The citrus leaf miner (CLM) is an important citrus pest. A thorough understanding of the biology and population dynamics of CLM are essential for development of reliable pest population prediction system. We investigated the developmental periods of the species under ten constant temperature schemes (12.5℃~39℃). Furthermore, we established a development model of CLM, based on the result of a laboratory experiment. The immature developmental duration of CLM at constant temperatures were 63.5 days at 15℃, 23.9 days at 21℃, 15.6 days at 27℃, and 12.3 days at 33℃, showing statistically significant difference among temperature regimes. The lower threshold temperature and thermal constant were 11.3℃ and 243.7 DD, respectively, for immature development. In relation to temperature, non-linear development models were established for each developmental stage of CLM.

The citrus leaf miner (CLM) is a of important citrus pests in Jeju island, but it’s not clear about ecology of over-wintering in Jeju. We investigated the developmental stage to know how the CLM overwinters in 20 sites. And we investigated the mortality of larvae, pupae and adult stage of CLM in open citrus cultivated field December, 2017 to April 2018 and growth chamber conditions(from –10 to 5 ℃). As a result, no larvae and adult survived open field during winter. We concluded that the CLM usually overwinters as pupa during winter.

Major loci controlling flowering time and maturity of short-day plant soybean, E1, E2, E3, E4, E5, E6, E7 and E8, have been identified in soybean. The gene corresponding to E2 locus is a homolog of Arabidopsis GIGANTEA (AtGI). We identified three GI homologs in soybean and are verifying their roles in day-length dependent flowering. Expression anlysis indicated that GmGIs are ubiquitously expressed at all developmental stages of soybean plants. Diurnal expression of GmGIs fluctuates within light/dark cycles of long-day (LD) and short-day (SD). GmGI2 and GmGI3 have identical expression patterns under both day length conditions with the highest peak at zeitgeber time 8 h (ZT8) under LD and at ZT4 under SD. GmGI1 shows the peak at ZT12 under LD and at ZT8 under SD. All of GmGIs exhibit the earlier peak and the shorter phase under SD than LD. The results indicated that day length affects expressions of GmGIs. Subcellular localization analysis showed that GmGIs are mainly targeted to nucleus, similar to the localization of AtGI. Overexpression of GmGIs in Arabidopsis transgenic plants showed no significant effect on flowering time nor rescue of gi-2 mutant phenotype. The results suggested that GmGIs have different molecular functions in flowering time regulation of short-day plant soybean compared to long-day plant Arabidopsis. To investigate the molecular mechanisms of GmGIs’ functions in soybean flowering time control, we intend to identify target gene of GmGIs and interacting proteins by using yeast two-hybrid assay.

FT is one of the major floral activator in photoperiod-dependent flowering pathway. To understand the role of FT homologs in flowering time control of short-day plant soybean, we identified ten soybean FT genes and named GmFTs. Phylogenetic analysis revealed that ten GmFT genes were further categorized into three subclades. Gene expression analysis showed that the most GmFT genes are mainly expressed in leaves. The expression of GmFT2a, GmFT2b, GmFT5a, and GmFT6 was strongly induced under the floral inductive short-day condition, but GmFT4 exhibited opposite expression pattern compared to those of GmFT2a, GmFT2b, GmFT5a, and GmFT6. To understand roles of GmFT genes in flowering, we generated Arabidopsis transgenic plant overexpressing GmFT genes. Both 35S:GmFT2a and 35S:GmFT5a transgenic plants showed extremely early flowering. In contrast, overexpression of GmFT4 delayed flowering of transgenic plants compared to wild type Arabidopsis. The results indicated that GmFT2a and GmFT5a might function as floral activators, while GmFT4 has an opposite function in soybean flowering. Moreover, domain swapping approaches between GmFT2a and GmFT4 revealed that the substitution of the segment B region alone, which is located in 4th exon, was sufficient to change the function of GmFT2a to floral repressor and GmFT4 to floral activator. The results suggested that soybean FT homologs have been functionally diversified during evolution and might play different roles in photoperiod-dependent flowering of soybean.

Phosphorus is one of the macronutrients essential for plant growth and development, as well as crop productivity. Many soils around the world are deficient in phosphate (Pi) that plants can utilize. To cope with the stress of Pi starvation, plants have evolved many adaptive strategies, such as changes of root architecture and enhanced Pi acquisition form soil. To understand molecular mechanism underlying Pi starvation stress signaling, we characterized the activation-tagged mutant showing altered responses to Pi deficiency compared to wild type Arabidopsis and named hsp3 (hypersensitive to Pi starvation3). hsp3 mutant exhibits enhanced phosphate transporter activity, resulting in higher Pi content than wild type. However, in root architectural change under Pi starvation, hsp3 shows hyposensitive responses than wild type, such as longer primary root elongation, lower lateral root density. Histochemical analysis using hsp3 mutant expressing auxin-responsive DR5::GUS reporter gene, indicated that auxin allocation from primary to lateral roots under Pi starvation is aborted in hsp3 mutant. Molecular genetic analysis of hsp3 mutant revealed that the mutant phenotype is caused by the lesion in ENHANCED SILENCING PHENOTYPE4 (ESP4) gene whose function is proposed in mRNA 3’ end processing. Here, we propose that mRNA processing plays a crucial role in Pi homeostasis in Arabidopsis.