Identification of Heat Tolerant Cotton Lines Showing Genetic Variation in Cell Membrane Thermostability, Stomata, and Trichome Size and Its Effect on Yield and Fiber Quality Traits

Abstract

Heat stress in cotton reduces its productivity. The development of heat-tolerant cotton varieties having resilience against changing climate is feasible. The purpose of this study was to probe the genetic variability in upland cotton for heat tolerance, the association of cell membrane thermostability (CMT), stomata, and trichome size with cotton adaptation to high temperature and effective breeding strategy to advance the valued traits. Relative cell injury percentage (RCI%) in studied genotypes ranged from 39 to 86%. Seventeen genotypes were found heat tolerant on the basis of low RCI%, heat susceptibility index (HSI<1), higher number of boll/plant, and seed cotton yield (SCY). Scanning electron microscopy (SEM) of heat-tolerant genotypes revealed the presence of different size of stomata (21.57 to 105.04 μm2) and trichomes (177 to 782.6 μm) on leaves of selected genotypes. The regression analysis showed a strong and negative association of RCI% and stomata size with SCY. However, no association was observed between the trichome size, yield, and fiber traits. On the overall location basis, a significant genotype × environment interaction was observed. All selected genotypes produced a higher SCY as compared with check varieties. But the stability analysis showed that the high yielding genotypes NIA-M-30, NIA-80, NIA-83, and CRIS-342 were also wide adaptive with unit regression (bi∼1) and non-significant deviation from the regression line (S2d∼0). The ability for the combination of some heat-tolerant genotypes was estimated by using the line × tester method among nine hybrids along with their 3 testers (i.e., male) and 3 lines (i.e., females). Genotypes, CRIS-342 and NIA-Perkh, were observed as best general combiners for SCY with a negative general combining ability effects for RCI%. Five hybrids showed a positive specific combining ability and heterotic effects for studied traits and also found lowest for HSI. RCI% and SCY/plant displayed higher estimates of heritability and genetic advance, indicating the heritability due to additive gene effects and chances of effective selection. The identified heat-tolerant and wide adaptive germplasm can be further advanced and utilized in cotton breeding programs for developing heat-tolerant cultivars. Selection criteria involving CMT and stomata size concluded to be an effective strategy for the screening of heat-tolerant cotton.

Morphological and physio-biochemical responses under heat stress in cotton: Overview

“…A research on cotton ( Gossypium barbadense L.) found that a combination of drought and high temperatures had a negative impact on physiological processes such as development and advancement if compared to a single stress [ 24 , 4 ]. Cotton breeding initiatives should concentrate on selecting during combined drought and heat tolerance rather than just one of these conditions [ 25 ].The main objectives of this review are to focus on the environmental factors, such as temperature, heat and drought, influences the growth and development, morphology and physio-chemical alteration of cotton. Furthermore, recent advancement on cotton breeding to combat the serious threat of drought and heat.…”

“…However, as the daytime temperature rises above 30 °C, severe heat stress throughout blooming results in the loss of leaves and blooms. A rise in fruit production sites of 50% is observed as a result of temperature increases of 10 °C, or from 30 to 40 °C [ 25 ]. According to reports, freshly developed bolls begin to shed when the daytime average temperature is 32 °C or even higher.…”

“…A major problem is cultivating high-temperature economic cotton cultivars [ 22 ]. When faced with heat stress, seedlings' dynamic responses make identifying and confirming characteristics that confer resistance to high temperatures difficult [ 25 ]. Researchers are indeed investigating how plants may be handled in high-temperature environments.…”

Comprehensive evaluation and screening identification indexes of heat‐resistance indices in cotton (Gossypium hirsutum L.)

“…Moreover, previous studies have identified heat‐resistant cotton by measuring changes in field agronomic traits and physiological indexes under HT. These include fruit branch height (Singh et al., 2007), number of buds per plant (Saleem et al., 2018), pollen germination rate (Huang et al., 2022), pollen tube length (Kakani et al., 2005), boll shedding rate and sterile seed rate (Demirel et al., 2016), boll weight, boll number (Kakani et al., 2005), stomatal conductivity (Abro et al., 2022), chlorophyll content (Singh et al., 2007) and cell membrane thermal stability (Kakani et al., 2005; Malik et al., 1999; Rahman et al., 2004).…”

Mechanism of cotton resistance to abiotic stress, and recent research advances in the osmoregulation related genes

“…With the development of molecular biology, it has enabled people to understand the mechanism of plant resistance to stress at the molecular level of genetic composition, expression regulation, and signal transduction, especially in the molecular response of plants caused by abiotic stress. They will have severe impacts throughout the cotton growth and development stage, including a range of changes in plant morphology, physiology, quality and yield ( Pei et al, 2020 ; Abro et al, 2022 ). Therefore, studying the adaptability of cotton to abiotic adversity and cultivating new varieties of resistant cotton are of great practical significance for cotton production.…”