“ZAMONAVIY BIOLOGIYANING DOLZARB MUAMMOLARI VA
RIVOJLANISH ISTIQBOLLARI”
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THE EFFECT OF HEAT STRESS ON PEROXIDASE ACTIVITY AND COTTON
MORPHOLOGY
Toshmurodova Maftuna Jakhongir qizi
1
., Kuldoshova Karomat Mamanazarovna
2
.,
Kuziev Sherali Nasrulloyevich
3
Department of Biochemistry, Faculty of Biology and Ecology, National University of
Uzbekistan named after Mirzo Ulugbek, Tashkent, Uzbekistan, master student
1
toshmurodovamaftuna574@gmail.com
Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan,
Tashkent, Uzbekistan, PhD, junior scientific researcher
Department of Biochemistry, Faculty of Biology and Ecology, National University of
Uzbekistan named after Mirzo Ulugbek, Tashkent, Uzbekistan, head teacher
2
zarabarlos90@gmail.com
Department of Biochemistry, Faculty of Biology and Ecology, National University of
Uzbekistan named after Mirzo Ulugbek, Tashkent, Uzbekistan, PhD, head of department
3
kuziev.sherali@gmail.com
https://doi.org/10.5281/zenodo.15603010
Annotation:
High-temperature stress is a major abiotic factor that adversely affects plant
growth and development, particularly in cotton (
Gossypium
spp.). This study aimed to investigate the
impact of heat stress (45°C for 6 hours) on peroxidase enzyme activity and morphological traits in
two cotton cultivars: Surkhan-103 (conventionally bred) and Ravnaq-1 (developed through marker-
assisted selection). The results demonstrated a significant increase (27.7%) in peroxidase activity in
the heat-tolerant Surkhan-103 cultivar, while a sharp decline (40%) was observed in the Ravnaq-1
cultivar, indicating its susceptibility to elevated temperatures. Morphological analyses further
confirmed these differences, with Surkhan-103 maintaining growth parameters under stress, while
Ravnaq-1 exhibited reductions in plant height, root length, and biomass. These findings highlight the
physiological and biochemical basis of heat tolerance in cotton and provide valuable information for
breeding programs targeting climate-resilient cultivars.
Keywords:
heat stress,
Gossypium hirsutum
, peroxidase activity, morphological traits, marker-
assisted selection.
Annotatsiya
: Yuqori haroratli stress o‘simliklarning o‘sishi va rivojlanishiga salbiy ta’sir
ko‘rsatadigan asosiy abiotik omillardan biridir. Ushbu tadqiqot 45°C haroratda 6 soat davomida
issiqlik stressi sharoitida ikkita paxta (
Gossypium
spp.) navida — an’anaviy seleksiya asosida
yaratilgan Surxon-103 va markerlarga asoslangan seleksiya (MAS) orqali olingan Ravnaq-1
navlarida peroksidaza fermenti faolligi hamda morfologik o‘zgarishlarni baholashga qaratildi.
Natijalar Surxon-103 navida peroksidaza faolligi nazoratga nisbatan 27,7% ga oshganini ko‘rsatdi,
Ravnaq-1 navida esa bu ferment faolligi 40% ga kamaydi. Bu Ravnaq-1 navining yuqori haroratga
nisbatan sezuvchanligini ko‘rsatadi. Morfologik ko‘rsatkichlar ham bu farqni tasdiqladi: Surxon-103
navi issiqlik sharoitida o‘sish parametrlarini saqlab qolgan bo‘lsa, Ravnaq-1 navida o‘simlik bo‘yi,
ildiz uzunligi va biomassasi sezilarli darajada pasaydi. Ushbu natijalar paxta navlarining issiqlik
stressiga chidamliligini baholash va mos navlarni tanlashda muhim ilmiy asos bo‘lib xizmat qiladi.
Kalit so‘zlar:
issiqlik stressi,
Gossypium hirsutum
, peroksidaza faolligi, morfologik
ko‘rsatkichlar, markerlarga asoslangan seleksiya.
Аннотация
:
Высокотемпературный
стресс
является
одним
из
основных
абиотических
факторов
,
негативно
влияющих
на
рост
и
развитие
растений
,
особенно
у
хлопчатника
(
Gossypium
spp.).
В
настоящем
исследовании
изучались
активность
пероксидазы
и
морфологические
изменения
у
двух
сортов
хлопчатника
при
температуре
45°C
в
течение
6
часов
:
Сурхон
-103 (
созданный
методами
классической
селекции
)
и
Равнак
-1 (
полученный
с
применением
маркер
-
ассоциированной
селекции
).
Полученные
данные
показали
,
что
у
сорта
“ZAMONAVIY BIOLOGIYANING DOLZARB MUAMMOLARI VA
RIVOJLANISH ISTIQBOLLARI”
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Сурхон
-103
активность
пероксидазы
увеличилась
на
27,7%
по
сравнению
с
контролем
,
тогда
как
у
Равнак
-1
она
снизилась
на
40%,
что
свидетельствует
о
его
чувствительности
к
высокотемпературному
стрессу
.
