“Trichomes: Surrogates of biotic and abiotic stress resistance in crop breeding”

UNIVERSITY OF AGRICULTURAL SCIENCES, GKVK,

BANGALORE

DEPARTMENT OF GENETICS AND PLANT BREEDING

SEMINAR- GPB 581 (0+1)

“Trichomes: Surrogates of biotic and abiotic stress resistance in crop breeding”

Plants are sessile in nature, therefore, they are exposed to various abiotic and biotic stresses, such

as drought, chilling injury, insects, and diseases attack. Pubescence in plants offers the opportunity for

them to withstand a number of stresses. Trichomes which are the epidermal outgrowths with single-cell

or multicellular structures, cover most aerial plant tissues and are present in the enormous number of

plant species. They play a vital role in plant growth and development, by protecting against herbivore

attacks and pathogens, acting as a shield against damaging ultraviolet (UV) radiation and preventing

excessive transpiration, and so on. 2

Plant trichome development generally includes three stages: (1) fate determination and initiation,

(2) branching, and (3) elongation and maturation. Many studies have confirmed that different

transcription factor families, such as HD-ZIP type proteins, C2H2 zinc finger proteins, basic helix-loop-

helix (bHLH) type proteins, and v-myb avian myeloblastosis viral oncogene homolog (MYB) family

proteins, all play a key role in plant trichome development. In addition, trichome development is strictly

regulated by a variety of plant hormones. 1

Non glandular trichomes play a crucial role in managing abiotic stress through various

adaptations. They contribute to drought resistance by lowering the transpiration rate, reflecting

sunlight, storing water and regulating leaf temperature. In the context of salt resistance, these trichome

sequester salt, enhance water retention and neutralize reactive oxygen species (ROS) activity. Dense

trichomes could also present a physical barrier to movement of microorganisms and feeding of insects,

thus protecting plants against biotic stresses. Glandular trichomes resist the insects and pathogens by

synthesizing and storing defensive chemicals like phenols, flavonoids, methyl ketones, acyl sugars and

terpenoids. 1

A study examined the role of trichomes on tomato plants in protecting against stresses like

disease, pests, drought, and cold damage. Four tomato varieties (3186 M, 3186 L, LA 3-071, JR) with

different trichome densities and types were analyzed to understand the relationship between trichomes

and stress resistance, aiming to improve tomato breeding and cultivation. 3 Another study on soybean

identified nine QTLs associated with trichome density while ten QTLs for trichome length, finding that

wild soybean had alleles for decreased length and increased density. The study also identified candidate

genes for the traits and found that leaves with short, dense pubescence (like wild soybean) were most

resistant to common cutworm, providing insights for breeding more resilient soybeans. 2

 REFERENCES:
1 HAN, G., LI, Y., YANG, Z., WANG, C., ZHANG, Y. AND WANG, B., 2022, Molecular mechanisms
of plant trichome development. Front. Plant Sci., 13: 9102.
2 LI, Y., CHU, L., LIU, X., ZHANG, N., XU, Y., KARIKARI, B., WANG, Y., CHANG, F., LIU, Z.,
TAN, L. AND YUE, H., 2022, Genetic architecture and candidate genes for pubescence length and
density and its relationship with resistance to common cutworm in Soybean. Front. Plant Sci., 12:
771850.
3 ZHANG, Y., SONG, H., WANG, X., ZHOU, X., ZHANG, K., CHEN, X., LIU, J., HAN, J. AND
WANG, A., 2020, The roles of different types of trichomes in tomato resistance to cold, drought,
whiteflies, and botrytis. Agronomy, 10(3): 411.