Argyranthemum frutescens (L.) Sch.Bip. and Rhodanthemum gayanum (Coss. & Durieu) B. H. Wilcox, K. Bremer & Humphries are capable of hybridization. To expand flower color variation in this intergeneric hybrid group, we performed crosses using A. frutescens as the seed parent and R. hosmariense (Ball) B. H. Wilcox, K. Bremer & Humphries, R. catananche (Ball) B. H. Wilcox, K. Bremer & Humphries as the pollen parent. One plantlet was obtained from each cross between the white to pale pink-flowered A. frutescens and white-flowered R. hosmariense, and from a cross between the pink-flowered A. frutescens and cream to pale yellow-flowered R. catananche, via ovule culture. The cross with R. hosmariense produced an individual with white to pale pink ray florets, and the cross with R. catananche produced an individual with red ray florets. The flower and leaf shape of the progenies was intermediate between the parents, and other morphological traits were also characterized in the same manner. Morphological observations and a cleaved amplified polymorphic sequence marker-based determination, using the internal transcribed spacer region as a target for amplification and the restriction enzyme Afl II, revealed that both individuals are hybrids between A. frutescens and R. hosmariense, R. catananche. To the best of our knowledge, this is the first study to report that crossbreeding between A. frutescens (seed parent) and R. hosmariense, R. catananche (pollen parent) is possible. Moreover, further development of Argyranthemum breeding, especially that of a series of hybrid cultivars with different flower colors, is expected.

Pea (Pisum sativum) is an agriculturally important leguminous crop cultivated worldwide. It is also the plant from which phytoalexin was isolated for the first time. Several studies have investigated gene functions using pea hairy root culture systems. However, the procedures for producing hairy roots are relatively complicated and only a few pea cultivars and Rhizobium strains have been used. In this study, we established a simple method for generating transgenic hairy roots using a pea cultivar and a Rhizobium strain available in Japan. The transformation efficiency for the transgenic hairy roots (approximately 14%) was calculated on the basis of GFP fluorescence because the binary vector used in this study carried a GFP cassette as a marker. Furthermore, we confirmed that the production of the phytoalexin (+)-pisatin was induced by a copper dichloride treatment, indicating that this system can be used to characterize the biosynthesis of (+)-pisatin, which is a compound with a unique pterocarpan structure. Interestingly, some of the hairy roots turned into crown galls during the culture period. In summary, our simple method enables the production of transgenic pea hairy roots using biological materials accessible in Japan. The generated hairy roots can be used to elucidate the molecular mechanisms underlying (+)-pisatin biosynthesis as well as hairy root/crown gall formation.

Nitrogen (N) availability is one of the most important factors regulating plant metabolism and growth as it affects global gene expression profiles. Dynamic changes in chromatin structure, including histone modifications and nucleosome assembly/disassembly, have been extensively shown to regulate gene expression under various environmental stresses in plants. However, the involvement of chromatin related changes in plant nutrient responses has been demonstrated only in a few studies to date. In this study, we investigated the function of histone chaperone NUCLEOSOME ASSEMBLY PROTEIN1 (NAP1) proteins under N deficient conditions in Arabidopsis. In the nap1;1 nap1;2 nap1;3 triple mutant (m123-1), the expression of N-responsive marker genes and growth of lateral roots were decreased under N deficient conditions. In addition, the m123-1 plants showed a delay in N deficiency-induced leaf senescence. Taken together, these results suggest that NAP1s affect plant growth under N deficient conditions in Arabidopsis.