Journal of Bioresource Management Volume 8 Issue 1 Article 15 Effect of Drought on Trichome Density and Length in Cotton (Gossypium Hirsutum) Muhammad Shahzad Institute of Plant Breeding and Biotechnology, MNS University of Agriculture Multan, Old Shujabad Road, Multan-60000 Pakistan., [email protected] Zulqurnain Khan Institute of Plant Breeding and Biotechnology, MNS University of Agriculture Multan, Old Shujabad Road, Multan-60000 Pakistan., [email protected] Wajad Nazeer Department of Plant Breeding and Genetics, Ghazi University, DG Khan, Pakistan, [email protected] Sarmad Frogh Arshad Institute of Plant Breeding and Biotechnology, MNS University of Agriculture Multan, Old Shujabad Road, Multan-60000 Pakistan., [email protected] Furqan Ahmad Institute of Plant Breeding and Biotechnology, MNS University of Agriculture Multan, Old Shujabad Road, Multan-60000 Pakistan. Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, P.R.China., [email protected] See next page for additional authors Follow this and additional works at: https://corescholar.libraries.wright.edu/jbm Recommended Citation Shahzad, M., Khan, Z., Nazeer, W., Arshad, S. F., Ahmad, F., Farid, B., Shahid, M. R., & Riaz, H. (2021). Effect of Drought on Trichome Density and Length in Cotton (Gossypium Hirsutum), Journal of Bioresource Management, 8 (1). DOI: https://doi.org/10.35691/JBM.1202.0174 ISSN: 2309-3854 online (Received: Feb 14, 2021; Accepted: Feb 22, 2021; Published: Mar 15, 2021) This Article is brought to you for free and open access by CORE Scholar. It has been accepted for inclusion in Journal of Bioresource Management by an authorized editor of CORE Scholar. For more information, please contact [email protected]. Effect of Drought on Trichome Density and Length in Cotton (Gossypium Hirsutum) Cover Page Footnote We acknowledge the technical support of Dr. Wajid Nazir, CRI, Multan during this study. Authors Muhammad Shahzad, Zulqurnain Khan, Wajad Nazeer, Sarmad Frogh Arshad, Furqan Ahmad, Babar Farid, Muhammad Rafiq Shahid, and Hasan Riaz © Copyrights of all the papers published in Journal of Bioresource Management are with its publisher, Center for Bioresource Research (CBR) Islamabad, Pakistan. This permits anyone to copy, redistribute, remix, transmit and adapt the work for non-commercial purposes provided the original work and source is appropriately cited. Journal of Bioresource Management does not grant you any other rights in relation to this website or the material on this website. In other words, all other rights are reserved. 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J Biores Manag., 8(1): 154-167 EFFECT OF DROUGHT ON TRICHOME DENSITY AND LENGTH IN COTTON (GOSSYPIUM HIRSUTUM) MUHAMMAD SHAHZAD1, ZULQURNAIN KHAN1*, WAJAD NAZEER5, SARMAD FROGH ARSHAD1, FURQAN AHMAD1, 4, BABAR FARID1, ZIA ULLAH ZIA2, MUHAMMAD RAFIQ SHAHID2 AND HASAN RIAZ3 1Institute of Plant Breeding and Biotechnology, MNS University of Agriculture Multan, Old Shujabad Road, Multan-60000 Pakistan. 2Cotton Research Institute, Multan, Pakistan. 3Institute of Plant Protection, MNS University of Agriculture Multan, Old Shujabad Road, Multan-60000 Pakistan. 4Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, P.R.China. 5Department of Plant Breeding and Genetics, Ghazi University, DG Khan, Pakistan *Corresponding author’s email: [email protected] ABSTRACT Cotton is a major cash crop and backbone of the textile industry in Pakistan which is badly affected by sucking insects. Drought is an important abiotic factor in trichome development. The objective of the study was to determine the effects of drought on trichome density and length. Trichome density was measured in two ways, one through the scaling method and the other through counting the trichome density manually. The scaling method is qualitative grading while quantitative grading includes trichome count in a card of optimized length. Three scales were finalized to classify leaves on the basis of trichomes which were counted in a specific area (0.25cm2) on abaxial side of the leaf. In drought stress, trichomes density and length were measured and compared to that in normal conditions. Trichome density varies from 12 to 56 in 0.25cm2 under drought stress. On the basis of correlation of trichome density with stomatal conductance, photosynthetic rate, PAR and transpiration ratio under drought and normal conditions, it was concluded that trichome density increased as a result of drought