Evaluating Anatomical Characteristics Associated With Leaf Rolling in Northeastern Thai Rice Cultivars During Drought by Decision Tree

Abstract

Leaf rolling is a common response to drought among members of the grass family. A detailed understanding of the structural changes that occur when rice leaves roll in response to drought may assist in determining the physiological mechanisms underlying this feature and determining its potential utility in plant breeding. The anatomical characteristics of rice cultivars native to northeastern Thailand in response to drought stress were evaluated in this study. Polyethylene glycol (PEG) treatments were applied to seedlings of 28 native rice cultivars and two rice breeding cultivars for 10 d. When cultivated in drought-prone environments, the native rice cultivars had a leaf rolling index between 4 and 7, which was classified as moderate to high leaf rolling. Rice leaf anatomy exhibited profound changes in response to drought, with smaller bulliform cells (36.8%), thicker epidermis (10.98%), smaller vascular bundles (7.41%), and smaller bundle sheath cells (11.95%). Decision trees were used to explore the association between the degree of leaf rolling and anatomical traits. According to the decision tree models generated on the basis of the gain ratio, information gain, and Gini index, the epidermis, leaf thickness, and bulliform cells were the major factors of the root nodes, and the maximum accuracy of the models was 70.90%. Overall, the models indicated that rice leaves with a thin epidermis, large bulliform cells, thin leaves, and small vascular bundles are more likely to display high leaf rolling adaptations under drought stress conditions.

Drought-Induced Changes in Leaf Morphology and Anatomy: Overview, Implications and Perspectives

“…In the rice plant exposed to drought, rolling occurs in the leaves due to bulliform cell shrinkage [10]. Similarly, a decrease in bulliform cell size is observed in rice varieties in arid conditions [20].…”

“…Since leaf morphology is important in plant growth and development, it significantly affects plant yield. The symptoms observed in the leaves in response to drought are important in the anatomical adaptation of the cultivars and are used in cultivar selection [10]. The responses of leaves to drought stress can be evaluated by looking at the leaf's anatomical features such as bulliform cells on the leaf surface, epidermal cells, and stomatal size.…”

“…Drought stress reduces leaf thickness in relation to the net carbon absorption and photosynthetic performance of plants [20]. If a plant has a high drought tolerance, it shows that biomass losses will be less [10].…”

“…By adjusting the leaf rolling, it is possible to control the efficiency of photosynthetic activity per unit leaf area. The amount of dry matter accumulation and transpiration may both be increased and decreased by minimizing the effect of sunlight on the leaves and achieving optimal leaf roll [10]. The rolling that occurs in the leaves also reduces the damage caused by light by reducing the areas exposed to the sun in the plant [53].…”

“…Drought is the condition of prolonged dryness, which adversely affects the anatomical, morpho-physiological and other fundamental processes in the plant leading to limited plant growth and productivity [9,10]. It also affects the location and density of the stomata on the leaf surface.…”