the Regulation of FLOWERING LOCUS T” has been published in PLoS ONE.