Molecular genetic approaches for enhancing stress tolerance and fruit quality of tomato

Antt Htet Wai,Aung Htay Naing,이도진,김창길,정미영 한국식물생명공학회 2020 Plant biotechnology reports Vol.14 No.5

Numerous eforts have been made to genetically improve tomato (Solanum lycopersicum) cultivars using various conventional breeding methods, despite severe restrictions to improve some target traits. Molecular approaches such as metabolic genetic engineering and genome editing tools have been able to overcome the restrictions and have achieved the generation of tomatoes with improved, commercially important traits. Due to continuing global climate change and market competition, the molecular approaches have been greatly applied in genetic improvement of agronomic (e.g., biotic and abiotic stress tolerance) and fruit quality (e.g., antioxidant enrichment and prolongation of shelf-life) traits in tomato. In this review, we summarize the results of previous studies that achieved genetic improvement of tomato agronomic and fruit quality traits using the molecular approaches and highlight how the molecular approaches are crucial for the genetic improvement of tomato. In addition, this review describes the functional roles of genes that enhance fruit quality and improve biotic/abiotic stress tolerance; therefore, it will also provide information of the specifc genes for further genetic improvement in other tomato cultivars or horticultural crops using the molecular approaches, thus allowing for a time-saving approach to advancing plant biology and the horticultural industry.

Axillary meristem initiation and bud growth in rice

Antt Htet Wai,Gynheung An 한국식물학회 2017 Journal of Plant Biology Vol.60 No.5

The morphology of a plant is not predestinedduring embryonic development and its myriad branchingarchitecture is post-embryonically determined by axillarymeristem (AM) activity as the plant adapts to a varyingenvironment. The shoot apical meristem produced duringembryonic development repetitively gives rise to a phytomerthat comprises a leaf, an AM, and an internode. The finalaerial architecture is regulated by shoot branching patternsderived from AM activity. These branching patterns aremodulated by two processes: AM formation and axillary budoutgrowth. Several transcription factors (TFs) that regulatethese processes have been identified. Various plant hormones,including strigolactones and auxin, have major roles incontrolling these TFs. In this review we focus on molecularmechanisms that guide AM initiation and axillary budgrowth, using rice as our main species of emphasis.

Histone Deacetylase 701 (HDT701) Induces Flowering in Rice by Modulating Expression of OsIDS1

조래현,윤진미,Antt Htet Wai,안진흥 한국분자세포생물학회 2018 Molecules and cells Vol.41 No.7

Rice is a facultative short-day (SD) plant in which flowering is induced under SD conditions or by other environmental factors and internal genetic programs. Overexpression of Histone Deacetylase 701 (HDT701) accelerates flowering in hybrid rice. In this study, mutants defective in HDT701 flowered late under both SD and long-day conditions. Expression levels of florigens Heading date 3a (Hd3a) and Rice Flowering Locus T1 (RFT1), and their immediate upstream floral activator Early heading date 1 (Ehd1), were significantly decreased in the hdt701 mutants, indicating that HDT701 functions upstream of Ehd1 in controlling flowering time. Transcript levels of OsINDETERMINATE SPIKELET 1 (OsIDS1), an upstream repressor of Ehd1, were significantly increased in the mutants while those of OsGI and Hd1 were reduced. Chromatinimmunoprecipitation assays revealed that HDT701 directly binds to the promoter region of OsIDS1. These results suggest that HDT701 induces flowering by suppressing OsIDS1.

Histone Deacetylase 701 (HDT701) Induces Flowering in Rice by Modulating Expression of OsIDS1

Cho, Lae-Hyeon,Yoon, Jinmi,Wai, Antt Htet,An, Gynheung Korean Society for Molecular and Cellular Biology 2018 Molecules and cells Vol.41 No.7

Rice is a facultative short-day (SD) plant in which flowering is induced under SD conditions or by other environmental factors and internal genetic programs. Overexpression of Histone Deacetylase 701 (HDT701) accelerates flowering in hybrid rice. In this study, mutants defective in HDT701 flowered late under both SD and long-day conditions. Expression levels of florigens Heading date 3a (Hd3a) and Rice Flowering Locus T1 (RFT1), and their immediate upstream floral activator Early heading date 1 (Ehd1), were significantly decreased in the hdt701 mutants, indicating that HDT701 functions upstream of Ehd1 in controlling flowering time. Transcript levels of OsINDETERMINATE SPIKELET 1 (OsIDS1), an upstream repressor of Ehd1, were significantly increased in the mutants while those of OsGI and Hd1 were reduced. Chromatin-immunoprecipitation assays revealed that HDT701 directly binds to the promoter region of OsIDS1. These results suggest that HDT701 induces flowering by suppressing OsIDS1.

