Complex meristematic activity induced by Eucecidoses minutanus on Schinus engleri turns shoots into galls

Structural patterns of Lepidoptera galls and the case of Andescecidium parrai (Cecidosidae) galls on Schinus polygama (Anacardiaceae)

Gall anatomical and metabolic peculiarities are determined by the feeding habit of the gall inducer, but develop under the constraints of the host plants. The chewing habit of the Lepidoptera larvae imposes a high impact on the host plant cells, and supposedly drives peculiar structural and histochemical patterns. So, our starting point was the search of such patterns in literature, and the test of these traits on the Andescecidium parrai (Cecidosidae)-Schinus polygama (Anacardiaceae) system, as a case study in Chilean flora. The literature on the structure of lepidopteran galls in the temperate and tropical regions comprises 13 works, describing stems as the most frequent host organs, followed by leaves, buds, and flowers. As common structural traits of Lepidoptera galls, the literature converge in describing the processes of cell hypertrophy and hyperplasia, resulting in a variable number of common storage parenchyma layers, interspersed by the redifferentiated sclerenchyma, vascular, and typical nutritive cells around the larval chamber. These nutritive cells accumulate lipids and proteins, which support the lepidopteran larvae nutrition. As expected, the A. parrai galls follow the patterns herein described for the lepidoptera-induced galls, but with peculiarities associated with its host organ. Even though the Lepidoptera galls have destructive mouthparts and can induce large and complex galls, they cannot alter important conservative features of their hosts' organs.

Can Molecularly Engineered Plant Galls Help to Ease the Problem of World Food Shortage (and Our Dependence on Pollinating Insects)?

The world faces numerous problems and two of them are global food shortages and the dwindling number of pollinating insects. Plant products that do not arise from pollination are plant galls, which as in the case of oak apples, can resemble fruits and be the size of a cherry. It is suggested that once research has understood how chemical signals from gall-inducing insects program a plant to produce a gall, it should be possible to mimic and to improve nature and "bioengineer" designer galls of different sizes, colorations and specific contents to serve as food or a source of medicinally useful compounds. To achieve this objective, the genes involved in the formation of the galls need to be identified by RNA-sequencing and confirmed by gene expression analyses and gene slicing. Ultimately the relevant genes need to be transferred to naïve plants, possibly with the aid of plasmids or viruses as practiced in crop productivity increases. There is then even the prospect of engineered plant galls to be produced by plant tissue culture via genetic manipulation without the involvement of insects altogether.