Морфологический
анализ
подтвердил
эти
различия
:
Сурхон
-
103
сохранял
основные
параметры
роста
,
в
то
время
как
у
Равнак
-1
наблюдалось
значительное
снижение
высоты
растения
,
длины
корней
и
биомассы
.
Эти
результаты
подчеркивают
значение
физиологических
и
биохимических
показателей
для
оценки
устойчивости
сортов
хлопчатника
к
жароустойчивости
и
их
дальнейшего
использования
в
селекционных
программах
.
Ключевое
слово
:
тепловой
стресс
,
Gossypium hirsutum
,
активность
пероксидазы
,
морфологические
показатели
,
маркер
-
ассоциированная
селекция
.
High temperatures have a detrimental effect on plant growth and metabolism, as each plant
species has an optimal temperature range for these physiological processes [1]. Currently, heat is
considered one of the major abiotic stress factors limiting crop production [2]. In particular, heat
stress significantly affects the physiological activity of cotton. Elevated temperatures disrupt various
physiological processes, including water exchange, photosynthesis, transpiration, stomatal
regulation, enzyme function, hormonal balance, and antioxidant defense mechanisms [3]. The aim of
this study was to analyze peroxidase enzyme activity and morphological changes in cotton cultivars
under high-temperature stress.
Two cotton cultivars were used in the study. One was Ravnaq-1, developed through marker-
assisted selection and provided by the Center for Genomics and Bioinformatics of the Academy of
Sciences of the Republic of Uzbekistan. The other cultivar, Surkhan-103 from the
Gossypium
barbadense
species, was developed through conventional breeding and obtained from the Research
Institute of Cotton Breeding, Seed Production, and Agrotechnology’s under the Ministry of
Agriculture of the Republic of Uzbekistan.
Seeds were germinated in darkness at 30°C for 7 days. To simulate hyperthermia stress, the
seedlings were exposed to a temperature of 45°C for 6 hours.
The results revealed an increase in peroxidase activity in the Surkhan-103 cultivar under 45°C
heat stress, whereas this response was not observed in the Ravnaq-1 cultivar developed via MAS
technology (Fig.1). Specifically, Surkhan-103 exhibited a 27.7% increase in peroxidase activity
compared to the control. In contrast, Ravnaq-1 showed the lowest peroxidase activity under heat
stress, with a 40% reduction relative to its control. These findings suggest that Ravnaq-1 is highly
sensitive to elevated temperatures, as indicated by the significant decline in peroxidase levels (Fig.1).
“ZAMONAVIY BIOLOGIYANING DOLZARB MUAMMOLARI VA
RIVOJLANISH ISTIQBOLLARI”
xalqaro ilmiy-amaliy anjuman materiallari
adu.uz
universaljurnal.uz
367
Figure 1.
The effect of 6-hour heat stress at 45°C on peroxidase activity and morphological
traits in two different cotton cultivars
In addition to enzymatic changes, high temperatures also markedly affected the morpho-
physiological characteristics of the tested cultivars (Fig.1). Experimental data indicated that Surkhan-
103 and Ravnaq-1 exhibited contrasting morphological responses to high-temperature stress (45°C).
Surkhan-103 appeared to be relatively heat-tolerant, with no significant alterations in morphological
traits such as plant height, root length, or biomass (Fig.1). The plants maintained their structural
integrity and growth capacity under stress, indicating the presence of inherent physiological
adaptation mechanisms.
Conversely, Ravnaq-1 displayed a pronounced sensitivity to elevated temperatures, with
evident morphological impairments (Fig.1). Plant height was reduced, likely due to impaired cellular
water balance, which in turn limits cell expansion and vegetative growth. Root development was also
adversely affected, as root elongation slowed and biomass decreased under heat stress, negatively
impacting water and nutrient uptake. Leaf morphology changed significantly: leaf size was reduced,
and leaf margins often curled or wilted. These symptoms are indicative of increased transpiration and
water loss, leading to dehydration stress.
The distinct responses of Surkhan-103 and Ravnaq-1 to high-temperature conditions clearly
demonstrate their differential tolerance to heat stress. These results provide valuable insights for
future cotton breeding and agronomic management practices aimed at improving heat resilience in
cotton.
References
1.
Hasanuzzaman, M., Nahar, K., Alam, M. M., Roychowdhury, R., & Fujita, M. (2013).
Physiological, biochemical, and molecular mechanisms of heat stress tolerance in plants.
International
Journal
of
Molecular
Sciences
,
14(5),
9643–9684.
https://doi.org/10.3390/ijms14059643
2.
Wahid, A., Gelani, S., Ashraf, M., & Foolad, M. R. (2007). Heat tolerance in plants:
An
overview.
Environmental
and
Experimental
Botany
,
61(3),
199–223.
https://doi.org/10.1016/j.envexpbot.2007.05.011
3.
Savicka, M., & Škute, N. (2010). Effects of high temperature on peroxidase activity in
wheat and maize seedlings.
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