KNOX Protein OSH15 Induces Grain Shattering by Repressing Lignin Biosynthesis Genes

Yoon, Jinmi,Cho, Lae-Hyeon,Antt, Htet Wai,Koh, Hee-Jong,An, Gynheung American Society of Plant Biologists 2017 Plant Physiology Vol.174 No.1

<P>Seed shattering is an agronomically important trait. Two major domestication factors are responsible for this: qSH1 and SH5. Whereas qSH1 functions in cell differentiation in the abscission zone (AZ), a major role of SH5 is the repression of lignin deposition. We have determined that a KNOX protein, OSH15, also controls seed shattering. Knockdown mutations of OSH15 showed reduced seed-shattering phenotypes. Coimmunoprecipitation experiments revealed that OSH15 interacts with SH5 and qSH1, two proteins in the BELL homeobox family. In transgenic plants carrying the OSH15 promoter-GUS reporter construct, the reporter gene was preferentially expressed in the AZ during young spikelet development. The RNA in situ hybridization experiment also showed that OSH15 messenger RNAs were abundant in the AZ during spikelet development. Analyses of osh15 SH5-D double mutants showed that SH5 could not increase the degree of seed shattering when OSH15 was absent, indicating that SH5 functions together with OSH15. In addition to the seed-shattering phenotype, osh15 mutants displayed dwarfism and accumulated a higher amount of lignin in internodes due to increased expression of the genes involved in lignin biosynthesis. Knockout mutations of CAD2, which encodes an enzyme for the last step in the monolignol biosynthesis pathway, caused an easy seed-shattering phenotype by reducing lignin deposition in the AZ. This indicated that the lignin level is an important determinant of seed shattering in rice (Oryza sativa). Chromatin immunoprecipitation assays demonstrated that both OSH15 and SH5 interact directly with CAD2 chromatin. We conclude that OSH15 and SH5 form a dimer that enhances seed shattering by directly inhibiting lignin biosynthesis genes.</P>

Chromatin interacting factor Os VIL 2 increases biomass and rice grain yield

Yang, Jungil,Cho, Lae‐,Hyeon,Yoon, Jinmi,Yoon, Hyeryung,Wai, Antt Htet,Hong, Woo‐,Jong,Han, Muho,Sakakibara, Hitoshi,Liang, Wanqi,Jung, Ki‐,Hong,Jeon, Jong‐,Seong,Koh, Hee John Wiley and Sons Inc. 2019 Plant biotechnology journal Vol.17 No.1

<P><B>Summary</B></P><P>Grain number is an important agronomic trait. We investigated the roles of chromatin interacting factor <I>Oryza sativa </I>VIN3‐LIKE 2 (OsVIL2), which controls plant biomass and yield in rice. Mutations in <I>OsVIL2</I> led to shorter plants and fewer grains whereas its overexpression (OX) enhanced biomass production and grain numbers when compared with the wild type. RNA‐sequencing analyses revealed that 1958 genes were up‐regulated and 2096 genes were down‐regulated in the region of active division within the first internodes of OX plants. Chromatin immunoprecipitation analysis showed that, among the downregulated genes, OsVIL2 was directly associated with chromatins in the promoter region of <I>CYTOKININ OXIDASE/DEHYDROGENASE2</I> (<I>OsCKX2</I>), a gene responsible for cytokinin degradation. Likewise, active cytokinin levels were increased in the OX plants. We conclude that OsVIL2 improves the production of biomass and grain by suppressing <I>OsCKX2</I> chromatin.</P>