In planta dynamics, transport-biases and endogenous functions of mobile siRNAs in Arabidopsis

In RNA interference (RNAi), small-interfering (si)RNAs processed from double-stranded RNA guide ARGONAUTE(AGO) proteins to silence sequence-complementary RNA/DNA. Plant RNAi can propagate locally and systemically, but despite recent mechanistic advances, basic questions/hurdles remain unaddressed. For instance, RNAi is inferred to diffuse through plasmodesmata, yet how its dynamics in planta compares with that of established symplastic-diffusion markers remains unknown. Also unknown is why select siRNA species, or size-classes thereof, are recovered in RNAi-recipient tissues, yet only under some experimental settings. Finally, RNAi shootward movement in micro-grafted Arabidopsis -necessary to study its presumptive transgenerational effects- has not been achieved thus far and endogenous functions of mobile RNAi remain scarcely documented. Focusing on non-amplified RNAi in Arabidopsis, we show here that (i) transgenic RNAi-movement, although symplasmic, only partially recapitulates the diffusion pattern of free GFP in planta, (ii) the presence/absence of specific AGOs in incipient/traversed/recipient tissues likely explains the apparent siRNA-selectivity observed during vascular movement, (iii) stress application allows endo-siRNA translocation against the shoot-to-root phloem flow, and (iv) mobile endo-siRNAs generated from a single inverted-repeat(IR) locus, have the potential to regulate hundreds of transcripts. Our results close important knowledge-gaps, rationalize previously-noted inconsistencies between mobile RNAi settings, and provide a framework for functional endo-siRNA studies.

VTA-projecting cerebellar neurons mediate stress-dependent depression-like behavior

Although cerebellar alterations have been implicated in mental depression, the exact contribution of the cerebellum to depressive symptoms remains to be elucidated. Here, we demonstrated the crucial role of cerebellar neurons projecting to the ventral tegmental area (VTA) in the chronic stress-induced development of depression-like behavior. The combination of adeno-associated virus-based circuit mapping and electrophysiological recording identified network connections from crus I to the VTA via the dentate nucleus (DN) of the deep cerebellar nuclei. Chronic chemogenetic activation of inhibitory Purkinje cells in crus I suppressed c-Fos expression in the DN and depression-like behavior, which were triggered by chronic stress application. Furthermore, specific inhibition of neurons in the DN that project to the VTA prevented stressed mice from showing depression-like behavior, whereas specific activation of these neurons alone triggered depression-like behavior that was comparable with the one triggered by chronic stress application. Our results indicate that the VTA-projecting cerebellar neurons proactively regulate depression-like behavior, raising the possibility that cerebellum may be an effective target for the prevention of depressive disorders.

The Enhancement of Phytochemical Compounds in Fresh Produces by Abiotic Stress Application at Postharvest Handling Stage

Fresh produces is one of functional food based on its phytochemical contents. The great amounts of the phytochemical compounds in fresh produces become the main core of quality jugdement from fresh produses as a functional food. The use of proper postharvest handling system of fresh produces can be as a tool to protect the loss of the external quality and also can be used to enhance the levels of phytochemical compounds therein at the same time. A good management of plant stresses in respect to key enzymes activation of phytocemicals pathway during postharvest handling treatments of fresh produces can trigger distinct change of contained phytochemicals that can promote their healthy beneficial effect for human life.

Agroecological aspects of application of Pseudomonas sp. DA1.2 in overcoming herbicidal stress in wheat

This article submits results of laboratory and field experiments on the effect of an auxin-producing bacterial strain Pseudomonas sp. DA1.2 in comparison with Pseudomonas koreensis IB-4 on wheat plants in conjunction with the “Chistalan” herbicide treatment. Our work shows the positive effect of bacterial treatments on plant growth, the relative water content in leaves and the role of bacteria in the redistribution of ABA and IAA in wheat shoots under conditions of herbicidal stress. Application of Pseudomonas sp. DA1.2 together with the herbicide in the field of the steppe zone led to an increase in yield by 20% relative to the control variant. This bacterial strain helps to overcome herbicidal stress and is a promising agent for improving the technology of using synthetic auxins herbicides.