Abstract
Ethylene (ET) is critical importance in the growth, development, and stress responses of plants. Plant hormonal stress responses have been extensively studied, however, the role of ET in plant growth, especially plant height (PH) remains unclear. Understanding the genetic control for PH in response to ET will provide insights into the regulation of maize development. To clarify the genetic basis of PH-related traits of maize in response to ET, we mapped QTLs for PH, ear height (EH), and internode length above the uppermost ear (ILAU) in two recombinant inbred line (RIL) populations of Zea mays after ET treatment and in an untreated control (CK) group. Sixty QTLs for the three traits were identified. Twenty-two QTLs were simultaneously detected under both ET treatment and untreated control, and five QTLs were detected at two geographic locations under ET treatment only. Individual QTL can be explained 3.87–17.71% of the phenotypic variance. One QTL (q2PH9-1, q1PH9, q1EH9/q1ILAU9-1, q2ILAU9, and q2EH9) for the measured traits (PH, EH, ILAU) was consistent across both populations. Two QTLs (q2PH2-5, q2ILAU2-2, q1PH2-2, and q1ILAU2-2; q1PH8-1, q1EH8-1, q2PH8-1) were identified for up to two traits in both locations and populations under both ET treatment and untreated control. These consistent and stable regions are important QTLs of potential hot spots for PH, ear height (EH), and internode length above the uppermost ear (ILAU) response to ET in maize; therefore, QTL fine-mapping and putative candidate genes validation should enable the cloning of PH, EH, and ILAU related genes to ET response. These results will be valuable for further fine-mapping and quantitative trait nucleotides (QTNs) determination, and elucidate the underlying molecular mechanisms of ET responses in maize.
Highlights
The gaseous endogenous plant hormone ethylene (ET) is important for plant growth and development [1,2,3]
The objectives of this study were: (1) to determine QTLs of additional genome regions of traits relating to plant height (PH), ear height (EH), and internode length above the uppermost ear (ILAU) under ET treatment conditions; (2) to estimate their differences in QTLs detected under both ET treatment and untreated control; and (3) to characterize and analyze the QTLs and candidate gene and compare the differences between the two recombinant inbred line (RIL) population associated with ET response
Using the population KUI3×B77 and parent B77 as examples, the average effect of ET treatment on the population was a decrease in PH from 170.16 to 150.52 cm, EH from 71.53 to 54.95 cm, and ILAU from 98.59 to 95.71 cm (P < 0.01)
Summary
The gaseous endogenous plant hormone ethylene (ET) is important for plant growth and development [1,2,3]. Plant height in response to ethylene by mapping in maize hormone, due to the role it plays in accelerating such processes as abscission, senescence, and ripening [6,7,8]. Components of the ET signal transduction pathway in Arabidopsis have been identified through genetic approaches. The basic model of ET signal transduction works as follows: ET receptors (ETR1, ERS1, ETR2, ERS2 and EIN4) and receptors activating CTR1 in the absence of ET keeps downstream signaling components EIN2 and EIN3 inactive. Upon binding ET, the receptors no longer activate CTR1, while EIN2 activates the EIN3/EIL transcription factors, inducing a transcriptional cascade and the establishment of ET responses [3, 9, 10]
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