Wolbachia in Black Spiny Whiteflies and Their New Parasitoid Wasp in Japan: Evidence of the Distinct Infection Status on Aleurocanthus camelliae Cryptic Species Complex

Wolbachia, an alphaproteobacterial reproductive parasite, can cause profound mitochondrial divergence in insects, which might eventually be a part of cryptic speciation. Aleurocanthus camelliae is a cryptic species complex consisting of several morphospecies and/or haplotypes that are genetically different but morphologically indistinctive. However, little is known about the Wolbachia infection status in these tea and Citrus pests. Thus, this study aimed to profile the diversity and phenotypic characteristics of Wolbachia natural infections in the A. camelliae cryptic species complex. A monophyletic strain of Wolbachia that infected the A. camelliae cryptic species complex (wAlec) with different patterns was discovered. Whiteflies that are morphologically identical to Aleurocanthus spiniferus (Aleurocanthus cf. A. spiniferus in Eurya japonica and A. spiniferus in Citrus) were grouped into uninfected populations, whereas the fixed infection was detected in A. camelliae B1 from Theaceae. The rapid evolution of wAlec was also found to occur through a high recombination event, which produced subgroups A and B in wAlec. It may also be associated with the non-cytoplasmic incompatibility (CI) phenotype of wAlec due to undetectable CI-related genes from phage WO (WOAlec). The current discovery of a novel cryptic species of A. camelliae led to a discussion about the oscillation hypothesis, which may provide insights on cryptic speciation, particularly on how specialization and host expansion have been recorded among these species. This study also identified a parasitoid wasp belonging to the genus Eretmocerus in A. camelliae, for the first time in Japan.

Priming and positioning of lateral roots in Arabidopsis. An approach for an integrating concept

Branching by de novo formation of lateral roots along the primary root of Arabidopsis seedlings follows a complex longitudinal and transverse pattern. How this pattern is generated is presently under debate. The 'bending hypothesis' proposes that lateral root primordia are initiated by a local accumulation of auxin at the convex side of bends resulting from deflections through obstacles, gravitropic bending, or other means. In contrast, the 'oscillation hypothesis' proposes the existence of an endogenous clock-type oscillator mechanism producing periodic pulses of gene expression in the root tip that determine the future sites of primordium initiation. Here we report physiological experiments dissecting periodic priming signals, pre-disposing the root to rhythmic lateral root formation, from bending-mediated signals responsible for the subsequent positioning of their initiation along the growing root. While the frequency of lateral roots can be promoted by auxin in the mature root, their positioning follows a pre-formed pattern determined by previous bending. Both types of signals turn out to be necessary, complementary components in an integrating concept of lateral root patterning.