The Evolution of HD2 Proteins in Green Plants.

In eukaryotes, protein deacetylation is carried out by two well-conserved histone deacetylase (HDAC) families: RPD3/HDA1 and SIR2. Intriguingly, model plants such as Arabidopsis express an additional plant-specific HDAC family, termed type-2 HDACs (HD2s). Transcriptomic analyses from more than 1300 green plants generated by the 1000 plants (1KP) consortium showed that HD2s appeared early in green plant evolution, the first members being detected in several streptophyte green alga. The HD2 family has expanded via several rounds of successive duplication; members are expressed in all major green plant clades. Interestingly, angiosperm species express new HD2 genes devoid of a zinc-finger domain, one of the main structural features of HD2s. These variants may have been associated with the origin and/or the biology of the ovule/seed.

Phylogeography and host association in a pollinating seed parasite Greya politella (Lepidoptera: Prodoxidae).

Inferring the historical context of ecological diversification is an important step in understanding the way that population-level processes result in a diversity of species and interactions in communities. We performed a phylogeographic analysis of mitochondrial DNA haplotypes from the pollinating seed parasite Greya politella (Lepidoptera: Prodoxidae) in order to determine the degree to which populations were structured according to geographical location and host-plant association. Ninety-eight individuals were sampled from 29 locations ranging from southern California to western Idaho. Restriction-site variation in 87 individuals (27 populations) was screened by digestion with 11 endonucleases, followed by Southern blotting; 38 restriction-site positions were mapped by double digests. Haplotypes were further defined by generating fragments 251 bases in length via PCR, screening them for sequence variation using denaturing gel gradient electrophoresis (DGGE), and sequencing the resulting variants. Parsimony analysis of the resulting 12 restriction-site and 15 sequence haplotypes indicated strong geographical structuring of populations: (i) most populations were monomorphic for haplotype; (ii) haplotypes from California and the Pacific Northwest (Oregon, Washington and Idaho) formed robust monophyletic groups. Population structure was significant both within and between the two regions, as reflected by NST. Patterns of host-plant association and haplotype phylogeny suggest that populations have recently undergone host-plant shifts in many different parts of the species range, although the direction and number of host shifts cannot be determined at the present level of sampling resolution.