Characterization of the starch synthase under terminal heat stress and its effect on grain quality of wheat
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ORIGINAL ARTICLE
Characterization of the starch synthase under terminal heat stress and its effect on grain quality of wheat Arti Kumari1 · Ranjeet R. Kumar1 · Jyoti P. Singh1 · Pooja Verma2 · Gyanendra P. Singh3 · Viswanathan Chinnusamy4 · Shelly Praveen1 · Suneha Goswami1 Received: 19 March 2020 / Accepted: 28 October 2020 © King Abdulaziz City for Science and Technology 2020
Abstract Terminal heat stress (HS) is a key barrier for wheat grain yield and quality. Various physiochemical and molecular parameters such as photosynthetic rate, expression analysis and activity of starch synthase (SS), total starch, amylose and amylopectin content, total amylolytic activity, and total antioxidant capacity (TAC) were analysed in wheat cvs.HD3059 (thermotolerant) and BT-Schomburgk (thermosusceptible) at grain-filling stage under HS (32 °C and 40 °C, 1 h). The decrease in photosynthetic rate was observed under HS. Expression analysis of the SS gene at transcript level showed downregulation in both the wheat cvs.HD3059 and BT-Schombugk under HS (32 °C and 40 ºC, 1 h) as compared to the control. Although the downregulation of SS gene transcript expression was less in HD3059 than BT-Schombugk. Both the cultivars showed decrease in starch synthase activity and starch content under HS and the overall content was higher in HD3059, compared to BT-Schomburgk. Higher total amylolytic activity and amylose content were observed in BT-Schomburgk. Scanning electron microscopy (SEM) showed un-structured starch granules under HS. Total antioxidant capacity (TAC) was found higher in HD3059 (14.07 mM FeSO4 gm−1 FW) compared to BT-Schomburgk (8.89 mM F eSO4 gm−1 FW) under HS (40 ºC, 1 h). Findings suggest that HS during grain filling stage had more severe impact on the overall physiochemical properties of the wheat grain. Thus the starch bisynthesis pathway associated gene(s) could be exploit to enhance the yield and quality of wheat under heat stress. Keywords Heat stress · Wheat · Starch biosynthesis pathway · Starch synthase · Scanning electron microscopy Abbreviations HS Heat stress SS Starch synthase SEM Scanning electron microscopy TAC Total antioxidant capacity
* Shelly Praveen [email protected]; [email protected] * Suneha Goswami [email protected]; [email protected] 1
Division of Biochemistry, Indian Agricultural Research Institute, New Delhi 110012, India
2
ICAR-Central Institute for Cotton Research, Nagpur, Maharashtra, India
3
Indian Institute of Wheat and Barley Research, Indian Council of Agricultural Research, Karnal, India
4
Division of Plant Physiology, Indian Agricultural Research Institute, New Delhi 110012, India
Introduction Wheat (Triticum aestivum L.) is the staple food grain crop providing 12% of carbohydrate, 40% calorie and 13% protein in the diet. The plant being sessile has to face many environmental constraints during their growth period which include a complex set of biotic and abiotic stresses. Among the abiotic stresses, HS is most damaging to wheat grow
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