Environmental and Experimental Botany 201 (2022) 104936 Available online 2 June 2022 0098-8472/© 2022 Elsevier B.V. All rights reserved. Shoot and root zone temperatures are critical in bidirectional regulation of tuberization in potato Srikanth Tengli a , Swetha Thavarekere Narasimhamurthy a , Appanna Koppad a , Geetha Govind b, * , Basavaiah Mohan Raju a, * a Department of Crop Physiology, University of Agricultural Sciences, Bangalore, India b Department of Crop Physiology, College of Agriculture, UAS-B, Hassan, India A R T I C L E INFO Keywords: Aeroponics Root and shoot zone temperature Stolon Tuberization ABSTRACT Multiple signals regulate tuberization in potato and among them, photoperiod and temperature are most crucial. Optimum temperature for tuberization is around 20 ◦ C and elevated temperatures above optimum drastically reduces tuberization. Our study therefore aims at understanding and establishing a system to study the effect of shoot and root zone temperatures on tuberization. Towards this, a less photosensitive cultivar, Kufri Jyoti was identifed initially by analysing the allelic variations in CDF1 gene. Using the aeroponic systems housed inside the poly house, the effect of temperature on tuberization was studied. Following staggered sowing on aeroponic chambers during rabi season (Oct-Dec), the shoot zone (Sz) and root zone (Rz) were exposed to elevated mean cumulative day temperatures with one set of chambers regulated to maintain optimum temperature of 19 ± 2 ◦ C in Rz (Rz-R) irrespective of date of sowing/ planting. With delayed planting, plants were exposed to high temperatures and our study demonstrated that, elevated temperatures in Sz and/or Rz had signifcant effect on growth attributes, tuber number and tuber weight per plant. While the tuber number was signifcantly higher under optimum root and shoot zone temperature, it was rather decreased by 3.5 and 2.3 for every degree rise in Rz (irrespective of Sz) and Sz (irrespective of Rz) temperature, respectively. However, regulating the Rz tem- perature inside the aeroponic chambers, reasonably a good number of mini-tubers per plant was produced regardless of the shoot zone temperatures suggesting that, root temperature is more crucial than shoot tem- perature. Furthermore, reduction in tuberization at elevated temperature was correlated well with reduction in expression of key positive regulators (StSP6A, StBEL5) and enhanced expression of key negative regulator, StSP5G in both leaves and solons. Taken together, our data suggest that, regulation of both root and shoot zone temperatures are important for effective tuberization and tuber yield in potato. 1. Introduction Potato, an important food crop of the world and a vegetable crop of India is grown in cooler climate with shorter photo-period. Potato was introduced to India and has adapted well to the tropics. In India, it is grown in the coolest season mostly on hilly areas and northern parts of the country with a few pockets in Karnataka where conditions are favorable. Although potato is grown in a wide range of climatic condi- tions around the world, the best yields are realized under adequate water supply in temperate regions with a day and night temperatures of 18–20 ◦ C and 15–18 ◦ C, respectively (Menzel, 1980; Minhas and Kumar, 2005; ´ Avila-Vald´ es et al., 2020). Tuberization in potato is controlled by many factors which include temperature, photo-period, phyto-hor- mones and nitrogen level (Kondhare et al., 2020). While the low tem- peratures coupled with short days and low level of GA and nitrogen favour tuberization; high temperatures with long days and high level of GA and nitrogen inhibit tuberization. Among so many factors, temper- ature seems to be the major player regulating tuberization in potato. A few degree rise in temperatures adversely affect tuberization and with predicted climate change and global warming, potato production is likely to be reduced signifcantly. In fact, several reports have clearly demonstrated that, high temperature has an inhibitory effect on tuber production. While, the low temperatures of around 18–20 ◦ C in root zone/ stolonization zone favour tuber induction, high temperature * Corresponding authors. E-mail addresses: srikanttengli@gmail.com (S. Tengli), shwesudhamurthy@gmail.com (S.T. Narasimhamurthy), appanna.vk@gmail.com (A. Koppad), geetha. govind@uasbangalore.edu.in (G. Govind), bmohanraju@uasbangalore.edu.in (B.M. Raju). Contents lists available at ScienceDirect Environmental and Experimental Botany journal homepage: www.elsevier.com/locate/envexpbot https://doi.org/10.1016/j.envexpbot.2022.104936 Received 4 March 2022; Received in revised form 23 May 2022; Accepted 24 May 2022