Molecular mechanism and physiological function of trichome formation in plant

Abstract

Trichome, as a protective barrier against natural hazards, plays an indispensable role in resisting ultraviolet radiation, pathogen invasion, herbivores feeding and water excessive transpiration during the process of plant growth and development. Trichomes may be unicellular or multicellular and some plants such as Arabidopsis thaliana may also have branches, according to the presence or absence of glands, it can be divided into glandular or non-glandular, the former can accumulate and secrete some alkaloids, such as nicotine and terpenoids, which have an exclusion effect on insects, while the latter can be enhanced the stress resistance during abiotic stress, such as extreme high and low temperatures, ultraviolet radiation, thereby promoting and controlling the normal growth of plants. The current study shows that the formation of trichome is co-regulation by many types and multiple genes, thus form a complex regulation network. The mechanism of the regulation and genes mining of the trichome in the dicotyledonous has made substantial progress in recent years, especially in Arabidopsis , Trichome formation in Athaliana is thought to be regulated by a competitive system, including the promotion and inhibition of the gene activities. More and more studies have shown that there are a variety of different genes can regulate the trichome formation in different plants. The genes controling trichome formation are generally a class of MYB transcription factors in Arabidopsis [31] , whereas a HD-Zip protein, Woolly (Wo) that interacts with Cyclin B2, plays an essential role for trichome formation and embryonic development in tomato. In addition, the Glabrous Rice 1(GLR1), which encodes a WUS-like homeobox gene (WOX), also regulates the formation of trichomes in rice. It was proposed that Trichome can also interact with the environment under the development process of plants, such as light refraction, light quantum radiation interception, leaf heat balance, wettability, droplet retention, water uptake and gas exchange. Leaf trichome density is variable and determined by genetic and environmental factors, climate drivers such as soil water deficit and high temperature can increase the trichome density. The studies have shown that leaf trichomes can reflect broad-spectrum electromagnetic radiation, and reducing light absorptance and modulating energy balance. Except as described above, trichome can promote gas exchange and limit pathogen growth and spread on leaves. According to the physiological characteristics of the trichome, the crop cultivation, production and utilization have important economic value and significance. In this article, We systematically reviewed and analyzed a series of related studies on the progress and physiological characteristics of genes which related to the regulation of plant trichome formation in recent years, The aim of this review was to elucidate the regulation mechanism of the trichome formation and the physiological and biochemical characteristics, so as to provide an important theoretical basis for further research on the excavation and functional characteristics of the trichome genes.