stress. Keywords: Cotton, trichome, drought stress, gene expression, sucking insects. moderate pubescence and pilose leaves INTRODUCTION with maximum hairiness (Bourland et al., Trichomes are thorn-like outgrowth 2003). on aerial parts of the plant, involved in It was observed that the average plant protection against insect attack. number of trichomes varies from 2 to 205 per cm2. A smooth leaf has 5 trichomes Cotton fibers are seed trichomes, which 2 are most abundantly used fiber in the cm (Smith, 1964). It was clear that plant textile industry (Larkin et al., 2003; leaves on the upper position exhibit more Wilkins et al., 2000). The degree of hairiness as compared to the lower and hairiness describes the chances of attack of middle positions. This study depended on sucking insects. Leaves with more visual observation of trichomes and leaves hairiness offer more resistance toward with thick trichome density offer more jassids attack and are less susceptible to resistance toward insect attack (Bourland damage (Sikka et al., 1966). There may be et al., 2003). different types of leaves with respect to It was reported that the smooth-leaf hairiness. Leaves with less hairy character trait is helpful in showing resistant towards are glabrous. Hirsute leaves are with sucking insects (Jenkins et al., 1996). A 154 Shehzad et al. (2021). Trichome under Drought. J Biores Manag., 8(1): 154-167 three-scale system was proposed later to deficiency. Molecular markers like SNP, categorize leaves on the basis of trichomes SSR are also important in recognition of (Nawab et al., 2014). These classes were smooth, moderately hairy and hairy genotypes resistant to drought and (Rayburn Jr and Libous, 1983). Three to detect polymorphism (Khandagale et al., phenotypes are common in cotton, 2007). Elevated temperature and drought Glabrous, hirsute, and pilose (Peter et al., stress are inversely related in drought 1995). conditions (Ackerson, 1980) fall due to In this article, a leaf pubescence decrease of stomatal conductance. The rating system based on visual examination decrease in stomatal conductance is due to of the relative density, distribution, and stomatal closure in drought stress while length of leaf trichomes on the abaxial leaf high temperature causes stomatal opening surface is introduced and tried to validate (Lu et al., 1994) and hence photosynthesis through comparisons with trichome and transpiration rate increased (Genty et densities and consistencies into different al., 1987) but up to a certain limit, genotypes under stress. temperature above 350C will stop the Molecular mechanisms and process of photosynthesis. genetics involved trichome development The study was mounted with the have been revealed by many researchers. It objective of evaluating trichome densities was observed that GLABRA1 (GL1) and associated with cotton plant for insect GL3 (transcription factors) are involved in resistance and its rating system under trichome development as positive drought stress conditions. regulators. R2-R3 MYB protein encoded by these transcription factors is a basic helix- MATERIAL AND METHODS loop-helix–related protein used in regulation of trichome development in Plant Materials and Growing Conditions cotton (Oppenheimer et al., 1991). Trichomes density and length is affected Ten different genotypes from by abiotic stresses. Drought stress different sources were grown in the field increases trichome density. In low with plant spacing 25cm and row to row moisture availability, plant trichomes spacing 75 cm. (Table 1) Drought increase in number and length to cover applications was started at seedling stage most of the plant surface to conserve the which continued to flowering stage. A water. Trichomes density and length vary replicate of these genotypes was also with the position of the leaf on the plant grown in Glasshouse to confirm the effect Top leaves have more trichome density as of drought on trichomes in controlled compared to medium leaves while medium conditions. Moisture level was measured leaves have more density of trichomes as through a moisture meter. compared to leaves on the bottom Quantitative Grading of Trichomes (Bourland et al., 2003). Water deficiency to the extreme limit is a single limiting Plants leaves were collected after four factor of photosynthesis which increases drought applications( these applications trichome density to conserve moisture were given after intervals of 5