An evolutionary and developmental approach toward understanding of growth variations of two closely related dwarfism of Galium verum

Galium L. is one of the largest and most widespread genus of Rubiaceae, consisting of more than 650 species worldwide. Galium verum var. asiaticum (G. verum a.) is a perennial herbaceous and widely distributed in in Korea peninsula. On the other hand, Galium verum var. asiaticum for. pusillum (G. verum a.p.) is endemic to Korea, inhabiting only on high land of Mt. Halla of Jeju. G. verum a.p. appears to be a dwarfism of G. verum a. We wondered what physiological, environmental, or genetic factors rendered those two taxa morphologically differentiated. We found that G. verum a.p. shows a low activity of the cell proliferation and was not associated with responsiveness contents of auxin and gibberellins. In order to search for genetic factors involved, we carried out an mRNA differential display method using the ACPs, and isolated several different expression genes between the two taxa. We chose one of those genes, which encoded RADIALIS-like proteins: GvaRADL1 from G. verum a. and GvapRADL1 from G. verum a.p. We discuss the relevancy of the genetic variations in regard to the differential expression patterns of those genes and the differential growth patterns of the two variants.

Novel Insect Picorna-Like Virus Identified in the Brains of Aggressive Worker Honeybees

ABSTRACT To identify candidate genes involved in the aggressive behavior of worker honeybees, we used the differential display method to search for RNAs exclusively detected in the brains of aggressive workers that had attacked a hornet. We identified a novel, 10,152-nucleotide RNA, termed Kakugo RNA. Kakugo RNA encodes a protein of 2,893 amino acid residues that shares structural features and sequence similarities with various picorna-like virus polyproteins, especially those from sacbrood virus, which infects honeybees. The Kakugo protein contains several domains that correspond to the virion protein, helicase, protease, and RNA-dependent RNA polymerase domains of various picorna-like virus polyproteins. When the worker bee tissue lysate was subjected to sucrose density gradient centrifugation, Kakugo RNA, except for the material at the bottom, was separated into two major peaks. One of the peaks corresponded to the position of Kakugo mRNA, and the other corresponded to the position of the poliovirus virion. These results suggest that the Kakugo RNA exists as an mRNA-like free RNA and virion RNA in the honeybee. Furthermore, injection of the lysate supernatant from the attacker heads into the heads of noninfected bees resulted in a marked increase in Kakugo RNA. These results demonstrate that Kakugo RNA is a plus-strand RNA of a novel picorna-like virus and that the brains of aggressive workers are infected by this novel virus. Kakugo RNA was detected in aggressive workers but not in nurse bees or foragers. In aggressive workers, Kakugo RNA was detected in the brain but not in the thorax or abdomen, indicating a close relation between viral infection in the brain and aggressive worker behaviors.