Antisense Expression of Apple TFL1-like Gene (MdTFL1) Promotes Early Flowering and Causes Phenotypic Changes in Tobacco

Apples (Malus × domestica Borkh.) require up to several years for flowering and bearing fruits. The transition from vegetative to reproductive phase is controlled by floral regulators such as TERMINAL FLOWER 1 (TFL1) and FLOWERING LOCUS T (FT). TFL1 mediates the maintenance of vegetative phase, unlike the antagonistic function of FT to promote the transition into reproductive phase. In this study, we isolated apple TFL1-like gene (MdTFL1) to elucidate various phenotypic traits triggered by the antisense expression of MdTFL1 in tobacco apart from its floral induction function. Early flowering was observed in the tobacco line with MdTFL1 knockout, indicating the reduced time for transition to vegetative phases. Quantitative reverse-transcription PCR showed upregulation of genes involved in the regulation of floral induction, including NtAP1, NtSOC1, NFL1, and NtFTs, and downregulation of carotenoid cleavage dioxygenases (CCDs) and CEN-like genes in transgenic lines. Interestingly, transgenic tobacco expressing antisense MdTFL1 exhibited distinct morphological changes in lateral shoot outgrowth, internode length, and the development of leaves, flowers, and fruits. The results suggested that using the antisense expression of MdTFL1 gene is one of the approaches to shorten the vegetable phase and proposed improvement of plant architecture in horticultural crops

Introducing <i>MdTFL1</i> Promotes Heading Date and Produces Semi-Draft Phenotype in Rice

Flowering time (in rice, termed the heading date), plant height, and grain number are crucial agronomic traits for rice productivity. The heading date is controlled via environmental factors (day length and temperature) and genetic factors (floral genes). TERMINAL FLOWER 1 (TFL1) encodes a protein that controls meristem identity and participates in regulating flowering. In this study, a transgenic approach was used to promote the heading date in rice. We isolated and cloned apple MdTFL1 for early flowering in rice. Transgenic rice plants with antisense MdTFL1 showed an early heading date compared with wild-type plants. A gene expression analysis suggested that introducing MdTFL1 upregulated multiple endogenous floral meristem identity genes, including the (early) heading date gene family FLOWERING LOCUS T and MADS-box transcription factors, thereby shortening vegetable development. Antisense MdTFL1 also produced a wide range of phenotypic changes, including a change in overall plant organelles that affected an array of traits, especially grain productivity. The transgenic rice exhibited a semi-draft phenotype, increased leaf inclination angle, restricted flag leaf length, reduced spikelet fertility, and fewer grains per panicle. MdTFL1 plays a central role in regulating flowering and in various physiological aspects. These findings emphasize the role of TFL1 in regulating flowering in shortened breeding and expanding its function to produce plants with semi-draft phenotypes

Morphological development and photosynthetic acclimation of Panax ginseng seedlings to irradiation by light-emitting diodes (LEDs)

To determine the optimal light intensity and enable plants to cope with various environmental stresses in plant factories, the morphological and photosynthetic characteristics of ginseng seedlings, including the secondary metabolites, were investigated under six light intensities: 25, 50, 75, 100, 125, and 150 mu mol m(-2) s(-1). The shoot length increased with lower light intensity up to 75 mu mol m(-2) s(-1), and the leaf area and specific leaf weight were greatest at 100 and 75 mu mol m(-2) s(-1), respectively. Stomata frequency was higher from 100 mu mol m(-2) s(-1) with higher light intensity, and single stomatal pore length also increased at 150 mu mol m(-2) s(-1). Net photosynthetic rate at light saturation and net photosynthetic rate in growth condition increased sequentially up to 100 mu mol m(-2) s(-1) before rapidly decreasing at 150 mu mol m(-2) s(-1). The dark respiration rate and light compensation point were significantly high at 150 mu mol m(-2) s(-1) only. Fv/Fm and chlorophyll content statistically differed from 63 and 84 days after seedling stand, respectively. Thus, the leaves withered to death with higher light intensity. The ginsenoside content in the roots significantly increased according to the light intensity, and the panaxadiol/panaxatriol (PT) ratio tended to decrease as the PT-type ginsenosides increased further. Taken together, the range of 75-100 mu mol m(-2) s(-1) was found to be beneficial for growth, photosynthetic acclimation response, and total accumulated ginsenosides of ginseng seedlings.N