title: Exogenous Cytokinins Increase Grain Yield of Winter Wheat Cultivars by Improving Stay-Green Characteristics under Heat Stress.
abstract: Stay-green, a key trait of wheat, can not only increase the yield of wheat but also its resistance to heat stress during active photosynthesis. Cytokinins are the most potent general coordinator between the stay-green trait and senescence. The objectives of the present study were to identify and assess the effects of cytokinins on the photosynthetic organ and heat resistance in wheat. Two winter wheat cultivars, Wennong 6 (a stay-green cultivar) and Jimai 20 (a control cultivar), were subjected to heat stress treatment from 1 to 5 days after anthesis (DAA). The two cultivars were sprayed daily with 10 mg L-1 of 6-benzylaminopurine (6-BA) between 1 and 3 DAA under ambient and elevated temperature conditions. We found that the heat stress significantly decreased the number of kernels per spike and the grain yield (P < 0.05). Heat stress also decreased the zeatin riboside (ZR) content, but increased the gibberellin (GA3), indole-3-acetic acid (IAA), and abscisic acid (ABA) contents at 3 to 15 DAA. Application of 6-BA significantly (P < 0.05) increased the grain-filling rate, endosperm cell division rate, endosperm cell number, and 1,000-grain weight under heated condition. 6-BA application increased ZR and IAA contents at 3 to 28 DAA, but decreased GA3 and ABA contents. The contents of ZR, ABA, and IAA in kernels were positively and significantly correlated with the grain-filling rate (P < 0.05), whereas GA3 was counter-productive at 3 to 15 DAA. These results suggest that the decrease in grain yield under heat stress was due to a lower ZR content and a higher GA3 content compared to that at elevated temperature during the early development of the kernels, which resulted in less kernel number and lower grain-filling rate. The results also provide essential information for further utilization of the cytokinin substances in the cultivation of heat-resistant wheat.
authors.affiliation: State Key Laboratory of Crop Biology, Agronomy College of Shandong Agricultural University, Tai'an, Shandong, P. R. China.
authors.forename: Dongqing
authors.initials: D
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Crop Biology, Agronomy College of Shandong Agricultural University, Tai'an, Shandong, P. R. China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Crop Biology, Agronomy College of Shandong Agricultural University, Tai'an, Shandong, P. R. China.|Agricultural Bureau of Yanzhou District, Jining, Shandong, P. R. China.
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Shi
authors.affiliation: State Key Laboratory of Crop Biology, Agronomy College of Shandong Agricultural University, Tai'an, Shandong, P. R. China.
authors.forename: Zhengyong
authors.initials: Z
authors.lastname: Cui
authors.affiliation: State Key Laboratory of Crop Biology, Agronomy College of Shandong Agricultural University, Tai'an, Shandong, P. R. China.
authors.forename: Yongli
authors.initials: Y
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Crop Biology, Agronomy College of Shandong Agricultural University, Tai'an, Shandong, P. R. China.
authors.forename: Mengjing
authors.initials: M
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Crop Biology, Agronomy College of Shandong Agricultural University, Tai'an, Shandong, P. R. China.
authors.forename: Jin
authors.initials: J
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Crop Biology, Agronomy College of Shandong Agricultural University, Tai'an, Shandong, P. R. China.
authors.forename: Yanxia
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Crop Biology, Agronomy College of Shandong Agricultural University, Tai'an, Shandong, P. R. China.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Yin
authors.affiliation: State Key Laboratory of Crop Biology, Agronomy College of Shandong Agricultural University, Tai'an, Shandong, P. R. China.
authors.forename: Zhenlin
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D001593:Benzyl Compounds / Q000494:pharmacology; D003583:Cytokinins / Q000494:pharmacology*; D005875:Gibberellins / Q000378:metabolism; D006358:Hot Temperature; D007210:Indoleacetic Acids / Q000378:metabolism; D007541:Isopentenyladenosine / Q000031:analogs & derivatives / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology*; D011687:Purines / Q000494:pharmacology; D014908:Triticum / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D001593:Benzyl Compounds; D003583:Cytokinins; D005875:Gibberellins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D011687:Purines; C030737:indoleacetic acid; D000040:Abscisic Acid; D007541:Isopentenyladenosine; C009699:zeatin riboside; C480551:benzylaminopurine